Synthesis, characterization and antioxidant activity of a new polysaccharide-iron (III) from Vaccinium bracteatum thunb leaves

In this paper, a new polysaccharide VBTLP-2b was extracted and purified from Vaccinium bracteatum Thunb leaves. Based on single factor experiments, the synthesis process of VBTLP-2b-iron (III) complex was optimized by response surface methodology. The characterization and antioxidant activity of VBTLP-2b-iron (III) were investigated. The optimal synthesis process of VBTLP-2b-iron (III) was pH of 8.8, temperature of 70 ℃ and mass ratio of VBTLP-2b to sodium citrate of 1.2:1. The average molecular weight of VBTLP-2b-iron (III) was 57.46 kDa. VBTLP-2b-iron (III) was composed of galactose, glucose, mannose, xylose and arabinose in a molar ratio of 22.3:55.1:6.3:9.9:6.4. Hydroxyl and carboxyl groups in VBTLP-2b participated in the coordination reaction and the iron core of VBTLP-2b-iron (III) was a polymerized β-FeOOH structure. VBTLP-2b-iron (III) had better thermal stability and stronger antioxidant activities compared with VBTLP-2b. The results indicated that VBTLP-2b-iron (III) could be potentially used as a novel iron supplement with good antioxidant activity.