Effects of glutathione peroxidase and catalase on hemolysis and methemoglobin modifications induced by photooxidized psoralen

Psoralen photooxidation products (POP products) were obtained by UVA irradi ation (365 nm, 180-640 W/m(2)) of an aqueous psoralen solution with fluence s of 0-800 kJ/m(2). Preincubation of POP products with glutathione peroxida se (GSHPer) or catalase, as well as presence of catalase during WA irradiat ion of the aqueous psoralen solution did not influence their hemolytic acti vity. However, both GSHPer and catalase inhibited POP-induced conversion of methemoglobin. This indicates that hydrogen peroxide and psoralen peroxide s destructible by GSHPer, which are being produced during psoralen photooxi dation, do not possess hemolytic activity. Furthermore, hydrogen peroxide d oes not appear to serve as an intermediate in the process of hemolysin form ation. Hydrogen peroxide generated during psoralen photooxidation is appare ntly the main POP product responsible for MetHb conversion. (C) 2000 Elsevi er Science S.A. All rights reserved.