Chemical composition and antimicrobial activity of essential oils from Mentha pulegium and Rosmarinus officinalis against multidrug-resistant microbes and their acute toxicity study

Abstract

This article aimed to study the antimicrobial activity, chemical composition, and acute oral toxicity of essential oils (EOs) of Mentha pulegium and Rosmarinus officinalis, two aromatic and medicinal plants widely used in the traditional Moroccan pharmacopeia. The average content of EOs was 3.2 and 2.5% for M. pulegium and R. officinalis, respectively. The chemical characterization showed a richness in some compounds identified by gas chromatography coupled with mass spectrometry (GC/MS): R(+)-Pulegone (45.48%), Menthone (14.2%), Piperitone (8.15%), and Isomenthone (7.18%) in M. pulegium and 1,8-Cineole (46.32%), Camphene (13.4%), and α-Pinene (9.52%) in R. officinalis. These metabolites showed a significant antimicrobial effect against the tested strains (bacteria and yeasts isolated from the hospital environment) compared to synthetic antibiotics that seem to be ineffective against resistant microorganisms. Based on lethal concentration LD50 >5,000 mg/kg (body weight), the oil was found to be marginally safe according to OECD guidelines and can be further explored (bio-product with low risk).

Keywords

• medicinal and aromatic plants
• mentha pulegium
• rosmarinus officinalis
• essential oil
• chemical characterization
• antimicrobial activity
• acute toxicity
• ld50