scholarly journals Characterization of the CYP3A4 Enzyme Inhibition Potential of Selected Flavonoids

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 3018
Author(s):  
Martin Kondža ◽  
Mirza Bojić ◽  
Ivona Tomić ◽  
Željan Maleš ◽  
Valentina Rezić ◽  
...  
Keyword(s):  
Covalent Binding ◽  
Inhibitory Effect ◽  
Residual Concentration ◽  
Flavonoid Aglycones ◽  
Irreversible Inhibitors ◽  
Cyp3a4 Enzyme ◽  
Kinetics Of ◽  
Kinetics Of Inhibition

Acacetin, apigenin, chrysin, and pinocembrin are flavonoid aglycones found in foods such as parsley, honey, celery, and chamomile tea. Flavonoids can act as substrates and inhibitors of the CYP3A4 enzyme, a heme containing enzyme responsible for the metabolism of one third of drugs on the market. The aim of this study was to investigate the inhibitory effect of selected flavonoids on the CYP3A4 enzyme, the kinetics of inhibition, the possible covalent binding of the inhibitor to the enzyme, and whether flavonoids can act as pseudo-irreversible inhibitors. For the determination of inhibition kinetics, nifedipine oxidation was used as a marker reaction. A hemochromopyridine test was used to assess the possible covalent binding to the heme, and incubation with dialysis was used in order to assess the reversibility of the inhibition. All the tested flavonoids inhibited the CYP3A4 enzyme activity. Chrysin was the most potent inhibitor: IC50 = 2.5 ± 0.6 µM, Ki = 2.4 ± 1.0 µM, kinact = 0.07 ± 0.01 min−1, kinact/Ki = 0.03 min−1 µM−1. Chrysin caused the highest reduction of heme (94.5 ± 0.5% residual concentration). None of the tested flavonoids showed pseudo-irreversible inhibition. Although the inactivation of the CYP3A4 enzyme is caused by interaction with heme, inhibitor-heme adducts could not be trapped. These results indicate that flavonoids have the potential to inhibit the CYP3A4 enzyme and interact with other drugs and medications. However, possible food–drug interactions have to be assessed clinically.

scholarly journals KD determination from time-resolved experiments on live cells with LigandTracer and reconciliation with end-point flow cytometry measurements

2021 ◽  
Author(s):  
Diana Spiegelberg ◽  
Jonas Stenberg ◽  
Pascale Richalet ◽  
Marc Vanhove
Keyword(s):  
Flow Cytometry ◽  
Live Cells ◽  
Time Resolved ◽  
Surface Receptors ◽  
Full Characterization ◽  
End Point ◽  
Titration Curves ◽  
Kinetics Of

AbstractDesign of next-generation therapeutics comes with new challenges and emulates technology and methods to meet them. Characterizing the binding of either natural ligands or therapeutic proteins to cell-surface receptors, for which relevant recombinant versions may not exist, represents one of these challenges. Here we report the characterization of the interaction of five different antibody therapeutics (Trastuzumab, Rituximab, Panitumumab, Pertuzumab, and Cetuximab) with their cognate target receptors using LigandTracer. The method offers the advantage of being performed on live cells, alleviating the need for a recombinant source of the receptor. Furthermore, time-resolved measurements, in addition to allowing the determination of the affinity of the studied drug to its target, give access to the binding kinetics thereby providing a full characterization of the system. In this study, we also compared time-resolved LigandTracer data with end-point KD determination from flow cytometry experiments and hypothesize that discrepancies between these two approaches, when they exist, generally come from flow cytometry titration curves being acquired prior to full equilibration of the system. Our data, however, show that knowledge of the kinetics of the interaction allows to reconcile the data obtained by flow cytometry and LigandTracer and demonstrate the complementarity of these two methods.

scholarly journals Determination of rate parameter for kinetics of nitrification

2018 ◽  
Vol 4 (2) ◽  
pp. 234
Author(s):  
S R Juliastuti ◽  
J Baeyens ◽  
C Creemers ◽  
J Degreve
Keyword(s):  
Oxygen Uptake ◽  
Organic Compounds ◽  
Total Nitrogen ◽  
Uptake Rate ◽  
Oxygen Uptake Rate ◽  
Inhibitory Effect ◽  
Rate Parameter ◽  
Autotrophic Biomass ◽  
Kinetics Of

