Catechin-3-O-rhamnoside chain extender units in polymeric procyanidins from mangrove bark

Abstract

Acid-catalysed cleavage of ‘purified’ condensed tannin isolates from Bruguiera gymnorrhiza (tancang) bark in the presence of phloroglucinol as a capture nucleophile gave, in addition to the expected procyanidin- and prodelphinidin-phloroglucinol adducts, 3-O-α-l-rhamnopyranosyl-(+)-catechin-(4α→2)-phloroglucinol, thus providing evidence for covalently bonded glycoside moieties in the chain extender units of mangrove bark tannins. Keywords: Bruguiera gymnorrhiza; Rhizophoraceae; mangrove; bark; condensed tannins; proanthocyanidins; 3-O-α-l-rhamnopyranosyl-(+)-catechin-(44α→2)-phloroglucinol; flavan-3-ol glycosides.