The Most Powerful Natural Antioxidant Discovered to Date

Cycling of Antioxidants

Because free radical scavenging anti-oxidants are of great interest to us, we now look at how they participate in re-dox reactions, focusing attention on vitamin E as an example. Vitamin E is a fat-soluble antioxidant that protects fatty acids, such as those in the plasma membrane, from oxidation. To prevent the electrons of fatty acids from being lost to an oxidant or to replace them after they are lost, vitamin E sacrifices its electrons. This creates a vitamin E molecule that is now itself a free radical (i.e., it is missing an electron). Other antioxidants, commonly vitamin C, sacrifice an electron to the vitamin E radical, thus becoming free radicals themselves but regenerating vitamin E so that it can act again as an antioxidant. In a chain reaction of electron transport, the unbalance in electrons that started with the invading free radical moved first to vitamin E, then to vitamin C, and finally to NADH, the fundamental electron source within cells.3 The electrons for NADH are...

Sources of Free Radicals

Many of the free radicals we are concerned with are grouped under the term reactive oxygen species (ROS). As discussed in Chapter 2, these are either free radicals themselves (for example, the hydroxyl radical) or easily converted into free radicals (molecular oxygen and hydrogen peroxide). The primary source of ROS in a cell is molecular oxygen (O2), which is converted to free radicals or other ROS during cell respiration, immune activity, and redox reactions with trace metals. ROS can also be introduced from sources outside the body, such Immune cells like macrophages destroy invading pathogens and cancer cells by spitting out noxious chemicals. These chemicals include ROS such as the superoxide radical (O2* ), which is easily converted to the more damaging hydroxyl radical (OH *). (The dot signifies a free radical.) In addition, macrophages produce nitric oxide (NO *), a free radical based on nitrogen rather than oxygen. Thus the environment surrounding an activated macrophage is...

Antioxidants in Nuts and Seeds

Antioxidant Defense 56 Antioxidants 57 Dietary Compounds with the Ability to Directly Scavenge or Neutralize Reactive Oxidants 57 Measurements of Total Antioxidant Contents in Foods Methodological Total Amounts of Antioxidants Total Amounts of Antioxidants in Nuts and Seeds 60 Potential Health Effects of Dietary Antioxidants 63 Summary Points 63 References 64 TEAC, the acid equivalent antioxidant capacity

Measurements Of Total Antioxidant Contents In Foods Methodological Considerations

Several assays have been used to assess the total antioxidant content of foods. The acid (Trolox) equivalent antioxidant capacity (TEAC) assay (Miller & Rice-Evans, 1996), the ferric reducing ability of plasma (FRAP) assay (Benzie & Strain, 1996), and the oxygen radical absorbance capacity (ORAC) assay (DeLange & Glazer, 1989) are among the methods most often used. Different chemical reaction mechanisms are involved in the various assays. The assays can mainly be divided into two groups inhibition assays and reduction assays. The inhibition assays are based on antioxidants' ability to react with or neutralize free radicals generated in the assay system (e.g., ORAC, TEAC), while the reduction assays are based on the ability of antioxidants to reduce an oxidant which also functions as a probe that changes color when it is reduced (e.g., FRAP). Based on careful considerations (Blomhoff, 2005), we chose to use a modified version of the FRAP assay by for total antioxidant analysis...

Antioxidants and Nutritional Support

The second category in Table 12.1 is compounds that are antioxidants or provide nutritional support. All cells need proper nutrition to function optimally, and immune cells are no exception. Although these require a variety of micro- and macronutrients, we focus here on a select few nutrients that have been extensively studied. In particular, several antioxidant vitamins appear to support immune function when their levels are low, immune function can be hampered. Animal and human studies have reported that vitamins C and E support immune function through a number of mechanisms. For example, immune cells produce various noxious compounds, including reactive oxygen species (ROS) and reactive nitrogen species antioxidants may help protect immune Antioxidants may also support immune function via their effects on intracellular glutathione levels. Glu-tathione plays an important role in immune function for three reasons. First, as a primary intracellular antioxidant, adequate glutathione is...

Theory on Antioxidant Effects

Data and goes beyond the simplistic argument of whether antioxidants are good or bad. Instead, we focus attention on how different conditions within various patients might alter the effects of antioxidants on cancer cell proliferation. The conclusions from this theory were summarized in Chapter 2, where we stated that depending on the circumstances, antioxidants used alone could produce beneficial, detrimental, or insignificant effects in cancer patients. When used in combination with other anticancer compounds (i.e., natural compounds or chemotherapy drugs), however, their effects are more likely to be beneficial, or at least not harmful. Lastly, we concluded that even when beneficial, the effects will probably be mild for many patients. For these reasons, we see anti-oxidants as supportive agents, best used in larger combinations of cancer-inhibiting compounds. The graphs presented here pull together our knowledge about the relationship between changes in oxidative stress and...

Effects of Antioxidants on Metastasis

There are concerns that antioxidants may facilitate metastasis. That they may have this effect in some situations should not be surprising, given the above discussions. In one of the few animal studies that tested combined antioxidants, metastasis increased.192 In this study, high and very high doses of antioxidants were given in drinking water to rats with established, carcinogen-induced tumors. The high doses were about 2.4 grams of vitamin C and 1,200 I.U. of vitamin E per day (as scaled to humans). The very high doses were 10fold greater. Both groups received selenium (at 2 mg kg) and a thiol antioxidant compound (2-MPG, at 15 mg kg). The high-dose therapy was not effective in increasing life span nor was tumor size greater, but secondary metastases increased. Life span was increased 1.4fold in the very high dose group, but again secondary metastases increased equal to the high-dose group. The results suggest the antioxidants may have protected me-tastasizing cells from apoptosis....

The Antioxidant Responsive Element A Site for Nrf2 Transcription Factor Binding

As mentioned above, common to several phase II detoxification enzymes is their transcriptional regulation by a conserved element located in the promoter region designated as antioxidant responsive element (ARE). This cis-acting regulatory element has been identified in the 5' flanking region of GST Ya and NQO1 genes in mammals and may also be present in other phase II enzymes. The ARE shows sequence similarity to activator protein (AP-1), and has been demonstrated to be a binding site for c-Jun, jun-B, jun-D, Fra1, and c-fos. More recent investigations have also identified a small basic leucine zipper protein (bZIP), designated Nrf-2, that can interact with the ARE, and is the prime candidate for mediating the induction of detoxification gene expression (Fig. 4). The important role of Nrf2 has been demonstrated by the work of Bloom et al. Using site-directed mutagenesis in the DNA-binding region of Nrf2, Bloom and colleagues demonstrated a decreases in Nrf2's ability to interact with...

Equivocal Effects of Antioxidants

As mentioned earlier, the flavonoids of chrysanthemum are strong antiox-idants and they may play a role in reducing the redox level in the cell. Their antioxidant effects may be also closely related to other chemopreventive properties such as anticarcinogenesis and antimutagenesis. On the other hand, recent studies revealed that flavonoids could also act as a pro-oxidant under some specific circumstances. For example, kaempferol induces significant concentration-dependent nuclear DNA degradation concurrent with lipid peroxidation. These effects were enhanced by iron(III) or copper(II) (129). Either nitric oxide or flavonoid alone does not induce strand breakage significantly in plasmid pBR322, but nitric oxide, when combined with flavonoids, significantly induces DNA single-strand breakage (130). The antioxidant and pro-oxidant behavior of flavonoids is related to their structures. In general, the more hydroxyl substitutions, the stronger the antioxidant and pro-oxidant activities....

Free Radicals And Antioxidants

Free radicals are highly reactive transient chemical species characterized by the presence of unpaired electrons usually denoted by a point suffix (*). They are involved in a variety of metabolic and pathophysiological processes including both beneficial and detrimental reactions. They can be produced as by-products of normal metabolism, for example, in the mitochondrial electron transport system 15 , In biological systems, free radicals may be typically centered on oxygen, nitrogen, carbon or sulfur atoms. Biologically important free (Table 12.1). Hydrogen peroxide (H202) is an oxidizing species and potential source of free radicals, but is not are therefore conveniently classed as reactive oxygen species (ROS). In general, free radicals are continuously Cells are protected from free radical induced damage by a variety of free radical scavenging antioxidants. Antioxidants enzymes, which are capable of eliminating free radical species that cause tissue damage, include catalase,...

Alcoholic Liver Disease Role Of Free Radicals

A substantial body of evidence exists to support the contention that ROS generated during ethanol metabolism may be involved in the pathogenesis of alcoholic liver disease (ALD). Decades ago, it was already emphasized by Lieber that the induction of cytochrome P450 is a critical event with respect to the development of ALD 85 , If free radical production and lipid peroxidation play a role in the development of ALD, depletion of dietary antioxidants such as vitamin E or an increase in oxidants such as non-heme iron in the liver, should enhance the ethanol induced liver damage. Indeed, a diet deficient in vitamin E has been shown to reduce hepatic vitamin E stores, increase lipid peroxidation and increase serum transaminase activities after alcohol feeding in rats 86 , Furthermore, iron supplementation in the diet increases ethanol-induced serum transaminase activities, lipid peroxidation and fibrosis 41 , In addition, a significant correlation between hepatic lipid peroxidation,...

Characterization Of Antioxidant Constituents From Licorice Roots

Licorice root contains flavonoids with biological activities, several of which were isolated and purified. Licochalcone B and D, isolated from the roots of Glycyrrhiza inflata, were shown to inhibit superoxide anion production in the xantine xantine oxidase system (79), and to have free-radical-scavenging activity toward the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical. These phenolic compounds were also shown to be effective in protecting biological systems against various oxidative processes. They inhibit mitochondrial lipid peroxidation induced by Fe(III)-ADP NADH, scavenge superoxide anions in microsomes, and protect red blood cells against oxidative hemolysis (79). Other antioxidant constituents that were isolated from licorice were identified as the isoflavans glabridin, hispaglabridin A, hispaglabridin B, 4-O-methyl glabridin, and two chalcones isoprenylchalcone and isoquitirigenin (80). Among these compounds, glabridin was the major flavonoid in the licorice root extract (5 g...

