Free Sterol Composition of Deep-Sea Holothurian Orphnurgus cf. glaber

The free sterol fraction from the deep-sea holothurian Orphnurgus cf glaber Walsh, 1891, has been isolated and studied by GC–MS. Sterols containing Δ7, Δ0, Δ5, polyunsaturated and 5,8-epidioxy modified cores were found. A high percentage of compounds with polyunsaturated cores distinguish this composition from those of previously studied holothurians. Almost all identified compounds had saturated side chains, which is also a specific feature of this fraction. Peculiarities of biosynthesis and metabolism of the found sterols are discussed.