The Invasive Anemone Condylactis sp. of the Coral Reef as a Source of Sulfur- and Nitrogen-Containing Metabolites and Cytotoxic 5,8-Epidioxy Steroids.

The Condylactis -genus anemones were examined for their proteinaceous poisons over 50 years ago. On the other hand, the current research focuses on isolating and describing the non-proteinaceous secondary metabolites from the invasive Condylactis anemones, which help take advantage of their population outbreak as a new source of chemical candidates and potential drug leads. From an organic extract of Condylactis sp., a 1,2,4-thiadiazole-based alkaloid, identified as 3,5-bis(3-pyridinyl)-1,2,4-thiadiazole ( 1 ), was found to be a new natural alkaloid despite being previously synthesized. The full assignment of NMR data of compound 1 , based on the analysis of 2D NMR correlations, is reported herein for the first time. The proposed biosynthetic precursor thionicotinamide ( 2 ) was also isolated for the first time from nature along with nicotinamide ( 3 ), uridine ( 5 ), hypoxanthine ( 6 ), and four 5,8-epidioxysteroids ( 7 - 10 ). A major secondary metabolite (-)-betonicine ( 4 ) was isolated from Condylactis sp. and found for the first time in marine invertebrates. The four 5,8-epidioxysteroids, among other metabolites, exhibited cytotoxicity (IC 50 3.5-9.0 μg/mL) toward five cancer cell lines.