Chemical composition and biological activity of some essential oils from traditional medicinal plants against clinical isolates of Staphylococcus aureus from bovine mastitis

摘要

Staphylococcus aureus is the main agent that causes bovine mastitis, an inflammation in cow's udder, which is the most costly disease in dairy cattle. The treatment of intramammary infections is usually based on antibiotics therapy, but the increase of resistance has led to the search for new treatment alternatives. In this work the authors evaluated the antibacterial activity of four essential oils obtained from plants commonly used in Brazil folk medicine, namely Cinnamomum zeylanicum, Casearia sylvestris, Lavandula angustifolia and Mentha pulegium. Antibacterial activity was evaluated by the disk diffusion and microboth dilution methods against 14 strains of S. aureus isolated from subclinical cases of bovine mastitis, obtained in southern Brazil. The composition of the oils was determined by GC and GC/MS analysis.Three out of four essential oils analysed inhibited the S. aureus tested.The oil from leaves of C. zeylanicum was the most active with MIC values of 0.3 mg/ml. The main components of C.zeylanicum essential oil were benzyl benzoate (63%) and cinnamaldehyde (15%). The essential oils of C. sylvestris and L angustifolia showed moderate activity. Results revealed the potential of C. zeylanicum leaf oil as an antibacterial agent against S. aureus strains isolated from bovine mastitis, supporting the concept that this essential oil alone and combined with the oils of C. sylvestris and L angustifolia should be further investigated for possible use as phytotherapeutic agents. Clinical trials will be evaluated to confirm the in vitro results.