Procyanidins from Myrothamnus flabellifolia

From the ethyl acetate soluble fraction of an acetone-water extract of the twig tips of Myrothamnus flabellifolia Welw. (Myrothamnaceae), a variety of flavan-3-ols (epicatechin, epigallocatechin and their 3-O-galloylated analogues) and procyanidins (DP <= 3) were isolated and identified for the first time: Procyanidin B3 [catechin-(4 alpha -> 8)-catechin], B4 [catechin-( 4 alpha -> 8)-epicatechin], B6 [catechin-(4 alpha -> 6)-catechin] and catechin-(4 alpha -> 8)-epigallocatechin along with the galloylated analogues B4-3'-O-gallate, procyanidin B2-3'-O-gallate [epicatechin-( 4 beta -> 8)-epicatechin-3-O-gallate], B2-3,3'-di-O-gallate, procyanidin B5-3,3'-O-gallate [epicatechin-3-O-gallate-(4 beta -> 6)-epicatechin-3-O-gallate], catechin-(4 alpha -> 8)-epigallocatechin-3-O-gallate, the trimer procyanidin C1-3 ''-O-gallate[epicatechin-(4 beta -> 8)-epicatechin-(4 beta -> 8)-epicatechin-3-O-gallate] and the new epicatechin-3-O-gallate-(4 beta -> 6)-epicatechin-3-O-p-hydroxybenzoate. The structures were elucidated by 1D- and 2D-NMR experiments of their peracetylated derivatives, partial acid-catalysed degradation with phloroglucinol, ESI-MS and CD spectra.