Abstract
Certain bactericidal antibiotics target mitochondrial components and, due to the leakage of electrons from the electron transport chain, one-electron reduction might occur that can lead to intermediates passing the electron to suitable acceptors. This study aimed at investigating the one-electron reduction mechanism of selected penicillin derivatives using pulse radiolysis techniques. Penicillins can accommodate the electron on each of their carbonyl carbon. Ketyl radicals are thus produced, which are reducing agents with possibility to interact with suitable biomolecules. A detailed mechanism of the reduction is reported.
Highlights
The introduction of antibiotics into medical practice, many decades ago, is regarded as a milestone in the history of medicine saving countless millions of life, generating economic welfare
Kohanski et al [1] have reported that bactericidal antibiotics induce production of reactive oxygen species (ROS), which can contribute to drug mediated cell death in bacteria
The hydrated electron is accommodated on the carbonyl carbons of these molecules
Summary
The introduction of antibiotics into medical practice, many decades ago, is regarded as a milestone in the history of medicine saving countless millions of life, generating economic welfare. The decay of the band assigned to the carbon centered radical (Scheme 2c) follows first order kinetics, with k = 200, 50 and 30 s1 for ampicillin, 6-aminopenicillanic acid and cloxacillin, respectively, indicating that cloxacillin provides the most stable electronic structure for these species (in case of amoxicillin the decay could not be characterizeddue to the overlap ~380 nm, see Figure 2A). In cloxacillin (Figure 1C) there is a shift to shorter wavelength compared to ampicillin and amoxicillin (Figures 1A and 2A) in line with the relatively electron-poor aromatic ring. In the latter case we are rather close to the spectra of 6-aminopenicillanic acid (Figure 1D) with absence of the aromatic ring. We propose that this effect is delivered through the space owing to the possibility of a “coiled” (compact) conformation of the molecules [22,23]
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