<i>β</i> -amyrin heptadecanoate, a new oleanane triterpenoid with <i>α</i> -glucosidase inhibitory and cytotoxic activities from the leaves of <i>Averrhoa bilimbi</i> L.

A previously unreported oleanane triterpenoid, <i>β</i>-amyrin heptadecanoate (<b>1</b>), was isolated from the leaves of Thai <i>Averrhoa bilimbi</i> (Oxalidaceae), along with five known compounds, <i>β</i>-amyrin (<b>2</b>), <i>β</i>-sitosterol (<b>3</b>), <i>β</i>-sitosterol-D-glucoside (<b>4</b>), <i>β</i>-sitosteryl oleate (<b>5</b>), and <i>α</i>-tocopherol (<b>6</b>). Their structures were elucidated through spectroscopic analysis, including extensive NMR and HRESIMS, and by comparison with the previous literature. All isolated compounds were evaluated for their <i>α</i>-glucosidase inhibitory and cytotoxic activities. Compound <b>6</b> exhibited the highest <i>α</i>-glucosidase inhibition (IC₅₀ of 0.72 ± 1.02 <i>µ</i>M), significantly outperforming the standard acarbose (IC₅₀ of 82.00 ± 0.24 <i>μ</i>M). Furthermore, compound <b>4</b> demonstrated the most potent cytotoxicity against HeLa cells (IC₅₀ of 34.92 ± 0.45 <i>μ</i>M), while compound <b>3</b> exhibited the strongest cytotoxicity towards A549 cells (IC₅₀ of 9.17 ± 0.30 <i>μ</i>M). Additionally, a molecular docking study was conducted on the active <i>α</i>-glucosidase inhibitors to estimate their binding affinities and to identify the ligand-binding sites within the enzyme.