Black Wattle Catechin

Abstract

CONDENSED tannins present in black wattle or commercial ‘mimosa’ extracts from the bark of Acacia mollissima show absorption behaviour (λmax. = 203 and 280 mµ) in the ultra-violet spectrum1, which is typical of the natural catechins and flavan-3.4-diols2 and also of their constituent phenols. Furthermore, the degradation products resulting from the fusion of the tannins with alkali under anhydrous conditions (mainly resorcinol and gallic acid, but also phloroglucinol and protocatechuic acid), and from alkaline permanganate oxidation of the methylated tannins, resemble those degradation products usually obtained by similar methods from flavans3. On such evidence and by analogy with Freudenberg and Maitland's4 earlier concept of ‘quebracho catechin’, one of us previously5 regarded the catechin structure, 3.7.3′.4′.5′-pentahydroxyflavan (I), as a possible prototype of many of the complex tannins present in black wattle extract.