Efficient DNA Cleavage Induced by RhIII(TMPyP)5+ in the Presence of Ascorbic Acid

Abstract

The ability of Rh(III) tetrakis-N-methylpyridyl porphyrin, Rh III (TMPyP) 5+ , to interact with and cleave DNA was, investigated by UV-visible, luminescence, circular dichroism (CD), electron spin resonance (ESR) and gel electrophoresis methods in the presence or absence of ascorbic acid. UV-absorption data showed that Rh III (TMPyP) 5+ is capable of interacting with DNA, as indicated by the appearance of a red shift and hypochromicity of the Soret band. The CD data revealed that Rh III (TMPyP) 5+ was capable of binding to DNA via an external binding mode. The Rh III (TMPyP) 5+ showed fluorescence and phosphorescence at room temperature. The phosphorescence increased in the presence of DNA and this could be attributed to the shielding of the metal-porphyrin by DNA. Gel electrophoresis studies revealed that Rh III (TMPyP) 5+ was only able to cleave DNA in the presence of the reducing agent ascorbic acid. ESR data indicated the formation of Rh II (TMPyP) 5+ by reduction of Rh III (TMPyP) 5+ with ascorbic acid. The involvement of Rh(III)/Rh(II) species in catalytic DNA cleavage and a possible DNA cleavage mechanism is discussed.

Porphyrins in Photodynamic Therapy: A Review

“…26 As such, several approaches have been explored to enhance its therapeutic outcome in PDT, including PS formulations containing combinations of TMPyP and other hydrophilic PSs, 151,159 conjugations of TMPyP with graphene oxide, 158,163 Au, [164][165] Ag, [166][167] iron oxide NPs, [168][169] nanoencapsulation 170 and metalation with biologically active metals. 156,[171][172][173][174] TMPyP has a net charge of four units which imparts to its necessary hydrophilicity for photobiological applications. However, numerous publications have suggested that PSs bear a combination of high cationic charges and that added lipophilicity usually translates to better therapeutic efficacy.…”