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

Nanda Gunawardhana, Shingo Homi, Masaaki Tabata


The ability of Rh(III) tetrakis-N-methylpyridyl porphyrin, RhIII(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 RhIII(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 RhIII(TMPyP)5+ was capable of binding to DNA via an external binding mode. The RhIII(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 RhIII(TMPyP)5+ was only able to cleave DNA in the presence of the reducing agent  ascorbic acid. ESR data indicated the formation of RhII(TMPyP)5+ by reduction of RhIII(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.

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DOI: http://dx.doi.org/10.5539/ijc.v4n3p42

International Journal of Chemistry   ISSN 1916-9698 (Print)   ISSN 1916-9701 (Online)

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