Flavan-3-ols and prodelphinidins from Stryphnodendron adstringens

Six flavan-3-ols and eight proanthocyanidins have been isolated from the stem bark of Stryphnodendron adstringens, which is traditionally used in Brazil against various diseases. Two new flavan-3-ols were isolated as epigallocatechin 3-0-(3,5-dimethyl)-gallate and epigallocatechin 3-0-(3-methoxy-4-hydroxybenzoate). Isolation and elucidation of four new proanthocyanidins gave epigallocatechin-(4 beta --> 8)-epigallocatechin 3-O-(4-hydroxy)benzoate epigallocatechin-(4 beta --> 6)-epigallocatechin, gallocatechin-(4 alpha --> 8)-epigallocatechin 3-O-gallate and gallocatechin(4 alpha --> 8)-epigallocatechin 3-O-(4-hydroxy)benzoate. So the bark of S. adstringens is a rich source of proanthocyanidins with biologically active pyrogallol units.