New anti-inflammatory cembranoid diterpenoids from the Vietnamese soft coral Lobophytum crassum

Four new cembranoid diterpenes lobocrasols A−D (1-4), were isolated from the methanol extract of the soft coral Lobophytum crassum. Their structures were elucidated by spectroscopic analysis and by comparison of the spectroscopic data with those of similar compounds previously reported in literature. The anti-inflammatory effects of isolated compounds were evaluated using NF-κB luciferase and reverse transcription polymerase chain reaction (RT-PCR). Compounds 1 and 2 significantly inhibited TNFα-induced NF-κB transcriptional activity in HepG2 cells in a dose-dependent manner, with IC50 values of 6.30 ± 0.42 and 6.63 ± 0.11 μM, respectively. Furthermore, the transcriptional inhibition of these compounds was confirmed by a decrease in cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) gene expression levels in HepG2 cells.