Chemical Characterization and Bioactivity Analysis of Polysaccharides Extracted from Ginkgo Folium Residue with Different Solvents

Ginkgo Folium residues contain a large number of polysaccharide substances that need to be exploited to achieve a deeper utilization of the resource. In this paper, the effects of hot water, acid, alkali, salt, ultrasonic-assisted extraction, and enzyme-assisted extraction on the chemical composition and biological activity of polysaccharides as major components of Ginkgo Folium residues are compared horizontally. Chemical composition analysis showed that all of the six polysaccharides obtained by different methods were acidic heteropolysaccharides. Ultrasonication broke the glycosidic bonds compared to the samples extracted with water. Both in acidic and alkaline extraction environments, the glycosidic bonds were broken, which greatly reduced the relative molecular weight of the polysaccharides. The Maillard reaction may have occurred in the alkali-extracted samples. The FT-IR spectrum of the salt-extracted sample was significantly different from the other samples, probably due to the consumption of hydroxyl groups during the extraction of polysaccharides by ammonium oxalate. The antioxidant results showed that the antioxidant capacity of alkaline medium was significantly higher than other samples. Acid and salt-extracted samples also have high antioxidant activity. Preliminary in vitro anti-inflammatory activity screening showed that the alkaline extraction method has some anti-inflammatory potential. The polysaccharides of Ginkgo Folium were extracted in different ways that could significantly inhibit LPS-induced NO secretion in RAW264.7 cells. These results provide a reference for extracting and applying polysaccharides from Ginkgo Folium residues.