A phytochemical investigations on the n-butanol fraction of Lavandula angustifolia Mill. residues resulted in the isolation of ten compounds, including two new ones, 4,4'dimethoxy-2,2'di-O-β-d-glucopyranosyl-truxinate (1) and 2-(β-d-glucosyloxy)-trans-cinnamic acid butyl ester (2), along with eight known compounds. The structures of compounds were confirmed by NMR and HR-ESI-MS techniques and comparison with published data. The NMR data for 3 were attributed for the first time. Compound 2 was proofed to be a natural compound in plant rather than a butyl ester artifact formed by esterification reaction with butanol by comparative HPLC-DAD analysis with the ethanol extract which was obtained prior to the application of butanol. All isolated compounds were evaluated for their antioxidant and anti-hypoglycaemic activities. Among them, compounds 4 and 5 showed strong anti-oxidant activities against DPPH with IC50 values of 12.99 and 31.74 μM, respectively. Compound 5 exhibited moderate inhibitory activity against PTP1B with an IC50 value of 31.28 μM.
Keywords: Lavandula angustifolia Mill.; PTP1B; antioxidant activity; chemical constituents; cinnamic acid esters; structure elucidation; truxinic acid derivative.