FLAVONOID BIOCIDES: PHYTOALEXIN ANALOGUES FROM CONDENSED TANNINS

Article abstract of DOI:10.1016/S0031-9422(00)82256-6

Flavonoids containing a single alkyl chain can be synthesized from condensed tannins by thiolysis with an alkyl thiol to give epicatechin-4-alkylsulphides.A number of flavonoid derivatives were made with side chains ranging from C6 to C16 and tested for fungitoxic and bactericidal activities.Maximum activity was usually found for the decane derivative.Minimum inhibitory concentrations varied with the organism tested, from about 10 ppm for some rapidly growing fungi and Gram-positive bacteria, to over 500 ppm for other fungi and Gram-negative bacteria.The structural and toxicity characteristics of the epicatechin-4-alkylsulphides suggests they are acting as analogues of prenylated isoflavonoid phytoalexins.Key Word Index - Condensed tannins; phytoalexins; flavonoids; antifungal activity; antibacterial activity.