A glycoprotein from Salvia miltiorrhiza bunge: Insights into their chemical characteristics and antioxidant activity

A glycoprotein (DSGP) from Salvia miltiorrhiza Bunge was purified by Tris-HCl extraction followed by DEAE-52 ion exchange chromatography. The approximate molecular weight (25.0 kDa) and monomeric nature were determined by reduced and non-reduced SDS-PAGE. The structure of DSGP was characterized by a practical and reliable “protein-polysaccharide analyzed by spectroscopy combined with chemical analysis” strategy. This study is the first to demonstrate that DSGP is an O -linked glucomannan protein, wherein its glycan moiety is a glucomannan chain with an average degree of polymerization (DP) of approximately 7. Hemagglutination assays confirmed that DSGP lacks lectin activity, indicating favorable safety properties. DSGP exhibits significant free radical scavenging activity and a unique advantage over ascorbic acid, namely that it does not produce hydrogen peroxide (H₂O₂) when exerting its antioxidant effects. In addition, as a hydrophilic colloid, DSGP can inhibit the sedimentation of pulp particles by enhancing electrostatic repulsion within the system, thereby exerting an excellent stabilizing effect on fruit juices. Therefore, these results suggested that glycoprotein DSGP could be used as a natural antioxidant and stabilizer in beverage industry.