Grapes flavonoids

Impact of Varietal and Environmental Factors on Grape Flavonoids.275... 

Grape flavonoid composition also varies with environmental conditions and... 

FIGURE 20.3. Structure of main classes of grape flavonoids. 

Thousands of polyphenols from fruits (grapes, apples, etc.), vegetables (horse beans), and teas have been identified, many having good coloring properties, especially anthocyanins and some flavonoids. Well-documented reviews discuss the coloring capacities of some polyphenols including procyanidins. - Detailed presentations of anthocyanin and flavonoid properties and analysis are included in Sections 2.3, 4.3, and 6.3. The soluble proanthocyanidins of the colored horse bean Viciafaba L. seed coats were isolated and separated by solvent partition. 

Waterhouse AL, Walzem RL (1997) Nutrition of grape phenolics. In Rice-Evans CA, Packer L (eds) Flavonoids in Health and Disease. Marcel Dekker, New York, p 359... 

Some flavonoids, such as procyanidins, have antidiabetic properties because they improve altered glucose and oxidative metabolisms of diabetic states (Pinent and others 2004). Extract of grape seed procyanidins (PE) administered orally to streptozotocin-induced diabetic rats resulted in an antihyperglycemic effect, which was significantly increased if PE administration was accompanied by a low insulin dose (Pinent and others 2004). The antihyperglycemic effect of PE may be partially due to the insuli-nomimetic activity of procyanidins on insulin-sensitive cell lines. 

Downey MO, Dokoozlian NK and Krstic MP. 2006. Cultural practice and environmental impacts on the flavonoid composition of grapes and wine a review of recent research. Am J Enol ViUc 57 257— 268. 

Freedman and others (2001) determined the effects of purple grape juice and its main flavonoids on the functionality of platelets and the production of NO. They observed that incubation of platelets with diluted grape juice resulted in the inhibition of aggregation, increased production of NO, and decreased production of superoxide. To confirm the relevance of these findings, 20 healthy subjects were supplemented with 7 mL of black grape juice/kg/day for 14 days. The inhibition of platelet aggregation was also observed ex vivo there was an increase in the production of NO from 3.5 1.2 to 6.0 1.5 pmol/108 platelets and a decrease in the release of superoxide, from 29.5 5.0 to 19.2 3.1 arbitrary units. Under these conditions the antioxidant capacity of protein-free plasma increased by 50% (Freedman and others 2001). 

Freedman JE, Parker C 3rd, Li L, Perlman JA, Frei B, Ivanov V, Deak LR, Iafrati MD and Folts JD. 2001. Select flavonoids and whole juice from purple grapes inhibit platelet function and enhance nitric oxide release. Circulation 103 2792—2798. 

This method is also used to measure ex vivo low-density lipoprotein (LDL) oxidation. LDL is isolated fresh from blood samples, oxidation is initiated by Cu(II) or AAPH, and peroxidation of the lipid components is followed at 234 nm for conjugated dienes (Prior and others 2005). In this specific case the procedure can be used to assess the interaction of certain antioxidant compounds, such as vitamin E, carotenoids, and retinyl stearate, exerting a protective effect on LDL (Esterbauer and others 1989). Hence, Viana and others (1996) studied the in vitro antioxidative effects of an extract rich in flavonoids. Similarly, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Wang and Goodman (1999) examined the antioxidant properties of 26 common dietary phenolic agents in an ex vivo LDL oxidation model. Salleh and others (2002) screened 12 edible plant extracts rich in polyphenols for their potential to inhibit oxidation of LDL in vitro. Gongalves and others (2004) observed that phenolic extracts from cherry inhibited LDL oxidation in vitro in a dose-dependent manner. Yildirin and others (2007) demonstrated that grapes inhibited oxidation of human LDL at a level comparable to wine. Coinu and others (2007) studied the antioxidant properties of extracts obtained from artichoke leaves and outer bracts measured on human oxidized LDL. Milde and others (2007) showed that many phenolics, as well as carotenoids, enhance resistance to LDL oxidation. 

Some structural changes of the native flavonoids occur during wine conservation, and one of the most studied of those changes concerns red wine color evolution, called wine aging. It has been demonstrated that as a wine ages, the initially present grape pigments slowly turn into new, more stable red pig-... 

Recently, the possible synergistic interaction between flavonoids has been thoroughly discussed in connection with the cardioprotective effect of red wine and purple grape juice. 

In addition to their possible prooxidant activity (see above) polyphenols and flavonoids may influence cancer cells via their antioxidant properties. Recently, Jang et al. [219] studied cancer chemopreventive activity of resveratrol, a natural polyphenolic compound derived from grapes (Chapter 29). These authors showed that resveratrol inhibited the development of preneoplastic lesions in carcinogen-treated mouse mammary glands in culture and inhibited tumorigenesis in a mouse skin cancer model. Flavonoids silymarin and silibinin also exhibited antitumor-promoting effects at the stage I tumor promotion in mouse skin [220] and manifested antiproliferative effects in rat prostate cancer cells [221]. 

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