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

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 C₅position, 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 EC₅₀value of 0.04 μM against the C33A cell line compared to the CaSki cell line (EC₅₀20 μM). These data reveal the anticancer properties of tuaimenal analogs and suggest unique antiproliferation mechanisms across these secondary metabolites.