Rate Constnats for Reaction of Hydroxyl Radicals with Water-Soluble Porphyrins and Metalloporphyrins

概要

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To determine the rate constants for the reaction of hydroxyl radicals with water-soluble porphyrins and their metalloporphyrins, tetrakis(4-sulfophenyl)porphine(TPPS), tetrakis(5-sulfothienyl)porphine (T(5-ST)P), tetrakis(4-N-methylpyridyl)porphine (TMPyP) and tetrakis(4-N-trimethylamino-phenyl)porphine (TTMAP), and Mn(III), Fe(III), Co(III) and Cu(II) complexes of TPPS and TMPyP, the γ-irradiation method, in which the fluorescence of hydroxybenzoates produced through reaction of benzoate with hydroxyl radicals generated by water-radiolysis is measured, were tried. However, since the porphyrins and metalloporphyrins show the characteristic absorption spectra in the visible region, the fluorescence of hydroxybenzoate products was disturbed by the colors. To separate the hydroxybenzoates from the colored solute, the products were extracted into ether under an acidic condition. The hydroxybenzoates were extracted thoroughly into the ether layer from an aqueous layer of less than pH 3 ; the residue was redissolved in phosphate buffer, pH 7.5; the solution was used to determine the rate constants. The rate constants for anionic porphyrins, TPPS, T(5-ST)P, were in the order of 10^9,and the constants for cationic porphyrins, TMPyP, TTMAP, in the order of 10^<10>. Metal complexes of TPPS and TMPyP showed the rate constants of 6.9 to 11.4×10^9M^<-1>S^<-1> and of 3.2 to 19.7×10^9M^<-1>S^<-1>, respectively.
公益社団法人日本薬学会の論文
1995-03-15