lipid lipid steroid 0 Steroid KEGG:C00377 CHEBI:9263 CHEBI:26768 CHEBI:35341 259.450 steroids C19H31R chebi_ontology a steroid 259.24258 MetaCyc:Steroids C12C(C3C(C(CC3)*)(C)CC1)CCC4C2(CCCC4)C CHEBI:13687 Any of naturally occurring compounds and synthetic analogues, based on the cyclopenta[a]phenanthrene carbon skeleton, partially or completely hydrogenated; there are usually methyl groups at C-10 and C-13, and often an alkyl group at C-17. By extension, one or more bond scissions, ring expansions and/or ring contractions of the skeleton may have occurred. Natural steroids are derived biogenetically from squalene which is a triterpene. organic polycyclic compound