Tannins and Related Polyphenols of Melastomataceous Plants. VIII.Nobotanins L, M and N, Trimeric Hydrolyzable Tannins from Tibouchina semidecandra

Abstract

Three new hydrolyzable tannins, nobotanins L, M and N, were isolated from the water-soluble portion of the leaf extract of Tibouchina semidecandra, and their trimeric structures were elucidated from spectral and chemical evidence. Nobotanins L and N exist as equilibrium mixtures of four anomers due to the presence of two unacylated anomeric centers.