Extraction, isolation, immunoregulatory activity, and characterization of Alpiniae oxyphyllae fructus polysaccharides.

For further applications of Alpiniae oxyphyllae fructus in modern clinical medicine, Alpiniae oxyphyllae fructus polysaccharide (AOFP) was studied in the present work. The extraction conditions of AOFP were optimized by the response surface method with a Box-Behnken design. The maximum extraction rate of AOFP was 3.18%. An anion-exchange DEAE-52 cellulose column and a Sephadex G-100 gel column were used to isolate the AOFP, and three polysaccharides (AOFP1, AOFP2, AOFP3) were obtained. All three polysaccharides possessed immunoregulatory activity, but the effects of AOFP1 were greater than the other two polysaccharides. AOFP1 significantly stimulated Th1- and Th2-type immune responses and specific immune responses. Meanwhile, the characterization of AOFP1 was studied. AOFP1 was composed of arabinose, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid at a molar ratio of 16.46:12.7:4.9:17.11:4.35:6.52:6 with an average molecular weight of 43.4 kDa. These results suggest that AOFP1 can be developed as a natural immunomodulatory drug.