Impact Of Barley Variety Baking Procedure And Storage On The Antioxidant Properties Of Breads With Added Barley Flours

The phenolics occurring in barley impact bread quality, but the baking process itself will also affect the total amount of phenolics found in the finished product as well as the overall antioxidant properties of the breads. Barley and wheat have different phenolic profiles. This is also valid among barley varieties. Thus, the antioxidant properties of different flour mixtures and the resulting barley breads vary according to the different barley flours incorporated in the bread formula (Figure 32.3) (Holtekj0len, Bsvre, et al, 2008). As seen in the figure, the barley wheat flour mixtures contain a higher total amount of phenolics (S-P determined by the Folin Ciocalteu assay) than the whole grain wheat mixture, except for barley variety 3. Pearling affects the amount of phenolics found in the resulting flours, and a higher extraction rate increases the amount of phenolics. However, despite the lower extraction rate of the barley flours tested, compared to the whole wheat (100...

Antioxidant Properties Of Inositol Phosphates In Vitro

Phytate is a very stable and potent chelating agent that exhibits the ability to complex a variety of divalent and trivalent ions. At physiological pH, InsP6 forms complexes with Cu2+, Zn2+, Co2+, Mn2+, Fe2+, and Ca2+ 3 . Because phytate binds essential minerals and can prevent their absorption, most human nutritionists view the compound negatively. However, its unique chelating action with iron provides phytate with antioxidant characteristics. In the iron-assisted Haber-Weiss reaction, the formation of OH requires the availability of at least one reactive iron coordination site, as well as iron solubility. Evidence that all six phosphates on myoinositol are not required for the inhibition of hydroxyl radical formation was presented by Hawkins et al. 6 . They showed that Ins(1,2,3,4,6)P5 and DL-Ins(1,2,3,4,5)P5 were effective at inhibiting hydroxyl radical formation to a greater degree than Ins(1,3,4,5,6)P5 and DL-Ins(1,2,4,5,6)P5 and concluded that the 1,2,3-trisphosphate grouping...

Antioxidant Properties Of Inositol Phosphates In Vivo

A question that remains is whether this antioxidant property of phytate might function in vivo, and whether it mediates the potential disease-sparing characteristics of phytate that have been observed in cancer studies 10 . To test this hypothesis, researchers have used cells in culture or animal models and measured the ability of phytate to attenuate the oxidative stress induced by various means. To date, the literature on this question is equivocal, with some studies indicating that InsP6 provides some antioxidant protection, whereas other studies have found no effect or a pro-oxidant effect. It is important to recognize that oxidative stress protection in biological systems is a complex and multifaceted process 11,12 , thus the ability of phytate to contribute as an antioxidant in vivo may only be evident under conditions in which stress is invoked. In contrast to the previously discussed studies in which some evidence of antioxidant function in vivo was presented, other studies...

Phytate As An Antioxidant In Chicken And Beef

Graf and coworkers 2,12 were the first to evaluate phytate as an antioxidant in a meat system. In cooked, minced chicken breast muscle +10 added water, phytic acid (1.5 mM, pH 6.0) was highly effective in reducing thiobarbituric acid (TBA) values (Figure 12.1) and warmed-over flavor (WOF) intensity (Figure 12.2), compared to controls 12 . Phytic acid (2 mM) was more effective than other antioxidants (2 mM ascorbic acid, BHT, or EDTA) for lowering TBA values in fresh beef homogenates incubated for 60 min at 37 C 13 .

Combined Antioxidant Vitamins

A small number of in-vitro studies have reported that combinations of antioxidant vitamins (for example, vitamin C, VES, ATRA, and beta-carotene) used in conjunction with chemotherapy drugs produced a greater cytotoxic effect against cancer cells than the chemotherapy drugs alone. For example, these four vitamins in Lastly, at least two human studies have been conducted. In a nonrandomized uncontrolled study, oral administration of vitamin A (at 15,000 to 40,000 I.U., as retinyl palmitate), vitamin C (at 2 to 5 grams), vitamin E (at 300 to 800 I.U.), along with other vitamins and minerals, appeared to increase the mean survival time of patients with small-cell lung cancer treated with combination chemotherapy and radiotherapy. The two-year survival was 33 percent, compared with about 15 percent from historical data.191 The second study was a prospective, randomized, double-blind, and placebo-controlled study on 26 patients receiving radiotherapy or chemotherapy that investigated the...

Antioxidant Properties Of Wild Rice In Cooked Meat Products

A cheaper alternative to phytate is the addition of high-phytate grains to cooked ground meats. Textured soy proteins (TSP) or textured vegetable proteins (TVP) are economical extenders of ground beef patties 31 . Lower thio-barbituric acid (TBA) values were reported for ground beef patties extended with TSP 32 , indicating possible antioxidant effects during storage. Addis and coworkers 3,33-35 at the University of Minnesota demonstrated the feasibility and acceptability of wild rice addition to ground beef patties and pork sausage 36 . In addition to a lowering ofTBA values with the addition of wild rice (Table 12.5), panel evaluations indicated an actual preference for beef patties with 15 or 30 cooked wild rice, compared to all beef controls 33 . Whole-grain wild rice was a more effective antioxidant in ground beef patties than ground wild rice 3 . The antioxidant properties of wild rice kernels were due to the presence of phytic acid 34 , as indicated by the identical HPLC...

Why is the disarming of free radicals so important in cancer prevention

It is important to disarm free radicals because they can damage double bonds in phospholipids of cell walls and of DNA, altering cell permeability and causing genetic mutation affecting cell behaviour (including abnormal growth patterns such as proliferation of undifferentiated cells). Damaged mitochondrial membranes (the energy power-houses inside every cell) reduce the ability of cells to utilise oxygen. The vitamins C, E and A (beta carotene) have an anti-oxidant effect, disarming free radicals. They work closely with the important anti-oxidant enzymes Superoxide Dismutase (SOD) containing zinc, manganese and copper, and Glutathione Peroxidase (GP) containing the mineral selenium.

Antioxidants CellSupporting Agents

A number of theories as to what causes PD at the cellular level include oxidative stress and free radical formation, mitochondrial impairment, intracellular protein clumping, inflammation, apoptosis (programmed cell death), and excitotoxicity (5). Many of the prescribed supplements, minerals, and vitamins by alternative practitioners are based upon these theories and the belief or hope that cellular function will be restored and or future brain cell injury prevented with their use. Currently, there is little if any scientific study to support the use of most of these supplements in the treatment of PD and it is critical to acknowledge that their use specifically for the treatment of PD is based upon theory only and not upon evidence-based clinical research. Despite the lack of research supporting their use for PD, some of these, in particular, the antioxidants that control potentially damaging free radicals or support mitochondrial function may hold the greatest promise for finding a...

Impact Of Wheat Sprouts On Antioxidant Status Of Human Plasma

Grains are thought to be particularly rich sources of phenolic acids, which are located in the bran layer. The most abundant phenolic compounds in cereals belong to the chemical class of hydroxycinnamic acids. The main phenolic compound is ferulic acid, followed by diferulic acids and sinapic acid, p-coumaric acid, and caffeic acid. Germination of grains leads to an increase of these phenolic compounds by up to 150 (Koehler et al, 2007 Liukkonen et al, 2003). In our study, we demonstrated that the content of phenolic compounds increased by 40 after 4 days of germination (Andersen et al, 2008). It is well-known that free hydroxycinnamic acids are effective antioxidants. However, approximately 95 of grain phenolic compounds are covalently linked to cell wall polysaccharides. Ferulic acid is bound to the arabinoxylans via an ester bond with the primary hydroxyl group at the C5 position of a-l-arabinofuranosyl residues. However, the antioxidant capacity of these bound phenolic compounds...

Antioxidant Properties

Purple wheat flour bread (PWB) and two bread controls, whole wheat meal bread (WWB) and white flour bread (WFB), were prepared according to the method described by Gelinas and McKinnon (2006), and their antioxidant properties were evaluated. Their 2,2-diphenyl-1-picryhydrazyl free radical (DPPH ) scavenging activity and kinetics are shown in Table 6.1 and Figure 6.1, respectively. Purple wheat bread PWB had the highest DPPH scavenging activity (47.58 ) at 60 min compared to wholemeal bread WWB (34.06 ) and white bread WFB (32.20 ). The DPPH* scavenging activity from kinetics curve was also in the order PWB WWB WFB (see Figure 6.1). The DPPH* scavenging activity of whole meal in several wheat genotypes was 33.51 for black-grained wheat, 25.57 for purple-grained wheat, 23.66 for blue-grained wheat, and 25.40 for white-grained wheat (Li et al., 2005). The oxygen radical absorbance capacity (ORAC) of three bread extracts decreased in the same order PWB (12.09 g kg) WWB (10.64 g kg) WFB...

Total Amounts Of Antioxidants In Nuts And Seeds

Our analyses (Table 6.2) demonstrate that walnuts contain massive amounts of antioxidants about 20 mmol antioxidants per 100 g. Pecans, chestnuts, peanuts, pistachios, and sunflower TABLE 6.2 Antioxidants in Nuts and Seeds TABLE 6.2 Antioxidants in Nuts and Seeds Antioxidant Content (mmol 100 g) TABLE 6.2 Antioxidants in Nuts and Seeds continued Antioxidant Content TABLE 6.2 Antioxidants in Nuts and Seeds continued TABLE 6.2 Antioxidants in Nuts and Seeds continued Procured in Antioxidant Content (mmol 100 g) seeds are also very rich in total antioxidants, with about 8, 5, 1, 1 and 6 mmol 100 g, respectively. Hazelnuts, almonds, Brazil nuts, macadamias, pine kernels, cashew nuts, flax seeds, poppy seeds, and sesame seeds also contain significant amounts of total antioxidants (about 0.5 1.0 mmol 100 g). Peanut butter, a common form of nut consumption, contains only about 50 of the total antioxidants of peanuts though not in the top ranks of antiox-idant-containing foods, it is still an...

