Derivative UV-VIS Spectrophotometry for Porphyrins Interactions in Photodynamic Therapy

Derivative spectrophotometry is an analytical technique of great utility for extracting both qualitative and quantitative information from spectra composed of unresolved bands by calculating and plotting one of the mathematical derivatives of a spectral curve. In photodynamic therapy (PDT) by irradiation with light, the porphyrin used as drugs induced DNA cleavage mainly via a Type II (singlet oxygen mediated) mechanism, and more rarely a Type I (radicals mediated) mechanism. In the present paper, it is estimated the distinct interactions between DNA and 5,10,15,20-tetra-sulphonated-phenyl-porphyrin (TSPP) by means of: UV-Vis derivative spectrophotometry coupled with melting point, fluorescence, and polarization fluorescence techniques. An exemplification of TSPP effect on DNA from K562 cells is also discussed.