Physicochemical characteristics and biological activities of polysaccharides from the leaves of different loquat (Eriobotrya japonica) cultivars

In order to explore polysaccharides from loquat leaves (LLP5) as functional food ingredients for prevention and treatment of obesity and type 2 diabetes, the physicochemical characteristics, in vitro binding properties, and inhibitory effects on alpha-amylase and alpha-glucosidase of polysaccharides from the leaves of different loquat cultivars, including Taiyu', 'Chuannong8', 'Yuanbao', and 'Dawuxing', were investigated and compared. Results showed that the contents of total uronic acids and degree of esterification in LLP5 ranged from (27.04 +/- 1.76)% to (41.46 +/- 1.91)%, and from (20.54 +/- 0.11)% to (26.90 +/- 0.10)%, respectively. The weight-average molecular weights of LLPs ranged from 4.307 x 10(6) Da to 5.101 x 10(6) Da, and the major constituent monosaccharides of LLPs were rhamnose, galacturonic acid, arabinose, and galactose. Furthermore, LLPs exerted strong in vitro fat binding, cholesterol binding, and bile acid binding capacities, as well as remarkable inhibitory effects on alpha-amylase and alpha-glucosidase, which might be attributed to their molecular weights, molecular weight distributions, and degree of esterification. Results are helpful for better understanding of chemical structures and bioactivities of polysaccharides from loquat leaves, and LLPs had good potential to be explored as functional food ingredients for prevention and treatment of obesity and type 2 diabetes. (C) 2019 Elsevier B.V. All rights reserved.