Mollusca sterols

Variation within the phylum Mollusca has been noted before. More species from the order Mesogastropoda again show that squalene and sterols can be synthesized. Although previous work with the class Bivalvia was unable to demonstrate the ability to synthesize steroids, androstane derivatives were metabolized.Detailed studies with the slug Ariolimax (order Stylommato-phora) showed how cholesterol was metabolized to pregnenolone, 17a-hydroxy-pregnenolone, and thus to androstane derivatives. 

Generally the sterols in Mollusca are a complex mixture of Cje-, C27-, C28- and C29-sterols [124]. In the classes of Gastropoda, Bivalvia and Cephalopoda, A -sterols including cholesterol are the most abundant sterols. In the class Amphineura, A7-sterols are predominant in all species, and 5 -cholest-7-en-3)8-ol is the major sterol. Cephalopoda contain cholesterol as about 90% of the total sterols. Gastropoda and Bivalvia also contain cholesterol as the major sterol (50-60%). In some species of Bivalvia, the sterol fraction is a mixture of C27-, C28- and Cjg-sterols, and in some species dihydrobrassicasterol is the major sterol (34-65%). The most... 

Milkova et al. (325) investigated the sterol composition of Black sea organisms belonging to the phyla Coelenterata and Mollusca, in order to study food chains in this ocean and to shed light on the origin of sterols in marine organisms. 

Milkova, T., S. Popov, N. Marekov, I. Stoilov, S. Andreev, and G. Kovachev Sterols from Black Sea Coelenterata and Mollusca. Bull. Soc. Chim. Belg. 89, 1081... 

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