C. Matos, C. Ribeiro, L. R. Gomes
Aug 26, 2015
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Journal
Medicinal Chemistry Research
Abstract
This work presents a comparative study of the interaction of three porphyrins: the cationic meso-tetra(4-N,N,N-trimethylanilinium) porphine tetrachloride (T973); the anionic meso-tetra(4-carboxyphenyl) porphine (T790); and the neutral meso-tetra(p-hydroxyphenyl) porphine (T679) with model membranes, at two different pH values. The models for the biological membrane used were micelles of hexadecylphosphocholine and large unilamellar liposomes of egg yolk phosphatidylcholine. The liposome–buffer partition coefficients (K) were determined by derivative spectrophotometry at two different pH values (7.4 and 5.8), in order to mimic plasma and tumor tissue conditions, respectively. Different types of partition were observed for different molecules, systems and pH values. Theoretical mathematical models, which accounted for the stoichiometry of the interaction, were used to fit the experimental data and determine the value of K. The values of K obtained are important in the choosing of a promising light-sensitizing agent to be used in photodynamic therapy for cancer treatment, since this parameter governs the distribution of the drug in the organism and the amount of drug that can be found on the site of irradiation.