Applications To Health Promotion And Disease Prevention

Legumes have been cultivated for thousands of years, and play an important role in the traditional diets of many regions throughout the world. In particular, beans have been recognized for their high protein content, and more recently for their soluble fiber. In recent years, functional compounds from legume crops, such as flavonoids, have raised a lot of interest (Prati etal. 2007).

FIGURE 115.1

Natural tetraploid of Trifolium pratense L. (Elgi red clover) in the experimentation gardens of Ankara University's Department of Biology in the Faculty of Science (Prof. Sahabettin Elci (left) and Dr Hatice Qolgecen (right)).

FIGURE 115.1

Natural tetraploid of Trifolium pratense L. (Elgi red clover) in the experimentation gardens of Ankara University's Department of Biology in the Faculty of Science (Prof. Sahabettin Elci (left) and Dr Hatice Qolgecen (right)).

FIGURE 115.2

Natural tetraploid of Trifolium pratense L. (Elçi red clover): dried flowers (left); yellow and dark brown seeds of natural tetraploid of T. pratense L. (right).

FIGURE 115.2

Natural tetraploid of Trifolium pratense L. (Elçi red clover): dried flowers (left); yellow and dark brown seeds of natural tetraploid of T. pratense L. (right).

Trifolium pratense contains isoflavonoids, flavonoids, coumarin derivatives, cyanogenic glycosides, volatile oil, saponins, and trace vitamins and minerals. Major isoflavonoids are biochanin A, daidzein, formononetin, and geinstein, which have estrogenic activities. It has therefore been used to ease menopausal symptoms, for the maintenance of the cardiovascular system and improvement of bone health, and for its beneficial effects in breast, ovarian, and prostate cancers. In vitro and in vivo studies, as well as clinical trials, have been conducted in an attempt to find a scientific basis for the usage of red clover extract and isoflavonoids isolated from it. However, studies with methodological faults in clinical trials, small sample sizes, lack of control groups, and vague statistical analyses of the results obtained from the extracts and placebos have caused conflicting outcomes. There are limited numbers of well-designed experiments proposing a decline in menopausal complaints such as hot flashes, and an improvement in bone density and arterial compliance, as well as a decrease in serum lipid levels.

In this chapter, we will first discuss clinical studies involving the application of red clover dietary supplements; this will be followed by discussion of selected in vitro studies (Krenn et al. 2002). Although there are numerous studies on the phytochemical composition and health benefits of Trifolium species, very few studies have dealt with the seed of red clover (Prati et al., 2007).

Limited studies of the seed extract of T. pratense have indicated the presence of the flavonoid compounds quercetin, taxifolin (trans-dihydroquercetin), taxifolin-O-hexos derivatives, hyperoside (quercetin-3-O-galactoside), and isoquercitrin (quercetin-3-O-glucoside), and small amounts of other phenolic compounds, some of which had previously been revealed in aerial parts of the plant. The total flavonoid content in three cultivars of T pratense was examined and compared with the soybean reference cultivar (37G). The highest amount of total flavonoid was determined in the 47F coded T. pratense cultivar as 1.5 mg diosmin/g fresh seed weight. High performance liquid chromatography-diode array detection (HPLC-DAD) analysis of the extract from T pratense (21F, red clover) seeds indicated the presence of four main flavonoid compounds; however, small amounts of other phenolic compounds were also present (Prati et al. 2007).

Another study revealed that quercetin and its glycosides are the major compounds; additionally, soyasaponin I and its 22-O-glycoside, 22-O-diglycosides, and astrogaloside VIII were also determined (Oleszek & Stochmal, 2002). Although the seeds of red clover are not the main source of quercetin and taxifolin derivatives, those flavonoids are the major components of the seeds, along with soyasaponin and its glycosides. Bioactivity of the compound quercetin was studied extensively in in vivo and in vitro studies. In particular, antioxidant, anticarcino-genic, anti-inflammatory, and cardioprotective properties are several biological activities attributed to quercetin. Research on quercetin showed that it has a significant antioxidant effect, which increases the value of the compound, as a function of the chemical structure of quercetin. A number of authors have associated the gastroprotective, anti-inflammatory, anticarcinogenic, and cardiovascular effects to the antihistaminic and antioxidant and free radical scavenging properties of quercetin. Quercetin has been shown to modify eicosanoid biosynthesis and protect low density lipoprotein from oxidation, thus preventing atherosclerotic plaque formation and platelet aggregation, and promoting relaxation of cardiovascular smooth muscle by antihypertensive, anti-arrhythmic effects. Therefore, quercetin might be a significant aid in the prevention of certain diseases, such as cancer, atherosclerosis, and chronic inflammation (Murota & Terao 2003). Anxiolytic and cognitive-enhancing effects of intranasal quercetin liposomes on rats were also reported by Priprem et al. (2008), correlated with the radical scavenging activity of the compound. Quercetin reduces the severity of hypertension in spontaneously hypertensive rats (SHR). Taxifolin, 3,3',4',5,7-pentahydroxi-flavanon has been shown to exhibit anti-inflammatory effects in protection against oxidative cellular injury in rat peritoneal macrophage and human endothelial cells (Sendra et al., 2007). The concentration of these glycosides in seeds of Trifolium species is similar to the concentration in other leguminous plants. Studies revealed multiple health-promoting properties, including plasma cholesterol lowering, anticarcinogenic, hepatoprotective, and antiviral activities (Hayashi et al., 1997). Studies investigating the biological activities of soyasaponin derivatives have been limited to in vitro experiments and a few animal studies.

The high concentration of quercetin and the presence of soyasapogenol B glycosides make the seeds of some Trifolium species a promising plant material to be used in human nutrition as nutraceuticals or food additives.

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Health And Fitness 101

Health And Fitness 101

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