Applications To Health Promotion And Disease Prevention

FAT LOSS Activation

Best Weight Loss Programs That Work

Get Instant Access

Mature, dried seeds of C. pepo are described by a positive monograph of the German Commission E as a drug. Naked pumpkin seeds are, compared with hulled seeds, richer in 6 7-sterols. Pumpkin seeds and seed extracts represent a complex mixture of substances, and their effects may not be attributed to just few ingredients. 67-Sterols are significant for the treatment of BHP, a condition that commonly affects men 50 years and older and involves enlargement of the prostate gland. One of the factors that contributes to BPH is over-stimulation of the prostate cells by testosterone and its conversion product, DHT. As aging occurs, the amount of DHT in the prostate gland remains high, even though the circulating testosterone level drops. Components in pumpkin seed and seed oil appear to interrupt this triggering of prostate cell multiplication by testosterone and DHT, although the exact mechanism for this effect is still a matter of discussion. The reason for 6 7-sterols efficiency may be in their structural similarity to DHT (Strobl, 2004). Pumpkin seeds also contain citrulline, which is attributed an anti-edematous effect. Furthermore, some as yet not fully described ingredients have antimicrobial and anti-inflammatory activity, as well as a regulatory influence on the bladder musculature. The carotenoids found in pumpkin seeds

have been studied for their potential prostate benefits, and it was concluded that men with higher amounts of carotenoids in their diet have less risk for BPH (Brawley & Barnes, 2001). The same is valid for selenium and vitamin E. Other effective ingredients are zinc, linoleic, oleic, palmitic and stearic acids, and magnesium salts. They are ubiquitous in pumpkin seeds, but the question of whether they are significant in the relief from BHP-associated discomfort remains unanswered. Pumpkins also contain biologically active components that include polysaccharides, proteins, and peptides. However, the presence of antinutritients in pumpkin seeds limits their nutritional value. It was found that technologies such as germination and fermentation could reduce antinutritional materials and affect the pharmacological activities of pumpkin. Pumpkin and other species of the Cucurbita family possess an unusual amino acid, known as cucurbitin, which is the main and most active chemical principle which is essentially the reason for the antihelmintic activity displayed by a pumpkin seed remedy (Rybaltovskii, 1966) .

In recent years, there has been a growing interest in studying phenolic compounds of oilseeds, their skins, hulls, and oil cake meals, because they represent potentially health-promoting substances and have industrial applications. Due to their antioxidant, antimicrobial, antiproliferative, and preservative properties, phenolic acids, which account for 30% of total dietary plant polyphenols, have an important role in plant resistance towards diseases, in human health maintenance (inhibition of oxidative damage diseases such as coronary heart disease, stroke, cancers, diabetes, neurodegenerative diseases, cataracts, and age-related functional decline), and in prevention of food deterioration. In many cases, aldehyde analogs are also grouped with, and referred to, as phenolic acids. Phenolic compounds occur in free and bound forms. Bound phenolics may be linked to various plant components through ester, ether, or acetal bonds, and are typically involved in cell-wall structure. For this reason, hydrolytic procedures have been employed to quantify total phenolics. Phenolics behave as antioxidants, due to the reactivity of the phenol moiety (hydroxyl substituent on the aromatic ring). Although there are several mechanisms, the predominant mode of antioxidant activity is believed to be radical scavenging via hydrogen atom donation.

Other established antioxidant, radical-quenching mechanisms are through electron donation and singlet oxygen quenching. Substituents on the aromatic ring affect the stabilization and therefore the radical-quenching ability of these phenolic acids. Different acids therefore have different antioxidant activity. The antioxidant behavior of free, esterified, glycosylated, and non-glycosylated phenolics has been reported (Robbins, 2003). Phenolic acids are divided into two main groups: hydroxycinnamic (caffeic, p-coumaric, ferulic, sinapic) and hydrox-ybenzoic (protocatechuic, p-hydroxybenzoic, vanillic, syringic, gentisic, gallic) acids. Greater antioxidant capacity of hydroxycinnamic acid derivatives (compared to hydroxybenzoic acid derivatives) is linked to the presence of the propenoic side chain, instead of the carboxylic group. The conjugated double bond in the side chain could have a stabilizing effect by resonance on the phenoxyl radical, thus enhancing the antioxidant activity of the aromatic ring. The resonance stabilization of the phenoxyl radical is shown in Figure 109.3.

