Studies on the constituents of bark of Parameria laevigata Moldenke

Abstract

One new trimeric proanthocyanidin, epicatechin-(2beta-->O-->7, 4beta-->6)-epicatechin-(2beta-->O--->7, 4beta-->8)-epicatechin (5) and two new tetrameric proanthocyanidins, epicatechin-(2beta-->O-->7, 4beta-->8)-[epicatechin-(4beta-->6)]-epicatechin-(4beta-->8)-epicatechin, named as parameritannin A-1 (6), and epicatechin-(2beta-->O-->5, 4beta-->6)-[epicatechin-(2beta-->O-->7, 4beta-->8)]-epicatechin-(4beta-->8)-epicatechin, named as parameritannin A-2 (7), have been isolated from the bark of Parameria laevigata Moldenke (Apocynaceae) along with the two known dimers, proanthocyanidin A-2 (1) and proanthocyanidin A-6 (2), and two trimers, cinnamtannin B-1 (3) and aesculitannin B (4). These structures were elucidated by spectral and chemical evidence.