Current Nutrition & Food Science, 2012, 8, 19-24 19 In Vitro Inhibition of Key Enzymes Related to Diabetes by the Aqueous Extracts of Some Fruits of West Bengal, India Susmita Das, Sukriti Das and Bratati De* Phytochemistry and Pharmacognosy Research Laboratory, Department of Botany, University of Calcutta, 35 Bally- gunge Circular Road, Kolkata 700019, India Abstract: Aqueous extracts of different seasonal as well as less popular but edible indigenous fruits of West Bengal, India were studied for their -glucosidase and -amylase inhibitory properties. Of the 22 different species of fruits, sixteen fruits inhibited both the carbohydrate digesting enzymes. Concentrations of the extracts are presented as fresh weight of fruit used to make extract / ml. Very high -amylase (IC 50 value = 5.0 g/ml) and -glucosidase (IC 50 value = 9.0 g/ml) inhibitory activity was shown by extracts of Phoenix sylvestris. Achras sapota also showed high -amylase (IC 50 value = 53.0 g/ml) and -glucosidase (IC 50 value = 56.0 g/ml) inhibitory activities. During the present study, no correlation could be established between total phenol / flavonoid content and -amylase / -glucosidase inhibitory activity. Unweighted pair-group average (UPGA) dendrogram showing interrelationships between the investigated species shows that the fruits can be grouped into two high level clusters. The cluster I brought together Borassus flabellifer and Physalis peruviana having very low -glucosidase inhibitory activity. The cluster II included fruits with moderate to high - glucosidase inhibitory activity. Keywords: -amylase, -glucosidase, fruits, antidiabetic, phenols, flavonoids, Achras sapota, Phoenix sylvestris. INTRODUCTION One factor that contributes to postprandial hyperglycemia can be related to the amount and digestion rate of consumed starch, which is the primary source of blood glucose. Hence, one approach of managing postprandial hyperglycemia is to reduce or slow dietary carbohydrate digestion and absorption [1-3] that can be achieved by inhibiting starch-hydrolyzing enzymes in the gut [3]. Mammalian starch digestion primarily occurs in the small intestine through the action of -amylase, yielding both lin- ear maltose and branched isomaltose oligosaccharides, which are further hydrolyzed by -glucosidases to release glucose [4]. Suppression of the mammalian -amylase and - glucosidase enzyme in the human digestive system would delay the degradation of starch and oligosaccharides to monosaccharides before they can be absorbed. This would decrease the absorption of glucose and consequently reduce postprandial blood glucose level [5]. The control of kinetics of carbohydrate digestion and monosaccharide absorption could be of value in the prevention and control of conditions such as diabetes, obesity, hyperlipoproteinaemia and hyper- lipidaemia. In this respect inhibitors of glycosidases e.g. - glucosidase, -amylase are of particular interest [5, 6]. Syn- thetic -glucosidase inhibitors (e.g. voglibose) cause hepatic disorders and various negative gastrointestinal symptoms at high doses as carbohydrates blocked from absorption in the small intestine are fermented by bacteria in the colon [7]. Food grade phenolic -amylases inhibitors from dietary *Address correspondence to this author at the Phytochemistry and Pharma- cognosy Research Laboratory, Department of Botany, University of Cal- cutta, 35 Ballygunge Circular Road, Kolkata 700019, India; Tel: +919831120700; Fax: 91 33 2461 4849; E-mail: bratatide@hotmail.com plant extracts are potentially safer, and therefore may be a preferred alternative for modulation of carbohydrate diges- tion and control of glycaemic index of food products [8]. Current scientific evidence demonstrates that much of the morbidity and mortality of diabetes can be eliminated by aggressive treatment with diet, exercise and new pharmacol- ogical approaches to achieve better control of blood glucose level. The possibility of preventing the onset of diabetes us- ing dietary supplements and/or herbal medicines has at- tracted increasing attention [9]. Much research work has focused on attempting to isolate active inhibitory compounds from food products in order to study and understand their functions for pharmaceutical application [10-15]. Recent world is experiencing sharp increase in incidence and prevalence of type 2 diabetes. So the present investiga- tion is aimed to study the effect of 22 different seasonal as well as less popular but edible indigenous fruits of West Bengal, India on -glucosidase and  -amylase inhibition. MATERIALS AND METHODS Materials Edible fruits, just at the ripe stage, from 21 plants were collected from local markets of Kolkata during the peak fruiting season of each fruit. Wild variety of Morus alba L. (Moraceae) was collected from Malda district of West Ben- gal. Voucher No., vernacular and common names of the fruits are shown in Table 1. Preparation of Extract The juicy pulp of each fruit was weighed, crushed, warmed at 100ºC with distilled water for 5 minutes and then strained through sieve and the extract obtained was centri- - /12 $58.00+.00 © 2012 Bentham Science Publishers