Cationic porphyrin-quinoxaline conjugate as a photochemically triggered novel cytotoxic agent.

ABSTRACT

A novel cationic porphyrin-quinoxaline conjugate 8 was prepared in good yield by the coupling of activated quinoxaline carboxylic acid 5 with an appropriate aminoporphyrin. The UV-vis spectra of conjugate 8 with the addition of ctDNA shows substantial hypochromicity (39%) and a red shift (12 nm) in the Soret band indicating intercalation and self stacking along the surface. The binding constant of conjugate 8 with ctDNA was determined to be 1.26×10(6) M(-1). The porphyrin-quinoxaline conjugate 8 displayed enhanced photocytotoxicity (IC50=0.06 µM) when compared to TMPyP against A549 cancer cells.