Biochemical Mechanisms Of Action A Detoxification Antioxidant Actions

In Vitro Antioxidant Activities Lignans isolated from FS were found to possess antioxidant properties (74,75). Their inhibitory effect on lipid peroxidation reaction has been extensively investigated in a number of in vitro assay systems using micro-somes and mitochondria prepared from brain, liver, and kidney cells tissues as the lipid source (76-81). In all cases, the lignans, including Sch B and Gom A, were found to be more potent than a-tocopherol or its analogues, in the inhibition of lipid peroxidation. Using electron spin resonance measurement, lignans with different structures and configurations were investigated for scavenging activity on reactive oxy-radicals generated from human polymor-phonuclear leukocytes stimulated by phorbol myristate acetate (82). The free-radical-scavenging activity was found to be dependent on the stereo-configurations of the lignans, in that S(-) Sch B produced a stronger effect than that of R( + ) Sch B. Interestingly, the scavenging effect of S,R...

Antioxidant Effects of Isoflavones Flavones Flavonols and other Phenols

Phenolic compounds, including isoflavones, flavones, and flavonols, can act as antioxidants due to the hydrogen-donating capacity of their phenolic groups and, in some cases, their metal-chelating potential. The latter may block the generation of copper- and iron-induced free radicals. Table 19.1 ranks various phenolics and other antioxidants in comparison to vitamin C in their ability to scavenge aqueous free radicals in vitro. As seen, most flavonoids are more active than vitamins C and E. Some phenolic compounds that normally act as anti-oxidants can also act as prooxidants under the right circumstances (see Chapter 15). For example, some in-vitro conditions are adequate to auto-oxidize quercetin, and the prooxidant effect produced may account for some of quercetin's ability to cause gene mutations in vitro. In one study that tested 55 flavonoids, quercetin was the most mutagenic.74 Other flavonoids in Table 19.1 do not appear to auto-oxidize as readily or tend to be mutagenic in...

Prostate Cancer Inflammation and Antioxidants

This review focuses on the mechanisms of free radical formation and ROS signalling in prostate cancer on the basis of current literature. We also highlight the mechanisms by which inflammatory processes contribute to prostatic carcinogenesis and how antioxidants react to neutralize free radicals. Living cells have three main systems for protection and repair under oxidative stress (1) direct antioxidant enzymes (Superoxide dismutase (SOD), catalase, peroxidises), (2) proteases and phospholipases activated by oxidative modification of membranes, (3) lipid and water soluble antioxidants (Sies, 1997 Finkel and Holbrook, 2000). Normalization of malignant gene transcription in an organ requires dietary correction of the etiologic long-standing metabolic deficiency involving six or more inter-linked natural factors aided by hormonal equilibrium, enhanced by specific autologous immunotherapy. In bio-immunotherapy this therapeutic bio-modulation is aims to simulate specific leukaemia,...

Role Of Acetaldehydeprotein Adducts And Free Radicals

The increase in malondialdehyde-acetaldehyde protein adducts supports previous suggestions that alcohol induces cardiac lipid peroxidation 83,84 concomitant with endogenous cardiac-derived acetaldehyde formation, possibly via alcohol dehydrogenase (ADH) or cytochrome P450 actions. However, although the activity of cardiac alcohol dehydrogenase is low, catalase may also generate acetaldehyde 85-88 , The importance of these studies relates to the observation that malondialdehyde-acetaldehyde adducts are cytotoxic, inducing the release ofTNF-alpha and up-regulating ICAM-1 in endothelial cells in vitro 89 , Reactive oxygen free radical species may play a prominent role in alcohol-induced heart muscle damage. Cardiac tissue from chronic alcohol misusers shows increased 'agepigments indicative of damage by reactive oxygen species 90 , Involvement of reactive oxygen species damage is also implicated by studies showing that in alcohol-fed rats, the resulting shift in fatty acid profile is...

Sms Modulates Cellular Antioxidant Potential Through Induction Of

GPX is an enzyme participating in the capture of H2O2 and hydroperoxides produced in the cell. Therefore, the change in the activity reflects more or less overall tissue damage or cellular potential of antioxidant defense. Thus the preventive effect of SMS on GPX activity loss was further studied by the immunohistchemical method in culture cells using anti-GPX monoclonal antibody conjugated with FITC fluoroprobe. As shown in Figure 4, GPX activity was significantly induced by incubating cells with SMS prior to H2O2 stress, although H2O2 also induced GPX, as was reported elsewhere (13). This SMS-dependent enhancement of GPX activity was also confirmed by RT-

Dietary Antioxidants and Human Health

Partes Del Cuerpo Humano

Plants produce a very impressive array of antioxi-dant compounds, including carotenoids, flavonoids, cinnamic acids, benzoic acids, folic acid, ascorbic acid, tocopherols, and tocotrienols, and plant-based foods are our major source of dietary antioxidants. Antioxidant compounds are concentrated in the oxidation-prone sites of the plant, such as the oxygen-producing chloroplast and the PUFA-rich seeds and oils. Plants make antioxidants to protect their own structures from oxidant stress, and plants increase antioxidant synthesis at times of additional need and when environmental conditions are particularly harsh. Humans also can upregulate the synthesis of endogenous antioxidants, but this facility is very limited. For example, production of the antioxidant enzyme SOD is increased with regular exercise, presumably as an adaptation to the increased ROS load resulting from higher oxygen use. However, an increase in other endogenous antioxidants, such as bilirubin and uric acid, is...

Non Nutrient Antioxidants

Plant-based foods contain a multitude of antioxi-dants other than vitamin C and vitamin E. The two major classes of these other dietary-derived antioxidants are the carotenoids and the polypheno-lic flavonoids. There are hundreds of different car-otenoids and thousands of flavonoids, and these compounds give fruits, vegetables, teas, and herbs their wonderful colors in shades of red, orange, yellow, and purple. These compounds are synthesized exclusively in plants and have no known function in human metabolism. No deficiency state for either class of compounds has been identified in humans. Consequently, there is no recommended daily intake or agreed requirement for any of these compounds, and they are regarded as 'non-nutrients.' Nonetheless, there is evidence that diets rich in carotenoids and flavonoids are beneficial to health. For example, in a study of 1299 elderly people in the USA, those with diets rich in carote-noid-containing fruits and vegetables were found to have a...

Antioxidants Found Within the Human Body

Lipoprotein Mitochrodria Ros

The structures of the human body are exposed continuously to a variety of ROS. Humans have evolved an effective antioxidant system to defend against these damaging agents. Different sites of the body contain different antioxidants or contain the same antioxidants but in different amounts. Differences are likely to reflect the different requirements and characteristics of these sites. Human plasma and other biological fluids are generally rich in scavenging and chain-breaking antioxidants, including vitamin C (ascorbic acid) and 'vitamin E.' Vitamin E is the name given to a group of eight lipid-soluble tocopherols and toco-trienols. In the human diet, 7-tocopherol is the main form of vitamin E, but the predominant form in human plasma is a-tocopherol. Bilirubin, uric acid, glutathione, flavonoids, and carotenoids also have antioxidant activity and are found in cells and or plasma. Scavenging and chain-breaking anti-oxidants found in vivo are derived overall from both endogenous and...

Antioxidant Functions of Vitamin E

Vitamin E functions as a lipid antioxidant both in vitro and in vivo a number of synthetic antioxidants will prevent or cure most of the signs of vitamin E deficiency in experimental animals. Polyunsaturated fatty acids undergo oxidative attack by hydroxyl radicals and superoxide to yield alkylperoxyl (alkyl-dioxyl) radicals, which perpetuate a chain reaction in the lipid-withpotentially disastrous consequences for cells. Similar oxidative radical damage can occur to proteins (especially in a lipid environment) and nucleic acids. Vitamin E is one of the most active radical-trapping, chain-breaking antioxidant phenols that has been investigated, and is the major lipid-soluble antioxidant in tissues (Burton and Ingold, 1984). As shown in Figure 4.4, the a- and -tocopheroxyl radicals have three resonance forms compared with two for the y - and S-radicals, and are therefore more stable and have a greater antioxidant activity. In simple solution, a-tocopherol and a-tocotrienol are...

Antioxidant Activity of RSVPotential Cardioprotective Effect

Excessive accumulation of ROI is kept in check by the cellular antioxidant defense mechanism comprised of a number of intracellular enzymes, such as glutathione (GSH), superoxide dismutase (SOD), and catalase (Halliwell and Gutteridge, 1999). A defect in the cells' inherent ability to counteract the production of ROI results in their abnormal accumulation, a state commonly referred to as'' oxidative stress.'' Exposure of cellular macro-molecules (lipids, proteins, and nuclei acids) to ROI results in their oxidative modifications with deleterious potential (Packer, 1992). A classic example of this is the oxidative modification of low-density lipoproteins (LDL) (Esterbauer et al., 1992), the so-called ''bad'' cholesterol implicated in atherosclerosis and increased incidence of coronary artery disease. Generated by lipolytic remodeling of VLDL, normal circulating LDL is endocytosed via the specific LDL receptor. While the endocytosis of normal LDL is tightly regulated, oxidized...

The Observational View of Dietary Antioxidants

Cancer and cardiovascular disease (CVD) are the two leading causes of death worldwide, diabetes mellitus is reaching epidemic proportions, and dementia and maculopathy are largely untreatable irreversible disorders that are increasingly common in our aging population. The prevalence and standardized mortality rates of these diseases vary considerably between and within populations. Mortality from CVD varies more than 10-fold amongst different populations, and incidences of specific cancers vary 20-fold or more across the globe. This enormous variation highlights the multiple factors at play in the etiology of chronic age-related diseases. These factors include smoking habit, socioeconomic status, exposure to infectious agents, cholesterol levels, certain genetic factors, and diet. Dietary factors have long been known to play an important role in determining disease risk. Indeed, 30-40 of overall cancer risk is reported to be diet-related, and there is a wealth of compelling...

