COMPARATIVE IN-VITRO OXYGEN RADICAL SCAVENGING ABILITY OF ZINC METHIONINE AND SELECTED ZINC SALTS AND ANTIOXIDANTS

1. The concentration-dependent scavenging abilities of zinc DL-methion ine, zinc sulfate, zinc gluconate, zinc picolinate and selected free r adical scavengers, including superoxide dismutase (SOD), catalase, man nitol, allopurinol and DL-methionine, were examined against biochemica lly generated superoxide anion, hydroxyl radical and hypochlorite radi cal plus hypochlorous acid, by chemiluminescence and cytochrome c redu ction. 2. Zinc methionine was the most effective of the zinc compounds that were tested. Following incubations with superoxide anion, hydrox yl radical, and hypochlorite radical-generating systems, in the presen ce of 50 mu M zinc DL-methionine approximately 38%, 47% and 28% inhibi tion in reactive oxygen species generation was observed, respectively, compared to control groups. 3. The protective abilities of various zi nc salts, as well as selected free radical scavengers and antioxidants were also assessed on phorbol ester (TPA)-induced lactate dehydrogena se (LDH) release from cultured PC-12 cells. Preincubation showed bette r protection than coincubation. Approximately 45% and 50% inhibition i n TPA-induced LDH leakage was observed following preincubation with 50 mu M zinc DL-methionine and 50 mu M vitamin E succinate, respectively . Zinc DL-methionine exhibited better protection against LDH leakage t han any other zinc salt tested. 4. The results indicate that zinc DL-m ethionine can attenuate the biochemical consequences of oxygen free ra dicals, and is comparable to other well-known antioxidants and free ra dical scavengers in the in vitro system that was employed. Copyright ( C) 1997 Elsevier Science Inc.