Chemical composition and antibacterial activity of the essential oils of some medicinal plants

Abstract

Infectious diseases are the second leading cause of death worldwide. Treatment of infections continues to be a problem in modern time because of the side effects of some drugs and resistance to antimicrobial agents. Herbal medicines have received much attention as a source of safe and effective antibacterial drugs. In the present study, essential oils of some medicinal plants: Stachys pubescens, Thymus kotschyanus, Thymus daenensis and Bupleurum falcatum were investigated for antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, Streptococcus pneumoniae, Pseudomonas aeruginosa, Klebsiella pneumoniae,Escherichia coli, and Salmonella typhi. This study determines the MIC and MBC of the essential oils and comparison with reference antibiotics Ciprofloxacin and Gentamicin. The chemical composition of the essential oils was analyzed by Gas chromatography (GC) and Gas chromatography-mass spectrometry (GC-MS). The essential oils isolated from the leaves of S. pubescens, T. kotschyanus and B. falcatum showed a high level antibacterial activity. T. daenensis essential oil showed less activity comparing to other oils. The result showed the presence of 24, 23, 20 and 15 components in the essential oils of T. kotschyanus, S. pubescens,T. daenensis, and B. falcatum respectively. Resistance to first-line drugs in most of the pathogens causing these diseases ranges from zero to almost 100%. Thus, these essential oils exhibited interesting bacteriostatic and bactericidal activity. Key words: Antibacterial, Stachys pubescens, Thymus kotschyanus, Thymus daenensis. Bupleurum falcatum, GC-MS.