Cassan Diterpenoids With Ca_v3.1 T‐type Calcium Channel Inhibitory Activity From the Seeds of <i>Caesalpinia decapetala</i> (Roth) Alston

Phytochemical investigation of the 80% ethanol extract from the seeds of Caesalpinia decapetala (Roth) Alston led to the identification of nine compounds, which included three new cassane-type diterpenoids, caesalpideplins A-C (1-3), and six known analogs (4-9). The structures of 1-3 were determined using a comprehensive analytical method that involved detailed infrared, high-resolution electrospray ionization mass spectrometry studies, as well as proton, carbon-13, and two-dimensional nuclear magnetic resonance analyses. The absolute configuration of 1 was established through X-ray single crystal diffraction analysis, while the absolute configurations of 2 and 3 were determined by comparing their calculated and experimental electronic circular dichroism data. Additionally, compounds 3, 4, 5, 7, and 8 demonstrated notable inhibitory activity against the Ca_v3.1 T-type calcium channel with half-maximal inhibitory concentration values of 23.13, 9.46, 29.53, 34.02, and 24.33 µM, respectively. These results suggest that cassane-type diterpenoids may have potential therapeutic applications for diseases related to the Ca_v3.1 calcium channel.