Abstract
The present study is focussed on an in vitro approach to evaluate the antidiabetic potential of some selected traditional medicinal plants used by traditional practitioners of South India for curing hyperglycaemia. The study emphasized on the potential of the extracts to reduce post-prandial glucose levels through inhibition of carbohydrate hydrolyzing enzyme, α-amylase and its mode of inhibition. Four different solvent fractions (Petroleum ether fraction, Chloroform fraction, Ethyl acetate fraction and 80% methanolic fraction) of extracts of shoots of Tinospora crispa (L) Hook.f. and Thomson, denoted as PE TC, CH TC, EA TC, 80%M TC and roots of Anacardium occidentale L, denoted as PE AO, CH AO, EA AO and 80%M AO were selected for antidiabetic screening. Phytochemical profiling of the extracts revealed that the all of the eight extracts were a rich repository of secondary metabolites. Ensuing to standard acarbose drug (IC50 value = 0.19 mg/mL), PE TC (IC50 value =1.49 mg/mL) outperformed among the fractions evaluated to exhibit an uncompetitive mode of inhibiting the α-amylase enzyme. 80%M AO, CH AO too exhibited substantial inhibitory activity on the enzyme followed by CH AO that showed a mixed inhibitory response. Remaining fractions remained uncompetitive. All the extracts exhibited potential antioxidant activity, 80% M AO being the best with an IC50 value of 0.026 mg/mL followed by EA AO (IC50 value =0.031 mg/mL). The cytotoxicity assay of the extracts on the MIN6 pancreatic cell lines revealed all the extracts to be least cytotoxic. Thus, PE TC and 80%M AO offers to be promising lead candidates to be developed as an efficient antidiabetic agents for post-prandial hyperglycaemia.

Key words: α-Amylase, Enzyme kinetics, Antioxidant activity, Cytotoxicity, Tinospora crispa, Anacardium occidentale.