Proficient sonophotocatalytic degradation of organic pollutants using Co3O4/TiO2 nanocomposite immobilized on zeolite: Optimization, and artificial neural network modeling.

The health of all living organisms is greatly influenced by the quality of the water. Therefore, developing cost-effective, eco-friendly, and easily accessible methods is desperately needed to meet the high global demand for clean water. Recently, nanozyme-based dye degradation methods have been promising for the remediation of water pollution. In this work, peroxidase-mimic Co3O4/TiO2 nanocomposite was synthesized and characterized for its size, morphology, and crystalline structure. Colorimetric assay results showed that the peroxidase-like activity of the Co3O4/TiO2 nanocomposite was considerably enhanced compared to the pure Co3O4 NPs and TiO2 NPs. Besides excellent enzyme-mimic activity, the higher sonophotocatalytic dye degradation capability of the nanocomposite after immobilization on zeolite (Co3O4/TiO2@Ze) was also demonstrated. Under optimal conditions (pH = 5.0, 25 °C), 0.1 g/L of catalyst was able to degrade 100 % of methylene blue (MB) with 600 µM in the presence of 30 µM H2O2 within 12 min. GC/MS analysis and toxicity studies revealed less toxic metabolite production after treatment of MB with sonophotocatalytic Co3O4/TiO2@Ze. Modeling of MB degradation using artificial neural networks (ANN) with a 5:6:1 topology was successfully performed, and the results confirmed the fitness of theoretical and experimental outputs according to the calculated correlation coefficient values. The prepared nanocomposite could thus be used as a promising and highly effective catalyst for the removal of organic dyes from polluted water.

Interaction of bovine serum albumin with ellagic acid and urolithins A and B: Insights from surface plasmon resonance, fluorescence, and molecular docking techniques.

Human serum albumin (HSA) shows the sequence homology and structural similarity with bovine serum albumin (BSA). Therefore, here, the interaction of natural phenolic antioxidants, ellagic acid (ELA), and its derivatives-urolithins A (ULA) and B (ULB)-with BSA was investigated. The results of surface plasmon resonance (SPR) indicated a high affinity of ELA, ULA, and ULB to BSA, with KD value < 1 × 10-6 M. The KD values of binding of the studied compounds to BSA increased with temperature, revealing a reduction in affinity with an increase in temperature. Fluorescence data showed that the quenching of BSA by tested compounds occurred via a static quenching. However, the affinity of ELA for BSA was higher than that of ULA and ULB, which may be because of the presence of a large number of hydroxyl groups in its structure. The assessment of the antioxidant activity of BSA and BSA-ELA/ULA/ULB complexes using the DPPH assay indicated that the DPPH scavenging activity of BSA increased after complex formation with ELA/ULA/ULB in the following order: BSA-ELA > BSA-ULA > BSA-ULB > BSA, which was due to their structural differences. The results of the docking analysis were in agreement with the experimental results.

A sensitive colori/fluorimetric nanoprobe for detection of polyphenols using peroxidase-mimic plasma-modified MoO3 nanoparticles.

Herein, MoO3 nanoparticles were synthesized and modified using Argon cold plasma treatment (Ar-MoO3NPs) for the first time. Various characterization studies were performed using various methods, including SEM, XRD, and FTIR techniques. The catalytic activity of MoO3NPs before and after modification was investigated using fluorometric and colorimetric experiments. The results indicated that the enzyme-mimic activity of MoO3NPs increased after plasma-surface modification (1.5 fold). Also, a fluorometric method based on the oxidation of a non-fluorescent terephthalic acid by Ar-MoO3NPs in the presence of H2O2 and the production of a compound with a high emission was designed for polyphenols detection. Quercetin was used as a polyphenol standard for the optimization of the proposed system. Under the optimum conditions, the dynamic ranges of the calibration graphs and the detection limits were calculated for different polyphenols (µmol/L): quercetin (2-232, 12.22), resveratrol (2-270, 61.89), curcumin (39-400, 38.89), gallic acid (2-309, 21.5) and ellagic acid (39-309, 16.25). Also, the precision of the method, which was expressed as RSD%, was in the range of 0.286-1.19%. The proposed system could detect individual polyphenols and total polyphenols in three different fruit extracts (apple, orange, and grapes) with high sensitivity. The obtained total concentrations of polyphenols in real samples were comparable to those calculated by the spectrophotometric method. So, a novel and sensitive optical nanosensor for the detection of polyphenols was reported as an alternative to the routine Folin-Ciocalteu spectrophotometric technique.

