Kinetic analysis of inhibition of reverse transcriptase by streptonigrin.

The antitumor antibiotic, streptonigrin (1), was first isolated from Streptomyces flocculus1^. Later, the inhibition of avian myeloblastosis virus (AMV) reverse transcriptase by 1 was reported by Chirigos et al.2\ while no inhibition was observed with methyl streptonigrin (2), suggesting the importance of the carboxyl group for this activity. To confirm this aspect, the biological properties of the newly synthesized streptonigrin-2/-carboxyl amide derivatives were studied comparatively with those of 1 and 2. Unlike 2, the amide-type derivatives unexceptionally inhibited AMVreverse transcriptase to the same extent with 1, though their antimicrobial and cytocidal activities were much lower than those of 13~5). Moreover, the nature of these