Distribution of unusual cholesterol precursors, 4-methyl- and 4, 4-dimethylsterols with δ8 unsaturation, in gonads of marine archaeogastropods.

: In the present study, we show that four unusual cholesterol precursors, 5α-cholesta-8,14-dien-3β-ol, 4-methyl-5α-cholesta-8,24-dien-3β-ol (4-methylzymosterol), 4,4,14-trimethyl-5α-cholesta-8,24-dien-3β-ol (lanosterol), and 4,4-dimethyl-5α-cholesta-8,24-dien-3β-ol (4,4-dimethylzymosterol) are present in testes of the limpet Cellana grata, which is part of one of the most primitive gastropod families (Nacelllidae Family). The distribution of these sterols in testes and ovaries of four dominant species of limpets, Cellana grata, Cellana toreuma, Nipponacmea concinna, and Nipponacmea fuscoviridis, was examined by capillary gas chromatography-mass spectrometry. Based on the data, we discuss about the biological roles and possible application as bio-resources of these sterols. This is the first identification of 5α-cholesta-8, 14-dien-3β-ol, 4-methylzymosterol, and 4,4-dimethylzymosterol in marine invertebrate gonads.