Ultrasound-assisted extraction of polysaccharides from Ginkgo biloba: Process optimization, composition and anti-inflammatory activity.

Plant derived polysaccharides can enhance immune function in the human body, effectively prevent diseases, and reduce the probability of bacterial infections. Ginkgo crude polysaccharide (GCP) was obtained from Ginkgo biloba by ultrasonic-assisted hot water extraction. Our data showed that the best extraction conditions of GCP were as follows: extraction temperature 80 °C, ultrasonic time 35 min, extraction time 3 h, and solid‒liquid ratio 1:30. Fourier transform infrared spectrometer (FT-IR) data showed that this polysaccharide might be an acidic polysaccharide with a carboxylic acid ring structure. Further studies implied that GCP was mainly composed of glucose, galacturonic acid, rhamnose, galactose and arabinose, accounting for 39.45 %, 25.01 %, 15.40 %, 11.94 % and 4.25 %, respectively. 0.1, 1 and 10 mg/mL GCP reduced the release of inflammatory factors in RAW264.7 cells via inhibition of the nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) signalling pathway. GCP was separated into five components with different molecular weights by an ultrafiltration membrane. Our data showed that GPa with a molecular weight ≥100 kDa was the main component of GCP. 1 mg/mL GPa, GPb, GPc and GPd had anti-inflammatory activities, and 1 mg/mL GPa had the best anti-inflammatory activities. Our results preliminarily reveal the elements and biological activity of GCP, which will provide a reference for the development of Ginkgo biloba.