drug identification nonhuman 6 drug analysis 4 mass spectrometry 4 drug isolation 3 drug synthesis 3 nuclear magnetic resonance 3 proton nuclear magnetic resonance 3 theoretical study 3 Synthesis 2 drug structure 2 infrared spectrometry 2 priority journal 2 radioisotope 2 20 hydroxy 3 oxo 23 norchol 4 enoic acid c 14 1 22 dehydrocholesterol 1 24 ethylcholesta 5,22 dien 3beta ol 1 24 methyl 27 norcholesta 5,22 dien 3beta ol 1 24 methylcholesta 5,22 dien 3beta ol 1 24 methylcholesta 5,24(28) dien 3beta ol 1 24 methylcholesterol 1 24 norcholesta 5,22 dien 3beta ol 1 3 oxo 23 norchola 4,20(22) dienoic acid c 14 1 3beta acetoxy 5beta pregnan 20 one 1 3beta hydroxy 23 norchol 20(22) enoic acid c 14 1 3beta hydroxy 23 norchola 5,20(22) dienoic acid c 14 1 3beta,20 dihydroxy 23 norchol 5 enoic acid c 14 1 3beta,20 dihydroxy 23 norcholanic acid c 14 1 5beta pregnan 3beta ol 20 one c 14 1 Alkaloids 1