Unusual Steroid Constituents from the Tropical Starfish Leiaster sp

Two polar steroid compounds, taurochenodeoxycholic acid sodium salt (1) and a rare cyclic steroid glycoside luzonicoside A (2), were isolated from the tropical starfish Leiaster sp. and identified by extensive NMR and ESIMS techniques. The isolation of primary bile acid 1 is the first report from a representative of the class Asteroidea and on the whole in invertebrates. Its presence confirms the hypothesis about the digestive role of some polar steroids in starfish and possibly demonstrates the parallel evolution of fat emulsifying agents in vertebrates and some starfish. Compound 2 was also obtained from starfish belonging to this genus for the first time. This finding indicates that cyclic steroid glycosides are more widely distributed in starfish than the two species of the genus Echinaster from which they were isolated earlier.