Chemical and antihyperglycemic activity changes of ginseng pectin induced by heat processing

Six pectic polysaccharides were obtained from white ginseng (GPW-1 and GPW-2), red ginseng (GPR-1 and GPR-2, steamed ginseng at 100 °C) and steamed ginseng (GPS-1 and GPS-2, steamed ginseng at 120 °C) by combination of water extraction, ion-exchange and gel permeation chromatographies. Based on the data from monosaccharide composition and 13C NMR analysis, GPW-1, GPR-1 and GPS-1 were identified as type-I rhamnogalacturonan (RG-I)-rich pectins, GPW-2, GPR-2 and GPS-2 were homogalacturonan (HG)-rich pectins with different degrees of methyl-esterification. Remarkably, GalA increased with the increase of processing temperatures in these six fractions, which might be caused by the transformation of esterified GalA into un-esterified form during heat processing. In vivo animal experiments showed that GPs exhibited significant antiohyperglycemic and antioxidant activities in alloxan-induced diabetic mice, and the effects increased with the processing temperature, with the most potent activity in GPS.