Tuaimenals B–H, Merosesquiterpenes from the Irish Deep-Sea Soft Coral Duva florida with Bioactivity against Cervical Cancer Cell Lines

[Image: see text] Previous chemical investigation of the Irish deep-sea soft coral Duva florida led to the identification of tuaimenal A (10), a new merosesquiterpene containing a highly substituted chromene core and modest cytotoxicity against cervical cancer. Further MS/MS and NMR-guided investigation of this octocoral has resulted in the isolation and characterization of seven additional tuaimenal analogs, B–H (1–7), as well as two known A-ring aromatized steroids (8, 9), and additional tuaimenal A (10). Tuaimenals B, F, and G (1, 5, 6), bearing an oxygen at the C(5) position, as well as monocyclic tuaimenal H (7), show increased cervical cancer inhibition profiles in comparison to that of 10. Tuaimenal G further displayed potent, selective cytotoxicity with an EC(50) value of 0.04 μM against the C33A cell line compared to the CaSki cell line (EC(50) 20 μM). These data reveal the anticancer properties of tuaimenal analogs and suggest unique antiproliferation mechanisms across these secondary metabolites.