title: Photodynamic efficacy of chlorin p6: a pH dependent study in aqueous and lipid environment.
abstract: Photodynamic efficacy of chlorin p6, a potential candidate of photodynamic therapy (PDT), has been studied at pH 5.0, 6.0 and 7.6 in aqueous and lipid environment. Increased chlorin p6 mediated photodynamic bleaching of N,N-dimethyl-4-nitrosoaniline (RNO), a measure of singlet oxygen yield, was obtained at higher pH. Rate of photodynamic bleaching of RNO was also higher at higher pH and the rate decreased with lowering in pH of irradiated solution. Photodynamic oxidation of tryptophan was also found to be higher at higher pH. Diminished oxidation of RNO was obtained with decrease in pH of irradiated solution. Both, RNO bleaching and tryptophan oxidation was significantly reduced by sodium azide, a known quencher of singlet oxygen. At lower pH, chlorin p6 mediated photodynamic malondialdehyde (MDA) and lipid hydroperoxide formation in egg lecithin liposome was higher. At higher pH chlorin p6 was found to be photodynamically more effective in aqueous environment whereas at lower pH chlorin p6 was photodynamically more effective in hydrophobic environment.
authors.affiliation: Biomedical Application Section, Block-D, Center for Advanced Technology, Indore 452 013, India. bbose@cat.ernet.in
authors.forename: Biplab
authors.initials: B
authors.lastname: Bose
authors.forename: Alok
authors.initials: A
authors.lastname: Dube
mesh_terms: D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D015227:Lipid Peroxidation; D008055:Lipids; D008958:Models, Molecular; D008968:Molecular Conformation; D009603:Nitroso Compounds / Q000528:radiation effects; D010778:Photochemotherapy / Q000379:methods; D011166:Porphyrins / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D026082:Singlet Oxygen / Q000032:analysis; D014364:Tryptophan / Q000528:radiation effects; D014867:Water
chemical_list: D008055:Lipids; D009603:Nitroso Compounds; D011166:Porphyrins; D014867:Water; C008651:4-nitrosodimethylaniline; D026082:Singlet Oxygen; C072905:chlorin p6; D014364:Tryptophan