Eight previously undescribed cassane-type diterpenoids from the seeds of Caesalpinia minax.

Abstract

Phytochemical investigation of the seeds of Caesalpinia minax Hance led to the isolation and characterization of twenty-six cassane-type diterpenoids, including eight previously undescribed compounds (1-8). Their structures were elucidated through comprehensive spectroscopic analyses of UV, HR-MS, and NMR data, together with ECD calculations and gauge-including atomic orbital (GIAO) NMR calculations combined with DP4+ probability analysis. Considering the previously reported lipid-lowering and inflammation-related activities of cassane-type diterpenoids, all isolated compounds were evaluated for their effects on proprotein convertase subtilisin/kexin type 9 (PCSK9) secretion in HepG2 cells, as well as glucocorticoid receptor (GR)-, NRF2-, and NF-κB-related reporter assays in A549 cells. Among them, caesalpin T (5) showed a notable inhibitory effect on PCSK9 secretion, with activity comparable to that of the positive control berberine at the tested concentration. In contrast, no significant activities were observed in the reporter assays.