Abstract:  In order to develop a novel organic zinc supplement, Polygonatum rhizoma polysaccharide from the medicinal and edible herb Polygonatum rhizoma was chelated with zinc sulfate to prepare Polygonatum rhizoma polysaccharide chelate zinc. We optimized the chelation process,  characterized and evaluated the chelated compound by using UV-Visible spectroscopy,  Fourier transform infrared spectroscopy (FT-IR),  scanning electron microscopy (SEM),  and an in vitro Caco-2 cell absorption model experiments. The experimental results show that the optimal chelation process is at a temperature of  60 ℃,  pH=7,  t=60 min and a polysaccharide-to-zinc  ratio of 8∶1, the chelation rate can reach 58.7% under the conditions. Zn²⁺ adsorbs onto Polygonatum rhizoma polysaccharide and forms chelates with  carboxyl,  hydroxyl,  and carbonyl groups as  chelating sites. The  expression levels of zinc transport proteins ZnT-4,ZnT-6 and ZnT-8 are increased in Caco-2 cells. Therefore, the prepared Polygonatum rhizoma polysaccharide chelate zinc has good chelating properties and potential to promote zinc absorption.

Key words: Polygonatum rhizoma polysaccharide chelate zinc, in vitro Caco-2 cell absorption model,  , transport protein