The protective effect of natural phenolic compound on the functional and structural responses of inhibited catalase by a common azo food dye.

In this research retrieval effects of natural yellow (NY) on the performance of carmoisine (CAR) inhibited bovine liver catalase (BLC) was studied using multispectral and theoretical methods. Kinetic studies showed that CAR inhibited BLC through competitive inhibition (IC50 value of 2.24 × 10-6 M) while the addition of NY recover the activity of CAR-BLC up to 82% in comparison with the control enzyme. Circular dichroism data revealed that NY can repair the structural changes of BLC, affected by CAR. Furthermore, an equilibrium dialysis study indicated that NY could reduce the stability of the CAR-catalase complex. The surface plasmon resonance (SPR) data analysis indicated a high affinity of NY to BLC compared to CAR and the binding of NY led to a decrease in the affinity of the enzyme to the inhibitor. On the other hand, fluorescence and molecular docking studies showed that the quenching mechanism of BLC by CAR occurs through a static quenching process, and van der Waals forces and hydrogen bonding play a crucial role in the binding of CAR to BLC. MLSD data demonstrated that NY could increase the binding energy of CAR-BLC complex from -7.72 kJ mol-1 to -5.9 kJ mol-1, leading to complex instability and catalase activity salvage.

Dual enzymes-mimic activity of nanolayered manganese-calcium oxide for fluorometric determination of metformin.

There are different analytical methods available for the determination of metformin, as an oral hypoglycemic and antidiabetic drug, in biological samples. However, most of these methods suffer from some drawbacks, including high-priced materials and equipment, damaging chemical reagents, time-consuming nature, and tedious operation procedures. So, in this work a new, sensitive and simple method was reported for the detection of metformine. In this regard, nanolayered manganese-calcium oxide (NL-MnCaO2) were synthesized and characterized using scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRD) techniques. Also, we studied the enzyme-like activity of synthesized particles and reported a bifunctional nanozyme, which performs the dual roles for peroxidase and catalase-mimicking. The results demonstrated the hindering effect of metformin on the peroxidase-mimic activity of NL-MnCaO2 and this effect was increased by raising metformin concentration. So, a sensitive fluorometric detection system was designed for the analytical assay of metformin, based on the terephthalic acid (TA)-H2O2 reaction with NL-MnCaO2. An acceptable linearity was observed between the metformin concentration and fluorescence quenching of the system in the range of 0.07-0.77 mM. Limit of detection (LOD) and limit of quantification (LOQ) were 0.17 µM and 0.96 µM, respectively. The proposed system was applied for the estimation of metformin concentration in serum samples by recoveries of 86.68-106%. So, the proposed fluorometric method provides some main advantages such as wide linear range, low detection limit, rapid detections, high sensitivity, and good practicability for the determination of metformin in biological samples.

Probing the Interactions of Lamotrigine and Phenobarbital with Tau Protein: Experimental and Molecular Modeling Studies.

Tau, as a small protein in neurons, plays a main role in stabilizing and assembling the internal microtubules. Here, the effects of antiepileptic drugs, including lamotrigine (LTG) and phenobarbital (PHB), on tau protein structure have been investigated by surface plasmon resonance (SPR), fluorescence spectroscopy along molecular modeling. Fluorescence data analysis revealed that both drugs quench the intrinsic emission intensity of tau protein via a static quenching mechanism. Analysis of SPR data at three different temperatures revealed that binding of LTG and PHB to tau protein leads to a decrease and increase in equilibrium constants (KD) values with increasing temperature, respectively. Therefore, the affinity of LTG decreases and PHB increases with increasing temperature. In addition, molecular docking studies indicated that both LTG and PHB bind to the S1 pocket of tau protein. Our data demonstrated the preventive effect of two important antiepileptic pharmaceuticals on the aggregation of tau protein. Given that any damage to the tau protein possibly leads to neurodegenerative diseases, this study can provide useful and important information and a basis for further research and study to treat tauopathy.