H"

FIGURE 109.3

Phenoxyl radical resonance. The high reactivity of phenolic compounds to scavenge harmful free radicals may be explained by their ability to donate a hydrogen atom from their hydroxyl group. During this reaction the phenoxyl radical is formed, which undergoes a change to a resonance structure by redistributing (stabilizing) the unpaired electron on the aromatic core. Thus, the phenoxyl radical exhibits a much lower reactivity compared to free radicals.

CHAPTER 109

Phenolic Acids in Pumpkin Seed

However, despite the ubiquitous presence of phenolic acids in plant-based food, and their role as dietary antioxidants, until recently the literature about the presence of phenolic compounds in pumpkin C. pepo has been limited. In pumpkin peel, for example, small amounts of vanillic, p-coumaric and sinapic acids were reported; in puree, chlorogenic, syringic, and caffeic acid were found; while in seed oil, p-coumaric and trans-cinnamic acid were quantified. Pericin et al. (2009) investigated two varieties of C. pepo seeds (Figures 109.2A, B), and reported that p-hydroxybenzoic acid was the dominant phenolic acid, with 34.72, 67.38, and 51.80% of the total phenolic acid content in whole hull-less seed, kernels (from hulled seed), and hulls, respectively. Besides p-hydroxybenzoic acid, the most abundant phenolic compounds, in decreasing order of quantity, were caffeic, ferulic, and vanillic acids in whole hull-less seeds. In the hulled pumpkin variety, kernels were rich in trans-sinapic and protocatechuic acids, and p-hydroxybenzaldehyde; in the hulls, p-hydroxy-benzaldehyde, vanillic, and protocatechuic acids were present in valuable quantities. The same authors also determined that the sum of phenolic acids present in three forms (free, esterified, and insoluble-bound) was much higher in the outer seed layers (skin and hull) than in the whole naked seed and in kernels from the hulled variety of C. pepo. That result was expected, because skins and hulls, as a rule, contain much higher concentrations of phenolic compounds than inner layers, as they represent the first line of the plant's defense against the environment. It is not surprising, then, that the total sum of phenolic acids in whole hull-less seed (kernel + thin green skin) was higher than in kernels from the hulled variety, at 77.02 versus 51.53 mg/kg dry weight, respectively.

The structures of phenolic acids identified in pumpkin seed are shown in Figure 109.4, while the content and distribution of phenolic acids in whole naked seed, and kernel from the hulled variety of C. pepo, are presented in Table 109.2. In all investigated samples the bound phenolic acids content (esterified and insoluble) was higher than the free phenolic acids content, indicating that the major phenolic acids were released upon alkaline hydrolysis — that is, they were present in the cell-wall structure. This was most noticeable in defatted flour from whole hull-less pumpkin seeds, where the esterified form comprised 63.06% and the insoluble-bound 21.07% (in sum 84.13%) of the total phenolic acids. Thus, without including the bound phenolic acids, the total phenolic content of pumpkin Cucurbita pepo seeds would clearly be underestimated.

FIGURE 109.4

Hydroxybenzoic (A—E) and hydroxycinnamic (F—I) acid derivatives present in pumpkin seed. (A) p-Hydroxybenzoic acid, (B) p-hydroxybenzaldehide, (C) protocatechuic acid, (D) vanillic acid, (E) syringic acid; (F) p-coumaric acid, (G) caffeic acid, (H) ferulic acid, and (I) sinapic acid. Hydroxybenzoic acids possess a carboxylic group, while hydroxycinnamic acids have a propenoic side chain.

FIGURE 109.4

Hydroxybenzoic (A—E) and hydroxycinnamic (F—I) acid derivatives present in pumpkin seed. (A) p-Hydroxybenzoic acid, (B) p-hydroxybenzaldehide, (C) protocatechuic acid, (D) vanillic acid, (E) syringic acid; (F) p-coumaric acid, (G) caffeic acid, (H) ferulic acid, and (I) sinapic acid. Hydroxybenzoic acids possess a carboxylic group, while hydroxycinnamic acids have a propenoic side chain.

