Salvia miltiorrhiza has exhibited various bioactive functions due to the existence of polysaccharides, hydrophilic phenolic acids, diterpenoid quinones, and essential oils. However, little research has reported the glycoprotein preparation and corresponding bioactivities. In this study, the water-soluble glycoprotein from S. miltiorrhiza roots was firstly isolated with the extraction process optimized by response surface methodology, and then, the preliminary structural properties, and the antioxidant and immunoregulatory activities were investigated. Results showed that the extraction conditions for higher extraction yields were identified as follows: ultrasonic power of 220 W, ultrasonic time of 2.0 h, extraction temperature of 60 °C, liquid/solid ratio of 20 mL/g, and the glycoprotein yields of 1.63 ± 0.04%. Structural analysis showed that the glycoprotein comprised protein and polysaccharide (contents of 76.96% and 20.62%, respectively), with an average molecular weight of 1.55 × 105 Da. Besides, bioactivities analysis showed that the glycoprotein presented strong scavenging effects on multiple free radicals, and effectively enhanced the antioxidant enzyme activities and immunological indicators in cyclophosphamide-induced immunocompromised mice dose-dependently. These data demonstrated that S. miltiorrhiza glycoprotein presented the potential to be a novel edible functional compound, and could be practically applied in the food industry.
Keywords: S. miltiorrhiza glycoprotein; bioactivities; optimization; structural properties.