Preparation, Characterization and in Vitro Bioactivity of Chondroitin Sulfate Chelated Zinc

In this paper, the preparation process condition of chondroitin sulfate chelated zinc was optimized by orthogonal test. Chondroitin sulfate and zinc sulfate were selected as the raw materials, chelating rate of zinc as evaluation index, the effects of pH, reaction time, mass ratio of chondroitin sulfate to zinc sulfate heptahydrate, and reaction temperature on chelating rate of zinc were investigated by single factor test and orthogonal test. The structural characterization of chondroitin sulfate chelated zinc was analyzed by UV spectroscopy, fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric and X-ray diffraction analysis. The bioavailability of zinc irons in chondroitin sulfate chelated zinc was determined by in vitro simulated gastrointestinal digestion and absorption. The results showed that optimal preparation conditions of chondroitin sulfate chelated zinc were as follows: pH4, reaction time was 1 h, mass ratio was 1:1, and reaction temperature was 30 ℃. Under these conditions, chelating rate of zinc was (80.6%±1.31%). UV spectrum combined with Fourier infrared spectrum analysis showed that chondroitin sulfate chelated zinc was formed by zinc ions combine with hydroxyl, carboxyl, sulfonic groups in chondroitin sulfate. Scanning electron microscopy and X-ray diffraction analysis showed that the micromorphology of chondroitin sulfate chelated zinc was microparticles with crystal structure. Thermogravimetric analysis proved that thermal stability of chondroitin sulfate chelated zinc was better than that of chondroitin sulfate. In vitro simulated gastrointestinal digestion and absorption analysis showed that the bioavailability of chondroitin sulfate chelated zinc was better than that of inorganic zinc salt. The research results would provide theoretical basis and technical support for the development of new zinc supplements.