Synthesis, anticancer and cytostatic activity of some 6H-indolo[2,3-b]quinoxalines

Various 6-aralkyl-9-substituted-6H-indolo[2,3-b]quinoxalines were synthesized by reaction of 1,5-disubstituted 2,3-dioxo-2,3-dihydroindole with orthophenylene diamine. Appreciable anticancer activity of compounds 5b, 5d, 5g and 5l at various cell lines among 59 human tumor cell panels was observed. All the synthesized compounds were evaluated for cytostatic activity against human Molt 4/C8 and CEM T-lymphocytes as well as for murine L1210 leukemia cells. Compound 5h exhibited an IC₅₀ of 71 µmol mL^-1 against Molt 4/C8 and 117 µmol mL^-1 against CEM compared to melphalan 3.2 µmol mL^-1 and 2.5 µmol mL^-1, respectively. The IC₅₀ for compound 7i against L1210 was 7.2 µmol mL^-1 compared to melphalan 2.1 µmol mL^-1.