Abstract: Objective: To explore optimal extraction process and in vitro antioxidant activity of polysaccharides from dried pulp of Malus micromalus Makino (PMM). Methods: A three-factor, three-level orthogonal array design was used to investigate the effects of three extraction conditions including temperature, time and solid-to-solvent ratio on polysaccharide yield. In order to assess the in vitro antioxidant activity of PMM using vitamin C as control, their DPPH radical scavenging activity was measured and meanwhile, their total antioxidant capacity and hydroxyl radical scavenging activity of PMM were tested by ABTS assay and Fenton reaction, respectively. Results: The optimal conditions for the extraction of polysaccharides from dried pulp of Malus micromalus Makino were 6 h extraction at 90 ℃ and a solid-to-solvent ratio of 1:10 (g/mL), resulting in a polysaccharide yield of 6.75%. Although its antioxidant activity was weaker than that of vitamin C, PMM still revealed strong scavenging effect on hydroxyl, DPPH and ABTS+ free radicals. PPM was more effective in scavenging hydroxyl free radicals than DPPH and ABTS+ free radicals. Conclusion: The developed optimal procedure for the extraction of PMM is reliable. PMM has a strong antioxidant activity in vitro.

Key words: Malus micromalus Makino, polysaccharide, extraction, antioxidant activity in vitro