Antioxidant Composition Of Fruits Of O Fcus Indica

Organic extracts in dichloromethane (DCM) and aqueous extracts in methanol of the yellow, red, and white fruits from Sicilian cultivars of O. ficus indica have been analyzed for lipid-soluble and water-soluble antioxidants, respectively (54). Very limited amounts of lipophilic antioxidant vitamins have been found, a-tocopherol, trans- h-Carotene, and retinyl palmitate representing the major compounds, with minor variations among the cultivars. Retinyl oleate and trans-retinol are absent. In contrast, all cultivars are a good source of vitamin C (Table 1). Negligible amounts of flavonols (237 20 ng 100 g fruit pulp) have been found in the aqueous extracts from the red fruit only (9). TABLE 1 Major Antioxidant Vitamins in Prickly Pear Fruit from Yellow, Red, and White Cultivars TABLE 1 Major Antioxidant Vitamins in Prickly Pear Fruit from Yellow, Red, and White Cultivars

Antioxidant Properties in Food and Biological Systems

During storage of prepared or dehydrated food, lipid autoxidative degradation products such as hydroperoxides, malondialdehydes, aldehydes, ketones, and hydroxy fatty acids may occur if the food is not properly protected by antioxidants. These products not only result in unpleasant flavors but may also be a health risk (25). Lipid oxidation is an autocatalyzed radical chain reaction induced by free radicals (26). Polyphenolic antioxidants possess a relatively reactive phenolic hydrogen atom, which functions as a donor, allowing formation of the antioxidant phenoxyl radical. Various extracts have been shown to act as effective antioxidants in food systems such as stabilization of animal fats and vegetable oils as well as wheat, rice, oat or potato flakes, frozen ground pork patties, and dehydrated chicken meat (2732). Extracts of rosemary containing the polyphenolic antioxidants, or preparations of the essential oil, show potent antimicrobial properties, inhibiting the growth and...

Dietary Recommendations for Increased Antioxidant Defense

Dietary recommendations that would result in increased antioxidant defense are not inconsistent with accepted recommendations for healthy eating. The recommendation to increase the consumption of plant-based foods and beverages is one that is widely perceived as health promoting, and the consistent and strong epidemiological links between high fruit and vegetable intake and the greater life expectancy seen in various groups worldwide whose diet is high in plant-based foods indicate that more emphasis should be given to this particular dietary recommendation. Vitamin C, vitamin E, various carotenoids, flavonoids, isoflavonoids, phenolic acids, organosul-fur compounds, folic acid, copper, zinc, and selenium are all important for antioxidant defense, and these are found in plant-based foods and beverages such as fruits, vegetables, nuts, seeds, teas, herbs, and wines. Dietary strategies for health promotion should be directed towards optimizing the consumption of these items. people in...

Potential Health Effects Of Dietary Antioxidants

The highly reactive and bioactive phytochemical antioxidants are postulated to in part explain the protective effect of plant foods. An optimal mixture of different antioxidants with complementary mechanisms of action and different redox potentials is postulated to work in synergistic interactions. Still, it is not likely that all antioxidant-rich food items are good sources, or that all antioxidants provided in the diet are bioactive. Bioavailability differs greatly from one phytochemical to another, so the most antioxidant-rich food items in our diet are not necessarily those leading to the highest concentrations of active metabolites in target tissues. The antioxidants obtained from foods include many different molecular compounds and families with different chemical and biological properties that may affect absorption, transport, and excretion, cellular uptake and metabolism, and, eventually, their effects on oxidative stress in various cellular compartments. Biochemically active...

Dietary Compounds With The Ability To Induce Production Of Endogenous Antioxidants

An important antioxidant defense mechanism involves detoxification enzymes such as members of the glutathione S-transferase family, g-glutamyl cysteine synthetase, and NAD(P) H quinone reductase (quinone reductase) (Talalay 2000). These enzymes are generally referred to as phase 2 enzymes because they catalyze conversion of xenobiotics, mutagenic if benign or non-damaging plant compounds induce the phase 2 enzymes, cells are more readily able to neutralize toxic agents such as free radicals and other toxic electrophiles when they appear. The major plant compounds believed to be able to support the antioxidant defense via this mechanism includes the glucosinolates and several other sulfur-containing plant compounds. Glucosinolates are widespread plant constituents, and it is believed that glucosinolate breakdown products (such as the isothiocyanate sulforaphane) induce phase 2 enzymes and are therefore responsible for the protective effects shown by Brassica vegetables. Allium...

Tocopherols as Antioxidants

Cellular systems have evolved a powerful and complex antioxidant defence system to limit inappropriate exposure to these stressors. a-Tocopherol is quantitatively the most important chain-breaking antioxidant in plasma and biological membranes. The antioxidant activities of chain-breaking antioxi-dants are determined primarily by how rapidly they scavenge peroxyl radicals, thereby preventing the propagation of free radical reactions. When the chromanol phenolic group of a-tocopherol (TOH) encounters a ROO it forms hydroperoxide (ROOH), and in the process a tocopheroxyl radical (TO ) is formed The rate constant (k1) for hydrogen abstraction from a-tocopherol is 2.35 106M-1 s , which is higher than that for the other tocopherols and related phenols. Because the rate constant (k2) for the chain propagation reaction between ROO and an unsatu-rated fatty acid (RH) (ROO' + RH ROOH) is much lower than k1, at approximately 102 M-1 s-1 a-tocopherol outcompetes the propagation reaction and...

Changes in Antioxidant Capacity

Antioxidant capacity of the blood may be one indicator of a food's ability to act as an in vivo antiox-idant. Two commonly used measures of overall antioxidant capacity are the ORAC assay (oxygen radical absorbance capacity) and the FRAP assay (ferric reducing ability of plasma). Dietary interventions do alter the antioxidant capacity of blood. For example, individuals consuming a high cocoa and chocolate diet for 2 weeks have higher serum ORAC than when they consume a control diet. However, these results are not always consistent. For example, in individuals consuming pro-cyanidins in similar amounts of cocoa powder and chocolate, there is no change in plasma ORAC after 6 or 12 weeks. Green tea consumption rapidly increases FRAP but the effect appears to be short-lived and is perhaps related to the short half-life of the antioxidant tea phytochemicals in plasma. Moreover, green tea appears to have a greater antioxidant capacity (FRAP) than black tea, and the consumption of black or...

Antioxidant Defense System

Although zinc is not itself an antioxidant, there are several ways in which it participates in the antiox-idant defense system of the body, with important implications for health. It can bind to thiol groups in proteins, making them less susceptible to oxidation. By displacing redox-reactive metals such as iron and copper from both proteins and lipids it can reduce the metal-induced formation of hydroxyl radicals and thus protect the macromolecules. Its role in inducing MT has already been mentioned, and this protein scavenges hydroxyl radicals. Increased oxidative stress results in the release of zinc from MT, presumably making it more available for other proteins. Copper zinc superoxide dismu-tase is an important zinc-containing antioxidant enzyme whose activity is impaired in the deficient state. In general, animal studies have revealed an association between zinc deficiency and increased oxidative stress. The likelihood of increased oxida-tive stress under conditions of zinc...

Antioxidant and Prooxidant Actions of Ascorbate

Chemically, ascorbate is a potent reducing agent, both reducing hydrogen peroxide and also acting as a radical trapping antioxidant, reacting with superoxide and a proton to yield hydrogen peroxide or with the hydroxy radical to yield water. In each case the product is monodehydroascorbate, which, as shown in Figure 1, undergoes dismutation to ascorbate and dehydroascorbate. In studies of ascor-bate depletion in men there is a significant increase in abnormalities of sperm DNA, suggesting that vitamin C may have a general, nonspecific radical-trapping antioxidant function. Ascorbate also acts to reduce the tocopheroxyl radical formed by oxidation of vitamin E in cell membranes and plasma lipoproteins. It thus has a vitamin E sparing antioxidant action, coupling lipo-philic and hydrophilic antioxidant reactions. The antioxidant efficiency of ascorbate is variable. From the chemistry involved, it would be expected that overall 2 mol of tocopheroxyl radical would be reduced per mole of...

Traditional Chinese Herbal Medicine As A Model Of Antioxidantbasedcompounds Formula

In this sense, traditional Chinese herbal medicine (TCM) is interesting because herbs have been used to treat many complex disorders such as diabete mellitus, cancer, and others for which Western medicine may not have an appropriate diagnostic name. TCM is usually prescribed with several herbal constituents having different functions and the synergistic action exhibited by the multicomponent formula is effective for the management of many complicated diseases (8). Moreover, their therapeutic strategy is modulation of the inherent potential to recover the distorted balance of the physical condition (disease condition) by either suppressing or stimulating physiological reactions with a multifunctional-compound formula comprising several herbal components. It is also known that free-radical or reactive oxygen species (ROS) are exclusively involved in the pathogenesis of such disorders for which the Chinese herbal medicines are effectively applied. Therefore, antioxidant TCM is an...

Pro and Antioxidant Roles of Ascorbate

Ascorbate can act as a radical-trapping antioxidant, reacting with superoxide and a proton to yield hydrogen peroxide, or with the hydroxy radical to yield water. In each case, the product is monodehydroascorbate. The antioxidant activity of ascorbate is variable. From consideration of the chemistry involved, itwouldbe expectedthat, overall, 2 moles ofperoxyl radical would be trapped per mole of ascorbate, because of the reaction of 2 moles of monodehydroascorbate to regenerate ascorbate and yield dehydroascorbate (see Figure 13.3). However, as the concentration of ascorbate increases, so the molar ratio decreases, and it is only at very low concentrations of ascorbate that it tends toward the theoretical 2 1. As well as its antioxidant role, ascorbate can be a source of hydroxyl and superoxide radicals. At high concentrations, it can reduce molecular oxygen to superoxide, being oxidized to monodehydroascorbate. At lower concentrations of ascorbate, both Fe3+ and Cu2+ ions are reduced...

