In Vitro Antibacterial Activity, Synergistic Effect and Cytotoxic Analysis of some Traditional Plants against Multidrug Resistant Pathogens

Bacteria are becoming antibiotic-resistant and therefore show multidrug resistance. Therefore, this study aims to evaluate the plant extracts as natural antibacterial agents against multidrug resistant pathogens along with their cytotoxic potential. For this purpose, five different plants Syzygium aromaticum (clove), Cinnamomum verum (cinnamon), Origanum vulgare (oregano), Cuminum cyminum (cumin), and Foeniculum vulgare (fennel) were used against Escherichia coli, Streptococcus pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. Antibacterial activity of plant extract alone and in combination was identified using agar well diffusion assay and the minimum inhibitory concentration (MIC) was calculated through tube dilution method. Moreover, the cytotoxicity of the plant extracts was determined by 3-(4, 5 dimethyliazol-2-y1) 5 (3carboxymethoxyphenyl) 2 (4 sulfophenyl) 2H tetrazolium (MTS) assay. Results revealed that the antibacterial activity of oregano proved to be most effective, giving a zone of 17 mm against S. aureus, and clove was second best against E. coli, giving a 15 mm zone. Furthermore, the synergistic effect showed significant antibacterial activity of oregano + fennel 25 mm zone and cumin + fennel 22 mm against S. aureus as the pre-eminent results. The MIC of Oregano against S. aureus, oregano and clove against E. coli, and clove against P. aeruginosa all had the most potent activity with a MIC value of 1.562 mg/mL. In addition, the cytotoxic analysis of the plant extracts showed promising results and has no toxic effect of these plants on NIH 3T3 mouse fibroblast cell lines. All of the plants showed more than 85% of cell viability. Thus, it is concluded that these plants extracts can be utilized to eliminate multidrug resistant organisms and treat bacterial infections as they do not cause side effects to human health. However, further human clinical trials need to be done in manufacturing therapeutics.