steroid fundamental parent pregnane 0 288.282 288.51054 C21H36 CAS:481-26-5 CHEBI:8386 InChI=1S/C21H36/c1-4-15-9-11-18-17-10-8-16-7-5-6-13-20(16,2)19(17)12-14-21(15,18)3/h15-19H,4-14H2,1-3H3/t15-,16?,17-,18-,19-,20-,21+/m0/s1 JWMFYGXQPXQEEM-WZBAXQLOSA-N KEGG:C01523 [H][C@]1(CC)CC[C@@]2([H])[C@]3([H])CCC4([H])CCCC[C@]4(C)[C@@]3([H])CC[C@]12C chebi_ontology pregnane