Polyphenolic constituents from the aerial parts of Thymus quinquecostatus var. Japonica collected on Ulleung Island

Phytochemical investigation on the polar constituents in the aerial parts of Thymus quinquecostatus var. japonica resulted in the isolation of three flavonoids along with four known phenolic components. The isolated compounds were characterized as 2(S)-5,7,3',5'-tetrahydroxyflavanone (1), (+)-taxifolin (2), (+)-aromadendrin (3), rosmarinic acid (4), caffeic acid (5), protocatechuic acid (6), and protocatechuic aldehyde (7) from comparisons of their physicochemical and spectroscopic data (¹H-, ¹³C-NMR, two-dimentioal NMR, and mass spectrometery) with those of authentic samples and reference data. This is the first report on the isolation of compounds 1-7 from T. quinquecostatus var. japonica. In addition, compounds 2 and 4 exhibited the most potent pancreatic lipase inhibitory activities in a concentration-dependent manner with IC₅₀ values of 15.4±0.8 and 62.8±2.7 μM, respectively.