Inhibitory Effect of Soybean Seed Extracts on Human Salivary Amylase: An in vitro Study

Enzymes are biological catalysts that accelerate the rate of metabolic reactions. Amylases are the class of hydrolase, split the (1-4) glycosidic bonds of polysaccharides into glucose or maltose. Salivary and pancreatic α-amylases share 92 % of analogy in their catalytic region. In diabetic condition, α-amylases become a major challenge in managing postprandial hyperglycemia. Natural inhibitors have been well-known to treat diabetes and were accounted to contain compounds with anti α-amylase activity. Soybean has been reported to have anti-diabetic activity because of its rich phytochemical content. The aim of the present study is to examine the in vitro inhibitory effects of aqueous, methanol and acid methanol extracts on the salivary amylase activity. Soybean seeds were procured from the Chikkapet market of Tumakuru, Karnataka State, India. Salivary amylase activity was estimated by the DNS method using maltose as standard. Amylase activity was found to be high at pH of 6.8 and a temperature of 37𫌱C. Amylase inhibition exhibited by different solvent extracts of soybean has been recorded (92% in aqueous extract, 93% in methanol extract, 98% in acid methanol extract) and inhibition concentration (aqueous, 45.73 μg; methanol, 34.26 μg; acid methanol, 18.20 μg).Total polyphenolic contents of various solvent extracts of soybean (0.29% in aqueous extract, 0.25% in methanol extracts and 0.27 % in acid methanol) might be the reason for the significant inhibition of amylase activity. Consequently, the results obtained in the present investigation can be considered as useful in controlling the digestion of complex sugars among the diabetic population by influencing the catalytic activity of salivary amylase.