Biofilm blocking sesquiterpenes from Teucrium polium

The chemical composition and antibacterial activity of Teucrium polium L. (Lamiaceae) were assessed; sixteen compounds were isolated from a CH₂Cl₂/MeOH extract of the aerial parts of the plant including four sesquiterpenes 4 beta,5 alpha-epoxy-7 alpha H-germacr-10(14)-en-6 beta-ol-1-one, 4 beta,5 alpha-epoxy-7 alpha H-germacr-10(14)-en,1 beta-hydroperoxy1,6 beta-ol, 4 beta,5 alpha-epoxy-7 alpha H-germacr-10(14)-en,1 beta-hydroperoxy1,6 beta-ol and 4 beta,5 alpha-epoxy-7 alpha H-germacr-10(14)-en,1 beta-hydroperoxyl,6 alpha-ol, together with seven known sesquiterpenes, one known iridoid glycoside, two known flavonoids, and one known phenylpropanoid glycoside. Structures were elucidated on the basis of spectroscopic (UV, H-1 and C-13 NMR) data, as well as two-dimensional NMR (H-1-H-1 COSY, HMQC, NOESY and HMBC), and ESI-MS analysis. The relative stereochemistiy of the ketone was established by X-ray crystallography, while its absolute configuration was attained by a modified Mosher's method. Antibacterial activity of the crude extract, as well as with four of the isolated metabolites, was observed with Staphylococcus aureus anti-biofilm activity in the low mu Mol range. Diverse sesquiterpene-skeleton structure and corresponding comprehensive enzyme capacity is discussed.