Sterols of the spongeTethya amamensis: Occurrence of (24E)‐24‐ethylidenecholesta‐5,7‐dienol, (24E)‐24‐propylidenecholesta‐5,7‐dienol, and (24Z)‐24‐propylidenecholesta‐5,7‐dienol

The spongeTethya amamensis, collected from Kagoshima Bay, Japan, contained at least 24 sterols, including Δ(5)-sterols (82.2% of total sterols) and Δ(5, 7)-sterols (17.8%). The predominant sterols were cholesterol (29.0%), cholesta-5,22-dienol (13.8%), 24-methylcholesta-5,22-dienol (10.9%), 24-methylenecholesterol (8.3%), 24-methylcholesta-5,7,22-trienol (6.8%), 24-ethylcholest-5-enol (6.1%), and isofucosterol *4.1%). Combined gas liquid chromatography-mass spectrometry suggested the presence of 3 uncommon sterols, (24E)-24-ethylidenecholesta-5,7-dienol, (24E)-24-propylidenecholesta-5,7-dienol, and (24Z)-24-propylidenecholesta-5,7-dienol as minor components. The sterols ofT. amamensis also contained small amounts of 24-norcholesta-5,7,22-trienol and (24Z)-24-ethylidenecholesta-5,7-dienol.