DNA binding ability and cytotoxicity, cell cycle arrest and apoptosis inducing properties of a benzochromene derivative against K562 human leukemia cells.

Chromene and its derivatives are generally spread in nature. Heterocylic-based compounds like chromenes have displayed pharmacological activities. Chromene derivatives are critical due to some biological features such as anticancer activity. CML, chronic myelogenous leukemia, is a fatal malignancy determined by resistance to apoptosis and contains the Philadelphia chromosome. Induction of apoptosis is one of the main approaches in cancer therapy. In this research, benzochromene derivative, 2-amino-4-(4-methoxy phenyl)-4H-benzochromene-3-carbonitrile (4-MC) was tested for cytotoxic and apoptotic induction activities in the human leukemic K562 cell line. The MTT growth inhibition assay was used to determine the cellular growth and survival. Moreover, the binding attribute of 4-MC with double helix DNA was assessed by some spectroscopic and viscosity measurement, and also for docking analysis. 4-MC exhibited good cytotoxicity on K562 cell line and the IC50 value was calculated to be 30 µM. Furthermore, the mechanisms of apoptosis induction were determined morphologically by fluorescence dual staining with acridine orange and ethidium bromide and cell cycle analysis was based on DNA content, as well as the presence of phosphatidyl serine on the outside of the cells by the flow cytometric method. The results showed that 4-MC had potent cytotoxic activity via sub-G1 cell cycle arrest and induction of apoptosis. The experimental and simulation studies reported that 4-MC binds to ctDNA through groove binding mode with the binding constant (Kb) of 2.5 × 103 M-1. These data represent a considerable anticancer potential of 4-MC and could be suggested for further pharmacological studies.

Biodegradation of malachite green by a novel laccase-mimicking multicopper BSA-Cu complex: Performance optimization, intermediates identification and artificial neural network modeling.

In this work, a soluble biopolymer was prepared by conjugating the bovine serum albumin (BSA) with transition metal ion (Cu2+). BSA-Cu complex was synthesized and characterized using UV-vis absorption, fluorescence and ATR-FTIR spectroscopies. A colorimetric guaiacol oxidation based method, was used to study the catalytic activity of complex and the results indicated its laccase-like activity. Compared with laccase, BSA-Cu complex showed a higher Km value and a similar Vmax value at the same mass concentration. Also, the ability of the BSA-Cu complex to decolorize malachite green (MG) was tested and the results showed that the complex was able to complete the decolorization process of MG within 30 min. Using gas chromatography/mass spectrometry (GC-MS) the resultant metabolites of MG degradation were analyzed and the toxicity of degradation products was assessed against Escherichia coli and Bacillus subtilis. The results confirmed the formation of less toxic products after degradation of MG by BSA-Cu complex. To predict the decolorization efficiency (DE%) of MG, an artificial neural network (ANN) was designed with five, five and one neurons in the input, hidden and output layers, respectively. The obtained results showed the ability of the designed ANN to predict MG removal successfully.

A Sensitive, Simple and Direct Determination of Pantoprazole Based on a "Turn off-on" Fluorescence Nanosensor by Using Terbium-1,10-phenanthroline-silver Nanoparticles.

A new sensitive, simple, rapid, reliable and selective fluorometric method for the determination of pantoprazole (PAN) in human plasma and a pharmaceutical formulation has been developed. This technique is based on a quenching effect of silver nanoparticles (AgNPs) on the emission intensity of a fluorescent probe, terbium(III)-1,10-phenantroline (Tb(III)-phen) complex (due to a fluorescence resonance energy transfer (FRET) phenomenon between the Tb(III)-phen complex and AgNPs), and then restoring the fluorescence intensity of the Tb(III)-phen-AgNPs system upon the addition of PAN (turn off-on process). The effects of various factors on the proposed method including time, temperature, pH, order of the addition of various reagents and the concentration of AgNPs were investigated. Under the optimal conditions, a good linear relationship between the enhanced emission intensity of the Tb(III)-phen-AgNPs system and the PAN concentration was observed in the range of (10 - 1000) × 10-8 M. The limit of detection (LOD) and the limit of quantitation (LOQ) were 7.2 × 10-8 and 24.2 × 10-8 M, respectively. Also, the interferences of some common interfering species on the fluorescence intensity of the system were investigated. This simple and sensitive method was successfully applied for the determination of PAN in spiked human plasma samples and in its capsule formulation. The analytical recoveries were in the range of 88.54 - 101.33 and 90.07 - 98.85%, respectively.

