Pregnane glycosides from Solanum nigrum

Abstract

Two new pregnane saponins, solanigroside A (1) and solanigroside B (2), along with two known compounds (3 and 4), were isolated from 60% ethanolic extract of the dried herb of Solanum nigrum L. The structures of 1 and 2 were elucidated as 5α-pregn-16-en-3β-ol-20-one 3-O-β-d-xylopyranosyl-(1 → 3)-O-[α-l-arabinopyranosyl-(1 → 2)]-O-β-d-glucopyranosyl-(1 → 4)-O-[α-l-rhamnopyranosyl-(1 → 2)]-O-β-d-galactopyranoside (1) and 5α-pregn-16-en-3β-ol-20-one 3-O-β-d-glucopyranosyl-(1 → 2)-O-[β-d-glucopyranosyl-(1 → 3)]-O-β-d-glucopyranosyl-(1 → 4)-O-β-d-galactopyranoside (2), respectively, on the basis of extensive spectroscopic analysis as well as comparison with reported spectroscopic data of related compounds. This paper deals with the isolation and structural characterisation of pregnane glycosides from S. nigrum L.

Keywords:

• Solanum nigrum
• Steroidal saponin
• Pregnane saponin
• Solanigrosides A and B

Acknowledgements

The authors are grateful to Professor QiShi Sun of Shenyang Pharmaceutical University for identifying the plant materials, and Ms Qian Li and Mr Yi Dai of the Institute of Traditional Chinese Medicines and Natural Products, Jinan University for measuring all NMR and MS spectra.