Hypoglycaemic and anorexigenic activities of an α-amylase inhibitor from white kidney beans (Phaseolus vulgaris) in Wistar rats

Abstract

An inhibitor of a-amylase was isolated and purified from an extract of white kidney beans (Phaseolus vulgaris). The acute oral administration of the inhibitor (50 mg/kg body weight) to adult Wistar rats together with a starch load (2 g/kg body weight suspended in NaCl (9 g/l)) reduced the increase in glycaemia over the basal value (NaCl, 222 (SEM 49); inhibitor, 145 (SEM 16) mmol/l £ 180 min; P, 0·05) without modifying the insulin response. On administering the inhibitor orally (50 mg/kg body weight dissolved in NaCl (9 g/l)) for 21 d to rats fed on a standard diet, a decline was observed in the glycaemia values on day 0 (NaCl, 5·53 (SEM 0·12); inhibitor, 5·25 (SEM 0·16) mmol/l) relative to those obtained on days 10 (NaCl, 5·00 (SEM 0·14); inhibitor, 4·60 (SEM 0·08) mmol/l; P,0·05) and 21 (NaCl, 5·22 (SEM 0·22); inhibitor, 4·50 (SEM 0·12) mmol/l; P,0·01) of treatment, without modifying the plasma concentration of insulin. There was found to be a significant anorexigenic action of the inhibitor; there was reduced food intake (NaCl, 23·07 (SEM 0·31); inhibitor, 19·50 (SEM 0·49) g/ d; P,0·01), a reduced weight gain (NaCl, 52 (SEM 3); inhibitor, 2 1·33 (SEM 8·9) g/21 d; P, 0·01), as well as changes in the activity of some intestinal enzymes such as maltase (NaCl, 87 (SEM 7); inhibitor, 127 (SEM 11) U/g proteins; P,0·05). The present study has shown, for the first time, that the prolonged administration of an a-amylase inhibitor reduces blood glucose levels and body-weight gain in Wistar rats.a-Amylase inhibitor: Glycaemia: Weight: Food intake: Disaccharidases

Effect of non-oil-seed pulses on glycaemic control: a systematic review and meta-analysis of randomised controlled experimental trials in people with and without diabetes

“…Dietary pulses (dried leguminous seeds, including chickpeas, beans, peas and lentils) are a good source of amylose starch, fibre, vegetable protein and antinutrients, such as phytates, phenols, lectins and enzyme inhibitors, some of which may act as natural inhibitors of both α-amylase and α-glucosidase [10]. In early studies, pulses were shown to result in exceptionally low glycaemic responses when fed to healthy volunteers [11], and in later experiments were demonstrated to possess a carbohydrate component that was more slowly digested than that of other foods such as cereals [12].…”

Antidiabetic potential of α-amylase inhibitor from the seeds ofMacrotyloma uniflorumin streptozotocin-nicotinamide-induced diabetic mice

“…The decrease in the food and water intake in the MUAI treated mice may be attributed to α-amylase inhibition. Proteinaceous α-amylase inhibitors produce satiety by delaying gastric emptying (Tormo et al, 2004). Pancreatic histology of diabetic control mice showed small size of the islets of Langerhans while acarbose, MUAI and MUAI+2% starch treated mice showed normal size of the islets which confirmed protection of pancreatic β cells from the toxic effect of streptozotocin.…”

AnIn VitroandIn VivoStudy of the α-Amylase Activity of Phaseolamin

“…[18][19][20] The polypeptide at 45 kDa may be phaseolin (45-50 kDa). 21 This polypeptide is the most abundant, representing approximately 80% of total bean protein content.…”

“…This result is in agreement with previous studies where diabetic rats were chronically treated with phaseolamin. 19,20,27 Administration of this commercial sample did not affect body weight. This agrees with previous studies where diabetic animals were given acute and subchronic phaseolamin treatments.…”