Low-glycemic foods with wheat, barley and herbs (Terminalia chebula, Terminalia bellerica and Emblica officinalis) inhibit α-amylase, α-glucosidase and DPP-IV activity in high fat and low dose streptozotocin-induced diabetic rat

Abstract

Wheat, barley or wheat + barley and herbs (Terminalia chebula, Terminalia bellerica and Emblica officinalis) based low-glycemic-index (low-GI) foods were developed and studied α-amylase, α-glucosidase and DPP-IV inhibition property in vitro and in the streptozotocin-induced diabetic rats. The GI of products ranged from 47 to 53 than control white bread (GI = 95). Total phenolic (20.1 ± 1 mg gallic acid/g dry wt.) and flavonoids (15.2 ± 1 mg quercetin/g dry wt.) were higher in wheat + barley than barley (17.2 ± 1; 13.6 ± 2) and wheat (16.9 ± 1; 14.9 ± 2) products. The in vitro α-amylase (4-10%), α-glucosidase (5-17%) and DPP-IV (3-26%) inhibition (IC₅₀) of methanol extracts were higher than the aqueous extracts. The fasting blood glucose (50.85, 33.22 and 24.52%) and oral glucose tolerance (AUC = 32.1, 36.04, and 27.73%) was lower in barley, wheat, and wheat + barley fed diabetic groups than diabetic control group (1571.5 ± 13.5 mg/dL/120 min). Feeding wheat, barley, and W + B foods for 60 days inhibited the intestinal α-amylase (1.2, 1.1 and 1.5-folds), α-glucosidase (1.3, 1.2 and 1.7-folds) and DPP-IV (1.6, 1.5 and 2.1-folds) activity compared to diabetic control. Low-GI foods lower the systemic glucose level, inhibit the glycolytic enzymes and DPP-IV activity and hence desirable for diabetes management.

Supplementary information: The online version contains supplementary material available at 10.1007/s13197-021-05231-0.

Keywords: Antidiabetic; Cereals; Glycolytic enzymes; Herbs; Low-GI.

Fig. 1

Phenolic profile of a barley product, b wheat product and c wheat + barley product

Fig. 1

Phenolic profile of a barley product, b wheat product and c wheat + barley product

Fig. 2

Sensory characteristics of a wheat product b barley product and c wheat + barley products

Fig. 3

Effect of wheat (W), barley (B) and wheat+barley (W+B) products on oral glucose tolerance in diabetic rats (a). The area under curve of the blood glucose values (b). Values are mean ± SD (n = 4/group). *P < 0.05 vs diabetic, ** P < 0.05 vs experimental groups. Note: C: control, D: diabetic, B: barley product, W: wheat product, W+B: wheat+barley product

Fig. 4

α-Amylase (a), α-glucosidase (b) and DPP4 (c) enzyme activity in rat intestine and serum glucose level (d). α-Amylase activity was determined by measuring the maltose released per minute. α-glucosidase activity measured by estimating p-nitrophenol release per minutes and DPP4 enzyme activity expressed by p-nitoaniline equivalent released per min. Values are Mean ± SD (n = 4/group). Note: C: control, D: diabetic, B: barley product, W: wheat product, W + B: wheat + barley product