Antibacterial activity of different extracts of Achillea falcata, Calamintha origanifolia, Ferula cassii and Stachys ehrenbergii

Abstract

According to WHO (2018) antibiotics resistance is one of the biggest threats to global health, where a growing number of infections that were once curable are now becoming harder or sometimes impossible to treat. Plants used in traditional medicine are considered to include some active components that can act as an alternative to antibiotics. The aim of this study is to evaluate the antibacterial activity of four Lebanese plant extracts, Achillea falcata, Ferula cassii, Stachys ehrenbergii and Calamintha origanifolia. These plants are common in the Mediterranean region. They are used in Lebanon in herbal teas and as spices for flavoring foods and are known in folk medicine to treat fever, cough, ulcers and inflammatory diseases (Pirbalouti & Koohpyeh, 2011) (Hilan, Sfeir & Aitour, 2011). The whole plants were air dried, blended and extracted with water at 70º C for 2 hours. The Minimum inhibitory concentration (MIC) was evaluated for the extracts against different strains of Staphylococcus aureus, Escherichia coli, and Acinetobacter baumannii. Then two plants Stachys ehrenbergii and Calamintha origanifolia with lower MICs were selected and further analyzed. Stachys ehrenbergii and Calamintha origanifolia aqueous and methanolic extracts were found to have a promising antibacterial activity against S. aureus, E. coli and A. baummanii strains. Aqueous and methanol extracts of both plants were able to delay coagulation for 15 mins in almost all strains tested at sub-MIC. Aqueous extracts of both plants were also able to reduce biofilm formation in almost all strains tested at sub-MIC by an average of 39% for C. origanifolia and 45% for S. ehrenbergii. Further studies on these plants should be done to identify active compounds and to understand their mechanism of actions against bacteria.