The in vitro and in vivo metabolism of optically active methylcyclohexanols and methylcyclohexanones

The in vitro reduction and oxidation of the isomeric methylcyclohexanones and methylcyclohexanols by horse liver alcohol dehydrogenase, in the presence of NADH2 or NAD has been studied. The enzymic reactions closely resemble the corresponding in vivo metabolic conversions and support the view that the oxido-reductase in the animal body is similar to liver alcohol dehydrogenase. The findings are discussed in terms of the conformations of the alcohols and ketones and a correlation of the observed rates, Km values, and the steric specificity supports the view that the in vivo inversion of the thermodynamically less stable alcohols (±)-cis-2-, (±)-trans-3-, and cis-4-methylcyclohexanol could occur through a ketone intermediate.