Insulin Secretagogue,Alpha-glucosidase and Antioxidant Activity of Some Selected Spices in Streptozotocin-induced Diabetic Rats

Spices are extensively used to enhance the taste and flavor of foods and are known to possess several medicinal properties. Myristica fragrans, Parmelia perlata, Illicium verum, Trachyspermum copticum and Myristica malabarica, the commonly used spices in India were assessed for antidiabetic activity in streptozotocin induced diabetic rats. In the in vitro insulin secretion studies on isolated islets of Langerhans, M. fragrans, T. copticum and M. malabarica showed dose dependent insulin secretion. At 1 mg/ml, P. perlata showed significant in vitro alpha-glucosidase inhibitory activity with IC₅₀ value of 0.14 mg/ml followed by M. malabarica (0.64 mg/ml), I. verum (0.67 mg/ml), M. fragrans (0.85 mg/ml) and T. copticum (0.92 mg/ml). The DPPH free radical scavenging activity of the extracts at a concentration of 1 mg/ml was as M. malabarica (90.45%), M. fragrans (89.89%), I. verum (87.22%), P. perlata (76.70%) and T. copticum (38.14%). P. perlata showed the highest phenolic content (i.e., 118.5 mg gallic acid equivalents/g) followed by M. malabarica (84.13 mg gallic acid equivalents/g). M. malabarica showed the highest flavonoid content (i.e., 38.35 mg quercetin equivalents/g). Regular use of these spices may prevent postprandial rise in glucose levels through inhibition of intestinal alpha-glucosidase and may maintain blood glucose level through insulin secretagogue action.     

Quality of potato tubers as affected by freezing: I. texture,ascorbic acid and enzymatic discoloration

The effect of freezing on the turgor, ascorbic acid content and enzymatic discoloration of Katahdin and Atlantic potatoes was studied. Tubers were exposed to a temperature of ?20°C for 24 hrs. then thawed for 1 hr. at 20°C before analysis. Frozen tubers were then compared with unfrozen controls. Both varieties lost turgor following freezing and exuded a sticky liquid with increased thawing time. At the end of 3 hrs. thawing, a sponge-like texture was observed in both varieties. In both varieties freezing resulted in a significant reduction (p<.01) in ascorbic acid and phenolic content (p<.01). Enzymatic discoloration was also significantly reduced (p<.01) in both varieties.