Structural requirements of microsomal N-oxygenations derived from studies on amidines

A short description of the chemical and pharmacological properties of amidines is followed by a comprehensive discussion of investigations on the N-oxidative biotransformations of amidines. The results of these investigations have confirmed the author's hypothesis, based on mechanisms, that N-oxygenation by the cytochrome P-450 enzyme system is observed particularly when N-dealkylation is not possible because of the absence of hydrogen atoms on the carbon atoms adjacent to the nitrogen atom, alpha-H-atoms. The results obtained with amidines are discussed in their relationship to other microsomal N-oxygenations both by cytochrome P-450 and flavine-containing monooxygenase. Attempts are made to deduce a scheme for predicting N-oxygenations.