Extraction, characterization, and biological activity in vitro of polysaccharides from discarded young fig fruits based on various extraction methods

Discarded young fig fruits (DYFFs) are rich in polyphenols, polysaccharides, and other active substances, and fig polysaccharides (FPs) extracted from DYFFs using different methods vary in structure, processing characteristics, and biological activities, which are of great research value. The polysaccharides extracted from DYFFs using different extraction methods were used to compare the structures, processing characteristics, and biological activities of FPs, and to research the conformational relationships. The yield of MDP (6.45% ± 0.03%) prepared by microwave-assisted deep eutectic solvent extraction was nearly double that of HWP (2.59% ± 0.01%) prepared by hot water extraction. The FPs extracted by different methods were free of other impurities, with molecular weights (M_w) ranging from 16.78 to 102.20 kDa, and were mainly composed of xylose, arabinose, glucose, galactose, and glucuronide. MDP exhibited significantly higher processing characteristics (water-holding capacity = 5.17 ± 0.50g/g; oil-holding capacity = 3.88 ± 0.54), antioxidant capacity (ABTS radical scavenging rates [10.41 ± 0.06 mg/g]; ferric-reducing antioxidant powers [51.73 ± 1.23 mg/g]; the reducing powers [37.35 ± 0.11 mg/g]), and hypoglycemic activity compared to other polysaccharides, whose inhibitory effect on α-amylase of MDP (IC₅₀ = 1.48 mg/mL) was higher than 10 times that of HWP. FP structures affect processing characteristics and biological activities. MDP has a higher extraction rate, better processing characteristics and biological activities, and MDP has a better potential to be developed as a natural antioxidant and α-amylase inhibitor.