Neolignan Glycoside and Other Constituents From the Leaves of Ligustrum sinense and Their Anti-Inflammatory Activity

Objectives: The aim of the project was the isolation, structure elucidation, and anti-inflammatory evaluation of compounds from the leaves of Ligustrum sinense Lour. Methods: Chromatographic techniques were used to isolate anti-inflammatory compounds from the methanol extract of L sinense leaves. The structures of compounds were elucidated by analyses of mass spectra, nuclear magnetic resonance data, and Circular dichroism spectra. Compounds were evaluated using anti-inflammatory assays. Results: One new neolignane glucoside, neoligustrume A (1), along with eleven known compounds, ligujaponoside A (2), ligujaponoside B (3), ligustroside (4), oleuropein (5), ligustaloside A dimethyl acetal (6), ligustaloside B dimethyl acetal (7), olivil (8), (+)-cycloolivil (9), kaempferol 3- O-β-D-glucopyranoside-7- O-α-L-rhamnopyranoside (10), oleanoic acid (11), and hydroxytyrosol (12) were isolated from the methanol extract of L sinense leaves. Compounds 2, 3, and 12 showed significant inhibitory NO production with IC50 values of 16.3 ± 0.5, 18.2 ± 1.1, and 15.7 ± 1.9 μM, respectively. Compounds 4-7 and 11 showed moderate inhibitory NO production with IC50 values ranging from 21.4 to 45.0 µM. Moreover, compound 12 showed the most TNF-α inhibition with 58.1 ± 5.7% at a concentration of 50 μM. Conclusions: One new and 11 known compounds were isolated from L sinense. This is the first report of compounds 2-9 from L sinense. Compounds 2, 3, and 12 showed significant inhibitory NO production with IC50 values of 16.3 ± 0.5, 18.2 ± 1.1, and 15.7 ± 1.9 μM, respectively. Compound 12 could be the anti-inflammatory source.