title: Biphasic dose-response of antioxidants in hypericin-induced photohemolysis.
abstract: In the present paper the photodynamic effect of hypericin on superoxide dismutase activity and the possibility of reduction of hypericin phototoxicity by antioxidants were studied. It was shown an almost twice decrease in superoxide dismutase activity of red blood cells under the photosensitization by hypericin. The influence of antioxidants (ascorbic acid and quercetin) on hypericin photodynamic action has revealed that these antioxidants suppress or stimulate photohemolysis caused by hypericin. The photosensitization reaction realized by hypericin could be shifted from type II to type I or vice versa by manipulating the antioxidant concentration. Strengthening of photohemolysis by antioxidants in some concentrations indicates the switching of alternative mechanisms of hypericin photodynamic action and its complicated manner. Thus the selection of antioxidant concentrations is of extreme importance for changing the efficacy of photodynamic therapy with hypericin.
authors.affiliation: Russian-Armenian (Slavonic) University, Biomedical Faculty, Hovsep Emin 123, Yerevan 0051, Armenia. alina mart@list.ru
authors.forename: Alina S
authors.initials: AS
authors.lastname: Martirosyan
authors.forename: Hrachik R
authors.initials: HR
authors.lastname: Vardapetyan
authors.forename: Susanna G
authors.initials: SG
authors.lastname: Tiratsuyan
authors.forename: Ashkhen A
authors.initials: AA
authors.lastname: Hovhannisyan
mesh_terms: D000465:Algorithms; D000873:Anthracenes; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D008297:Male; D010544:Peroxidases / Q000187:drug effects; D010569:Perylene / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D011794:Quercetin / Q000008:administration & dosage / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors; D013482:Superoxide Dismutase / Q000187:drug effects; D013997:Time Factors
chemical_list: D000873:Anthracenes; D000975:Antioxidants; D015220:Calcium Channels; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D010569:Perylene; C004965:hypericin; D011794:Quercetin; D010544:Peroxidases; D013482:Superoxide Dismutase; D011493:Protein Kinase C; D001205:Ascorbic Acid