Noncompetitive Inhibition of Bovine Liver Catalase by Lawsone: Kinetics, Binding Mechanism and in silico Modeling Approaches.

Lawsone (2-hydroxy-1,4-naphtoquinone; LAW), as a naphthoquinone derivative, is the biologically active component of Henna leaves. In this study, the structural and functional effects of LAW on bovine liver catalase (BLC), has been studied utilizing ultraviolet-visible (UV-vis) absorption, fluorescence, and ATR-FTIR spectroscopic techniques, and molecular docking approach. In-vitro kinetic study showed that by adding gradual concentrations of LAW, catalase activity was significantly decreased through noncompetitive inhibition mechanism. UV-vis and ATR-FTIR spectroscopic results illustrated that additional concentration of LAW lead to significant change in secondary structure of the enzyme.The fluorescence spectroscopic results at different temperatures indicated that LAW quenches the intrinsic fluorescence of BLC by dynamic mechanismand there is just one binding site for LAW on BCL. Changing the micro-environment nearby two aromatic residues (tryptophan (Trp) and tyrosine (Tyr)) were resulted from synchronous fluorescence. The thermodynamic parameters were implied that the hydrophobic bindings have a significant impress in the organization of the LAW-catalase complex. Molecular docking data in agreement with experimental results, confirmed that hydrophobic interactions are dominant. Inhibition of enzyme activity by LAW, showed that along withits helpful effects as ananti-oxidant compounds, the side effects of LAW should not be overlooked.

An ultrasensitive label-free colorimetric biosensor for the detection of glucose based on glucose oxidase-like activity of nanolayered manganese-calcium oxide.

During the last years, enzyme-based biosensors have gained much more attention among the researchers and have had great success in the determination of different biological macromolecules. Nanomaterials with intrinsic enzyme-mimic activity are widely used in biomedicine as artificial enzymes. Here, we report glucose oxidase-mimic activity of nanolayered manganese-calcium (Mn-Ca) oxide nanoparticles (NL-MnCaO2). In this work, NL-MnCaO2nanoparticles were synthesized and characterized using different techniques including transmission electron microscopy (TEM), scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD). Also, the ability of these compounds for the glucose and hydrogen peroxide (H2O2) determination was investigated. A non-enzymatic strategy for the colorimetric detection of glucose and H2O2 was reported which can be utilized not only for the rapid detection and analysis of glucose by the naked eye but also the quantitative assay of glucose by spectrophotometry. The in situ generated H2O2 and gluconic acid (GA) from the oxidation of glucose through the glucose oxidase-mimicking activity of NL-MnCaO2 was detected using a colorimetric method. Also, the results confirmed the application of these compounds for the detection of glucose in human serum samples with a detection limit (LOD) of 6.12 × 10-6 M. The results showed that NL-MnCaO2 can be used as an alternative for the natural enzymes and act as a simple, sensitive and enzyme-free biosensor for the detection of glucose in real samples. The proposed strategy shows some advantages including sensitivity, short detection time and low detection limit.

Surface plasmon resonance, fluorescence, and molecular docking studies of bovine serum albumin interactions with natural coumarin diversin.

In the present study the binding of diversin (DIV), a prenylated coumarin isolated from Ferula diversivittata, to bovine serum albumin (BSA) was investigated using surface plasmon resonance (SPR), spectrofluorimetry, and molecular docking approaches. Following the activation of carboxylic groups, via NHS/EDC, BSA was immobilized on the carboxymethyl dextran (CMD) hydrogel coated Au sensor, and was used for real-time monitoring of the interactions between DIV and BSA. KD value of DIV binding to BSA increased with increasing temperature, confirmed that the affinity between BSA and DIV decreases with rising temperature. In addition, the fluorescence and synchronous fluorescence spectroscopic data revealed that the intrinsic emission intensity of BSA was quenched via a dynamic mechanism. In addition, the micro-region around BSA tyrosine residue was changed upon interaction with DIV. The thermodynamic parameter findings suggested that the hydrophobic interactions were dominant in the binding and formation of the BSA and DIV complex. The molecular docking outputs indicated that there is only one binding site on BSA for DIV, in agreement with experimental data, and DIV bind BSA in subdomain IB.