Determination of rate parameter for kinetics of nitrification The nitrification process is the bottleneck step in the total nitrogen removal. The formation of nitrate is considered as the rate limiting step in the whole process and its kinetics determine the design of the nitrification reactor. Heavy metals (Zn2+ and Cu2+) and different organic compounds are used as micropollutants. These kinetics were experimentally measured by respirometry. In line with the aim of the paper, the experimental investigation are conducted to develop design equations to describe kinetic rate relationships under optimum conditions, study the parameter influence such as pH and inhibition by reaction intermediates and inhibition by external pollutants. Results demonstrate that the maximum value of the specific growth rate of autotrophic biomass() is 1.02 day at pH=7 and decreases at pH 7.5; inhibition occurs at substrate (NH4) concentrations in excess of 15 mg N/l; inhibition occurs at increasing concentrations of NO –N and Cu2+ has more pronounced inhibitory effect than Zn2+. The inhibitory effect of organic compounds are listed as the Chlorobenzene > Trichloroethylene> Phenol> Ethyl benzene; the experimental oxygen uptake rate (OUR)-test results the autotrophic kinetic parameter values, which can be used in design equations. Keywords: Respirometry,  Autotrophic Biomass,  Nitrification, Oxygen Uptake Rate Abstrak Proses nitrifikasi merupakan langkah penting pada penurunan kadar total nitrogen. Pembentukan nitrat dianggap sebagai tahap pembatas kecepatan reaksi pada keseluruhan proses dan kinetikanya menentukan perancangan dari bagian proses nitrifikasi. Logam berat (Zn2+ dan Cu2+) dan berbagai jenis komponen organik digunakan sebagai mikropolutan. Kinetika ini secara eksperimental diukur menggunakan respirometer. Tujuan penelitian adalah mengembangkan persamaan perancangan yang menggambarkan hubungan laju kinetika pada kondisi optimum, studi pengaruh parameter seperti pH, inhibisi karena reaksi intermediat, dan inhibisi oleh polutan dari luar. Hasil penelitian ditunjukkan sebagai berikut: harga laju pertumbuhan  biomasa autotrof maksimum spesifik  adalah 1,02 hari-1 pada pH=7 dan menurun pada pH 7,5; inhibisi terjadi pada konsentrasi substrat (NH4+) lebih besar dari 15 mg N/l; inhibisi terjadi pada peningkatan  konsentrasi NO -N ;Cu2+  lebih dikenal sebagai penyebab  inhibisi  daripada Zn2+. Efek inhibisi dari komponen organik di daftar mulai dari Chlorobenzene sampai Ethylbenzen. Tes OUR menghasilkan harga parameter kinetika yang dapat dipakai pad apersamaan perencanaan  lumpur aktif nitrifikasi. Kata Kunci: Respirometer, BiomasaAutotrof, Nitrifikasi, Laju Kenaikan Oksigen

scholarly journals Kinetic and substrate complex characterization of RamA, a corrinoid protein reductive activase from Methanosarcina barkeri

2020 ◽  
Vol 367 (17) ◽  
Author(s):  
Katherine A Huening ◽  
Ruisheng Jiang ◽  
Joseph A Krzycki
Keyword(s):  
Direct Evidence ◽  
Atp Hydrolysis ◽  
Methanogenic Archaea ◽  
Methanosarcina Barkeri ◽  
Serine Residue ◽  
Substrate Complex ◽  
Apparent Kinetic Parameters ◽  
Kinetics Of

ABSTRACT In microbial corrinoid-dependent methyltransferase systems, adventitious Co(I)-corrinoid oxidation halts catalysis and necessitates repair by ATP-dependent reductive activases. RamA, an activase with a C-terminal ferredoxin domain with two [4Fe-4S] clusters from methanogenic archaea, has been far less studied than the bacterial activases bearing an N-terminal ferredoxin domain with one [2Fe-2S] cluster. These differences suggest RamA might prove to have other distinctive characteristics. Here, we examine RamA kinetics and the stoichiometry of the corrinoid protein:RamA complex. Like bacterial activases, K+ stimulates RamA. Potassium stimulation had been questioned due to differences in the primary structure of bacterial and methanogen activases. Unlike one bacterial activase, ATP is not inhibitory allowing the first determination of apparent kinetic parameters for any corrinoid activase. Unlike bacterial activases, a single RamA monomer complexes a single corrinoid protein monomer. Alanine replacement of a RamA serine residue corresponding to the serine of one bacterial activase which ligates the corrinoid cobalt during complex formation led to only moderate changes in the kinetics of RamA. These results reveal new differences in the two types of corrinoid activases, and provide direct evidence for the proposal that corrinoid activases act as catalytic monomers, unlike other enzymes that couple ATP hydrolysis to difficult reductions.

scholarly journals Characterization of two types of fetal hemoglobin: alpha 2G gamma 2 and alpha 2A gamma 2

