Antitumor activity of 2-amino-4,4 alpha-dihydro-4 alpha, 7-dimethyl-3H-phenoxazine-3-one, a novel phenoxazine derivative produced by the reaction of 2-amino-5-methylphenol with bovine hemolysate.

2-Amino-4,4 alpha-dihydro-4 alpha,7-dimethyl-3H-phenoxazine-3-one (Phx) was synthesized by the reaction of 2-amino-5-methyl-phenol with bovine hemolysates. Since Phx is a phenoxazine derivative like actinomycin D, which exerts a strong anti-tumor effect by intercalating DNA, we examined the effects of Phx on cell proliferation and cell cycle progression in human epidermoid carcinoma cells (KB cells). Phx inhibited the proliferation of Kb cells in a dose-dependent manner. When KB cells were incubated for 9 h with medium containing 50 microM Phx, a transient accumulation of cells in S and G2/M phase was observed and at 24 h many of cells had lower DNA content. Although Phx had antitumor activity, the drug did not intercalate DNA, showing a different mode of action from actinomycin D.