The experimental evaluation in vivo of hypoglycemic properties of functional food ingredient - polyphenolic food matrix
The aim of this study was the evaluation of hypoglycemic action of functional food ingredient (FFI) - a polyphenol food matrix in 3-month in vivo experiment with the use of fat male mice C57BL/6. The food matrix was produced by means of incubation of bilberry leaves extract (2% solution, pH 3.6) with buckwheat flour in ratio 1:50 during 45 min at 25 oC. The polyphenol content in experimental batch of matrix was 26.6±0.5 mg-equivalent of gallic acid per 1 g of flour. The experiment was conducted with the use of 46 male mice C57Bl/6c. Blood glucose level was estimated before starting the feeding experiment. An oral fasting glucose tolerance test (GTT) was also conducted, the area under the curve (AUC) was calculated. The animals were randomly divided into 4 groups (according to the body weight, glucose level and AUC): control group K1, fed with standard semisynthetic diet, control group K2 (n=10) and experimental groups G3 and G4 (n= 13). The symptoms of type 2 diabetes in groups K2, G3 and G4 were modeled with the use of high-fat high-carbohydrate diet (HFHC diet, 30% fat, 20% sucrose). FFI was included into the diet of animals of experimental groups G3 and G4 in doses 2.5 and 5 g per 100 g of ration, respectively. The GTT test was repeated on the 40th and 82nd days of experiment. On the 15th, 54th and 91st days the insulin resistance test (IRT) was conducted. The consumption of HFHC diet by K2 group animals resulted in development of obesity in these animals to the week 11, which was characterized by increase in the body weight gain (37.1±4.9%) in comparison with control group K1 animals (23.4±2.2%). The introduction of FFI into animal's diet decreased significantly body weight gain of these animals in comparison with K2 group. On the week 8, the significant increase in blood glucose level of animals fed with HFHC diet was found (K2 - 8.2±0.3, G3 - 8.1±0.3, G4 - 8.5±0.3 mmol/L), in comparison with control group K1 (7.1±0.3 mmol/L). On the 91st day of experiment this difference remained significant only for group K2 (9.3±0.6 against K1 group - 7.7±0.3 mmol/L), what shows the beneficial hypoglycemic action of the FFI in both doses (for G3 group - 8.5±0.2, for G4 - 8.4±0.3 mmol/L). On the week 8 the disorder in glucose tolerance was found in animals of group K2, what is one of type 2 diabetes symptoms. The introduction of FFI in a dose 2.5 g/100 g into group G3 diet inhibited the development of these disease symptoms. The introduction of FFI in a higher dose (5 g/100 g of a diet) to a certain extent inhibited the development of insulin resistance. There was no effect of FFI, introduced into animal's diet, on cognitive functions and short-term and long-term memory.
Keywords:polyphenols, bilberry leaves extract, food matrix, hyperglycemia, obesity, insulin resistance, glucose tolerance
Voprosy pitaniia [Problems of Nutrition]. 2018; 87 (4): 5-13. doi: 10.24411/0042-8833-2018-10036.