Steroidal saponins from the roots of Chlorophytum borivilianum

In continuation of our phytochemical investigation of the dried roots of Chlorophytum borivilianum [1], we have further isolated six new steroidal saponins. The n-BuOH layer of an ethanol extract of the roots was submitted to several chromatographic steps (VLC, Flash, MPLC) over silica-gel and reversed phase silica-gel RP-18, yielding two new furostanol and four new spirostanol steroidal saponins. The structures were determined mainly by 600MHz 2D NMR techniques (COSY, TOCSY, NOESY, HSQC, HMBC) and FABMS mass spectrometry as: (25R)-3β,5α,22α-22-methoxy-furostan-3,22,26-triol 3-O-β-D-xylopyranosyl-(1→3)-[β-D-glucopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranosyl 26-O-β-D-glucopyranoside (1) and its structural analogue (2) having the same sugar sequence and (25R)-3β,5α-furost-ene-20(22)-3,26-diol as aglycone, tigogenin 3-O-β-D-xylopyranosyl-(1→3)-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (3), 3β,5α-spirost-ene-25(27)-3-ol 3-O-α-L-rhamnopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→3)-α-L-arabinopyranosyl-(1→3)-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→6) ]-β-D-galactopyranoside (4) and its structural analogue (5) having the same sugar sequence and tigogenin as aglycone, 3β,5α-spirost-ene-25(27)-2,3-diol 3-O-β-D-glucopyranosyl-(1→3)-[β-D-glucopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (6). 3, 4 and 5 showed moderate cytotoxicity against HT-29 human cancer cells and moderate insecticidal activity against Helicoverpa armigera.

Acknowledgements: The authors are thankful to IFCPAR-CEFIPRA, New Delhi, India for financial support.

References: 1. Acharya, D. et al (2007) Planta Med. 73: 958.