Four new briarane diterpenoids from the gorgonian coral Junceella fragilis

Chemical investigation of the gorgonian coral Junceella fragilis, collected by scuba diving in Taiwan, resulted in the isolation of four new briarane-type diterpenoids, frajunolides A-D (1-4), along with three known briaranes. Their structures were elucidated on the basis of spectroscopic studies, especially 1- and 2D-NMR as well as HR-MS experiments. The inhibitory effect of all isolated metabolites towards superoxide-anion generation and elastase release by human neutrophils in response to formylmethionyl-leucyl-phenylalanine/dihydrocytochalasin B (FMLP/CB) was evaluated.