The metabolism of the isomeric decalones.

1. The metabolism of (+/-)-cis-1-, (+/-)-trans-1-, (+/-)-cis-2- and (+/-)-trans-2-decalone in the rabbit has been investigated. 2. (+/-)-cis-2- and (+/-)-trans-2-Decalone were both reduced to racemic secondary alcohols, conformationally related to the ketones administered, and possessing an equatorial hydroxyl group. These alcohols were excreted in the urine as glucuronides in amounts equal to about half the dose administered. The glucuronides were isolated both as triacetyl methyl esters and as sodium salts. The ester obtained after feeding with (+/-)-cis-2-decalone proved to be methyl (cis-cis-2-decalyl tri-O-acetyl-beta-d-glucosid)uronate, whereas (+/-)-trans-2-decalone yielded methyl (trans-cis-2-decalyl tri-O-acetyl-beta-d-glucosid)uronate. The sodium salts were shown to be sodium (cis-cis-2-decalyl glucosid)uronate and sodium (trans-cis-2-decalyl glucosid)uronate. 3. Enzyme hydrolysis of the sodium salts and acid hydrolysis of the esters derived from (+/-)-cis-2-decalone yielded (+/-)-cis-cis-2-decalol, and of those from (+/-)-trans-2-decalone yielded (+/-)-trans-cis-2-decalol. 4. (+/-)-cis-1-Decalone was reduced mainly to (-)-cis-cis-1-decalol and excreted as [(-)-cis-cis-1-decalyl glucosid]-uronic acid. A small amount of the corresponding (+)-isomer was produced, yielding [(+)-cis-cis-1-decalyl glucosid]uronic acid on isolation. Enzyme hydrolysis of these compounds gave the corresponding aglycones; both alcohols possessed an equatorial hydroxyl group. 5. (+/-)-trans-1-Decalone was reduced to (+)-trans-trans-1-decalol, with an equatorial hydroxyl group, and in smaller amount to (+)-trans-cis-1-decalol possessing an axial group. The former alcohol was excreted as [(+)-trans-cis-1-decalyl glucosid]uronic acid, and the latter as [(+)-trans-cis-1-decalyl glucosid]uronic acid. 6. From a knowledge of the conformations, and in some cases the absolute configurations, of the compounds administered and excreted, and by making the assumption that the coenzyme concerned in the reductions is NADH (or NADPH), an explanation of the above findings in terms of steric hindrance and thermodynamic stability is given.