[Study on extraction and purification of polysaccharides from Astragalus membranaceus].

Objective: To optimize the extraction and purification procedure for polysaccharides from Astragalus membranaceus.

Methods: The orthogonal test was used to determine the optimal extraction technology in terms of the extraction rate of crude polysaccharides and the concentration of polysaccharides. The efficiency of deproteinization and decoloration with different methods were evaluated with the ration of protein and colorant removing as the indices. Their influence on the content of Astragalus polysaccharides was calculated as well.

Results: The optimum extraction procedure was as follows: 8 times of water extracting three times at 100 degrees C, 90 minutes per time. Deproteinization using pepsase combined with Sevage solvent and depigmenting with DEAE fibrin achieved a high purification rate.

Conclusion: The optimized extraction and purification procedure is simple, quick and efficient. The result establishes the foundation for the further study of the polysaccharides from Astragalus membranaceus.