“ mejor cialis o levitra show 6 more Substituents 17 hydroxysteroid 2 oxasteroid 3 oxo 5 alpha steroid 3 oxosteroid Alcohol Aliphatic heteropolycyclic compound Carbonyl group Carboxylic acid derivative Carboxylic acid ester Cyclic alcohol Delta valerolactone Delta_valerolactone Hydrocarbon derivative Hydroxysteroid Lactone Monocarboxylic acid or derivatives Naphthalene Naphthopyran Organic oxide Organic oxygen compound Organoheterocyclic compound Organooxygen compound Oxacycle Oxane Oxosteroid Pyran Steroid lactone Tertiary alcohol ”