Physico Chemical Modeling of the Role of Free Radicals in Photodynamic Therapy IV. Quantitative Aspects of Photodynamic Effects on Free Radicals Generated in Cell Cultures

Author： Németh A. Jakus J. Kriska T. vanyur R. Gál D.

Publisher： Elsevier

ISSN： 0006-291X

Source： Biochemical and Biophysical Research Communications, Vol.255, Iss.2, 1999-02, pp. : 360-366

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Abstract

Production and the mechanism of the interactions of free radicals generated by stimulated macrophages in the presence of luminol and a free radical inhibitor was investigated to determine the possibility of using luminol-dependent chemiluminescence for studying photodynamic effects in biology. Earlier measurements have been revisited and additional experiments performed indicating that oxidation products of luminol neither inhibit the in vitro formation of radicals nor quench CL. Simulation based on the mechanism suggested revealed that the likely value for the rate constant of the primary step between luminol and superoxide anion radicals producing luminol radicals is 5×10²–1×10³ M^-1s^-1. It has been established that the ratio of the concentration of radicals generated by the biological system to that formed by oxidation of luminol exceeds 10³; that is, the contribution of the latter is negligible and the system is appropriate to measure quantitatively the effect of excited photosensitizers on free radicals.