Hypoglycemic and antioxidant properties of konjac (Amorphophallus konjac) in vitro and in vivo.

The aim of this study was to evaluate the hypoglycemic and antioxidant potential of konjac in vitro and in vivo. Glucose diffusion and enzymatic starch digestion of konjac were assayed using α-amylase and α-glucosidase. Oral glucose tolerance test (OGTT) and oral starch tolerance test (OSTT) were performed at dose of 102 mg/Kg of body weight (equivalent to 1 g/meal in humans). Additionally, the antioxidant activity of konjac was evaluated through inhibition of lipid peroxidation. The konjac decreased glucose diffusion by 36% and 19% compared with the negative and positive controls, respectively. Additionally, konjac inhibited α-amylase and α-glucosidase activities by 14% and 90%, respectively. After OSTT, group treated with konjac showed significant lower glucose levels compared with control group (p = .03). Finally, konjac reduced lipid peroxidation in human plasma (93%) compared with the negative control. Our results suggest that konjac exhibits hypoglycemic and antioxidant activities in vitro and in vivo. PRACTICAL APPLICATIONS: Because the use of herbal products have emerged as an attractive therapeutic option for chronic diseases, konjac administration may be an adjuvant for the treatment of type 2 diabetes.

Hypoglycemic and antioxidant effects of five commercial turmeric (Curcuma longa) supplements.

We evaluate the hypoglycemic and antioxidant effects of five commercial turmeric (Curcuma longa) supplements: (1) bulk samples, (2) turmeric root from India, (3) curcuma turmeric Pronat® , (4) turmeric & black pepper Swanson® , and (5) C3 complex® turmeric curcumin. Glucose diffusion and enzymatic starch digestion assays, using α-amylase and α-glucosidase, were performed. The antioxidant activity of turmeric supplements was measured through lipid peroxidation inhibition and the scavenging radical assay. A starch dose of 102 mg/Kg of body weight (equivalent to 1 g/day in humans) was used to perform the oral starch tolerance test (OSTT) in Wistar male rats. All turmeric supplements decreased glucose diffusion and α-glucosidase enzyme activity, and inhibited lipid peroxidation. The rats that received bulk samples and CT showed significantly lower glucose levels than rats receiving acarbose and those of negative control group. Our results show that biological activities of turmeric supplements vary according to the commercial presentation. PRACTICAL APPLICATIONS: The study results suggest that the hypoglycemic and antioxidant effects of five commercial turmeric supplements vary among them. The information provided would be useful to physicians and individuals using these supplements.