The Effects of Ethanol and Methanol Extracts of Ziziphus Spina-christi, Peganum Harmala, Salvia Officinalis, and Querqus Brantii on the Growth and Biofilm Formation by Staphylococcus Aureus in Vitro

Medicinal plants are one of the most important natural resources in each country. The aim of this study was to evaluate the anti-biofilm effect of ethanol and methanol extracts of Ziziphus spina-christi leaves, Peganum harmala, Salvia officinalis, and Querqus brantii on the growth and formation of biofilm by Staphylococcus aureus.

Following evaluation of the susceptibility of the studied Staphylococcus aureus strain to various antibiotics, the growth inhibitory effect of extracts on the bacterium was investigated by disc diffusion method and then the inhibitory effect of the extracts on biofilm formation was evaluated in 96 well micro-titer plates. The means were compared with ANOVA test.

The results from antibacterial effect of the extracts showed that the methanol extract of Peganum harmala and Querqus brantii seeds at 350 and 450 mg/ml concentrations had a greater inhibitory effect on the growth of Staphylococcus aureus than other extracts as well as synthetic antibiotics. The results from anti-biofilm formation effect of the extracts showed that methanol extract of Salvia officinalis leaves and Querqus brantii seeds at 350 mg/ml concentration, and ethanol extract of Salvia officinalis leaves at 350 mg/ml concentration were the lowest concentrations that showed the greatest inhibitory effect on biofilm formation by Staphylococcus aureus. Other extracts inhibited biofilm formation by this bacterium in higher concentrations. The lowest anti-biofilm effect on Staphylococcus aureus was observed by ethanolic and methanolic extracts of Ziziphus spina-christi leaf.

The studied extracts in this study, especially the methanol extracts of Salvia officinalis leaves and Peganum harmala seeds, and ethanol extract of Salvia officinalis leaves are good solutions for S. aureus infection and biofilms formation control and are suggested that be evaluated in In vivo experiments and clinical applications.