Microsomal N ‐Oxygenation of Adenine to Adenine 1‐ N ‐Oxide

During investigations on the N ‐oxygenation of adenine ( 1 ) the enzymatic formation of adenine 1‐ N ‐oxide 3 was demonstrated for the first time. The identity of this metabolite was confirmed by its chromatographic behaviour and UV‐spectrum recorded after HPLC separation. Adenine 1‐ N ‐oxide ( 3 ) and similar oxygenated derivatives of adenine were synthesized as reference substances. The enzymatic formation of 3 exhibits the typical characteristics of a reaction catalysed by microsomal mono‐oxygenases. In induction experiments, an increase in the rate of formation of 3 after pretreatment with phenobarbital was observed. A participation of those isoenzymes of the cytochrome P‐450 enzyme system which can be induced by phenobarbital is assumed.