Four New Flavan-4-ol Glycosides from <i>Pneumatopteris pennigera</i>

Abstract

From the fronds of Pneumatopteris pennigera , four new flavan-4-ol glycosides, named pneu- matopterins A, B, C and D, were isolated. Their structures were determined as (2 S ,4 R )-5,7-di-ß-D-glucopyranosyloxy-6-hydroxymethyl-8-methylflavan-4-ol, (2 S ,4 R )-5,7-di-ß-D-glucopyranosyloxy-6,8-dimethylflavan-4-ol, (2 S ,4 R )-5-ß-D-glucopyranosyloxy-7-hydroxy-6-hydroxymethyl-8-methyl-4,2''-oxo-flavan, and (2 S ,4 R )-5-ß-D-glucopyranosyloxy-7-hydroxy-6,8-dimethyl-4,2''-oxo-flavan, respectively, on the basis of spectroscopic data and chemical correlations.