Structural characterization of three acidic polysaccharides from Opuntia dillenii Haw. fruits and their protective effect against hydrogen peroxide-induced oxidative stress in Huh-7 cells

Abstract

Three novel acidic polysaccharide fractions (OFPP-1, OFPP-2, OFPP-3) with different m olecular weights (803.7, 555.1 and 414.5 kDa) were isolated from the peeled Opuntia dillenii Haw. fruits by alkali-extraction, graded alcohol precipitation and column chromatography. Structural analysis indicated that OFPPs were pectic polysaccharides consisting of rhamnose, arabinose and galactose residues. The backbone of OFPP-1 consisted of a repeating unitwhich was branched at the O-4 position of →2,4)-α-L-Rhap-(1→. Moreover, these three polysaccharide fractions could protect Huh -7 cells against H 2 O 2induced oxidative stress to different extents by decreasing the MDA content and increasing the SOD, CAT, GSH-Px activities and the GSH level in the Huh-7 cells. These results suggest that OFPPs have the potential to be used as natural antioxidants.