Natural Compounds Antioxidant and Antiandrogens in the Prevention of Prostate Cancer In vivo Evidences from Murine

Mouse models have significantly contributed to our understanding of PCa biology through their identification of new cancer genes and biomarkers, and their illustration of the molecular and cellular mechanisms underlying tumor initiation and progression. They have also been employed in a preclinical setting to test novel preventive and or therapeutic strategies 5,6,8-12,80 . Mice, in fact, offer several advantages. They are small, relatively inexpensive, and reproduce rapidly with large litters. More importantly, technical advances have facilitated the generation of defined genetic modifications that can also be spatially controlled, to mimic human prostate carcinogenesis. In general, and perhaps not surprisingly, a variety of phenotypes are obtained depending on the specific genetically engineered mouse model, but none exactly mimics the human disease. Although preclinical studies and the epidemiological evidence suggest that specific dietary components or nutritional supplements...

Total Amounts Of Antioxidants In Foods

We have recently performed a systematic measurement of the total antioxidant content of more than 3100 foods. This novel antioxidant food table enables us to calculate the total antioxidant content of complex diets, to identify and rank potentially good sources of antioxidants, and to provide the research community with comparable data on the relative antioxidant capacity of a wide range of foods. There is not necessarily a direct relationship between the antioxidant content of a food sample consumed and the subsequent antioxidant activity in the target cell. Factors influencing the bioavailability of phytochemical antioxidants include the food matrix, absorption, and metabolism. Also, the methods measuring total antioxidant capacity do not identify single antioxidant compounds, and they are therefore of limited use when investigating the mechanisms involved. This is, however, not the scope of this initial study. With the present study, food samples with high antioxidant content are...

Antiinflammatory And Antioxidant Activity

Dandelion extract was shown to exhibit a mild analgesic and anti-inflammatory effect in mice (Tito et al 1993), and an aqueous dandelion extract was found to prevent diabetic complications due to lipid peroxidation and free radicals in diabetic rats (Cho et al 2002). Dandelion extract has also been found to have a protective effect against CCK octapeptide-induced acute pancreatitis in rats (Seo et al 2005) and dandelion flower extract demonstrated marked antioxidant activity that has been attributed to its phenolic content, with suppression of reactive oxygen species and nitric oxide (Hu & Kitts 2003, 2005, Kery et al 2004). Extracts of dandelion flowers, roots and stem have been found to have significant OH-radical scavenging activity (Kaurinovic et al

In Vitro and Ex Vivo Evidence of Antioxidant Properties of Polyphenols

Radicals and reactive oxygen species. In fact, in vitro, many polyphenols found in fruits and vegetables are better scavengers than the essential nutrient antioxidants. For example, compared to vitamin E and vitamin C, flavonols (quercetin, kaempferol, and rutin) are 1.3- to 4.7-fold more effective at scavenging free radicals. Flavan-3-ols and theaflavins are 2.5-6.9 times more effective than vitamin C and vitamin E at free radical quenching. Tea beverage has strong antioxidant properties, being 3.5-3.8 times more effective than vitamin C and vitamin E at free radical scavenging. Green tea is more effective than oolong tea, which is more effective than black tea. In comparison, carotenoids (lycopene, a-carotene, and -carotene) and xanthophylls ( 3-cryptoxanthin, zeaxanthin, and lutein) are 1.3- to 2.9-fold more effective at in vitro free radical scavenging. In addition to scavenging radicals and oxidants, tea polyphenols have also been demonstrated in vitro to be able to chelate...

Antioxidant and Biomarker Evidence from Intervention Studies in Humans

There are limited data from diet-controlled randomized crossover studies of humans on tea and other flavonoid-containing foods. Most intervention studies, apart from design considerations, suffer from lack of diet control, making them difficult to interpret. Results from intervention studies that employ dietary recalls, food records, and self-administered diets are notorious for introducing error that can mask treatment effects. Clinical studies in humans have focused on the antioxidant capacity of blood and oxidative damage to protein, lipid, and DNA as well as a number of risk factors associated with cardiovascular disease, including lipids, hemostasis, platelet aggregation, endothelial function, and blood pressure. Interventions have included high- and low-flavonoid diets, tea, chocolate, cocoa, wine, grape extracts, and fruit juices.

Antioxidant Potential Of Sms Determined In Vitro

We first examined the antioxidant property of SMS by five different antioxidant assays in vitro and the antioxidant activity was compared using Trolox as the reference antioxidant in each antioxidant assays. (Table 1). Interestingly, SMS was found to have extremely strong hydroxyl-radical-scavenging activity. This characteristic was emphasized when the antioxidant activity was compared with those determined for four typical TCM or Kampo (Japanese traditional herbal prescriptions) formulations that have been tested for post stroke treatment or dementia Cho-To-San, Zokumei-To, Ryou-Kei-Jutsu-Kan-To, and Keishi-Bukuryo-Gan + Yokuinin. All these prescriptions commonly had stronger scavenging activity toward superoxide radical than TABLE 1 Antioxidant Potential of SMS as Trolox Equivalent Determined by Several In Vitro Assay Systems Antioxidant assay Trolox equivalent (aM) Figure 1 Relative antioxidant activity of brain-directed TCM formulations. SMS, Shengmai San DTS, Cho-To-San LGSGT,...

Antioxidant Properties Of Ginger

A common mechanism offered to explain the actions and health benefits of ginger and other herbs and spices is related to their antioxidant properties (17,18). A systematic analysis (19) of several hundred dietary plants revealed that ginger root contained a very high concentration (3.85 mmol 100 g) of total antioxidants. Only pomegranate and several types of wild berries (e.g., dog rose, blueberry, strawberry, blackberry) had a higher total antioxidant concentration (19). In addition, Zancan et al. (20) recently presented a detailed report on the development of a process to produce ginger extracts with a high content of antioxidants, suggesting that antioxidant activity is widely accepted to be important in the effectiveness of ginger. Tumor promoters, including 12-O-tetradecanoylphorbol-13-acetate (TPA), are believed to act by promoting oxidative stress through the activation of the NADPH oxidase system and or the xanthine oxidase system. Many edible Japanese plants, including mioga...

Invivo Redox Effects of Antioxidants

As with in-vitro studies, the effects an antioxidant produces in vivo are likely to be dependent on its concentration, the presence of metal ions, and the amount of other antioxidants and ROS present. In addition, the metabolism of the compound can greatly affect its redox reactivity. For example, quercetin, which shows both antioxidant and prooxidant effects in vitro, occurs in the plasma mainly in its conjugate forms (i.e., quercetin combined with glucuronic acid, a derivative of glucose). The conjugate form is less reactive than free quercetin in vitro and generally acts as a mild antioxi-dant in vivo.139-143 Similar to vitamin C, normal dietary doses of most an-tioxidants will probably have antioxidant effects in most in-vivo conditions, and one is more assured if combinations of antioxidants are used.144 For example, oral administration of a diverse group and high quantity of antioxidants produced greater protection from oxidative damage in rodents than fewer antioxidants and...

Antioxidant

Studies have found that several compounds present in aloe gel protect tissues against oxidative damage caused by free radicals ('t Hart et al 1990, Singh et al 2000, Wu et al 2006, Yagi et al 2002, Zhang et al 2006). This is achieved by direct antioxidant activity and indirect activity through stimulation of endogenous antioxidant systems. Three-year-old aloe plants appear to have the highest amounts of flavonoids and polysaccharides and hence the best free radical scavenging capacity, as compared to 2- and 4-year-old plants (Hu et al 2003). Interestingly, the 3-year-old plant demonstrated antioxidant activity of 72.19 , compared to alpha-tocopherol at 65.20 .

Antioxidant Enzymes

Although the relatively small-sized antioxidants, vitamin C, vitamin E, and glutathione, have received the most public attention, large antioxidant enzymes in the cell also perform a vital role in neutralizing free radi-cals.a In fact, they act more efficiently than the small antioxidant compounds because they directly catalyze the conversion of free radicals to other, less harmful free radicals or to inert or useful compounds such as water and reduced glutathione. Unlike the small antioxidant compounds, antioxidant enzymes do not become free radicals that need to be regenerated. The conversion of free radicals by antioxidant enzymes is illustrated in Figure 5.2. The left side of the figure shows how oxygen (O2) loses an electron to produce the superoxide radical (O2* ). Superoxide is then converted to hydrogen peroxide by the enzyme SOD. Hydrogen peroxide is converted to harmless water (H2O) by the enzymes catalase, glutathione peroxidase, or both, with glutathione peroxi-dase...

Antioxidant Defense

The term antioxidant cannot be defined purely chemically it is always related to the cellular or organismal context, and to oxidative stress. Furthermore, every molecule can be both an oxidant and a reductant this is determined by the reduction potential of the molecule with which it reacts. An antioxidant is therefore defined as a redox active compound that limits oxidative stress by reacting non-enzymatically with a reactive oxidant, while an antioxidant enzyme is a protein that limits oxidative stress by catalysing a redox reaction with a reactive oxidant (Blomhoff, 2005). A complex endogenous antioxidant defense system has been developed to counteract oxidative damage and oxidative stress. Such an antioxidant defense is essential for all aerobic cells. The endogenous antioxidant defense has both enzymatic and non-enzymatic components that prevent radical formation, remove radicals before damage can occur, repair oxidative damage, and eliminate damaged molecules (Halliwell, 1996...

