Synthesis, DNA Photocleavage and Singlet Oxygen Measurement of Cationic Bisporphyrins

Abstract

With -<TEX>$OCH_2CO$</TEX>- as a linker, a non <TEX>${\beta}$</TEX>-substituted cationic bisporphyrin (4a) and a <TEX>${\beta}$</TEX>-substituted cationic bisporphyrin (4b) were prepared through methylation of the intermediate which was obtained from <TEX>${\beta}$</TEX>-amino-5,10,15,20-tetra (4-cyanophenyl) porphyrin or 5-hydroxylphenyl-10,15,20-tris(4-cyanophenyl) reacting with 5-hydroxy-10,15,20-trispyridinylporphyrin. Their structures were confirmed by <TEX>$^1H$</TEX> NMR, IR, UV-vis, MS and elemental analysis. DNA photocleavage ability and the singlet oxygen ability of those cationic bisporphyrins were investigated. DNA photocleavage activity of <TEX>${\beta}$</TEX>-substituted cationic bisporphyrin was significantly weaker than that of <TEX>$H_2TMPyP$</TEX>, but similar to that of non <TEX>${\beta}$</TEX>-substituted cationic bisporphyrin. While 4a and 4b showed substantial photocleavage activities toward DNA, with 68% and 66% observed at 10 <TEX>${\mu}M$</TEX>. The assessment of indirectly measured <TEX>$^1O_2$</TEX> production rates against <TEX>$H_2TMPyP$</TEX> were described and the relative singlet oxygen production yields were: free cationic bisporphyrins > <TEX>$H_2TMPyP$</TEX>. The results showed the cationic bisporphyrins with <TEX>${\beta}$</TEX>-substitution and non <TEX>${\beta}$</TEX>-substitution could be developed as potential photodynamic agents.