Abstract

INVESTIGATION OF METHANOLIC AND AQUEOUS EXTRACT OF LAVANDULA OFFICINALIS FOR TOXICITY AND ANTIBACTERIAL ACTIVITY

Abstract

This study is aimed at determining the toxicity and antibacterial activity of Lavandula officinalis flowers against pathogenic microorganisms by determination the minimal inhibitory concentration and to serve as criteria to recommend the ethno pharmacological uses of the plant. Plant flowers were dried, powdered and extracted by cold maceration with methanol for 48h. The extracts were screened against 24h broth culture of bacteria seeded in Muller Hinton Agar at concentration 200, 100, 50, 25, 12.5, 6.25, 3.125 and 1.56mg/ml in sterile distilled water and incubated at 37°C, for 18h and measuring the inhibition zone diameter (IZD). Minimum inhibitory concentrations (MICs) against three Gram-positive bacteria (Micrococcus luteus, Staphylococcus aureus and Bacillus subtilis), three Gram-negative bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli) were determined for the methanolic and aqueous extracts of Lavandula officinalis. The aqueous extract showed pronounced antibacterial than the Methanolic extract against all of the tested microorganisms. Aqueous extract inhibited with minimal inhibitory concentration of 1.56, 1.56, 3.13, 3.13, 6.25 and 6.25 mg/ml against Micrococcus luteus, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, respectively, while the methanolic extract inhibited with minimal inhibitory concentration of 6.25 mg/ml against all tested bacterial strains both Gram-positive and Gram-negative bacteria. The methanolic and aqueous extracts of L. officinalis demonstrated activities against certain bacteria confirming the use of the plant in ethno pharmacology.

Keywords: Lavandula officinalis; acute toxicity; minimal inhibitory concentration; antibacterial screening; bacterial strains; medicinal plant.