The essential oil of Melaleuca armillaris (Sol. ex Gaertn.) Sm. leaves from Pakistan: A potential source of eugenol methyl ether

Abstract

The importance of Melaleuca armillaris (Sol. ex Gaertn.) Sm. leaves as a commercially important source of aroma chemicals is known. This study aims at analyzing the chemical composition of M. armillaris essential oil and its antioxidant and antimicrobial activities for evaluating its potential use in the industry. The chemical composition was analysed by gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC–MS). Twenty-eight components were identified representing 90.6% of the total oil components. Melaleuca armillaris essential oil mainly consisted of aromatic compounds (84.5%). Eugenol methyl ether was identified as a major component (89.57%) followed by p-cymene (2.8%). The antioxidant potential was assessed by free radical scavenging activity, metal chelating activity and reducing power assay. It showed strong antioxidant activity with approximately 86.6% inhibition of 2,2-diphenyl-1-picrylhydrazyl radical and ferric reducing power (1.91±0.02%) at 100μg/ml while it did not show any metal chelating activity. In vitro antimicrobial studies were done by agar well diffusion and microdilution methods Melaleuca armillaris showed moderate activity against tested bacterial strains with inhibition zones (IZ) ranging from 11.0–19.3mm. It exhibited excellent activity against fungal strains with (IZ) 24.3–46.0mm. The minimum inhibitory concentration (MIC), minimum bactericidal concentrations (MBC) and minimum fungicidal concentrations (MFC) values of M. armillaris essential oil ranged from 2 to 8μg/ml for the tested microbial strains. Time kill assay showed a significant microbiocidal effect of essential oil for four weeks.