[The interactions of abiraterone and its pharmacologically active metabolite D4A with cytochrome P450 2C9 (CYP2C9)]. / Vzaimodeistvie abiraterona i ego farmakologicheski aktivnogo metabolita D4A s tsitokhromom R450 2S9 (CYP2C9).

Interactions of cytochrome P450 2C9 (CYP2C9) were studied with the antitumor drug abiraterone and its pharmacologically active metabolite D4A, promising as an agent for prostate cancer treatment. It was shown by absorption spectroscopy, that both investigated compounds induced spectral changes of CYP2C9, indicating interactions of the pyridine nitrogen atom with the heme iron ion of the active site of the enzyme, but interactions of the ligands with the enzyme could be mediated by a water molecule bound to the heme iron ion. Based on the spectral changes, the values of dissociation constants (KS) for complexes of abiraterone and D4A with CYP2C9 were calculated as 1.73±0.14 µM and 3.95±0.16 µM. Both compounds inhibited O-demethylase activity of CYP2C9 towards its substrate. At 100 µM concentration of naproxen the concentrations of abiraterone, D4A and sulfaphenazole inhibiting CYP2C9 activity by 50% (IC50) were determined as 13.9 µM, 40 µM and 41 µM, respectively. The obtained results can be used for prognosis of drug-drug interactions at CYP2C9 level during administration of abiraterone or D4A as an antitumor agent for prostate cancer treatment in complex pharmacotherapy.

[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.

[Methods for determining of cytochrome P450 isozymes functional activity]. / Metody opredeleniia funktsional'noi aktivnosti izofermentov tsitokhroma P450.

The review is dedicated to modern methods and technologies for determining of cytochrome P450 isozymes functional activity, such as absorbance and fluorescent spectroscopy, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), Raman, Mossbauer, and X-ray spectroscopy, surface plasmon resonance (SPR), atomic force microscopy (AFM). Methods of molecular genetic analysis were reviewed from personalized medicine point of view. The use of chromate-mass-spectrometric methods for cytochrome P450-dependent catalytic reactions' products was discussed. The review covers modern electrochemical systems based on cytochrome P450 isozymes for their catalytic activity analysis, their use in practice and further development perspectives for experimental pharmacology, biotechnology and translational medicine.

A New Method for Quantitative Determination of Steroid Metabolites of Cytochrome P450-Dependent Reactions Using Fluorescent Spectroscopy.

A method for determination of hydroxylase activity of cytochrome P450 3A4 (CYP3A4) towards its substrate hydrocortisone using fluorescent analysis of the product was developed. 6ß-hydroxycortisol, formed during CYP3A4-dependent electrocatalysis, has a characteristic fluorescent peak at λ = 427 ± 2 nm after treating with the sulfuric acid : ethanol (3 : 1) mixture and excitation at λ = 365 nm, which is different from the substrate (hydrocortisone) fluorescence (λ = 525 ± 2 nm). The limit of detection of 6ß-hydroxycortisol was 0.32 µM. The developed analytical approach was used to determine the kinetic parameters of CYP3A4-dependent hydrocortisone hydroxylation.