Optimization of Complex Enzyme Extraction Process of Astragalus Polysaccharides and Its α-Glucosidase Inhibitory Activities

Objective: To extract Astragalus polysaccharides (APS) from Astragalus membranaceus using compound enzymes (including papain, pectinase and cellulase), and to analyze the effect of process conditions on APS extraction. Methods: Orthogonal experiments were conducted to determine the proportion of compound enzymes. The response surface method was used to optimize the conditions of extracting APS with compound enzymes. The optimal process condition was obtained, and the α-glucosidase-inhibiting effect of APS was evaluated by pNPG method. Results: For 5 g of Astragalus herbs, the optimal ratio of papain, pectinase and cellulase were 88000 U, 65000 U and 6000 U, respectively. The optimal extraction condition was as follows: time of 2.82 h, temperature at 60.34 ℃, pH of 5.11, and solid-liquid ratio of 1:34.46 g/mL. The yield of APS under the optimal condition was up to 22.79%±0.14%. The half-inhibition concentration (IC50) of APS for α-glucosidase was 7.42 μg/mL. Conclusion: The yield of APS by compound enzymes is significantly higher than that by single enzymes, and APS can effectively inhibit the activity of α-glucosidase.