Preparation and characterization of a novel Astragalus membranaceus polysaccharide-iron (III) complex

•The iron (III) complex from Astragalus membranaceus polysaccharide (ASP) was successfully synthesized and characterized.•The iron content of APS-iron (III) complex reached 19.32% at the optimum conditions.•The synthesized APS-iron (III) complex still had strong anti-oxidative activity and good bioavailability by iron release of APS-iron (III) complex in vitro assay.

Astragalus membranaceus polysaccharide-iron (III) complex (APS-iron) was synthesized and characterized. Based on single factor and response surface optimization experiments of APS-iron (III) complex synthesis, the optimum conditions of APS-iron (III) complex were obtained as follows: the reaction temperature 89.46 °C, pH 8.16, reaction time 46.04 min and ratio of catalyst to APS 0.75, respectively. The reaction temperature was the most significant factor, followed by pH, reaction time and the ratio of catalyst to APS in the four reaction parameters. The highest iron content (19.32%) of APS-iron (III) complex was obtained at the optimum conditions, which was characterized by fourier transform infrared (FTIR), scanning electron microscopy (SEM), antioxidant activities of the APS-iron (III) complex and iron release of APS-iron (III) complex in vitro assay. The results indicated the APS-iron (III) complex had good bioavailability and antioxidant activities in vitro assays. So, it was potential for APS-iron (III) complex as a candidate for iron supplements.