Supercritical CO2 fluid extraction, physicochemical properties, antioxidant activities and hypoglycemic activity of polysaccharides derived from fallen Ginkgo leaves

Abstract

In this study, supercritical CO2 fluid extraction (SFE-CO2) with ethanol as a cosolvent was used to obtain a polysaccharide from fallen Ginkgo leaves (FGPs). A highest yield of FGPs (10.13 ± 0.12 g/100 g) was obtained using the response surface methodology (RSM) with optimized SFE-CO2 conditions (Time 99.0 min, pressure 42 MPa, Temperature 63.0 °C, and cosolvent 68.0%). Results of this analysis revealed that FGPs were mainly composed of total sugar (65.23 ± 2.35 g/100 g), uronic acid (14.59 ± 0.91 g/100 g), acidophobes (10.21 ± 1.02 g/100 g), and protein (2.86 ± 0.84 g/100 g). FGPs were comprised of Man, Rha, GlcA, GalA, Glc, Gal, and Ara at a molecular ratio of 3.64:4.25:8.48:9.10:4.39:50.30:19.84, respectively. The average molecular weight of its major component (accounting for 61.19% of FGPs) was determined to be 218.50 kDa. In addition, FGPs showed good scavenging activity for DPPH, hydroxyl radicals, ABTS, and superoxide anion radicals. In vitro and in vivo experiments demonstrated that FGPs have significant hypoglycemic effects. Therefore, FGPs may act as natural antioxidants and hypoglycemic agents.