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

Abstract

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).

Keywords: Caesalpinia pulcherrima; cassane diterpenoids; cytotoxicity; pulcherrilactones C and D; α-glucosidase inhibition.