Plants are important sources of chemical constituents with potential antioxidant activity and inhibitors of α-amylase and can be employed for therapeutic benefits. The leaves of medicinal plants viz., Cajanus lineata W. & A., Leucas ciliata Benth., Rauwolfia densiflora Benth. ex. Hook. and Gomphostemma heyneanum Wall., were collected from the Talacauvery subcluster of Western Ghats, India. The powdered leaves were extracted in various solvents and analyzed for the phytochemical constituents, antioxidative and α-amylase inhibitory potentials. All extracts indicated the presence of flavonoids, terpenoids, steroids and reducing sugars. Among the solvent extracts, the aqueous extract of L. ciliata leaves contained high total phenolics (105± 2.45 μg GAE/g). The solvent extracts of the leaves of this species also exhibited higher antioxidant activity. The standard ascorbic acid showed 50% inhibition at 67±1.23 μg/ml. The aqueous and methanol extracts of L. ciliata had FRAP activity of 110± 2.88 μM Fe (II)/g and 115± 3.46 μM Fe (II)/g followed by the aqueous extract of R. densiflora (82± 2.37 μM Fe (II)/g). The methanolic extract of L. ciliata showed positive results for the inhibition of α-amylase by starch-iodine color assay. Further quantification by DiNitroSalicylic Acid (DNSA) method revealed that the methanol extract of L. ciliata, showed 72.9% inhibition with IC50 values of 138.7± 3.47 μg/ml in comparison to the standard inhibitor Acarbose™ (IC50 value of 96.29± 2.89 μg/ml). The leaf extracts of L. ciliata could be used in the treatment of glucose metabolic related disorders. The study also indicates the antioxidative and anti-diabetic potentials of the plant species.
