Assessment of biological activities, essential oil constituents and phytochemical screening of Azadirachta indica grown in Ethiopia

Abstract

Background: A. indica is the most versatile medicinal plant. It is known as “the village pharmacy”. The plant is well known for its broad spectrum of biological activity in India and various countries throughout history by many different human cultures. The present study was undertaken to determine the antimalarial and antidiabetic properties of the leaf extracts of A. indica grown in Ethiopia when treated in vivo. This work has also concerned with determining essential oil composition and an antimicrobial activity of the plant in vitro.

Methods: Leaf extracts were prepared using three different selected solvents. Standard and clinical isolates were treated with extracts of the leaves of A. indica using agar well diffusion method. The antimalarial and antidiabetic tests were conducted in vivo in mice. Phytochemical screening was done using various chemical tests and the volatile oil constituents were determined using Gas chromatography–mass spectrometry (GC-MS).

Results: In vivo antimalarial activity studies showed 85.23%, 69.01% and 81.54% suppression of parasitemia for 70% ethanol, acetone and water extracts respectively. The extracts collected from the leaves also showed reduced blood sugar level in alloxan induced diabetic mice. In addition, the solvent extracts were shown to have inhibitory effect on the growth of microorganisms under the study. The minimum inhibitory concentration (MIC) ranged from 850 to 1050 µg/ml. The phytochemical investigation of the ethanol extracts showed the presence of secondary metabolites. Seventeen compounds (mainly sesquiterpenes) that represent 75.45% of the essential oil were characterized by GC/MS analysis.

Conclusion: The findings of this study demonstrate that leaf extracts of A. indica cultivated in Ethiopia retained biological activities comparable to those reported for plants grown in their native habitat. This suggests that the Ethiopian agroecological conditions do not adversely affect the plant's bioactive properties and support its potential as a reliable source of biologically active compounds for therapeutic and pharmaceutical applications. In addition, phytochemical investigation and GC-MS analysis of volatile oil constituents showed comparable results to those presented in India and elsewhere.