Many novel bacterial targets and natural inhibitors of enzymes are currently being considered to overcome antibiotic resistance of Escherichia coli. Hence, in this study, 20 essential oil constituents were screened for their potential inhibitory effect on E. coli ATP synthase. This enzyme is involved in the hydrolysis of ATP into ADP and inorganic phosphate (Pi). First, E. coli membrane ATP synthase was isolated via cell lysis. A spectrophotometric method was optimized to quantify the released phosphate from ATP hydrolysis in order to follow the enzymatic activity. The method was validated by determining the kinetic parameters of this reaction (Km = 144.66 μM and Vmax = 270.27 μM/min), and through the inhibition assays of ATP synthase using three reference inhibitors, thymoquinone (half maximal inhibitory concentration [IC50 ] = 50.93 μM), resveratrol (maximum inhibition of 40%), and quercetin (IC50 = 29.01 μM). Among the studied essential oil components, α-terpinene was the most potent inhibitor (IC50 = 19.74 μM) followed by β-pinene, isoeugenol, eugenol, and estragole.
Keywords: ATP synthase kinetics; Antibiotic resistance; Escherichia coli; essential oils components; inhibition screening.
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