Increasing the Efficiency of Cytochrome P450 3A4 Electrocatalysis Using Electrode Modification with Spatially Ordered Anodic Aluminum Oxide-Based Nanostructures for Investigation of Metabolic Transformations of Drugs.

A new approach for modifying electrodes using porous membranes based on anodic aluminum oxide with pore diameters of 0.1 and 0.2 µm and a membrane-like substance didodecyldimethylammonium bromide (DDAB) was proposed to study the electrocatalytic efficiency of the system. This approach makes it possible to increase the catalytic efficiency of the cytochrome P450 3A4-dependent N-demethylation of erythromycin by 132% when using a membrane with pore diameter of 0.1 µm and by 32% when using a membrane with 0.2 µm pore size. Electrode modification using porous membranes shifted the potential of electrochemical reduction and catalysis of cytochrome P450 3A4 in positive direction by 0.070-0.050 V, which indicates a thermodynamically more favorable process of electron transfer and enzymatic electrocatalysis.

[Modeling of drug-drug interactions between omeprazole and erythromycin with cytochrome P450 3A4 in vitro assay]. / Modelirovanie mezhlekarstvennogo vzaimodeistviia omeprazola i éritromitsina s ispol'zovaniem tsitokhrom R450-zavisimoi sistemy in vitro.

In the present study the electrochemical system based on recombinant cytochrome P450 3A4 (CYP3A4) was used for the investigation of potential drug-drug interaction between medicinal preparations employed for Helicobacter pylori eradication therapy. Drug interactions were demonstrated in association of omeprazole as a proton pump inhibitor (PPI) and macrolide antibiotic erythromycin during cytochrome P450 3A4-mediated metabolism. It was shown that in the presence of omeprazole the rate of N-demethylase activity of CYP3A4 to erythromycin measured by means of product (formaldehyde) formation decreased. Mass-spectrometry analysis of omeprazole sulfone as a CYP3A4-mediated metabolite demonstrated the absence of erythromycin influence on CYP3A4-dependent omeprazole metabolism. This phenomenon may be explained by lower spectral dissociation constant of CYP3A4-omeprazole complex (Kd = 18±2 µM) than that of CYP3A4-erythromycin complex (Kd = 52 µM). Using the electrochemical model of electrochemically-driven drug metabolism it is possible to register CYP3A4-mediated catalytic conversion of certain drugs. In vitro experiments of potential CYP3A4-mediated drug-drug interactions are in accordance with in silico modeling with program PASS and PoSMNA descriptors in the case of omeprazole/erythromycin combinations.

[Electroanalytical and electrocatalytical characteristics of cytochrome P450 3A4 using electrodes modified with nanocomposite carbon nanomaterials]. / Tsitokhrom R450 3A4 kak ferment biotransformatsii lekarstv: rol' modifikatsii sensornykh sistem v élektrokatalize i élektroanalize.

The electroanalytical characteristics of recombinant cytochrome P450 3A4 (P450 3A4) immobilized on the surface of screen-printed graphite electrodes modified with multi-walled carbon nanotubes have been studied. The role and the influence of graphite working electrode modification with carbon nanotubes on electroanalytical characteristics of cytochrome P450 3A4 have been demonstrated. The conditions for the immobilization of cytochrome P450 3A4 on the obtained screen-printed graphite electrodes modified with carbon multi-walled nanotubes have been optimized. The electrochemical parameters of the oxidation and reduction of the heme iron of the enzyme have been estimated. The midpoint potential E0' was -0.35±0.01 V vs Ag/AgCl; the calculated heterogeneous electron transfer rate constant ks, was 0.57±0.04 s-1; the amount of electroactive cytochrome P450 3A4 on the electrode Г0, was determined as (2.6±0.6)⋅10-10 mol/cm2. The functioning mechanism of P450 3A4-based electrochemical sensor followed the "protein film voltammetry". In order to develop electrochemical analysis of drugs being substrates of that hemoprotein and respective medical biosensors the voltammetric study of catalytic activity of immobilized cytochrome P450 3A4 was carried out. Electrocatalytic properties of cytochrome P450 3A4, immobilized on modified screen-printed graphite electrodes, has been investigated using erythromycin (macrolide antibiotics). It has been shown that the modification of electrodes plays a decisive role for the study of the properties of cytochromes P450 in electrochemical investigations. Smart electrodes can serve as sensors for analytical purposes, as well as electrocatalysts for the study of biotransformation processes and metabolic processes. Electrodes modified with carbon nanomaterials are applicable for analytical purposes in the registration of hemoproteins. Electrodes modified with synthetic membrane-like compounds (e.g. didodecyldimethylammonium bromide) are effective in enzyme-dependent electrocatalysis.