• Preventive Nutrition and Food Science
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• v.22 no.3
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• pp.166-171
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• 2017

In this study, we investigated whether Sargassum yezoense extract (SYE) could inhibit ${\alpha}-glucosidase$ and ${\alpha}-amylase$ activities, and alleviate postprandial hyperglycemia in streptozotocin (STZ)-induced diabetic mice. Freeze-dried S. yezoense was extracted with 80% ethanol and concentrated for use in this study. The hypoglycemic effect was determined by evaluating the inhibitory activities of SYE against ${\alpha}-glucosidase$ and ${\alpha}-amylase$ as well as its ability to decrease postprandial blood glucose levels. The half-maximal inhibitory concentrations of SYE against ${\alpha}-glucosidase$ and ${\alpha}-amylase$ were $0.078{\pm}0.004$ and $0.212{\pm}0.064mg/mL$, respectively. SYE was a more effective inhibitor of ${\alpha}-glucosidase$ and ${\alpha}-amylase$ activities than the positive control, acarbose. The increase in postprandial blood glucose levels was significantly alleviated in the SYE group compared with that in the control group of STZ-induced diabetic mice. Furthermore, the area under the curves significantly decreased with SYE administration in STZ-induced diabetic mice. These results suggest that SYE is a potent inhibitor of ${\alpha}-glucosidase$ and ${\alpha}-amylase$ activities and alleviates postprandial hyperglycemia caused by dietary carbohydrates.

• Preventive Nutrition and Food Science
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• v.21 no.3
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• pp.181-186
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• 2016

This study was designed to investigate the inhibitory effect of Gynura procumbens extract against carbohydrate digesting enzymes and its ability to ameliorate postprandial hyperglycemia in streptozotocin (STZ)-induced diabetic mice. G. procumbens extract showed prominent ${\alpha}$-glucosidase and ${\alpha}$-amylase inhibitory effects. The half-maximal inhibitory concentration ($IC_{50}$) of G. procumbens extract against ${\alpha}$-glucosidase and ${\alpha}$-amylase was $0.092{\pm}0.018$ and $0.084{\pm}0.027mg/mL$, respectively, suggesting that the ${\alpha}$-amylase inhibition activity of the G. procumbens extract was more effective than that of the positive control, acarbose ($IC_{50}=0.164mg/mL$). The increase in postprandial blood glucose levels was more significantly alleviated in the G. procumbens extract group than in the control group of STZ-induced diabetic mice. Moreover, the area under the curve significantly decreased with G. procumbens extract administration in STZ-induced diabetic mice. These results suggest that G. procumbens extract may help alleviate postprandial hyperglycemia by inhibiting carbohydrate digesting enzymes.

• Preventive Nutrition and Food Science
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• v.19 no.1
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• pp.5-9
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• 2014

This study was designed to investigate the inhibitory effects of Polyopes lancifolia extract (PLE) on ${\alpha}$-glucosidase activity, ${\alpha}$-amylase activitiy, and postprandial hyperglycemia in streptozotocin (STZ)-induced diabetic mice. The results of this study revealed a marked inhibitory effect of PLE on ${\alpha}$-glucosidase and ${\alpha}$-amylase activities. The $IC_{50}s$ of PLE against ${\alpha}$-glucosidase and ${\alpha}$-amylase were 0.20 mg/mL and 0.35 mg/mL, respectively. PLE was a more effective inhibitor of ${\alpha}$-glucosidase and ${\alpha}$-amylase activities than acarbose, the positive control. The postprandial blood glucose levels of STZ-induced diabetic mice were significantly lower in the PLE treated group than in the control group. Moreover, PLE administration was associated with a decreased area under the curve for the glucose response in diabetic mice. These results indicate that PLE may be a potent inhibitor of ${\alpha}$-glucosidase and ${\alpha}$-amylase activities and may suppress postprandial hyperglycemia.

• Journal of Life Science
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• v.28 no.4
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• pp.421-428
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• 2018

Postprandial hyperglycemia plays an important role in the development of Type 2 Diabetes and diabetic complications. Controlling postprandial hyperglycemia is the most important factor for reducing the risks of diabetic complications in Type 2 diabetic patients. This study was designed to determine whether Portulaca oleracea L. extract suppresses the activation of carbohydrate-digesting enzymes, and lowers postprandial hyperglycemia in diabetic mice through streptozotocin. P. oleracea was extracted with either 80% ethanol (PEE) or water (PWE), and the extract solutions were concentrated. The ${\alpha}$-glucosidase and ${\alpha}$-amylase inhibition assays were performed using the chromogenic method. Normal mice and STZ-induced diabetic mice were orally treated with PEE, PWE (300 mg/kg of body weight) or acarbose (100 mg/kg of body weight), with soluble starch (2 g/kg of body weight). The ${\alpha}$-glucosidase and ${\alpha}$-amylase inhibitory effectiveness by PEE were markedly more effective than PWE, and both extracts indicated a higher effectiveness than the acarbose (positive control). The rise in postprandial blood glucose due to starch loading was markedly inhibited in the PEE group when compared to the control group in diabetic and normal mice. Furthermore, the area under the concentration-time curve values were markedly declined by the PEE injection in the diabetic group when compared to that exerted for the control group. These results demonstrate that P. oleracea extracts lower postprandial hyperglycemia by inhibiting carbohydrate-digesting enzymes, and that the ethanol extract is more efficacious than the water extract.

