Electron transfer mechanism for β-lactam antibiotic action via side-chain imine

Electrochemistry of anticonvulsants: electron transfer as a possible mode of action

Reduction potentials were determined for various anticonvulsants, including progabide, SL 75.102, CGS 9896, pyridazines, zonisamide, 1,2,3-triazoles, and copper complexes. The values generally were in the range of about -0.1 to -0.6 V for the protonated drugs and the metal complexes. Reduction potentials provide information on the feasibility of electron transfer (ET) in vivo. If the value is relatively positive (greater than about -0.6 V), the agent can act catalytically as an electron acceptor from an appropriate cellular donor. A concomitant favorable influence on abnormal neuronal processes associated with epilepsy could occur. We describe ET as a possible mode of action of anticonvulsants as well as some antiepileptic agents with no electrochemical data based on this hypothetical ET approach.

Minimum essential structural requirements for lactam antibiotic action

A mechanism of action encompassing mono- and bicyclic beta-lactams has been proposed previously, which stresses the importance of formation of an electron transfer (ET) entity (conjugated iminium) as a requirement for antibiotic activity, in association with enzyme inactivation. Additional evidence in support of this contention is now provided. Reduction potentials for several cephalosporins and pyrazolidinones, all of which contain an oximino functionality in the side chain, were observed in the range of -0.6 to -0.7 V. Comparison is made with related compounds lacking imine. Agents containing side chain hydrazone, oxamazins (mono beta-lactams), and lactivicin are discussed based on the ET approach.

Reduction potentials of anthelmintic drugs: possible relationship to activity

Electrochemical data were acquired for several categories of anthelmintic agents, namely, iminium-type ions, metal derivatives and chelators, quinones and iminoquinones, and nitroheterocycles. Reductions usually were in the favorable range of +0.2 to -0.7 V versus normal hydrogen electrode. The drug effect is believed to result in part from either the catalytic production of oxidative stress or disruption of helminth electron transport systems. Relevant literature results are discussed.

Electrochemistry of cyclic alpha-imino carboxylates and their metal complexes: correlation with physiological activity

Cyclic voltammetry data were obtained for delta 1-pyrroline-2-carboxylate, delta 3-thiazoline-4-carboxylate, delta 2-thiazoline-2-carboxylate and their complexes with Cu(II), Fe(III), and Fe(II). The free ligands were reduced at about -0.35 V and were oxidized in the range of 0.42-0.52 V. Complexing the imine carboxylates with metal ions produces reduction and oxidation in the ranges of 0.05-0.37 V and 0.52-0.74 V, respectively. Prior reports show that these ligands take part in various biological functions. We propose that electron transfer may be involved in some aspects of the physiological activity. The captodative effect can be applied.

Electrochemistry of the anticancer agents methotrexate and alpha-difluoromethylornithine in iminium form

The electrochemical characteristics of the antitumor agents methotrexate and alpha-difluoromethylornithine were determined as their iminium derivatives. Iminium formation from methotrexate is accomplished in vivo via protonation by enzyme. The requisite imine precursor is generated from alpha-difluoromethylornithine by condensation with enzyme containing pyridoxal phosphate. Electroreduction occurs in the range of -0.2 to -0.6 V. The relationship of reduction to structure is discussed. A possible mode of anticancer action involving electron transfer is presented.