Abstract
Four undescribed diterpenoids, caesalcritins A-D (1, 2, 5 and 7), along with four known analogues, were isolated from the twigs and leaves of Caesalpinia crista. These diterpenoids belong to five structural subtypes: butenolide-bearing tricyclic 19-norcassanes (1-3), tricyclic cassanes (4 and 5), a furan-fused tricyclic cassane (6), a rosane (7), and an ent-labdane diterpenoid (8). This finding enriches the structural diversity of diterpenoids isolated from C. crista. Their structures were elucidated by HR-MS, 1D/2D NMR and CD spectroscopic analyses. Compound 3 suppressed NO production in LPS-induced RAW 264.7 cells, with an IC50 value of 35.58 ± 0.61 μM, slightly weaker than the positive control L-NMMA (IC50 = 35.26 ± 1.49 μM), which indicates its potential as an inhibitor of LPS-induced NO production.