A Polysaccharide-Rich Fraction Derived from Oviductus ranae with Antioxidant and Immunomodulatory Potentials

Oviductus ranae, an animal-based traditional Chinese medicinal material listed in Chinese Pharmacopeia is widely consumed as tonic, approximately twenty Oviductus ranae-related functional foods have been approved on the market by National Medical Products Administration in China. Proteins are well-defined bioconstituents in Oviductus ranae, little information is availabe on its polysaccharides. In present work, a Polysaccharide-Rich fraction (POR-3) was fractionated from Oviductus ranae based on antioxidant activity-guided isolation and its structure was partially characterized as well as its immunomodulatory potential was explored. POR-3 belonged to a heteropolysaccharide-protein fraction mainly consisted of Man, GlcN, GalA, Gal and Fuc at a molar ratio of 1: 2.28: 2.40: 3.00: 2.23 with binding proteins content of 6.42±0.16%. POR-3 possessed polydisperse property with MW of 999.586 kDa and PDI of 4.09. The UV and FT-IR analysis demonstrated that structures of POR-3 correspond with the characteristics of polysaccharide-protein complex. POR-3 elicited higher scavenging capacities against hydroxyl and DPPH radicals and exerted potent in vitro immunomodulatory activity via promoting macrophages phagocytosis and via stimulating NO production as well as appeared no proliferation on macrophages. POR-3 possesses high potentials to be consumed as a medicine or functional food with antioxidant and immune modulator properties.