Extraction, purification, structure, and antioxidant activity of polysaccharide from Rhodiola rosea

Rhodiola rosea polysaccharides are generally extracted using hot water, however, the structure and an-tioxidant activity of polysaccharides extracted by cold water are rarely reported. In this paper, a pec-tic polysaccharide (RRP-4) was successively prepared from Rhodiola rosea using a cold-water extraction method to explore its structural characteristics and antioxidant activity. Our findings revealed that RRP-4 (1.38 x10 6 Da) was composed of Rha, Ara, Gal, and GalA with the molar ratio of 0.23:1.00:0.24:0.42. The backbone was composed of -> 4)-alpha-GalpA-(1 -> , -> 4)-alpha-GalpA-6-OMe-(1 -> and -> 2,4)-alpha-Rhap-(1 -> , while Araf-based branches (alpha-Araf-(1 -> , 3)-alpha-Araf-(1 -> , -> 3,5)-alpha-Araf-(1 -> ) and Galp-based branches ( -> 3)-beta- Galp-(1 -> ) were attached to Rhap, suggesting that RRP-4 was a pectic polysaccharide including homo-galacturonan (HG) and rhamnogalacturonan I (RG-I) domains. RRP-4 showed obvious scavenging activities on DPPH, ABTS, hydroxyl radicals and superoxide anion radicals in a concentration-dependent manner (0.25-3.0 0 mg/mL of RRP-4), indicating that RRP-4 exhibited a good antioxidant activity in vitro . Animal experiments revealed that RRP-4 markedly increased the release of cytokines (IL-2, TNF-alpha and IFN-gamma) and proliferation and secretion of T lymphocyte cells (CD4+ and CD8+ T cells) dosage-dependently (50, 10 0, 20 0 mg/kg) via significantly reducing the oxygenation levels in cyclophosphamide (CTX)-induced mice. After administration of RRP-4, the activities of antioxidant enzymes (SOD, GSH-PX and CAT) were markedly increased and the level of MDA was reduced in a dose-dependent manner (50, 10 0, 20 0 mg/kg). These results indicated that the polysaccharide had the potential as a natural antioxidant and an im-munoregulation adjuvant for the treatment of oxidative damage and immunosuppression-related dis-eases. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

In this study, a pectic polysaccharide (RRP-4) was extracted from Rhodiola rosea using a cold-water extraction method. RRP-4 showed good antioxidant activity and immunomodulatory effects. It has the potential to be used as a natural antioxidant and immunoregulation adjuvant for the treatment of oxidative damage and immunosuppression-related diseases.