Steroidal saponins from Datura metel

Abstract

Datura metel L. (Solanaceae) is an annual herb that has been widely used in the traditional medicine for the treatment of coughs, bronchial asthma, and rheumatism. Chemical investigation of an acidic methanol extract of the whole plants of D. metel resulted in the isolation of five new steroidal saponins (1-3, 5, and 6), named metelosides A-E, and four known compounds (4, 7-9). Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D NMR and MS spectra. The structures of metelosides A and B were found to be unusual among the reported spirostane-type steroidal saponins due to the presence of the acetamide groups in the molecules. Compounds 2, 4, 5, and 6 were shown to be cytotoxic against three cancer cell lines, including HepG2, MCF-7, and SK-Mel-2 cells. Furthermore, compounds 3, 4, and 7 exhibited modest anti-inflammatory effects through inhibition of NO production in LPS-stimulated BV cells.

Keywords: Datura metel; Furostane; Solanaceae; Spirostane; Steroidal saponin.