Cladieunicellins M–Q, New Eunicellins from Cladiella sp.

Five new 7α-hydroxyeunicellin-based diterpenoids, designated as cladieunicellins M–Q (1–5), were isolated from a Formosan octocoral Cladiella sp. The structures of 1–5 were elucidated on the basis of spectroscopic methods and by comparison of the data with those of the related metabolites. Cytotoxicity of metabolites 1–5 against the human leukemia Molt 4 and HL 60 is also described. Among them, compounds 1, 3 and 5 exhibited moderate cytotoxicity toward Molt 4 cells with IC50 values 16.43, 14.17 and 15.55 μM, respectively. Preliminary SAR (structure activity relationship) information was obtained from these compounds and their analogues.