Three New Medicagenic Acid Saponins from Polygala micranthaGuill. & Perr.

Abstract

AbstractThree new medicagenic acid saponins, micranthosides A–C (1–3), were isolated from the roots of Polygala micrantha Guill. & Perr., along with six known presenegenin saponins. Their structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR experiments (1H, 13C, DEPT, COSY, TOCSY, NOESY, HSQC, and HMBC) and mass spectrometry as 3‐O‐β‐D‐glucopyranosylmedicagenic acid 28‐[O‐β‐D‐galactopyranosyl‐(1→4)‐O‐β‐D‐xylopyranosyl‐(1→4)‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐β‐D‐fucopyranosyl] ester (1), 3‐O‐β‐D‐glucopyranosylmedicagenic acid 28‐[O‐6‐O‐acetyl‐β‐D‐galactopyranosyl‐(1→4)‐O‐β‐D‐xylopyranosyl‐(1→4)‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐β‐D‐fucopyranosyl] ester (2), and 3‐O‐{O‐β‐D‐glucopyranosyl‐(1→3)‐O‐[β‐D‐glucopyranosyl‐(1→6)]‐β‐D‐glucopyranosyl}medicagenic acid 28‐{O‐β‐D‐apiofuranosyl‐(1→3)‐O‐β‐D‐xylopyranosyl‐(1→4)‐O‐[β‐D‐apiofuranosyl‐(1→3)]‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐β‐D‐fucopyranosyl} ester (3). Compounds 1–3 were evaluated against HCT 116 and HT‐29 human colon cancer cells, but they did not show any cytotoxicity.