The chemical composition, in vitro, and in silico studies of Lavandula mairei essential oil

Abstract

Lavandula mairei is an aromatic, and medicinal plant endemic to Morocco, mainly found in the southeastern region of the Kingdom, and used in traditional medicine for its many benefits. The purpose of the study was to identify the chemical composition of Lavandula mairei essential oil using Gas Chromatography - Tandem Mass Spectrometry, to evaluate the antimicrobial activity of the plant against bacterial strains (Staphylococcus aureus, Staphylococcus aureus MRSA, Enterococcus faecalis, Escherichia coli ATCC 25922, Escherichia coli ESBL, Klebsiella pneumoniae ATCC 700603), and two fungal strains (Aspergillus niger ATCC 10231, Candida albicans ATCC 16404) in order to measure the microbial growth inhibition zone diameter, and to determine the minimum inhibitory, bactericidal, and fungicidal concentration of the essential oil (MIC, MBC, and MFC). Concerning antioxidant activity, six assays (6DPPH, and 1ABTS Free Radical Scavenging Assay, Total Antioxidant Capacity, Hydroxyl Radical, Reducing Power, and β-Carotene Bleaching Inhibition) were performed to determine the antioxidant potential of the essential oil. For the in silico aspect, molecular docking studies were performed to explore the potential interactions of some compounds with five microbial targets (i) Dihydropteroate synthase (1AJ0), ii) The elongation factor EF-Tu (1OB2), iii) d-alanine ligase (2I80), iv) DNA gyrase (2XCT), v) The cytochrome P450 monooxygenase (5V5Z), and 2ADMET prediction analysis was completed on a compound designated as dehydroabietinol. Carvacrol was identified as the major compound (36.38%) by analysis of the chemical composition, E. coli ATCC 25922 (MIC = 1.87 mg/mL ± 0.00, MBC = 15.00 mg/mL ± 0.00), and Enterococcus faecalis (MIC = 0.23 mg/mL ± 0.00, MBC = 5.53 mg/mL ± 2.77) were the most sensitive to the antibacterial treatment, and Candida albicans was resistant to the essential oil. The highest antioxidant potential of the plant was observed in the β-carotene bleaching inhibition test (IC50 = 1.55 mg/mL ± 0.009 and 90 % of inhibition). In the in silico study, the compound dehydroabietinol provided relevant evidence for molecular docking, and this was confirmed by the ADMET prediction analysis. The results of the study were significant, and further experiments will be necessary to find out more about the biological properties of Lavandula mairei.