RESUMEN
Objective: To study the chemical constituents of a kind of soft coral Lobophytum sp. collected from Xisha islands of China. Methods: Isolation and purification of the chemical constituents were performed by silica gel and ODS gel column chromatographies as well as HPLC. Their structures were determined on the basis of physicochemical properties and spectroscopic methods. Results: Six diterpenoids were obtained in 95% ethanol extract from Lobophytum sp., including chilobolide B (1), (1S*,3S*,4S*,7E,11E)-3,4-epoxy-13-oxo-7,11,15-cembratriene (2), (2E,4E,7R,8S,12Z)-1-isopropylcyclotetradeca-4,8-dimethyl-7-hydroxy-1,3,11-triene-8,12-carbolactone (3), (2E,4E,8S,12Z)-1-isopropyl-4,8-dimethyl-7-oxocyclotetradeca-l,3,11-triene-8,12-carbolactone (4), sarcrassin D (5), and laevigatol B (6). Conclusion: Compound 1 is a new compound named chilobolide B. Compounds 2-4 are obtained from Lobophytum sp. for the first time.