CO CO

TD CD O

TABLE 109.2 Phenolic Acids in Defatted Whole Hull-less Pumpkin Seed, Kernels, and Hulls from Hulled Seed c t w a

TABLE 109.2 Phenolic Acids in Defatted Whole Hull-less Pumpkin Seed, Kernels, and Hulls from Hulled Seed

Phenolic Acid

Whole Hull-less Pumpkin Seed

Kernels from Hulled Seed

Hulls

Free

Esterified

Insoluble-

Free

Esterified

Insoluble-

Free

Esterified

Insoluble-

bound

bound

bound

Protocatechuic

ND

3.66 ± 0.35

0.72 ± 0.06

0.40 ± 0.03

1.49 ± 0.13

0.60 ± 0.05

6.64 ± 0.60

0.59 ± 0.03

1.34 ± .09

p-Hydroxybenzoic

3.64 ± 0.38

15.96 ± 1.20

7.14 ± 0.11

18.33 ± 1.73

5.81 ± 0.42

10.58 ± 1.02

52.28 ± 2.54

12.70 ± 1.12

17.24 ± 0.64

p-Hydroxybenzaldehyde

0.94 ± 0.09

0.35 ± 0.02

1.34 ± 0.12

1.15 ± 0.10

ND

1.23 ± 0.07

8.79 ± 0.82

1.04 ± 0.04

23.04 ± 1.71

Vanillic

ND

6.66 ± 0.57

1.37 ± 0.12

ND

0.72 ± 0.06

0.84 ± 0.06

5.72 ± 0.34

2.84 ± 0.26

14.61 ± 0.68

Caffeic

2.80 ± 0.25

12.20 ± 0.70

2.08 ± 0.20

ND

0.90 ± 0.08

0.86 ± 0.07

ND

ND

ND

Syringic

ND

0.36 ± 0.01

0.28 ± 0.05

ND

0.80 ± 0.06

NQ

ND

2.19 ± 0.13

2.13 ± 0.12

trans p-Coumaric

1.79 ± 0.16

1.82 ± 0.13

0.69 ± 0.01

1.00 ± 0.09

ND

0.87 ± 0.07

2.93 ± 0.20

0.49 ± 0.04

ND

Ferulic

1.01 ± 0.10

7.05 ± 0.16

1.78 ± 0.16

ND

ND

0.94 ± 0.08

ND

1.07 ± 0.09

ND

trans Sinapic

2.04 ± 0.18

0.51 ± 0.04

0.83 ± 0.08

1.98 ± 0.14

1.62 ± 0.12

1.38 ± 0.12

ND

3.09 ± 0.04

ND

Total phenolic acid

12.22 ± 0.22

48.57 ± 2.08

16.23 ± 0.11

22.87 ± 1.80

11.34 ± 1.01

17.32 ± 1.52

76.36 ± 5.75

24.01 ± 2.33

58.36 ± 3.21

content

The table shows the mean ± SD (In mg/kg dry weight) of three sets of analysis of defatted whole hull-less pumpkin seed, kernels, and hulls from hulled seed. SD, standard deviation; ND, not detected; NQ, not quantified.

The table shows the mean ± SD (In mg/kg dry weight) of three sets of analysis of defatted whole hull-less pumpkin seed, kernels, and hulls from hulled seed. SD, standard deviation; ND, not detected; NQ, not quantified.

CHAPTER 109

Phenolic Acids in Pumpkin Seed

Cell wall materials associated with bound phenolic compounds may survive upper gastrointestinal digestion conditions, and finally reach the colon. Colonic digestion of such materials by intestinal microflora may release the bulk of the bound phytochemicals, which exert their health benefits locally and beyond after absorption.

In the future, it would be interesting to investigate to what extent the phenolic acids from C. pepo seeds contribute to curing different disorders in humans.

Was this article helpful?

0 0
5 Ways To Get Rid Of The Baby Fat

5 Ways To Get Rid Of The Baby Fat

Many women who have recently given birth are always interested in attempting to lose some of that extra weight that traditionally accompanies having a baby. What many of these women do not entirely realize is the fact that breast-feeding can not only help provide the baby with essential vitamins and nutrients, but can also help in the weight-loss process.

Get My Free Ebook


Post a comment