Optimization of functional compounds extraction from Ginkgo biloba seeds using response surface methodology

Ginkgo biloba seeds are important raw material for foods and medicines. A response surface method was used to obtain the following optimized extraction conditions for Ginkgo biloba seed extracts (GBSE) with the high-est 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability: 0.08 g/mL material-to-liquid ratio, 70% ethanol concentration, 47°C extraction temperature and extraction time of 22 min. Fourier transform infrared spectroscopy revealed the polysaccharide structure of GBSE from three varieties of Ginkgo biloba seeds (Fozhi, Maling and Yuanling seed varieties). The extract yield, polysaccharides, total phenolics and total flavonoids in the three varieties were 5.77–6.11%, 11.45–364.69 mg/g, 22.34–25.54 mg/g and 14.87–16.47 mg/g, respectively. The GBSE has good antioxidant ability, including DPPH-reducing activity (1842.73–2616.00 micromol [mmol] Trolox Equivalents [TE]/gram [g]), ABTS (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); 185.03–217.63 mmol TE/g) and ferric-reducing antioxidant power (FRAP; 220.46–230.77 mmol TE/g). This study provides a method for preparing GBSE with high antioxidant activity and improving the utilization value of Ginkgo biloba seeds.