Effects of (-)-epigallocatechin gallate on the redox reactions of human hemoglobin.
The toxicity of acellular hemoglobin (Hb)-based therapeutics has been attributed in part to the uncontrolled oxidative reactions. A variety of antioxidant strategies to ameliorate potential oxidative damage in vivo have been suggested. We have examined the effects of (-)-epigallocatechin gallate (EGCG), a green tea polyphenol compound widely regarded as a chain-breaking antioxidant, on the oxidative stability of diaspirin crosslinked Hb (DBBF) and its cytotoxic ferryl intermediate. DBBF (ferrous) was rapidly oxidized to the ferric form in the presence of EGCG relative to the normal spontaneous oxidation of this Hb. The fast elimination of ferrous Hb is probably due to the ability of EGCG to produce hydrogen peroxide (H2O2) as these reactions were almost completely reversed by the addition of catalase and superoxide dismutase to the reaction medium. EGCG, however, effectively reduced ferryl back to ferric Hb in a biphasic kinetic reaction at physiological pH. At acidic pH where the autoreduction of protonated ferryl Hb is enhanced, a monophasic reduction process of the ferryl heme is achieved. A balance between pro and antioxidant properties of EGCG should be taken into account if EGCG is used in combination therapy with redox active acellular Hbs.
Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, National Institutes of Health Campus, Bethesda, MD 20892, USA. yiping.jia@fda.hhs.gov
Yiping
Y
Jia
Abdu I
AI
Alayash
D001241:Aspirin / Q000031:analogs & derivatives / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D010084:Oxidation-Reduction / Q000187:drug effects
D003432:Cross-Linking Reagents; D006454:Hemoglobins; C030830:succinyldisalicylic acid; D002392:Catechin; C045651:epigallocatechin gallate; D001241:Aspirin