Flavonoids as drugs at the small intestinal level.

Flavonoids represent a biologically active class of secondary plant compounds. For selected members there is convincing evidence regarding their beneficial effects on human health. Accordingly these compounds are tested as supporting or alternative therapies for a number of diseases such as cancer or type-II diabetes. Subsequent to their ingestion a first site of interference are digestive enzymes and transporters in the small intestine. Through interactions with glucose transporters in the apical membranes of enterocytes flavonoid glycosides and also some aglycones appear to reduce postprandial hyperglycaemia in diabetic patients. Moreover, many flavonoids have been shown to interfere with ATP-dependent drug-efflux transporters which are relevant for the resistance of cancer cells versus various cytostatic drugs and makes them candidates to overcome multidrug-resistance.