Alkaloidal, Megastigmane and Lignan Glucosides fromAntidesma membranaceum (Euphorbiaceae)

Abstract

Two novel alkaloidal glucosides derived from the recently discovered antidesmone (1), together with four known megastigmane and three lignan glucosides, two of which had not previously been described, were isolated from 1-butanol extracts of Antidesma membranaceum (Euphorbiaceae). The structural elucidation of (17RS)-17-(β-D-glucopyranosyloxy)antidesmone (2) and (17RS)-8-deoxo-17-(β-D-glucopyranosyloxy)antidesmone (3) is based on 1H, 13C, COSY, NOESY, HMQC and HMBC NMR spectra, together with LC/ESI-CIDMS and CD data. Determination of the absolute configuration at C-17 was accomplished by comparison with 1H NMR spectroscopic data for alk-2-yl β-D-glucopyranosides, an approach that also proved useful for the megastigmane glucosides blumenyl C β-D-glucopyranoside (4), 3-oxo-α-ionyl β-D-glucopyranoside (5), blumenyl B β-D-glucopyranoside (6) and blumenyl A β-D-glucopyranoside (7). The lignan glucosides lyoniresin-4-yl β-D-glucopyranoside (8), 4′-O-methyllyoniresin-4-yl β-D-glucopyranoside (9) and secoisolariciresin-4-yl β-D-glucopyranoside (10), featuring an unusual glucosylation position, were investigated with the aid of 1H and 2D NMR, CD and MS data.