Exploring the interactions of a Tb(III)-quercetin complex with serum albumins (HSA and BSA): spectroscopic and molecular docking studies.

Serum albumins (human serum albumin (HSA) and bovine serum albumin (BSA), two main circulatory proteins), are globular and monomeric macromolecules in plasma that transport many drugs and compounds. In the present study, we investigated the interactions of the Tb(III)-quercetin (Tb-QUE) complex with HSA and BSA using common spectroscopic techniques and a molecular docking study. Fluorescence data revealed that the inherent fluorescence emission of HSA and BSA was markedly quenched by the Tb-QUE complex through a static quenching mechanism, confirming stable complex formation (a ground-state association) between albumins and Tb-QUE. Binding and thermodynamic parameters were obtained from the fluorescence spectra and the related equations at different temperatures under biological conditions. The binding constants (Kb ) were calculated to be 0.8547 × 103 M-1 for HSA and 0.1363 × 103 M-1 for BSA at 298 K. Also, the number of binding sites (n) of the HSA/BSA-Tb-QUE systems was obtained to be approximately 1. Thermodynamic data calculations along with molecular docking results indicated that electrostatic interactions have a main role in the binding process of the Tb-QUE complex with HSA/BSA. Furthermore, molecular docking outputs revealed that the Tb-QUE complex has high affinity to bind to subdomain IIA of HSA and BSA. Binding distances (r) between HSA-Tb-QUE and BSA-Tb-QUE systems were also calculated using the Forster (fluorescence resonance energy transfer) method. It is expected that this study will provide a pathway for designing new compounds with multiple beneficial effects on human health from the phenolic compounds family such as the Tb-QUE complex.

Experimental investigation and molecular dynamics simulation of the binding of ellagic acid to bovine liver catalase: Activation study and interaction mechanism.

Ellagic acid (ELA), as a polyphenolic natural compound and food additive, which has reported to possess anti-carcinogenic, antioxidant, antidepressant, ameliorative and anti-mutagenic effects. In the current work, the effects of ELA on the conformation and catalytic activity of catalase were investigated by using spectroscopic techniques including ultraviolet visible (UV-vis), fluorescence, synchronous fluorescence and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy as well as molecular dynamics (MD) simulation. Kinetic studies showed that the enzymatic activity of catalase increases in the presence of ELA (almost 2-fold higher than free enzyme activity). Moreover, analysis of fluorescence data revealed two binding sites for ELA on the catalase and static type of quenching mechanism. The binding constants between ELA and catalase were obtained to be 47.35 × 107 M-1 (at 298 K) and 17.60 × 107 M-1 (at 310 K) and the binding distance was calculated to be 2.83 nm. Thermodynamic data showed that hydrogen bonds have a main role in the ELA-catalase complex formation. The best binding sites for ELA were, in the middle of ß-barrel and wrapping domain and in the middle of ß-barrel and helical domain, according to molecular docking data. MD simulation results were confirmed that ELA can increase catalase activity through increasing the distance between an upper side α-helix structure and a down side random coil structure.

Synergistic inhibition of catalase activity by food colorants sunset yellow and curcumin: An experimental and MLSD simulation approach.

Utilizing food additives at their optimized concentration is believed to be relatively safe, but their combinatorial effects remain largely unexplored. The influence of mixed food additives on the macromolecules may be altered by synergistic or antagonistic effects. It is previously shown that curcumin enhances the catalase activity by affecting its structural pocket in the active site. The aim of this study was to investigate the combination effects of food colorants sunset yellow FCF (SNY) and curcumin on the activation and/or inactivation of catalase activity using multispectral (fluorescence, FTIR, and UV-vis) analysis and simultaneous docking simulations. Kinetic studies demonstrated that SNY could significantly decrease catalase activity through a non-competitive inhibition mechanism. Fluorescence data indicated that SNY reduces intrinsic emission of catalase via a static quenching mechanism. Thermodynamic and molecular docking investigations suggested that catalase has one binding site for SNY, and hydrogen binding plays a main role in the binding reaction of catalase -SNY complex. Molecular dynamic simulation data indicated that the curcumin binding to the cavity, in the middle of the catalase helical domain, facilitates SNY binding to the enzyme pocket. For this purpose, the equilibrium dialysis system was used to study the stability and reversibility of SNY-catalase in the absence or presence of curcumin. The obtained data indicated that the binding of SNY-catalase is reversible and the stability of the complex is time-dependent. However, curcumin could make the complex more stable enhancing the SNY inhibition of catalase activity.

