Three new bioactive diterpenoids from the roots of Croton crassifolius

Phytochemical investigation of Croton crassifolius led to the isolation of two new halimane diterpenoids (1 and 2), a new nor-clerodane diterpenoid (3), along with three known analogues (4–6). Their structures including absolute configurations were elucidated by spectroscopic analysis, single-crystal X-ray diffraction, and CD analysis. All isolates were evaluated for their inhibitory effects on the nitric oxide (NO) production induced by lipopolysaccharide (LPS) in RAW264.7 macrophage cells, and compound 1 exhibited moderate inhibition of NO production with an IC₅₀ value of 25.8 ± 0.9 μM.