Abstract
Antibacterial activity of ethanolic and aqueous extracts of two medicinal plants including Oxalis corniculata (EtOc, AqOc) and Artemisia annua (EtAa, AqAa) as well as A. annua essential oil (EoAa) was investigated on multi-drug resistance (MDR) E. coli. Microdilution and agar well diffusion methods were used to determine the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) as well as the inhibition zone. The phytconstituents of these products were analyzed using Reverse-phase High- performance liquid chromatography (RP-HPLC) and gas chromatography-mass spectrometry (GC-mass). The order of bacteriostatic and bacteriocide rate of the products can be shown as follows: EoAa>AqOc>EtAa = AqAa>EtOc, but the bactericidal effect of A. annua extracts is higher than of O. corniculata based on the MIC/MBC ratio and the order is as follows: EoAa>EtAa = AqAa>EtOc>AqOc. The most potent product, i.e. EoAa with a 56.7% inhibition of all isolates, has the potential to substitute 13 used antibiotics including oxacillin, amoxicillin, ampicillin, amoxicillin-clavulanic acid, tetracycline, streptomycin, ciprofloxacin, ceftriaxone, cefazolin, cefuroxime, cefotaxime, ceftazidime and cefixime (P <0.05). Different terpenoids were detected and measured in EoAa and catechin flavonoids in extracts of both plants, quercetin in extracts of O. corniculata but it was only possible to detect chlorogenic acid polyphenol in AqAa. Due to the antibacterial activities of the studied products, more effective than some antibiotics and their edible consumption, these products can be suggested as an alternative to some antibiotics and food preservatives to fight against MDR E. coli.