Bioactivity-guided isolation of anti-inflammatory constituents from the bark of Streblus zeylanicus

Based on anti-inflammatory activity to evaluate the effects to the release of NO, bio-assay guided separation of the bark of Streblus zeylanicus led to identify fifteen compounds, including four new terpenes (1, 2, 9, and 10), one new pentanoid glycoside (12), one new rumenic ester (13), together with nine known compounds (3–8, 11, 14, and 15). Their structures were elucidated using extensive NMR and HRESIMS spectroscopic data analyses. The stereochemistry of compound 10 was established by comparing the calculated and experimental ECD spectroscopic data. Compounds 1 and 2 showed moderate inhibition on nitric oxide (NO) production, with IC50 values of 10.21 μM and 15.53 μM, respectively.