• Journal of Life Science
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• v.26 no.8
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• pp.921-927
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• 2016

Postprandial hyperglycemia is an early defect of type 2 diabetes and one of primary anti-diabetic targets. The alpha-glucosidase inhibitors regulate postprandial hyperglycemia by impeding the rate of carbohydrate (such as starch) digestion in the small intestine. This study was designed to investigate the inhibitory actions of mulberry fruit extract (MFE) on α-glucosidase and α-amylase activities, and its alleviating effect on postprandial hyperglycemia activities in vitro and in vivo. Male four-week old ICR mice and streptozotocin (STZ)-induced diabetic mice were treated with mulberry fruit extract. MFE showed strong inhibitory effects against α-glucosidase and α-amylase activities, with half-maximal inhibitory concentration (IC₅₀) values of 0.16 and 0.14 mg/ml, respectively, and was more effective than acarbose, which was used as a positive control. The increase in postprandial blood glucose levels was more significantly attenuated in the MFE-administered group mice than in the control group mice of both STZ-induced diabetic and normal mice. Moreover, the area under the glucose response curve significantly decreased following MFE administration in diabetic mice. These results indicate that MFE may be a potent inhibitor of α-glucosidase and α-amylase, and helpful in suppressing postprandial hyperglycemia in diabetic mice. The mulberry fruit extracts may be considered as a potential candidate for the management of diabetes.

• Natural Product Sciences
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• v.10 no.5
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• pp.223-227
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• 2004

This study was carried out to investigate inhibitory effect of extracts from the root of Paeonia lactiflora on postprandial hyperglycemia. Organic solvent (hexane, ethyl acetate, butanol, aqueous) extracts from the crude drug were fractionated by high performance liquid chromatography. These fractions were examined to evaluate ${\alpha}-glucosidase$ (EC 3. 2. 1. 20) inhibition by microplate colorimetric assay. Among the fractions examined, the ethyl acetate fraction from the roots of Paeonia lactiflora showed potent inhibitory effects on ${\alpha}-glucosidase$. Therefore, further fractionation of the fraction was carried out to isolate the active principles. Finally, we isolated and Purified 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG) as a active principle by activity-guided fractionation. These results suggest that the extract from the root of Paeonia lactiflora can be used as a new nutraceutial for inhibition on postprandial hyperglycemia and PGG might be a candidate for developing an ${\alpha}-glucosidase$ inhibitor.

• Nutrition Research and Practice
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• v.13 no.1
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• pp.11-16
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• 2019

BACKGROUND/OBJECTIVES: Fasting and postprandial hyperglycemia should be controlled to avoid complications of diabetes mellitus. This study investigated the effects of autumn olive (Elaeagnus umbellata Thunb.) berry (AOB) on fasting and postprandial hyperglycemia in mice. MATERIALS/METHODS: In vitro ${\alpha}$-glucosidase inhibitory effect of AOB was determined. Maltose solution (2 g/kg) with and without AOB extract at 500 mg/kg or acarbose at 50 mg/kg was orally administered to normal mice after overnight fasting and glucose levels were measured. To study the effects of chronic consumption of AOB, db/db mice received the basal diet or a diet containing AOB extract at 0.4% or 0.8%, or acarbose at 0.04% for 7 weeks. Blood glycated hemoglobin and serum glucose and insulin levels were measured. Expression of adiponectin protein in epididymal white adipose tissue was determined by Western blotting. RESULTS: In vitro inhibitory effect of AOB extract on ${\alpha}$-glucosidase was 92% as strong as that of acarbose. The AOB extract (500 mg/kg) or acarbose (50 mg/kg) significantly suppressed the postprandial rise of blood glucose after maltose challenge and the area under the glycemic response curve in normal mice. The AOB extract at 0.4% or 0.8% of diet or acarbose at 0.04% of diet significantly lowered levels of serum glucose and blood glycated hemoglobin and homeostasis model assessment for insulin resistance values in db/db mice. The expression of adiponectin protein in adipose tissue was significantly elevated by the consumption of AOB at 0.8% of diet. CONCLUSIONS: Autumn olive (E. umbellata Thunb.) berry may reduce postprandial hyperglycemia by inhibiting ${\alpha}$-glucosidase in normal mice. Chronic consumption of AOB may alleviate fasting hyperglycemia in db/db mice partly by inhibiting ${\alpha}$-glucosidase and upregulating adiponectin expression.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.1
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• pp.131-135
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• 2002

