Two new cassane diterpenoids with cytotoxic and α-glucosidase inhibitory activities from Caesalpinia pulcherrima stems

Two previously undescribed cassane diterpenoids, pulcherrilactones C and D (1 and 2), were successfully isolated from the stems of Vietnamese Caesalpinia pulcherrima. In addition, five known compounds (3–7) were also obtained. All isolated compounds were structurally characterised through extensive spectroscopic techniques, including IR, UV, NMR, and HRESIMS, along with ECD analysis. The cytotoxicity of 1–7 against MCF-7 and A549 cell lines, along with their α-glucosidase inhibitory activity, was evaluated. Considering all isolated compounds, compound 1 possessed the strongest cytotoxicity, with IC₅₀ values of 18.16 ± 1.50 µM (MCF-7) and 13.48 ± 0.97 µM (A549). Compounds 6 and 7 displayed pronounced α-glucosidase inhibitory effect (IC₅₀ 39.03 ± 0.66 and 40.69 ± 0.63 µM, respectively), being considerably more active than acarbose (IC₅₀ 160.00 ± 4.50 µM).