Therapeutic potential of flavonoids

Wang, H. K., The therapeutic potential of flavonoids. Expert Opin. Investig. Drugs (2000) 9(9), 2103-2119. 

The therapeutic potential of flavonoids has been investigated in various animal and human models. Their role in preventing inflammation, carcinogenesis, and cardiovascular diseases has been established. They have been reported to have antiangiogenic, antimetastatic, cardioprotective effects. A large clinical study reported that flavonoids may decrease mortality due to coronary heart disease [1]. All these studies are promising and indicate that flavonoids can be essential food compounds. However, most of the research conducted so far involves in vitro studies therefoie, it is difficult to draw definite conclusions about the usefulness of flavonoids in the diet. 

Chapters 8-11 are devoted to consideration of two main classes of phytochemicals Chapter 8 centers on organosulfur compounds from the Allium genus, and their role in cancer prevention, while subsequent chapters are devoted to polyphenols and their wide-ranging effects against cancers, cataracts, and cardiovascular disease. Chapter 9 examines the cancer-protective and therapeutic potential of polymethylated flavonoids such as occur in citras, while Chapter 10 summarizes recent cancer chemopievention research in an area particularly relevant to the British and Chinese backgrounds of the editors, notably tea. A much less well-studied area, that of cataracts and their prevention by dietary flavonoids, is presented in Chapter 11. 

At present, many natural and synthetic chelators have been studied as potential pharmacological agents for the treatment of iron or copper overload under various pathophysiological conditions. (The chelating activity of flavonoids was already discussed above and the application of chelators in thalassemia and some other pathologies is considered in Chapter 31.) There are specific thermodynamic demands to chelators to be efficient antioxidants [369], We will consider just several chelators of potential therapeutic importance. 

Despite interest in the anti-microbial and anti-insect activities of flavonoid C-glycosides (e.g. from maize), and the potential therapeutic value of isoflavone C-glycosides such as genis-tein 8-C-glucoside (Fig. 6) or puerarin from Pueraria lobata, no plant gene encoding a C-glycosyltransferase has yet been cloned. 

Compounds with different structures but with the same therapeutic activity isolated from different plant species act as active moieties for the treatment of particular diseases. Some of these compounds have been abandoned due to toxicity but these compounds apparently do not cause serious adverse effects. Some of these active principles originate from edible plants and their inclusion in the diet would undoubtedly be of some value because of their hypocholesterolemic potential. Several phytoconstituents including inulin, pectin, gugglu lipids, flavonoids, ginkoloids, saponins, tannins, and others obtained from various plant sources have proven hypolipidemic potentials as has been further explained in Tables I and II. The chemical structures of a few potential phytoconstituents with hypolipidemic activity are shown in Figure 2. It is hoped that as new additions are made to the list of these active compounds causing only minimum untoward side effects, these naturally... 

The involvement of oxidative stress in AD has opened a new door for potential therapeutic targets. In this regard, several antioxidants are currently in clinical trials such as Idebenone, a-Lipoic acid, acetyl-L-carnitine (ALC), vitamin E, vitamin C, flavonoids, P-carotene, gingko biloba, and metal-chelating agents. Idebenone is a metabolic antioxidant and is normally synthesized as part of the mitochondrial oxidative phosphorylation system. Improvements in clinical status after treatment with idebenone have been shown in a dose-dependent manner compared to placebo and tacrine (Thai et al., 2003). 

BDZs are the most widely prescribed class of psychoactive drugs in current therapeutic use, despite the important unwanted side-effects that they produce such as sedation, myorelaxation, ataxia, amnesia, ethanol and barbiturate potentiation, and tolerance. The existence of a new family of ligands with a flavonoid structure was recentlv demonstrated in the... 

Finally, a variety of chemicals, including PAHs, chlorinated biphenyls, and flavonoids were demonstrated to interact with (spectral binding) and to inhibit P450 2A6 (as well as P450 2A13) [477]. This inhibition has relevance to potential use of some of these compounds as therapeutic inhibitors as well as to interactions in the activation of them by P450 2A6 (and 2A13) [351],... 

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