Chromatographic separation of crude extracts from the leaves and stems of Croton poomae Esser led to the isolation of two new clerodane diterpenes crotonolide K (1) and furocrotinsulolide A acetate (2) and six known clerodane diterpenes (3-8), together with twelve known compounds (9-20). Their structures were established from spectroscopic analysis. The clerodane diterpenoids 1-8 were evaluated for inhibition of nitric oxide (NO) production in LPS-activated RAW 264.7 macrophages. Compounds 1, 2, 5, 7 and 8 showed potent inhibitory effects, with IC50 values ranging from 32.19 to 48.85 μM, which is better than both the standard drugs indomethacin (154.5 μM) and dexamethasone (56.28 μM).
Keywords: Anti-inflammatory; Croton poomae; clerodane diterpenoids; nitric oxide.