Steroidal glycosides from Nicotiana tabacum L. seeds and their biological activity

Steroidal glycosides of the spirostane and furostane series have been isolated from the methanolic extract of Nicotiana tabacum L. seeds by using gel filtration on silica gel and chromatography on a silica gel column. They were tentatively named nicotianosides A (1), B (2), C (3), D (4), E (5), F (6), and G (7). It has been shown that nicotianosides A (1), B (2), C (3), and D (4) are 3-O-beta-D-glucopyranoside-; 3-O-alpha-L-rhamnopyranosyl (1-->2)-O-beta-D-glucopyranoside-; 3-O-¿[alpha-L-rhamnopyranosyl (1-->2)].[alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside¿: 3-O-¿[alpha-L-rhamnopyranosyl (1-->2)-alpha-L-rhamnopyranosyl (1-->3)]-alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside¿: neotigogenin, respectively. The structures of nicotianosides E (5), F (6), and G (7) have been established as: 3-O-alpha-L-rhamnopyranosyl (1-->2)-O-beta-D-glucopyranoside; 3-O-¿[alpha-L-rhamnopyranosyl-(1-->2)]-[alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside¿: 3-O-¿[alpha-L-rhamnopyranosyl (1-->2)-[alpha-L-rhamnopyranosyl (1-->3)]-alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside): (25S)-5-alpha-furostane-3 beta, 22 alpha, 26-triol [-26-O-beta-D-glucopyranoside]. Growth-stimulating activities, prevention of virus attacks on tobacco, and a possible mechanism of action were established for the nicotianosides.