title: Antioxidative effect of quercetin and its equimolar mixtures with phenyltin compounds on liposome membranes.
abstract: Our earlier studies have shown that the compounds diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT) in the presence of UVC radiation enhanced the degree of phosphatidylcholine liposome membrane oxidation (J. Agric. Food Chem. 2005, 53, 76-83). The prooxidative behavior of the compounds has now been confirmed with the electron paramagnetic resonance method, which proved the possibility that the studied compounds can exist in free radical forms. The present work investigates the possibility of the protective action of quercetin on phosphatidylcholine liposome membranes exposed to the prooxidative action of DPhT and TPhT induced by UV radiation (lambda = 253.7 nm). The concentrations of quercetin and its equimolar mixtures with DPhT and TPhT were determined (and compared with well-known antioxidants as standards-trolox and butylated hydroxytoluene, also in the presence of phenyltins) as those that induce 50% inhibition in oxidation of liposomes radiated with UV. They are 5.1 +/- 0.10, 2.9 +/- 0.12, and 1.9 +/- 0.08 microM (differences between the values are statistically significant), constituting the following sequence of antioxidative activity: quercetin:TPhT > quercetin:DPhT > quercetin. This relation is confirmed by the results on the antiradical ability of quercetin and its mixtures with DPhT and TPhT toward the free radical 1,1-diphenyl-2-pricrylhydrazil. Similar sequences obtained in both studies suggest a possible mechanism of the antiradical action of the mixtures as free radical scavengers. We suggested that (i) quercetin's ability, documented by spectrophotometric, infrared attenuated total reflectance spectroscopy, (1)H NMR, and molecular modeling methods, to form complexes with phenyltins indicates a possible way of protection against the peroxidation caused by the free radical forms of phenyltins and (ii) the differentiation in the action of the quercetin/TPhT and quercetin/DPhT associates (statisticaly significant) may result from a different localization in the liposome membrane, which is indicated by the results of the fluorimetric studies.
authors.affiliation: Department of Physics and Biophysics, Agricultural University, 50-375 Wrocław, Norwida 25, Poland. jaga@ozi.ar.wroc.pl
authors.forename: Janina
authors.initials: J
authors.lastname: Gabrielska
authors.forename: Monika
authors.initials: M
authors.lastname: Soczyńska-Kordala
authors.forename: Jerzy
authors.initials: J
authors.lastname: Hładyszowski
authors.forename: Romuald
authors.initials: R
authors.lastname: Zyłka
authors.forename: Janusz
authors.initials: J
authors.lastname: Miśkiewicz
authors.forename: Stanisław
authors.initials: S
authors.lastname: Przestalski
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D002839:Chromans; D004578:Electron Spin Resonance Spectroscopy; D020404:Glycerophospholipids; D015227:Lipid Peroxidation / Q000187:drug effects*; D008081:Liposomes; D008958:Models, Molecular; D009947:Organotin Compounds / Q000737:chemistry / Q000494:pharmacology*; D011794:Quercetin / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D002839:Chromans; D020404:Glycerophospholipids; D008081:Liposomes; D009947:Organotin Compounds; C086691:phosphatidylchromanol; C086664:diphenyltin chloride; C063613:phenyltin; D011794:Quercetin; C012594:triphenyltin chloride