Two new cembrane-type diterpenoids from the xisha soft coral Lemnalia flava

Further chemical investigation of the South China Sea soft coral Lemnalia flava resulted in the isolation and characterization of two new cembranoids, namely, xishaflavalins G and H (1 and 2), along with three known related compounds (3–5). The structures of the new compounds were elucidated by detailed spectroscopic analysis and by the comparison of their spectroscopic data with those reported in the literature. The discovery of cembrane-type diterpenes from soft coral of the genus Lemnalia was reported for the first time. In addition, compound 5 exhibited moderate inhibitory effects on the ConA-induced T lymphocytes and/or lipopolysaccharide (LPS)-induced B lymphocytes proliferation.