The chelating ability of larch polyphenols to Ca~(2+) and Zn~(2+)

Purified through the way of X-5 resin separating, larch polyphenols could reach a purity of 71.4%. Effect of temperature, pH and quality ratio between larch polyphenols and metal ions on chelating reaction were investigated. Results showed that the optimum temperature for the chelating reaction of larch polyphenols with Ca2+ and Zn2+, respectively, were 50 ℃ and 60 ℃, pH 6.0 and quality ratio 30:1. Under these conditions, yield of chelation of metal ions were 36.43% and 47.51%. The antioxidant activity of chelate with Zn2+ was higher than that of larch polyphenol on scavenging DPPH· free radicals. On hydroxyl free radicals(·OH), The antioxidant activity of chelate of metal ions heightened in different degrees, among of which the antioxidant activity of chelate with Ca2+ was higher than that with Zn2+.