Effects of different extraction methods on physicochemical characteristics and bioactivities of fig (Ficus carica L.) leaves polysaccharides

The tea of fig (Ficus carica L.) has long been used as a medicine in China due to its excellent effects on hemorrhoids, damp heat diarrhea and other diseases. The present study was designed to evaluate the impacts of different extraction methods, including hot water extraction (HWE), microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), ultrasound assisted enzymatic extraction (UAEE), ultrasound-microwave assisted extraction (UMAE), alkali extraction (AE) and high-speed shearing homogeneous extraction (HSHE), on physicochemical characteristics and bioactivities of polysaccharide from fig leaves (FLPs). Results indicated that there were great differences between the structure and activity of FLPs prepared by seven methods. Among them, FLPs extracted by UAE (FLPs-UAE) showed the strongest antioxidant and hypoglycemic activities due to its higher Mw, total polysaccharide content (60.62 ± 3.06 %) and glucosamine (GlcN) content (7.68 %). In addition, FLPs extracted by HWE possessed more total polysaccharide content (62.03 ± 0.70 %), total phenolic compounds content (13.55 ± 0.02 %) and GlcN content (5.78 %) contributed to its strong antioxidant activity and the inhibition on α-amylase and α-glucosidase, which was second to FLPs-UAE. These finding suggested that UAE and HWE, especially UAE, were good ways to extract FLPs with high antioxidant and anti-diabetic activities, which provide foundations for choosing the suitable extraction strategy to prepare FLPs with desired bioactivities and promoting the application of FLPs in function food industries.