Abstract
The prevention of postprandial hyperglycemia and diabetic complications is crucial for diabetes management. Inhibition of α-glucosidase to slow carbohydrate metabolism is a strategy to alleviate postprandial hyperglycemia. In addition, suppression of non-enzymatic glycation can diminish the advanced glycation end products and reduce the oxidative stress and inflammation, thereby preventing the diabetic complications. In this study, an anti-oxidative proteoglycan (named FYGL) extracted from Ganoderma lucidum was investigated in vitro for its inhibitory effect on α-glucosidase and non-enzymatic glycation using molecular kinetics, intrinsic fluorescence assay, and bovine serum albumin glycation models. The molecular kinetics and fluorescence assay revealed that FYGL decreases α-glucosidase activity by forming a FYGL–α-glucosidase complex. To evaluate the anti-glycation effect, fructose-glycated and methylglyoxal-glycated BSA models were analyzed by spectroscopic and SDS-PAGE methods. Results showed that FYGL inhibited the glycation at every stage and suppressed glycoxidation, possibly due to its anti-oxidative capacity and FYGL–BSA complex formation. Furthermore, we demonstrated in vivo that FYGL could alleviate postprandial hyperglycemia in db/db mice as well as AGE accumulation and vascular injury in diabetic rats. Overall, FYGL possesses anti-postprandial hyperglycemia and anti-glycation functions and would be potentially used in clinic for diabetes and related complication management.
Highlights
Diabetes is a common metabolic disease characterized by hyperglycemia
With the concentration of FYGL increased, the inhibition rate of α-glucosidase activity was increased. These results indicated that FYGL inhibited α-glucosidase activity in a dosedependent manner
This work investigated the effect of FYGL on α-glucosidase activity and anti-nonenzymatic glycation in vitro
Summary
Postprandial blood glucose (PBG) and fasting blood glucose (FBG) are two major indicators of hyperglycemia. High postprandial blood glucose accelerates the occurrence of microvascular and macrovascular complications as well as type II diabetes [1]. Postprandial blood glucose reaches its peak due to the digestion of carbohydrates such as starch and sucrose in food. Starch is decomposed into oligosaccharides or disaccharides by α-amylase in the saliva and pancreatic juice and further decomposed into absorbable glucose by α-glucosidase at the brush edge of small intestinal epithelial cells, leading to the PBG peak reached. Continuous hyperglycemia in diabetic patients accelerates non-enzymatic glycation and increases the production of advanced glycation end products (AGEs) [5]. AGEs interact with their receptor on vascular endothelial cell surfaces, leading to the activation of the pathway of AGE and its receptor (RAGE) and oxidative stress and inflammation [6], which accelerate diabetic complications, especially vascular complications [7]
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