Health Benefits of Traditional Corn, Beans, and Pumpkin:In VitroStudies for Hyperglycemia and Hypertension Management

Abstract

Levels of obesity-linked non-insulin-dependent diabetes mellitus (NIDDM) and hypertension are highest among indigenous communities in North America. This is linked to changes in dietary pattern towards high calorie foods such as sugar, refined grain flour, and sweetened beverages. Therefore, a return to traditional dietary patterns may help to reduce these disease problems because of better balance of calories and beneficial nutrients. Further protective non-nutrient phenolic phytochemicals against NIDDM and hypertension are potentially high in these foods but less understood. In this study antidiabetic- and antihypertension-relevant potentials of phenolic phytochemicals were confirmed in select important traditional plant foods of indigenous communities such as pumpkin, beans, and maize using in vitro enzyme assays for -glucosidase, alpha-amylase, and angiotensin I-converting enzyme (ACE) inhibitory activities. In vitro inhibitory activities of these enzymes provide a strong biochemical rationale for further in vivo studies and dietary management strategy for NIDDM through the control of glucose absorption and reduction of associated hypertension. These enzyme inhibitory activities were further compared to total soluble phenolic content and antioxidant activity of the above-targeted plant foods. Pumpkin showed the best overall potential. Among the varieties of pumpkin extracts P5 (round orange) and P6 (spotted orange green) had high content of total phenolics and moderate antioxidant activity coupled to moderate to high alpha-glucosidase and ACE inhibitory activities. Therefore this phenolic antioxidant-enriched dietary strategy using specific traditional plant food combinations can generate a whole food profile that has the potential to reduce hyperglycemia-induced pathogenesis and also associated complications linked to cellular oxidation stress and hypertension.

In vitro inhibition activity of polyphenol-rich extracts from Syzygium aromaticum (L.) Merr. & Perry (Clove) buds against carbohydrate hydrolyzing enzymes linked to type 2 diabetes and Fe2+-induced lipid peroxidation in rat pancreas

“…It is noteworthy that the phenol-rich extracts from clove buds showed significantly (P< 0.05) higher alphaglucosidase inhibitory activities than their respective alphaamylase inhibitory activities. This result follows similar trend with previously published works that plant phytochemicals are mild inhibitors of alpha-amylase and strong inhibitors of alpha-glucosidase activities [7,11,16] . Therefore, stronger inhibition of ahpha-glucosidase activity and mild inhibition of alpha-amylase activity exhibited by the extracts may be of great nutraceutical importance, in minimizing some of the side effect (such as abdominal distention, flatulence, meteorism and possibly diarrhea) associated with the drugs (Acarbose and Voglibose), presently used for the management of diabetes.…”

“…Alpha-glucosidase inhibitors are essential in retardation of carbohydrates digestion and mitigation of postprandial hyperglycemic excursions [7] . Recent reports on the polyphenolic characterization of clove buds revealed the presence of gallic acid, ellagic acid, quercetin glucoside, ellagic acid derivative, and some other unidentified phenolic compounds [21] .…”

“…ABTS radical (ABTS . + ) was generated by reacting an ABTS aqueous solution (7 mM/L) with potassium peroxydisulfate (2.45 mM, final concentration) in the dark for 16 h and adjusting the absorbance of 734 nm to 0.700 with ethanol. Then, 0.2 mL of appropriate dilution of the extracts was added to 2.0 mL ABTS .…”

“…Recent reports suggest that one of the therapeutic approaches for decreasing post-prandial hyperglycaemia is to prevent absorption of glucose by the inhibition of carbohydrate-hydrolysing enzymes, such as alphaglucosidase and alpha-amylase [7] . Thus, the retardation of the action of alpha-glucosidase and alpha-amylase by inhibitors might be one of the most effective approaches to control type 2 DM [8] .…”

Vegetable product containing caseinomacropeptide and germinated seed and sprouts

“…Pancreatic α-amylase is involved in the breakdown of starch into disaccharides and oligosaccharides before intestinal α-glucosidase catalyzes the breakdown of disaccharides to liberate glucose, which is later absorbed into the blood circulation. Inhibition of these enzymes would slow down the breakdown of starch in the gastrointestinal tract, thus reducing postprandial hyperglycemia (Kwon et al 2007). Inhibition results were expressed as IC 50 , and acarbose, which is commonly used oral hypoglycemic agent in diabetic patients, was used as a positive control.…”