Hydroxygeranyllinalool glycosides from tobacco exhibit antibiosis activity in the tobacco budworm [Heliothis virescens (F)]

Leaves of Tobacco Introduction TI-165 were found to be resistant to tobacco budworm [Heliothis virescens (F.)] attack. HPLC profiles of leaf extracts showed that TI-165 had relatively high levels of two components (A and B) that were absent in susceptible varieties. Compounds A and B were isolated from TI-165 by a combination of preparative C-18, silicic acid column, and centrifugal thin-layer chromatography. They were identified as diterpene glycosides: compound A, 16-hydroxy-geranyllinalyl-3-O-[alpha-L-rhamnopyranosyl(1-4)]-beta-D-glucopyranoside-16-O-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranoside; compound B, 16-hydroxygeranyllinalyl-3-O-[alpha-L-rhamnopyranosyl(1-->4)]-beta-D-glucopyranoside-16-O-[alpha-L-rhamnopyranosyl(1-->6)]-[alpha-L-rhamnopyranosyl(1-->4)]-beta-D-glucopyranoside (hydroxygeranyllinalool glycosides). Budworm bioassays with whole tobacco leaves and purified mixtures of A and B showed significant correlation between larval weights and levels of A and B. HPLC analyses of freeze-dried leaves of 68 Nicotiana species indicated that 26 species had high levels of diterpene glycosides identical to or related to A and B.