Easy Access to Water‐Soluble Cationic Porphyrin‐β‐Carboline Conjugates As Potent Photocytotoxic and DNA Cleaving Agents

Microwave (MW)-assisted efficient and rapid approach is developed to prepare water-soluble cationic porphyrin-beta-carboline conjugates by coupling of beta-carboline acid and 5-(4-aminophenyl)tripyridyl porphyrin and followed by N-methylation of neutral porphyrin-beta-carboline conjugates. Prepared neutral and cationic conjugates were screened for photocytotoxicity against lung (A549) and colon (Colon-26) cancer cells. Conjugate 9 b was found to be the most potent conjugate with IC50 values ranging 39-47 nM against the tested cancer cell lines. Further, UV-visible spectroscopy studies demonstrated that the conjugate 9 b in the presence of visible light shows intercalation upon binding to double-stranded DNA. Additionally, the porphyrin-beta-carboline conjugate 9 b (2.3x10(6) M-1) having binding constant (K-b) similar to H2TMPyP (2.5x10(6) M-1) displayed efficient visible light-induced DNA cleavage and triggered cell death of A549 cells.