In-vitro alpha amylase inhibitory activity of the leaf extracts of Adenanthera pavonina

Background: Diabetes has caused a major burden to the health sector in the developing countries and has shown an increasing trend among the urban population. It is estimated that most patients are with type II diabetes which could be easily treated with dietary changes, exercise, and medication. Sri Lanka carries a long history ayurvedic medicine where it uses the plant for treating many diseases. Therefore it is important to screen medicinal plants scientifically so they could be used safely and effectively in the traditional medical system and also be used for further investigations. Adenanthera pavonina is a plant used in the Ayurvedic medical system in Sri Lanka for treating many diseases including diabetics. We evaluated the anti-diabetic properties and the antioxidant properties of Adenanthera pavonina leaves. Methods: The methanol extract of the leaves was sequentially extracted with petroleum ether and thereafter was partitioned between EtOAc, and water. The a-amylase inhibition assay was performed using the 3,5-dinitrosalicylic acid method. The antioxidant activities were measured using the DPPH free radical scavenging activity and the total phenolic content using Folin-Ciocalteu's reagent. The cytotoxicity of the extract was evaluated using the Brine shrimp bioassay. Results: The IC50 values of a amylase inhibitory activity of MeOH, EtOAc, petroleum ether, and water were 16.16 +/- 2.23, 59.93 +/- 0.25, 145.49 +/- 4.86 and 214.85 +/- 9.72 mu g/ ml respectively and was similar to that of Acarbose (18.63 +/- 1. 21 (mu g/ml). Antioxidant activities were also determined and the EtOAc fraction showed the highest total phenolic content (34. 62 +/- 1.14 mg/g extract) and the highest DPPH scavenging activity with an IC50 of 249.92 +/- 3.35 mu g/ml. Conclusion: The leaf extracts of Adenanthera pavonina exhibit remarkable a-amylase inhibitory activity in the crude methanolic extract. Hence leaves of Adenanthera pavonina has a potential to be used as a regular green vegetable and also be investigated further in isolating pure compounds with anti-diabetic activity.