Dietary Antioxidants

The human endogenous antioxidant system is impressive but incomplete. Regular and adequate dietary intakes of (largely) plant-based antioxi-dants, most notably vitamin C, vitamin E, and folic acid, are needed. Fresh fruits and vegetables are rich in antioxidants (Figure 6), and epidemio-logical evidence of protection by diets rich in fruits and vegetables is strong. To decrease the risk of cancer of various sites, five or more servings per day of fruits and vegetables are recommended. However, it is not known whether it is one, some, or all antioxidant(s) that are the key protective agents in these foods. Furthermore, it may be that antioxidants are simple co-travellers with other, as yet unidentified, components of antioxi-dant-rich foods. Perhaps antioxidants are not 'magic bullets' but rather 'magic markers' of protective elements. Nonetheless, the US recommended daily intakes (RDis) for vitamin C and vitamin E were increased in 2000 in recognition of the strong evidence that...

Antioxidants

In the following sections, we explore the effects of an-tioxidants in general. Many issues that applied to vitamin C apply to other antioxidants as well, and our preliminary conclusions regarding their use are the same TABLE 15.3 PROOXIDANT EFFECTS OF ANTIOXIDANTS IN VITRO In tests on a series of flavonoids, apigenin produced the greatest prooxidant effect independent of metal ions. Apparently, apigenin oxidized intracellular glutathione, and the oxidized glutathione then participated in the generation of additional free radicals.124,125 Apigenin and luteolin acted as antioxidants at low iron concentrations but as prooxidants at high iron concentrations.126 Induced apoptosis in cancer cells through a prooxidant mechanism, and antioxidants prevented curcumin-induced apoptosis.130,131 as those for vitamin C. In short, most antioxidants have the capacity to increase, decrease, or not effect cancer cell proliferation. To help assure an anticancer effect, they are best used as supportive...

Antioxidant Effects

Methanol extracts of 180 Oriental herbs were screened for their antioxidant activities by determining the peroxide values of linoleic acid during storage at 50 C (43). Among the herbal extracts tested, 44 selected herbal extracts were further studied in a methyl linoleate system for an extended storage time. Eleven herbs had particularly high antioxidant activities, where the antiox-idative effects of most herbal extracts were greatly dependent on the extraction solvent used. However, E. koreanum Nakai extract and three other herbs appeared to show significantly strong antioxidant activities regardless of the solvents used for the extraction (p 0.05). This result suggested that E. koreanum extract contains powerful antioxidative components. Phenolic acids and or flavonoids might be the possible antioxidative components because methanol is a good solvent for extracting these compounds from the plant materials. Also, Epimedium compound granules, which lower blood lipid, have anti-free...

The Potential Benefits of Moderate Alcohol Consumption

In 1992, French scientists published a report that indicated that cardiovascular mortality was much less among predominantly wine-drinking residents of the Mediterranean southern provinces of France than in northern provinces where wine is less frequently preferred, in spite of similar overall dietary components and rates of consumption of alcoholic beverages (Table 1). This report on the 'French paradox' was assumed to confer specific cardiopro-tective benefit to wine, but was soon tempered by in vitro studies, which showed that the protective effect of wine on the oxidation of low-density lipoprotein could be mimicked by constitutive antioxidant fla-vonoids present not only in grapes but in many other fruits and vegetables. Another epidemiological study concluded that the lower mortality risk among wine drinkers compared to non-wine drinkers could be attributed in large part to a better life style, including less smoking, more exercise, and better diet. Subsequent population studies...

Redox Activation and Deactivation of Proteins

We have discussed what free radicals are and how they are produced and neutralized now we turn to one primary means by which free radicals activate or deactivate proteins, thus returning to turn back to the primary topic of this chapter, transcription factors. Transcription factors, being proteins, can be affected by free radicals through this mechanism. Like trace metals and antioxidants, proteins can undergo redox reactions. This is especially true for proteins containing the amino acid cysteine. Such redox reactions alter cysteine molecules in a way that activates or deactivates the protein, much as if the cysteine portion of the protein were an on-off switch. The off mode comes into play when the sulfur atom in cysteine is oxidized (i.e., loses a hydrogen atom). When oxidation occurs for two sulfur atoms in adjacent cysteine molecules, the resulting unbalanced sulfur atoms can bond with one another. This bond, aptly called a disulfide bridge, is illustrated in Figure 5.3. The...

Celltocell Communication

Cell-to-cell communication is a dynamic, complex process. At least four large families of CAMs are involved, each with members that play somewhat distinct roles. In addition, several other proteins are involved in assuring cell-to-cell communication via gap junctions. Moreover, the signals generated by CAMs and the signals that control them travel to and from the nucleus via protein phosphorylation. For this reason, PTK, PKC, and other proteins involved in signal transduction, as well as free radicals, can affect CAM function and behavior. Any or all of these mediators of cell-to-cell communication can be abnormal in cancer cells. Despite the complexities, however, many natural compounds help restore normal cell-to-cell communication in such a way as to induce apoptosis or inhibit cancer cell migration, invasion, metastasis, or proliferation. For instance, PTK inhibitors can reduce the invasion of cancer cells through mechanisms related to cell-to-cell communication. Most of the...

Chronic Obstructive Pulmonary Disease COPD

The generation of oxygen free radicals by activated inflammatory cells produces many of the pathophys-iological changes associated with COPD. Common examples of COPD are asthma and bronchitis, each of which affects large numbers of children and adults. Antioxidant nutrients have therefore been suggested to play a role in the prevention and treatment of these conditions. A number of studies have demonstrated a beneficial effect of fruit and vegetable intake on lung function. For example, regular consumption of fresh fruit rich in vitamin C (citrus fruits and kiwi) has been found to have a beneficial effect on reducing wheezing and coughs in children. Vitamin C is the major antioxidant present in extracellular fluid lining the lung, and intake in the general population has been inversely correlated with the incidence of asthma, bronchitis, and wheezing and with pulmonary problems. Although some trials have shown high-dose supplementation (1-2g day) to improve symptoms of asthma in...

Possible Explanations for the Disagreement between the Findings of Observational Studies and Clinical Trials

Various explanations have been given for the different findings of observational studies and intervention trials. Clearly, nonrandomized studies are unable to exclude the possibility that antioxidants are simply acting as a surrogate measure of a healthy diet or lifestyle and that the protective effect of certain dietary patterns, which has been presumed to be associated with dietary antioxidants, may in fact be due to other compounds in plant foods, substitution of these foods for others, or a reflection of other health behaviors common to people who have a high fruit and vegetable intake. However, although intervention studies provide a more rigorous source of evidence than observational studies, they are not without The nature of the supplements used It has been suggested that the synthetic forms used in most trials may have different biological activity or potency from natural forms of these vitamins, although trials using the natural forms have not found different clinical...

Vitamin and Mineral Supplementation

Most studies involving vitamin or mineral supplementation in RA have focused on either the antioxidant nutrients (vitamin C, vitamin E, beta carotene, selenium) or B vitamins. Various studies have examined the effects of vitamins C, E, and selenium supplementation on the management of RA. In general, results from randomized controlled trials of vitamin E supplementation have been of relatively short duration and have led to conflicting results so that there continues to be a lack of concrete evidence to support vitamin E supplementation at a particular dosage. Nonetheless, patients with RA could certainly be encouraged to increase their intake of vitamin E-rich foods, including edible vegetable oils (sunflower, safflower, canola, olive), unprocessed cereal grains, and nuts. Similarly, the effect of dietary sources of other antiox-idant nutrients, such as selenium and vitamin C, on inflammatory symptoms in RA has also been ambiguous. It should be emphasized that providing individual...

Phytochemicals of Interest

Antioxidant Antioxidants that reduce plaque formation, and promote cell differentiation Antioxidants that block carcinogens, anti-inflammatory Antioxidant arthritis relief, deters ulcers Antioxidant carotenoid prostate cancer preventive Antioxidant anti-inflammatory inhibits carcinogen-induced cell proliferation

Well Established Metabolic Functions of Vitamin C that are Impaired in Deficiency

In the course of its functional roles, ascorbic acid is oxidized in two successive one-electron reversible steps, and it is thought that most, if not all, of its essential biological actions are centred around this key redox cycle. The first oxidation product is the free-radical form of the vitamin, which is known variously as 'mono-dehydroascorbate,' 'semidehydroascorbate,' or 'ascorbate free radical' (AFR). Although this intermediate shares with most other free radicals the properties of having a relatively short half life and a high degree of chemical reactivity, it is, nevertheless, more stable than many other free radicals, contrasting with the highly reactive and damaging radicals such as hydroxyl or superoxide radical that are derived from molecular oxygen. By reacting with, and thus quenching, these damaging oxygen free radicals, ascorbate can act as a free-radical chain terminator and can thereby protect vulnerable macromolecules such as DNA, lipids, and proteins from...

Vascular Endothelial Growth Factor

A major source of PDGF, EGF, and TNF within solid tumors is macrophages. The production of these and other growth factors by macrophages is discussed later in this chapter, as well as the effects of hypoxia on macrophages and VEGF production, but note here that antioxidants, PTK inhibitors, PKC inhibitors, and leu-kotriene inhibitors may all reduce production of VEGF by macrophages or other cells in response to growth factors or hypoxia. In addition, inhibitors of AP-1 may also block VEGF production, as has been reported for curcumin.12

Applications To Health Promotion And Disease Prevention

The kernel of bambangan is considered to be a waste product, since it is not eaten fresh, and is only occasionally used to make pickle. Our recent study has shown that bambangan kernel contains diverse antioxidant phytochemicals, and displays numerous potential health-beneficial properties. which are recognized as potent antioxidants with demonstrable health-beneficial properties Antioxidant activity Our recent study showed that bambangan fruit displayed high antioxidant activity (Abu Bakar et al., 2009a). The fruits were separated into flesh, peel, and kernel, and the antioxidant assessment of alcoholic extracts was conducted by a free radical scavenging assay (using DPPH) and a ferric reduction (FRAP) assay. The results showed that the kernel extract of the fruit displayed the highest DPPH scavenging effect, followed by the peel and flesh extracts (Table 21.2). The reducing ability of the tested extracts was in the order of kernel peel flesh the same trend as shown in the DPPH free...