This study was carried out to investigate the inhibitory effect of extracts from Paeoniae radix on postprandial hyperglycemia. Organic solvent (hexane, ethyl acetate, butanol, water) extracts from Paeoniae radix were fractionated by high performance liquid chromatography. These fractions were used to screen $\alpha$-glucosidase (EC 3.2.1.20) inhibitors by microplate colorimetric assay. The fractions 11, 12, 18, 19 of ethyl acetate extract from Paeoniae radix showed inhibitory activity by 85%, 84%, 77%, 77% at concentration of 20 $\mu\textrm{g}$/mL, respectively. The selected fractions (no. 10~no. 19) significantly reduced by 22% the blood glucose elevation in comparison with positive control in mice loaded with maltose. The fractions of Paeoniae radix were determined in vitro inhibitory activity on $\alpha$-glucosidase and in vivo inhibition effect on blood glucose elevation in mice. Therefore, these results suggest that the extract of Paeoniae radix can be used as a new nutraceutial for inhibition on postprandial hyperglycemia as well as resource pool for lead compounds as a $\alpha$-glucosidase inhibitor.

• Preventive Nutrition and Food Science
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• v.18 no.3
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• pp.163-168
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• 2013

In this study, we investigated the inhibitory effects of Baechu kimchi added Ecklonia cava on the activities of ${\alpha}$-glucosidase and ${\alpha}$-amylase and its alleviating effect on the postprandial hyperglycemia in STZ-induced diabetic mice. Baechu kimchi added Ecklonia cava (BKE, 15%) was fermented at $5^{\circ}C$ for 28 days. Optimum ripened BKE was used in this study as it showedthe strongest inhibitory activities on ${\alpha}$-glucosidase and ${\alpha}$-amylaseby fermentation time among the BKEs in our previous study. The BKE was extracted with 80% methanol and the extract solution was concentrated, and then used in this study. The BKE extract showed higher inhibitory activities than Baechu kimchi extract against ${\alpha}$-glucosidase and ${\alpha}$-amylase. The $IC_{50}$ values of the BKE extract against ${\alpha}$-glucosidase and ${\alpha}$-amylase were 0.58 and 0.35 mg/mL, respectively; BKE exhibited a lower ${\alpha}$-glucosidase inhibitory activity but a higher ${\alpha}$-amylase inhibitory activity than those of acarbose. The BKE extract alleviated postprandial hyperglycemia caused by starch loading in normal and streptozotocin- induced diabetic mice. Furthermore, the BKE extract significantly lowered the incremental area under the curve in both normal and diabetic mice (P<0.05). These results indicated that the BKE extract may delay carbohydrate digestion and thus glucose absorption.

• Journal of Life Science
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• v.27 no.9
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• pp.1052-1058
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• 2017

Gelidium amansii shows antioxidant and anti-obesity effects; however, the effect on postprandial blood glucose levels is not known. The objective of the present study was to investigate the inhibitory effect of Gelidium amansii extract (GAE) on carbohydrate-digesting enzymes and its ability to alleviate postprandial hyperglycemia in streptozotocin (STZ)-induced diabetic mice. Gelidium amansii was extracted with 80% ethanol and concentrated for use in this study. The ${\alpha}-glucosidase$ and ${\alpha}-amylase$ inhibition assays were performed using the colorimetric method. ICR normal and STZ-induced diabetic mice were orally administered GAE (300 mg/kg body weight) or acarbose (100 mg/kg body weight) alone or soluble starch (2 g/kg body weight). Blood samples were taken from the tail vein at 0, 30, 60 and 120 min. Our results indicated that GAE markedly inhibited ${\alpha}-glucosidase$ and ${\alpha}-amylase$ activities with $IC_{50}$ values of $0.099{\pm}0.009mg/ml$ and $0.178{\pm}0.038mg/ml$, respectively, and was a more effective inhibitor than acarbose, the positive control. Further, the postprandial blood glucose levels of STZ-induced diabetic mice in the GAE-administered group were significantly lower than those of control group mice (p<0.05). Moreover, the area under the curves (AUC) significantly decreased with GAE administration in STZ-induced diabetic mice (p<0.05). These results indicate that GAE may be effective in decreasing postprandial blood glucose levels by inhibiting carbohydrate-digesting enzymes such as ${\alpha}-amylase$ and ${\alpha}-glucosidase$. Therefore, GAE could be used as a potential functional food for alleviating postprandial hyperglycemia.