New steroidal glycosides from the rhizome of Anemarrhena asphodeloides

Abstract

Two new steroidal saponins, timosaponin X (1) and timosaponin Y (2), and one new pregnane glycoside, timopregnane B (3), were isolated from the rhizomes of Anemarrhena asphodeloides, as well as three known compounds 25S-timosaponin BII (4), protodesgalactotigonin (5), and timosaponin BII-a (6) isolated from this plant for the first time. By the detailed analysis of 1D, 2D NMR, MS spectra, and chemical evidences, the structures of new compounds were elucidated as 26-O-β-d-glucopyranosyl-(25S)-5β-22-methoxy-furost-3β,26-diol 3-O-β-d-glucopyranosyl-(1 → 2)-α-l-arabinopyranoside (1), 5β-pseudo-spirost-3β,15α,23α-triol 3-O-β-d-glucopyranosyl-(1 → 2)-β-d-galactopyranoside (2), (5β,17α)-Δ¹⁶⁽¹⁷⁾-20-one-pregn-2β,3β-diol 3-O-β-d-glucopyranosyl-(1 → 2)-β-d-galactopyranoside (3).

Keywords::

• Anemarrhena asphodeloides
• steroidal saponin
• pregnane glycoside
• NMR

Acknowledgments

The investigation was financially supported by National Natural Science Foundation of China (No. 81274053) and Major National Science and Technology Projects (Grant Nos 2009ZX09102-106 and 2011ZX09102-002-09). The NMR spectra were recorded at the National Center of Biomedical Analysis. The assistance of the staff is also gratefully acknowledged.