Agastache Agastache rugosa

The aerial part of A. rugosa (also called Korean mint) is used in traditional medicine to treat cholera, vomiting, and miasma, and exhibits antimicrobial activity (1). Sugar, amino acid, mineral, and polyphenol composition have been described (2), and extracts contain rosmarinic acid, agastinol, and agastenol. A new diterpenoid quinone, agastaquinone, was isolated from the roots and showed nonspecific cytotoxicity against several human cancer cell lines in vitro (3). Rosmarinic acid appears to be primarily responsible for the antioxidant activity (4).

Supplement Facts Label

In addition, DSHEA established standards for terms, such as high potency and antioxidant, and for the types of claims that could be made for a product. Claims that a dietary supplement may help to prevent or cure a disease cannot be made. Such claims are considered health claims and must be reviewed by the Food and Drug Administration for scientific accuracy prior to approval for use on a product label. Manufacturers may, however, use structure function claims that state that a product can, for example, help to promote healthy blood levels of cholesterol, but they may not state that a product helps to prevent heart disease. All structure function claims must be accompanied by the following disclaimer This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Tumour Hyaluronan Metabolism And Angiogenesis

Intracellularly, in the lysosomal system, after receptor mediated internalisation. In hepatocytes, kupffer cells and sinusoidal endothelial cells, catabolism appears to go to completion yielding acetate, ammonia and water (67,68). Initial extracellular depolymerization of HA or proteoglycan complexes, mediated by oxygen-derived free radicals, nitric oxide or proteinases, appears to be a necessary prerequisite for internalisation. Although this may be the case for circulating HA, our analysis of HA in wound tissues and tumours suggests that a large scale, sequential degradation of the whole population of HA molecules takes place. In addition, the extent of HA depolymerization appears to increase with increasing extracellular acidic

Distribution and Impact on Health

The epidemiological findings that the ingestion of tomato and tomato products is strongly correlated with a reduced risk of several types of cancer, particularly prostate cancer, has stimulated a great deal of research on the protective effects of lycopene. Lyco-pene is the most efficient biological antioxidant. Hence, it has been assumed that it is this anti-oxidant activity that is responsible for the protection against prostate cancer. However, a recent study in which carcinogenesis was induced in rats using

Hydrocarbon Carotenoid aCarotene

A-Carotene, another carotenoid frequently present in food, also has provitamin A activity. Based on its structure, it is only converted to one molecule of biologically active retinol after central cleavage. Like other carotenoids, it has antioxidant and possibly anticarcinogenic properties, and may enhance immune function as well. Some, but not all, epide-miological studies observed that higher a-carotene intake was associated with lower risk of cardiovascular disease and cancer, whereas others did not. Clinical trials to test a-carotene influences in humans have not been conducted to date. This is probably because a-carotene is usually associated with ample amounts of fi-carotene when found in fruits and vegetables and singling out a-carotene is difficult.

Xanthophyll bCryptoxanthin

3-Cryptoxanthin is one of the lesser known carote-noids that also has provitamin A activity and appears to have a protective health role. Several epidemiological studies suggest that dietary 3-cryptoxanthin is associated with lower rates of lung cancer and improved lung function in humans. A large prospective study on dietary intake and cancer, which included an interview on dietary habits and life style, identified -cryptoxanthin as protective against lung cancer after correcting for smoking. However, the beneficial effects for -cryptoxanthin suggested by these results could be merely an indicator for other antioxidants and or a measure of a healthy life style that are more common in people with high dietary intakes of -cryptoxanthin. In tissue culture, -cryptoxanthin has a direct stimulatory effect on bone formation and an inhibitory effect on bone resorption. Studies of these beneficial effects in humans have not been conducted.

Hydrocarbon Carotenoid Lycopene

Lycopene, while having no provitamin A activity, is a potent antioxidant with twice the activity of -carotene for quenching singlet oxygen and 10 times the antioxidant activity of a-tocopherol in some model systems. The antioxidant potential of food chemicals varies widely according to location in the body and the presence of other body chemicals. The primary sources of dietary lycopene are tomatoes and tomato products. Epidemiological evidence shows an inverse association between lycopene consumption and the incidence and development of certain cancers. This association is especially strong for prostate cancer, which is the most common cancer among men in Western countries and the second leading cause of cancer death in American men. Prostate cancer rates in Asian countries are much lower, but appear to be increasing rapidly. Lycopene is localized in prostate tissue. The current consensus is that a high consumption of tomatoes or high circulating Because lycopene is a potent...

Technological Issues

The diversity in composition among different amaranth genotypes necessitates in-depth characterization of biochemical constituents for its specific applications in the food industry. The smaller size granules in amaranth starch, which are similar to the size of fat globules of cow's milk, can be exploited to mimic fat in a number of food products. Some of the genotypes have higher polyphenols with higher antioxidant activity, which could also be utilized in the development of new products. Amaranth grain has the potential to be used in the development of various food products for people suffering from celiac disease, a disorder that makes the body intolerant to gluten proteins.

Background And Relevant Pharmacokinetics

Coenzyme Q10 (CoQ10) is an endogenous enzyme cofactor produced in humans from tyrosine through a cascade of reactions that itself requires eight vitamin coenzymes tetrahydrobiopterin, vitamins B6, C, B2, B12, folic acid, niacin, and pantothenic acid (Folkers et al 1990). CoQ10 is also a fat-soluble antioxidant vitamin that plays an indispensable role in intracellular energy production.

Cytokines and Immune Cell Activation

The primary cytokine that activates macrophages is IFN-gamma. TH1 cells activate macrophages by secreting IFN-gamma and other cytokines that assist IFN-gamma, including TNF and granulocyte macrophage-colony stimulating factor (GM-CSF). The activated macrophage then produces a wide variety of cytokine and noncytokine compounds, including free radicals, proteases, TNF, IL-1, and IL-6. Some of these stimulate other immune cells, and some destroy pathogens.

Absorption and Metabolism of Tea Polyphenols

The results described above suggest that the active components in tea, namely the antioxidant polyphenols, are absorbed to generate the effects noted. This has been measured directly through a number of distinct analytical methods, such as HPLC and other chromatographic procedures, that were used to determine circulating levels in humans by several different groups. Other effects measured were the effect of intake of polyphenols from tea on biochemical parameters, such as the in vivo antioxidant effects in humans (125-127). The direct measurement of metabolites of epigallocatechin gallate

Metabolism Of Vitamin E

In intestinal mucosal cells, all vitamers of vitamin E are incorporated into chylomicrons, and tissues take up some vitamin E from chylomicrons. Most, however, goes to the liver in chylomicron remnants. a -Tocopherol, whichbinds to the liver a -tocopherol transfer protein, is then exported in very low-density lipoprotein (VLDL) and is available for tissue uptake (Traber and Arai, 1999 Stocker andAzzi, 2000). Later, it appears in low-density lipoprotein (LDL) and high-density lipoprotein, as a result of metabolism of VLDL in the circulation. The other vitamers, which do not bind well to the a-tocopherol transferprotein, are not incorporated into VLDL, but are metabolized in the liver and excreted. This explains the lower biological potency of the other vitamers, despite similar, or higher, in vitro antioxidant activity.

Mechanisms Of Action

Reduction to a single mechanism is certainly not necessary. Nonetheless we can explain many of EGb 761's effects by its antioxidant action and its action on gene expression, two related but distinct phenomena. Extensive experimental data have confirmed that it acts as a free-radical scavenger (21,27), including in vivo in humans (22). This finding tends to explain its protective role of the nervous system in particular in the harmful processes associated with aging and with traumatic, ischemic, or toxic injuries most of the neurodegenerative disorders seems to be linked to a similar mechanism, i.e., the aggregation of toxic proteins and the effect of free radicals (28,29). More recently, effects have been observed on gene expression EGb 761 inhibits AP-1 transcription factor (30) and increases or decreases the expression of many genes in vitro (31). Studies have also shown that EGb 761 affects in vivo gene expression in animals (32). In several cases, the gene effect involves not only...

Requirements And Reference Intakes

Early reports suggested that vitamin E requirements increase with the intake of polyunsaturated fatty acids. Neither the United Kingdom (Department of Health, 1991) nor the European Union (Scientific Committee for Food, 1993) set reference intakes for vitamin E, but both suggested that an acceptable intake was 0.4 mg of a-tocopherol equivalent per g of dietary polyunsaturated fatty acid (PUFA). This should be readily achievable from PUFA-rich foods, which are also rich sources of vitamin E, but PUFA supplements may not contain adequate vitamin E. There is little evidence to support the figure of 0.4 mg of a-tocopherol equivalent per g of dietary PUFA, and indeed the need for vitamin E (and other antioxidants) depends more on the degree of unsaturation of fatty acids than the total amount, and dietary PUFAs undergo chain elongation and further desaturation in the body. Valk and Hornstra (2000) suggested an intake of 0.6 mg of a-tocopherol per g of linoleic acid, and noted that there...

Chemopreventative Effects

Chemopreventative actions demonstrated by n-3 EFAs include suppression of neoplastic transformation, cell growth inhibition and enhanced apoptosis, and anti-angiogenicity (Rose & Connolly 1999). The proposed mechanisms for these are extensive, including the suppression of n-6 eicosanoid synthesis influences on transcription factor activity, gene expression, and signal transduction pathways effects on oestrogen metabolism increased or decreased production of free radicals and reactive oxygen species, and influences on both insulin sensitivity and membrane fluidity (Larsson et al 2004). Ongoing research is attempting to elucidate the specific chemopreventative mechanisms of fish oils with the individual cancer cell lines.

Antiatherosclerotic Activity

Results from several recently published animal studies further confirm antiatherogenic effects and have investigated the mechanisms responsible (Durak et al 2002, Ferri et al 2003, Kwon et al 2003). One in-vivo study found that garlic activated antioxidant systems and decreased peroxidation in aortic tissue (Durak et al 2002) whereas ajoene inhibited smooth muscle cell proliferation in another (Ferri et al 2003).

