Rapid Isolation Method for Preparation of Immuno-Stimulating Rhamnogalacturonans in Citrus Peels

摘要

We developed a rapid isolation method for fractionation of polysaccharides with different characteristics, and optimized it for the polysaccharide mixture from Korean citrus peels. A crude polysaccharide mixture, citrus-peel-enzyme (CPE) fraction wasisolated from the citrus peels digested with pectinase and ethanol precipitation. CPE was ftirther fractionated with serially diluted ethanol solution (ethanohdeionized water=8:l, 4:1, 3:1, 2:1, 1.5:1, 1:1, and 0.5:1) to produce seven fractions labeled from CPE8 to CPE0.5. Fraction from CPE8 to CPEI were mostly composed of 11 different sugars, including rhamnogalacturonan (RG) I and II, and the sugars contained arabino-B-3,6-galactan moiety. However, CPE0.5 did not contain RG-II and arabino-B-3,6-galactans. Treatment of macrophages with fractions CPE8-CPE1 led to a dose-dependent increase in interleukin-6 production (IL-6), while treatment with CPEI and CPE0.5 fractions resulted in decreased levels of IL-6. These results indicate that this isolation method may be usefrjl for the rapid fractionation of bioactive RGs from polysaccharide mixtures.