Curcuma longa and Azadirachta indica are traditionally used in Indian cuisine and
Ayurvedic medicine as nutraceuticals against diabetes. The crude C. longa
isopropanol extract,
bisdemethoxycurcumin (BDMC), the purified bioactive component from C. longa, and
limonoids azadiradione,
gedunin from A. indica, are able to inhibit in vitro the
antidiabetic target human pancreatic α-
amylase independently. However, no reports on their in vivo efficacy in animal models exist. Thus, the
antidiabetic effect of these orally administered human pancreatic α-
amylase inhibitors was performed on
streptozotocin-induced Sprague-Dawley rats. Initially, the normal rats were treated with test compounds (10-100 mg/kg of
body weight) in
corn oil (5 ml/kg), and as no lethality was observed in these doses, further studies were carried out with lowest concentration of 10 mg/kg of
body weight. A reduction in area under curve (AUC) suggested
glucose-lowering effect of these compounds in
starch fed diabetic rats. The efficacy study showed a significant improvement in
body weight,
blood glucose levels, serum
amylase, and
fructosamine levels as well in other serum parameters associated with diabetes with respect to liver and renal functions. Hence, under in vivo conditions, inhibition of α-
amylase activity by BDMC and
limonoids affirms it as one of the mechanisms of action resulting in reduction of
blood glucose levels. PRACTICAL APPLICATIONS:
Bisdemethoxycurcumin from C. longa and
limonoids, namely,
azadiradione and
gedunin, from A. indica are potent inhibitors of the
antidiabetic target human pancreatic α-
amylase. Oral
Starch Tolerance Test (OSTT) and 28-day efficacy study to check the effect of these orally administered inhibitors in diabetic rat models showed significant improvements in serum blood
glucose and
amylase levels as well as in other diabetes related serum parameters, namely,
bilirubin,
lipids,
lactate dehydrogenase,
alkaline phosphatase, and
urea. The study contributes to understanding the action and efficacy of these pancreatic α-
amylase inhibitors and suggests a potential role for them as nutraceuticals/
therapeutics in management of post-prandial
hyperglycemia.