Several properties

including absorption spectraactiveoxygen production and the rate of autocxidation of HA and its complexes with magnesium and zinc ions

were investigated and compared in this paper. New absorption peaks at 620 nm (Zn)and 628 nm (Mg) appeared in HA-Zn and HA-Mg complex solutions respectively

while the original peaks at 540 nm and 580 nm in HA solution reduced

or even though disappeared at higher molecular ratio of metal ion to HA. These phenomena suggested that the intra-hydrogen bond between carbonyl and hydroxyl groups of HA were replaced by bivalent cations. ESR data indicated that efficiency of both singlet oxygen and superoxide anion radical reduced significantly in the solution of HA complexes compared with that of HA. A simple test we designed proved the direct electron transfering from semiquinone radical of HA to oxygen. However

the formation of semiquinone radical of HA was inhibited by magnesium of zinc ions and then resulted in reduction of superoxide anion radicals. The rate constants of autooxidation of HA-Mg and HA-Zn complexes were 8.2 and 3.0 times bigger than that of HA.