Malyngamide X: the first (7R)-lyngbic acid that connects to a new tripeptide backbone from the Thai sea hare Bursatella leachii.

Malyngamide X (1), the first (7R)-lyngbic acid connected to a new tripeptide backbone, was isolated from the Thai sea hare Bursatella leachii. The gross structure of 1 was established on the basis of 1D and 2D NMR and mass spectroscopic data. Combination of the NMR spectroscopic experiments with alpha-methoxy-alpha-(trifluoromethyl)phenylacetic acid esters, 2,2,2-trifluoro-1-(9-anthryl)ethanol chiral solvating agent, and molecular mechanics of 1 and the synthetic molecular fragments allowed us to determine the absolute stereochemistry of all six stereogenic centers without hydrolytic degradation of the compound. Compound 1 displayed moderate cytotoxic, antitubercular, and antimalarial properties.