The metabolism of 9-benzyladenine (BA) and isomeric 9-(nitrobenzyl) adenines (NBAs), i.e. 9-(2-nitrobenzyl)adenine (2NBA), 9-(3-nitrobenzyl)adenine (3NBA) and 9-(4-nitrobenzyl)adenine (4NBA), was investigated with normal hamster hepatic microsomes. Using HPLC, TLC, UV and MS techniques, it was established that metabolic N¹-oxidation occurred for all BA and NBAs. The N¹-oxidative rate was in the order 2NBABA3NBA and 4NBA. The results suggest that the introduction of a nitro group may interfere with the binding between substrates and related N¹-oxidase(s). This may be the reason for the lower N¹-oxidative rates of 3NB A and 4NB A. It is also suggested that 2NBA may possess the most favourable conformation and binding characteristics for the enzymes among the substrates studied as it was metabolised even faster than BA.
