Odoamide, a cytotoxic cyclodepsipeptide from the marine cyanobacterium Okeania sp.

The bioassay-guided fractionation of the Okinawan marine cyanobacterium Okeania sp. led to the isolation of the 26-membered cyclodepsipeptide odoamide (1). The gross structure of 1 was determined by 1D and 2D NMR analyses, whereas its absolute stereochemistry was determined using a variety of different methods, including synthesis and chemical degradation followed by chiral HPLC analysis. Notably, odoamide (1) showed potent cytotoxicity against HeLa S3 human cervical cancer cells with an IC50 value of 26.3 nM.

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