Teucrium polium Phenylethanol and Iridoid Glycoside Characterization and Flavonoid Inhibition of Biofilm-Forming Staphylococcus aureus

Abstract

The chemical composition and biofilm regulation of 15 metabolites from Teucrium polium are reported. Compounds were isolated from a CH2Cl2-MeOH extract of the aerial parts of the plant and included iridoid and phenylethanol glycosides and a monoterpenoid, together with nine known compounds. The structures were elucidated based on standard spectroscopic (UV, (1)H and (13)C NMR), 2D NMR ((1)H-(1)H COSY, HMQC, HMBC, and NOESY), and/or LC-ESIMS/MS data analyses. Inhibition of the biofilm-forming strain Staphylococcus aureus was observed with exposure to compounds 7 and 8.

Iridoid glycoside permethylation enhances chromatographic separation and chemical ionization

“…Moreover, these data revealed that 2 is similar to 1 except for an absence of the monosaccharide attached to position C‐5 of the basic skeleton; the presence of a methoxy group in 2 is supported by ion peaks at m/z 195, 155 and 127. In combination with previous NMR analyses of 7,8‐cyclopentene‐type IGs for stereochemical determination, the structure of 2 was assigned as teuhircoside; (1 S )‐5 α ‐methoxy‐1‐( β ‐D‐glucopyranosyloxy)‐5,9 α ‐dihydro‐8‐methylcyclopenta[c]pyran‐5(1 H )‐one.…”

“…Diagnostic MS/MS fragments allowed for the identification of IG components as well as plausible sugar‐iridoid linkages. In combination with previous NMR analyses of 7,8‐cyclopentene‐type IGs for stereochemical determination, 1 was assigned as teucardoside; (1 S )‐5 α ‐[(6‐deoxy‐ α ‐L‐mannopyranosyl)oxy]‐1‐( β ‐D‐glucopyranosyloxy)‐5,9 α ‐dihydro‐8‐methylcyclopenta[c]pyran‐5(1 H )‐one.…”

“…(c)). In combination with previous NMR analyses of 7,8‐cyclopentene‐type IGs for stereochemical determination, 3 was assigned as 1 α ‐( β ‐D‐glucopyranoxy)‐7 α ,8 α ‐epoxy‐5 β ,6 α ‐dihydroxy‐8‐methyl‐1,5,6,7,8,9 β ‐hexahydrocyclopenta[ c ]pyran.…”

“…Based on the fragmentation pattern and previously reported NMR data, 4 is similar to 1 except for a dihydropyran unit opening at an ether linkage and unsaturation of the C9–C1 bond. In combination with previous NMR analyses of 7,8‐cyclopentene‐type IGs for stereochemical determination, 4 was assigned as 1 α ‐( β ‐D‐glucopyranoxy)‐7 α ,8 α ‐epoxy‐5 β ,6 α ‐dihydroxy‐8‐methyl‐1,5,6,7,8,9 β ‐hexahydrocyclopenta[ c ]pyran.…”

“…Teucrium polium, a member of the Lamiaceae family, is a traditional medicinal herbal with solvent extracts exhibiting antibacterial and antitumor activity . In addition to the expected chemical profile of flavonoids and phenylpropanoid glycosides, aerial portions of the plant contain a less common class of compounds called iridoid glycosides (IGs) . The name originates from the ant genus Iridomyrmex , from which the original iridoid structure was identified .…”