Summary of Research and Conclusions

Lastly, vitamin C has been tested in combination with other antioxidants, again with conflicting results.37-41 For example, one animal study reported that a combination of antioxidants increase metastasis without affecting the growth of the primary tumor. On the other hand, one human study reported that a combination of antioxidants reduced the risk of recurrence after treatment for bladder These inconsistencies are certainly perplexing, and to some degree, they probably reflect the complex biochemistries of antioxidants oxidants found in vivo. In addition, some inconsistencies found in in-vitro, animal, and human studies may be attributed to differences in the experimental procedures used.

Introduction to Vitamin C

A primary reason for the slow progress and conflicting results in vitamin C research is that its effects on cancer are largely mediated through redox reactions, and the study of these in biological systems is a complex undertaking. Like all antioxidants, vitamin C can act as both an antioxidant and prooxidant. Its prooxidant effects are mediated through the vitamin C free radical, which in high concentrations inhibits tumor growth but in low concentrations may stimulate it. Unfortunately, much of our understanding of the effects of free radicals in health and disease has come only recently, and the role the vi- As an antioxidant, vitamin C may inhibit cancer progression through a variety of actions, listed in Table 15.1. Its ability to stimulate apoptosis is mediated by its prooxidant effect. AS AN ANTIOXIDANT, MAY Act as an antioxidant

Direct Effects of Vitamin C

In contrast to indirect effects, it seems probable that vitamin C can produce antitumor effects solely through direct effects on cancer cells. A large body of evidence suggests that the direct effects of vitamin C are mediated by its free radical. As stated earlier, however, prooxi-dant therapies have their drawbacks and are not advocated in this book. Nonetheless, the prooxidant effects of vitamin C are discussed below, to explain how vitamin C can kill cancer cells and to provide background for later discussions on other antioxidants. Moreover, at lower concentrations, the vitamin C free radical can stimulate proliferation of some tumors, and for that reason needs to be discussed.

Ascorbate Free Radical

Three important ideas are illustrated in the figure. First, each of these antioxidants cycles between a reduced (antioxidant) form and an oxidized form. Thus the figure shows three cycles, one for glutathione, one for vitamin C, and one for vitamin E. Second, the reduced forms of each antioxidant can recycle other antioxidants. For example, reduced glu-tathione can cycle oxidized vitamin C to its reduced form, producing oxidized glutathione in the process. Likewise, ascorbate can cycle oxidized vitamin E to its reduced form, producing oxidized vitamin C. These interactions are important in vivo, as they allow antioxi-dants to keep each other in their reduced forms.50,5152 Also of interest in the figure is that the source of electrons for reducing glutathione (and through glutathione, other antioxidants) is NADH, which is obtained from the burning of glucose (see Chapter 5). Thus in addition to providing energy for other cellular functions, glucose provides the fundamental energy to...

Inhibition of Cell Proliferation

Enge free radicals, but in the process AFR is produced vitamin C can react with oxygen to produce hydrogen peroxide and copper and iron ions can react with hydrogen peroxide to produce harmful hydroxyl radicals, DNA damage, and cell death. These concepts were introduced earlier and are discussed here in more detail to provide a more complete understanding of how vitamin C works against cancer. This reaction is illustrated in Figure 15.1. Thus ascorbate can keep vitamin E in its antioxidant (reduced) state, ready to protect the cell. Another important reaction in which vitamin C and some other antioxidants participate is the reduction of iron and copper. This reaction is important for two reasons it produces more AFR, and it produces reduced iron and copper, which can then react in other ways. In the following discussions, we use copper as the example, but similar reactions occur with iron. In some animal antitumor experiments, solutions of ascorbate and copper were administered. Thus...

Stimulation of Cell Proliferation

Before considering its effects in humans, let us examine how vitamin C could stimulate cancer. The fact that free radicals can stimulate cell proliferation is not a new concept to us the stimulating properties of radicals on growth factor receptors, PKC activity, and NF-kB activity were discussed in Chapter 5.74 75 In addition, AFR and other radicals may stimulate proliferation through a process called transmembrane electron transport, where cells reduce extracellular AFR to ascorbate by sending electrons through their plasma membrane. The reasons why transmembrane electron transport stimulates cell proliferation are still uncertain, but may be due partly to a subsequent increase in the intracellular pH, which favors cell proliferation.76, 77 Considering the above, it is not surprising that cancer cell proliferation can be stimulated by AFR under the right conditions, as well as by other radicals such as hydrogen peroxide and nitric ox-ide.77,78,79 In addition, there are a number of...

Synergism and Vitamin C

A number of natural compounds appear to act syner-gistically with vitamin C to produce cytotoxic effects via stimulation of free radicals. These include vitamin K3 and high-molecular-weight compounds such as PSK and lignans. Each is described briefly below. Since their clinical use would involve prooxidant mechanisms, as well as intravenous administration, such synergistic combinations are not advocated they are mentioned only because some readers may find references to them in the literature.

Implications for Cancer Therapy

From the above discussions, we see that high doses of antioxidant compounds can produce prooxidant effects in vivo, especially when single antioxidants are given. This, of course, is a drawback to using high doses in cancer therapy. An antioxidant effect is likely, however, if moderate to low doses of antioxidants are used, and they are used in combination. If antioxidants are used to produce an antioxidant rather than prooxidant effect, the antioxidant effect produced will generally be beneficial to the body. For example, immune cells may function better when they contain adequate antioxidants. Cancer cells may also benefit, however. Using antioxidants in cancer treatment is currently a matter of much debate, and it is especially heated regarding use of antioxidants in combination with chemotherapy. In theory, because many chemotherapy drugs act by generating ROS, anti-oxidants could reduce ROS-induced apoptosis in cancer cells. Indeed, several in-vitro studies have reported that...

Concluding Remarks

Blue-green algae are reported to accumulate heavy metals from contaminated pond water and consuming such food might result in metal toxicity. Interestingly, dietary S.fusiformis at a high dose of 800 mg kg body weight of rats reduced lead toxicity as judged by significant enhancement in survival time, animal weight, and the weights of their testes (54). In another study, exogenous administration of spirulina at a dose of 1500 mg kg reduced the levels of lipid peroxidation products such as malondialdehyde, conjugated diene, and hydroperoxide. Since similar effects were observed upon the adminstration of the antioxidant vitamin E or C, it was concluded that the antioxidant activity of spirulina exerted the protective effects during lead-induced toxicity (55). Thus it appears that when grown under conditions where it cannot accumulate heavy metals, spirulina can be used to reduce metal toxicity in animals. If it is to be accepted as a safe food, further controlled experiments are...

Limitations of Food Composition Data Poor Analytic Procedures

Technical expertise to use the equipment is not available. For many of the antioxidant compounds, such as carotenoids and tocopherols, quantification by mass spectrometry (MS) yields the most sensitive detection limits, although analysis using high-performance liquid chromatography (HPLC) is adequate in most cases. However, because the equipment, maintenance, and reagents are often too expensive, laboratories (particularly in developing countries) may use older methods, such as spectrophotometry combined with open-column chromatography. Nutrient values derived using such methods are less accurate than those resulting from HPLC and MS methods.

Fruits and Vegetables

Fruits and vegetables are also good sources of antioxidants (a subcategory of phytochemicals), which are believed to lower cancer risk. Antioxidants such as vitamins C and E, beta-carotene, and lycopene are found in many fruits and vegetables. Lycopene, believed to be a particularly powerful antioxidant, is found in tomatoes, apricots, guavas, watermelons, papayas, and pink grapefruit. As a rule, darker-colored fruits and vegetables are rich in phytochemicals and antioxidants. In some studies, fruit and vegetable supplements in pill form have been shown to raise antioxidant levels in the blood. The primary concern with such supplements is that while we know that fruits and vegetables are important in helping to prevent certain kinds of cancer, we aren't sure precisely which ingredients are the most important. In addition, since these foods contain possibly helpful components that have not been identified yet, the pill supplements are almost certainly not as good as eating at least...

Transport and cellular uptake

Free Cys can Ik* taken up by cells v la several transporters. Sodium-dependent transport occurs with systems ASC (cloned representatives ASCT1 'SLC1A4, ASCT2) and A. ATA2 ubiquitously expressed (Sugawara el a ., 2000), ATA3 is restricted to the liver (Hatanaka el ai, 2001). The glycoprotein-1 inked hcterocxchangers include LATI (SI.C7A5). L.AT2 (SLC7AN). and xCT. System x-c (representedby transporter xCT) is the major conduit for CssC uptake into macrophages (Sato el ai, 2001) and glial cells (Kim el a 2001), which have a high requirement for synthesis of the antioxidant tripeptide glutathione (Salo el al., 2001).

Cardioprotective Effects

Considering that GSE demonstrates antioxidant, antiplatelet and anti-inflammatory actions, it may have a role in the prevention of cardiovascular disease. A number of researchers have investigated this issue further, mainly using animal models. One series of studies was conducted by Bagchi et al (2003) using a natural, standardised, water-ethanol extract made from California red grapeseeds, which contained Grapeseed extract 646

European Regulations for Functional Foods

Antioxidant vitamins Cancer Dietary supplements containing vitamin (1) Some scientific evidence suggests that consumption of antioxidant vitamins may reduce the risk of certain forms of cancer. However, FDA has determined that this evidence is limited and not conclusive. (2) Some scientific evidence suggests that consumption of antioxidant vitamins may reduce the risk of certain forms of cancer. However, FDA does not endorse this claim because this evidence is limited and not conclusive. (3) FDA has determined that although some scientific evidence suggests that consumption of antioxidant vitamins may reduce the risk of certain forms of cancer, this evidence is limited and not conclusive.

Presentday Cultivation And Usage

Today, healthcare professionals use standardized extracts of grape seed to treat a range of health problems related to free radical damage, including blood sugar regulation problems, heart disease, and cancer. The antioxidants contained in GSE have also been reported to be beneficial in cancer prevention.