Terpenoids, flavonoids and caffeic acid derivatives from Salvia viridis L. cvar. Blue Jeans

Abstract

Three diterpenoids, 1-oxomicrostegiol (1), viroxocin (2), viridoquinone (3), were isolated from the roots of Salvia viridis L. cvar. Blue Jeans. Five known diterpenoids, microstegiol (4), 7α-acetoxy-14-hydroxy-8,13-abietadiene-11,12-dione (5; 7-O-acetylhorminone tautomer), 7α,14-dihydroxy-8,13-abietadiene-11,12-dione (6; horminone tautomer), ferruginol and salvinolonyl 12-methyl ether (7) were also found in the roots together with 1-docosyl ferulate (8), and a mixture of 2-(4'-alkoxyphenyl) ethyl alkanoates (9). Two lupane triterpenoids, 2α-acetoxy-lup-20(29)-en-3β-ol (10), and 3β-acetoxy-lup-20(29)-en-2α-ol (11) were found in the aerial parts together with known compounds, lup-20(29)-ene-2α,3β-diol (12), ursolic acid, oleanolic acid, β-sitosterol and β-sitosterol glucoside. A known phenylpropanoid, trans-verbascoside (or acteoside; 13), was the main constituent in the polar fraction of the aerial part, and it is now reported in the genus Salvia for the first time. Other polyphenolic compounds were cis-verbascoside (14), leucosceptoside A (15), martynoside (16), caffeic acid, 6-O-caffeoyl-glucose (18), rosmarinic acid, salidroside, luteolin-7-O-α-rhamnopyranosyl-(1→6)-β-galactopyranoside, luteolin-7-O-β-galactopyranoside, luteolin-7-O-α-rhamnopyranosyl-(1→6)-β-glucopyranoside, luteolin-7-O-β-glucopyranoside, and apigenin-7-O-β-glucopyranoside. The structures were determined by 1D-, 2D-NMR and HR-ESI-MS techniques. Compounds 6, 10, ferruginol, ursolic acid and oleanolic acid exhibited antibacterial activity against Enterococcus faecalis (ATCC 775) with MIC 50 μM, 25 μM, 50 μM, 12.5 μM, 12.5 μM respectively. Ferruginol, ursolic acid and oleanolic acid were also active against Staphylococcus aureus (ATCC 6571), and Bacillus cereus (ATCC 2599) with MIC 12.5-50 μM. 4 was also active against S.aureus (ATCC 6571) with MIC 50 μM. These values are consistent with previous studies on the antimicrobial activity of Salvia diterpenoids.

Keywords: Abietane; Antibacterial activity; Diterpenoid; Flavonoid; Lamiaceae; Lupane; Phenylpropanoid; Salvia viridis L.; Triterpenoid; Verbascoside.