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 4β,5α-epoxy-7αH-germacr-10(14)-en-6β-ol-1-one, 4β,5α-epoxy-7αH-germacr-10(14)-en,1β-hydroperoxyl,6β-ol, 4β,5β-epoxy-7αH-germacr-10(14)-en,1β-hydroperoxyl,6β-ol and 4α,5β-epoxy-7αH-germacr-10(14)-en,1β-hydroperoxyl,6α-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, (1)H and (13)C NMR) data, as well as two-dimensional NMR ((1)H-(1)H COSY, HMQC, NOESY and HMBC), and ESI-MS analysis. The relative stereochemistry 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 μMol range. Diverse sesquiterpene-skeleton structure and corresponding comprehensive enzyme capacity is discussed.