Structural analysis of oleanane-type saponins from the roots of Wisteria frutescens

In this paper, we report about the isolation of six oleanane-type saponins fromthe roots of W. frutescens. Their structures were established by a de-tailed 600 MHz NMR analysis including 1D and 2D NMR (1H,13CNMR, COSY, TOCSY, NOESY, HSQC, and HMBC) experiments and mass spectrometry as two previously undescribed triterpenoid saponins (1-2) (Fig. 1) and four known ones: 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranosyl-(1→2)-β-D-glucurono-pyranosyl-22-O-acetyl-3β,22β,24-trihydroxyolean-12-en-30-oic acid(3)(wistariasaponinG),[6]3-O-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranosyl-(1→2)-β-D-glucuronopyranosyl wistariasapogenol A(wistariasaponin A),[5]3-O-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranosyl-(1→2)-β-D-glucuronopyranosyl soyasapogenol B(wistariasaponin C),[5]and 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→2)-β-D-glucuronopyranosyl soyasapogenol B(azukisaponin V). The structural analysis of the native form of wistariasaponin G is described for the first time.