Phenolic compounds in grapes, wine could have anti-diabetic function: American study
Conducted by Auburn University, the study investigated the effects of resveratrol and its metabolite, piceatannol on α-glucosidase (an enzyme target for certain antidiabetic drugs), and found that they “consistently exerted strong inhibition of mammalian and yeast α-glucosidase activity”.
The study used 40 male mice randomly divided into four groups of 10 each. They were all put on a high-fat diet for two months, after which two groups were given either resveratrol or piceatannol, and the control groups were given either vehicle or acarbose following a 12-hour overnight fast.
They were then fed sucrose an hour later, before the first one-week washout period, during which their high-fat diets continued. The same process was repeated afterwards, with starch instead of sucrose. After the second and final week-long washout period, the process repeated, this time with glucose instead of sucrose or starch.
Resveratrol was found to be “2.5 times more potent than acarbose in inhibiting yeast α-glucosidase”, while piceatannol “inhibited the sucrase and maltase activity of α-glucosidase, similar to that of acarbose”. The mice that had been administered resveratrol and piceatannol had lower blood glucose concentrations than those in the control groups.
The study further stated that the “hypoglycemic effect of resveratrol and piceatannol was primarily dependent on its ability to inhibit α-glucosidase activity following an oral carbohydrate load”.
Resveratrol’s other anti-diabetic effects include improved glucose uptake in the liver and muscle, repression of insulin secretion in the pancreas, and caloric restriction, while piceatannol has been shown to modulate insulin signal transduction.
At the moment, commercial α-glucosidase inhibitors prescribed to type 2 diabetes patients consist of acarbose, miglitol and voglibose, which retard carbohydrate digestion and delay glucose absorption. However, their inhibitory effects vary: acarbose and voglibose effectively inhibit mammalian α-glucosidase but are far less effective against yeast α-glucosidase.
Conversely, catechins in green tea and oolong tea “inhibited yeast α-glucosidase but were ineffective inhibitors of mammalian α-glucosidase activity”.
The ability of resveratrol and piceatannol to inhibit both mammalian and yeast α-glucosidase activity led the study to conclude that they have “a promising therapeutic potential for (the) development of stilbene analogues in the control of hyperglycemia”.
Source: Journal of Nutritional Biochemistry
May 2017, volume 47, pages 86 — 93
Authors: Albert J. Zhang, et al.
