Characterization of a novel polysaccharide isolated from Rosa roxburghii Tratt fruit and assessment of its antioxidant in vitro and in vivo

Abstract

In this study, a novel water-soluble polysaccharide (RRTP1-1) was obtained from Rosa roxburghii Tratt fruit through the ultrasonic-assisted extraction followed by anion-exchange and size-exclusion chromatography purification. The primary structure of RRTP1-1 was investigated by UV, FT-IR, HPLC, GC-MS, ¹H and ¹³C NMR spectroscopy. Chemical composition analysis revealed that RRTP1-1 had an average molecular weight of 97.58kDa and consisted of Man, Rha, GlcA, GalA, Glc, Gal, Ara and Xyl in a molar ratio of 2.88:1.39:2.83:1.00:69.11:3.04:2.52:3.41. This polysaccharide was proven to be a kind of glucan, owning a backbone structure of →6)-α-d-Glcp-(1→6)-α-d-Glcp-(1→. Congo red test indicated that RRTP1-1 had no triple helix structure. Antioxidation tests performed in vitro revealed that RRTP1-1 possessed obviously DPPH, hydroxyl and superoxide radicals scavenging activities. Furthermore, antioxidant assays in vivo showed that RRTP1-1 at 200 or 400mg/kg dose could significantly enhance the activities of antioxidant enzymes (CAT, SOD, and GSH-Px), increase TAOC values, and decrease the LPO and MDA levels in different degrees in the serum of D-Gal aging-induced mice. The present results suggested that RRTP1-1 could be a new source of natural antioxidants for applications in functional foods and dietary supplemental products.

Keywords: Antioxidant activity; Characterization; Polysaccharide; Rosa roxburghii Tratt fruit; Structure.