2,3-Bifunctionalized quinoxalines: Synthesis, DNA interactions and evaluation of anticancer, anti-tuberculosis and antifungal activity

A variety of 2,3-bifunctionalized quinoxalines (6-14) have been prepared by the condensation of 1,6-disubstituted-hexan-1,3,4,6-tetraones (1-4) with o-phenylenediamine, (R,R)-1,2-diaminocyclohexane and p-nitro-o-phenylenediamine. It is concluded that strong intramolecular N-H-O bonds in the favoured keto-enamine form may be responsible for the minimal biological activities observed in DNA footprinting, anti-tubercular, anti-fungal and anticancer tests with these hyper π-conjugated quinoxaline derivatives. However, subtle alteration by addition of a nitro group affecting the charge distribution confers significant improvements in biological effects and binding to DNA.