Anti-inflammatory kaurane diterpenoids of Erythroxylum bezerrae

Five unusual kaurane diterpenes, designated as bezerraditerpenes A-E (1-5), along with six known ones (6-11), were isolated from the hexane extract of the stems of Erythroxylum bezerrae. Their structures were elucidated based on the interpretation of the NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis. The anti-inflammatory potential of the diterpenes 1-11 was screened through cellular viability and lipopolysaccharide (LPS)-induced nitric oxide (NO) production on murine macrophage-like cells RAW 264.7. Diterpene 6 (cauren-6 beta-ol) showed potent cytotoxicity and increased ability to inhibit NO production. Diterpenes 1 (bezerraditerpene A), 2 (bezerraditerpene B), and 8 (ent-kaur-16-ene-3 beta,15 beta-diol) exhibited the same significant anti-inflammatory activity with NO CI50 inhibition (3.21-3.76 mu M) without cytotoxicity, in addition to decreasing the levels of pro -inflammatory cytokines TNF-alpha and IL-6 in LPS-induced RAW264.7 cells.