A phenazine analogue of actinomycin D.

An analogue of actinomycin D (1), in which the phenoxazone chromophore has been replaced by a phenazine, has been synthesized and characterized. Although this compound (2) lacks the 2-amino group and does not possess the quinoid structure of 1, it does bind to DNA, but less tightly than either 1 or the 2-deamino derivative of 1. NMR and CD spectra indicate that the peptide conformations in 2 are approximately as in 1; there was no apparent asymmetry of the two peptide rings. Compound 2 inhibited nucleic acid synthesis in L1210 cell cultures more effectively than does 2-deaminoactinomycin D, but about one-tenth as well as does actinomycin D.