Blood ◽  
1990 ◽  
Vol 75 (10) ◽  
pp. 2070-2075 ◽  
Author(s):  
K Adachi ◽  
J Kim ◽  
T Asakura ◽  
E Schwartz
Keyword(s):  
Mechanical Stability ◽  
Oxygen Affinity ◽  
Fetal Hemoglobin ◽  
Surface Hydrophobicity ◽  
Inhibitory Effect ◽  
Kinetics Of Polymerization ◽  
Kinetics Of ◽  
Oxygen Equilibrium Curve ◽  
High Phosphate

Abstract The effect of differences in G gamma and A gamma fractions of fetal hemoglobin (HbF) on the kinetics of polymerization of HbS-HbF mixtures was studied. We also examined their effect on oxygen affinity, surface hydrophobicity, mechanical stability, and solubility of HbF. Differences in G gamma:A gamma ratio did not affect the polymerization of mixtures of HbF and HbS, suggesting that the inhibitory effect of HbF on the polymerization of HbS is independent of the G gamma:A gamma ratio of HbF and is totally dependent on the fraction of HbF in the mixture. The oxygen equilibrium curve of HbF was not affected by differences in the ratios of G gamma and A gamma in HbF. In contrast, surface hydrophobicity, mechanical stability, and solubility of HbF were affected by differences in the G gamma:A gamma ratio. The higher the G gamma:A gamma ratio, the smaller the elution volume on a TSK Gel SW hydrophobic column in high phosphate buffer. The mechanical stability of HbF was also dependent on the ratio of G gamma:A gamma; stability was greater at higher fractions of A gamma. Differences in the G gamma:A gamma ratio also affected solubility of HbF: HbF containing the higher fraction of G gamma was the more soluble. These data indicate that although alanine at the 136th position of the gamma chains has a stronger surface hydrophobicity than does glycine, this difference does not affect either the polymerization of HbS or the oxygen affinity of HbF.

scholarly journals Development of the First Covalent Monopolar Spindle Kinase 1 (MPS1/TTK) Inhibitor

2021 ◽  
Author(s):  
Ricardo Serafim ◽  
André Santiago ◽  
Caio dos Reis ◽  
Jessica Takarada ◽  
Priscila Mezzomo ◽  
...  
Keyword(s):  
Protein Kinases ◽  
Covalent Binding ◽  
Mitotic Checkpoint ◽  
Chemical Probes ◽  
Reversible Inhibitors ◽  
Irreversible Inhibitors ◽  
Monopolar Spindle ◽  
Differential Scanning Fluorimetry ◽  
Aggressive Tumors

Monopolar spindle kinase 1 (MPS1/TTK) is a key element of the mitotic checkpoint securing proper chromosome segregation. It is being evaluated as a target in the treatment of aggressive tumors such as triple-negative breast cancer with several reversible inhibitors currently undergoing clinical trials. While long drug–target residence times have been suggested to be beneficial in the context of therapeutic MPS1 inhibition, no irreversible inhibitors are known. Here we present the design and characterization of the first irreversible covalent MPS1 inhibitor <b>RMS-07</b> targeting a cysteine (Cys604) in the kinase's hinge region present only in few other protein kinases. The compound showed excellent MPS1 inhibitory potency and high selectivity against all protein kinases harboring an equivalent cysteine as well as in a larger differential scanning fluorimetry-based screening panel. Covalent binding was confirmed by mass spectrometry and X-ray crystal structure. We expect this tool compound to open new avenues for the design of MPS1-specific covalent chemical probes or drugs.

scholarly journals Characterization of two types of fetal hemoglobin: alpha 2G gamma 2 and alpha 2A gamma 2

Blood ◽  
1990 ◽  
Vol 75 (10) ◽  
pp. 2070-2075
Author(s):  
K Adachi ◽  
J Kim ◽  
T Asakura ◽  
E Schwartz
Keyword(s):  
Mechanical Stability ◽  
Oxygen Affinity ◽  
Fetal Hemoglobin ◽  
Surface Hydrophobicity ◽  
Inhibitory Effect ◽  
Kinetics Of Polymerization ◽  
Kinetics Of ◽  
Oxygen Equilibrium Curve ◽  
High Phosphate

