Steroidal glycosides from Petunia hybrida L. seeds and their biological activity.

Abstract

A new plant source containing steroidal glycosides of the furostane and spirostane series has been shown. Ten individual steroidal glycosides (petuniosides) of the spirostane and furostane series have been isolated from Petunia hybrida L. seeds. They differ in the structures of aglycone and oligosaccharide chain, four of them are novel compounds, and their chemical structures have been established. Petuniosides A, C, and E are 3-O-beta-D-galactopyranoside spirostane; 3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside spirostane; and 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside of (25R)-5 alpha-spirostan-3 beta-ol, respectively. Petuniosides B, D, and F are 3-O-beta-D-galactopyranoside spirostane; 3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside spirostane; and 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside of (25R)-5 alpha-spirostane-2 alpha, 3 beta-diol, respectively. Petuniosides E and F are new compounds, and B, C, and D have been detected in the Petunia genus for the first time. Glycosides of the furostane series, petuniosides I and K, are derivatives of (25R)-5 alpha-spirostane-3 beta, 22 alpha, 26-triol, and K and M of (25R)-5 alpha-spirostane-2 alpha, 3 beta, 22 alpha, 26-tetraol. Petuniosides I and L are new compounds, and K and M are known, but have been detected in the Petunia genus for the first time. Growth-stimulating activity has been established for petunioside M. This glycoside has been shown to enhance cucumber resistance to cucumber green eye-sport mosaic virus.