Polymeric proanthocyanidins from Psidium guajava

Abstract

From the aqueous acetone extract of the leaves of Psidium guajava L. the flavanols catechin and gallocatechin, the procyanidins B1, B2, B3 and two prodelphinidins (gallocatechin - (4α→8) - catechin; gallocatechin - (4α→8) - gallocatechin) were isolated. A more abundant proanthocyanidin polymer was also isolated, purified and its chemical constitution studied by 13C-NMR and phloroglucinol degradation. The mean molecular weight of the polymer was estimated to be about 9 to 10 flavan-3-ol-units with a ratio of procyanidin: prodelphinidin units at 2:1 some of which are derivatized by gallic acid. © Österreichische Apotheker-Verlagsgesellschaft m. b. H.