| Marine natural product is an important part of Natural Pharmaceutical Chemistry.Due to the different living environment between marine and terrestrial organisms,the biosynthesis pathways of marine-derived secondary metabolites showed significantly different characteristic from those of terrestrial organisms focusing on structural and biological diversity.Marine-drived natural organism materials showed diverse structures and biological properties,which played a vital role in exploring leading compounds and new drugs.We have systematically investigated the chemical composition and biological effects of one species of marine invertebrates(Litophyton nigrum)collected off the coast of South China Sea.From these organisms(Litophyton nigrum)collected off from Xisha Island,Sanya,Hainan Province,China,thirteen new compounds including seven nardosinene-type、one nornardosinene-type、three neolemnene-type、one seconeolemnene-type skeleton sesquiterpenes and one uncommon bis-sesquiterpenoid together with twenty-three known compounds were isolated and purified by comprehensive chromatography.36 compounds were isolated and determined including Their structure were elucidated on the basis of extensive spectroscopic analyses of UV、IR、1D/2DNMR、HRMS、ORD data.The absolute configurations of new compounds were determined by the applications of the modified Mosher’s method,the X-ray diffraction analysis using Cu Ka radiation,TDDFT-ECD calculation,and chemical transformation.We have carried out extensive bioactive screening on the isolates and found a group of compounds with potent biological activities.New compounds 3,9 and 10 showed medium cytotoxic activity against SNU-398.Compounds 19,22-26,29-33 exhibited weak inhibitory effect on BRD4(1).In this study,nardosinene-type、nornardosinene-type、neolemnene-type and seconeolemnene-type sesquiterpenes were firstly isolated and reported from Litophyton nigrum.It is also worth pointing out that a rare and intriguing sesquiterpene dimer was isolated from the soft corals of this genus.The bioactive screening tests showed that four compounds showed moderate cytotoxic activities against SNU-398,two compounds showed moderate cytotoxic activities against HT-29,Capan-1 and SNU398,elven compounds showed weak inhibitory activities against BRD4(1),and one compound showed weak inhibitory activity against PTP1B.This study not only improves our understanding of the chemical composition of the above biological materials,but also provides molecule template for the discovery of anti-tumor marine lead compounds and further research and utilization of marine biological resources. |