The effect of differences in G gamma and A gamma fractions of fetal hemoglobin (HbF) on the kinetics of polymerization of HbS-HbF mixtures was studied. We also examined their effect on oxygen affinity, surface hydrophobicity, mechanical stability, and solubility of HbF. Differences in G gamma:A gamma ratio did not affect the polymerization of mixtures of HbF and HbS, suggesting that the inhibitory effect of HbF on the polymerization of HbS is independent of the G gamma:A gamma ratio of HbF and is totally dependent on the fraction of HbF in the mixture. The oxygen equilibrium curve of HbF was not affected by differences in the ratios of G gamma and A gamma in HbF. In contrast, surface hydrophobicity, mechanical stability, and solubility of HbF were affected by differences in the G gamma:A gamma ratio. The higher the G gamma:A gamma ratio, the smaller the elution volume on a TSK Gel SW hydrophobic column in high phosphate buffer. The mechanical stability of HbF was also dependent on the ratio of G gamma:A gamma; stability was greater at higher fractions of A gamma. Differences in the G gamma:A gamma ratio also affected solubility of HbF: HbF containing the higher fraction of G gamma was the more soluble. These data indicate that although alanine at the 136th position of the gamma chains has a stronger surface hydrophobicity than does glycine, this difference does not affect either the polymerization of HbS or the oxygen affinity of HbF.

scholarly journals Mathematical Characterization of the Inhibitory Effect of Mg 2+ on the Kinetics of Mitochondrial Ca 2+ Uniporter

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Ranjan K. Pradhan ◽  
Feng Qi ◽  
Daniel A. Beard ◽  
Ranjan K. Dash
Keyword(s):  
Inhibitory Effect ◽  
Kinetics Of

scholarly journals Effect of the Exchanged Cation in an Algerian Montmorillonite Used as a Heterogeneous Catalyst for Biginelli Reaction

2021 ◽  
Vol 68 (2) ◽  
pp. 355-362
Author(s):  
Fatiha Belferdi ◽  
Farida Bouremmad ◽  
Shalima Shawuti ◽  
Mehmet Ali Gulgun
Keyword(s):  
Heterogeneous Catalyst ◽  
Catalytic Properties ◽  
Biginelli Reaction ◽  
Reaction Medium ◽  
Exchange Capacity ◽  
Basal Spacing ◽  
Exchange Operation ◽  
Kinetics Of

In this work, an Algerian montmorillonite (Mt) is exchanged by different cations from the transition metals family, namely: Cu2+, Ni2+, Cr3+, Co2+, Fe2+ and Fe3+, it is used as a heterogeneous catalyst for Biginelli reaction. The exchanged cations are known for their catalytic properties in homogeneous catalysis. The main purpose is to study the effect of the exchanged cations on the yield and the kinetics of the reaction. The characterization of montmorillonite was carried out by XRD, which allows us to follow the evolution of the basal spacing d001 as a function of the exchanged cation and to show that the exchange operation has not altered the montmorillonite structure. The cation exchange capacity (CEC) is determined by the titration of the exchanged cation by atomic absorption. The product of the reaction is characterized by NMR, IR and by the determination of the melting point. In addition, the importance of the introduction order of the reagents into the reaction medium has been demonstrated on the yield and the kinetics. Finally, the obtained results show that the exchanged montmorillonite is competitive with other costly heterogeneous and homogeneous catalysts.

scholarly journals The Inhibitory Effect of Flavonoid Aglycones on the Metabolic Activity of CYP3A4 Enzyme

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2553 ◽  
Author(s):  
Darija Šarić Mustapić ◽  
Željko Debeljak ◽  
Željan Maleš ◽  
Mirza Bojić
Keyword(s):  
Metabolic Activity ◽  
Higher Plants ◽  
Inhibitory Effect ◽  
Array Detector ◽  
Flavonoid Aglycones ◽  
Reversible Inhibition ◽  
Positive Effects ◽  
Cyp3a4 Enzyme

Flavonoids are natural compounds that have been extensively studied due to their positive effects on human health. There are over 4000 flavonoids found in higher plants and their beneficial effects have been shown in vitro as well as in vivo. However, data on their pharmacokinetics and influence on metabolic enzymes is scarce. The aim of this study was to focus on possible interactions between the 30 most commonly encountered flavonoid aglycones on the metabolic activity of CYP3A4 enzyme. 6β-hydroxylation of testosterone was used as marker reaction of CYP3A4 activity. Generated product was determined by HPLC coupled with diode array detector. Metabolism and time dependence, as well as direct inhibition, were tested to determine if inhibition was reversible and/or irreversible. Out of the 30 flavonoids tested, 7 significantly inhibited CYP3A4, most prominent being acacetin that inhibited 95% of enzyme activity at 1 µM concentration. Apigenin showed reversible inhibition, acacetin, and chrysin showed combined irreversible and reversible inhibition while chrysin dimethylether, isorhamnetin, pinocembrin, and tangeretin showed pure irreversible inhibition. These results alert on possible flavonoid–drug interactions on the level of CYP3A4.

Sign in / Sign up

Export Citation Format

Share Document