Multispectral and computational probing of the interactions between sitagliptin and serum albumin.

The binding of sitagliptin (SIT), an anti-diabetic drug, to human and bovine serum albumin (HSA and BSA; main serum transport proteins) was investigated using various spectroscopic and molecular docking techniques. The fluorescence data demonstrated that SIT quenched inherent fluorescence of these proteins through the formation of SIT-HSA/BSA complexes. The number of binding sites was obtained (~1) and binding constant (Kb) and effective quenching constant (Ka) were calculated as 104 for both systems. Based on thermodynamic parameters, the van der Waals forces and hydrogen bonding were the most important forces in the interactions between HSA/BSA and SIT, and the complex formation processes were spontaneous. The results of UV-vis absorption and FT-IR spectroscopic revealed that SIT induces small conformational changes in the structure of the proteins (HSA/BSA). The synchronous fluorescence (SF) spectroscopy demonstrated that the binding of SIT with HSA/BSA had no effect on the polarity around Trp and Tyr residues. The CD spectra showed changes in the secondary and tertiary structures of both proteins with a decrease in α-helices contents and an increase in ß-turn structures. The molecular docking and spectroscopic data verified the binding mechanisms between SIT and HSA/BSA, and revealed that SIT completely fits into the hydrophobic cavity between domain II and domain III of these proteins.

The impact of water molecules on binding affinity of the anti-diabetic thiazolidinediones for catalase: Kinetic and mechanistic approaches.

Water molecules play a vital role in efficient drug binding to its target. Thiazolidinediones (TZDs), a class of anti-diabetic drugs, are widely used for treatment of type 2 diabetes mellitus. In the present study, the possible contribution of water molecules to the binding of TZDs to catalase, a potential target in the liver, was investigated by different experimental and theoretical methods. These studies indicated that TZDs could significantly improve the catalase catalytic function with a significant contribution from water molecules. As a probe for the differential number of released water molecules during the catalase transition from E to E* states, the activity of TZDs-catalase complexes was demonstrated to be mainly dependent on water activity. However, free catalase decomposed the substrate more independently. In addition, the spectrofluorimetry studies showed that the binding of TZDs to catalase needed the release of water molecules from the enzyme's binding pocket. The thermodynamic studies indicated that the binding enthalpy and entropy of TZDs for catalase were decreased with lower water activity. The favorable process contributes to release of water molecules from the binding pocket through the formation of hydrophobic interactions between catalase and TZDs in an enthalpic manner. Molecular docking simulations confirmed that the depletion of water molecules from the binding cavity is essential for effective interactions between TZDs and catalase.

Aspirin in retrieving the inactivated catalase to active form: Displacement of one inhibitor with a protective agent.

Aspirin as a potential drug is able to bind to different targets and also could affect on the binding process of other ligands. In the present work, aspirin was considered as a protective agent to retrieve the inactivated catalase by farnesiferol C (FC) through displacement manner. The catalytic assessment revealed that aspirin is able to remarkably retrieve the activity of FC-catalase from 4.2 ±â€¯0.2% to 98 ±â€¯0.1% compare to the control sample. Furthermore, displacement study and CD spectroscopy indicated that aspirin could reduce the stability of FC-catalase complex. Based on the obtained data, it is shown that the binding of aspirin to catalase led to decrease the affinity of catalase to the inhibitor. The releasing analysis of FC from the complex showed that the dissociation constant (Kd) of FC-catalase was increased, considerably from 8.9 ±â€¯0.2 µM to 256 ±â€¯01 µM in the presence of aspirin at 298 K. Also, molecular simulation proved the instability of FC-catalase following the binding of aspirin to the complex.

Activation of catalase via co-administration of aspirin and pioglitazone: Experimental and MLSD simulation approaches.

Aspirin (ASP) and pioglitazone (PGL) are the most common drugs that are widely used by diabetic patients to control the blood sugar and hinder cardiovascular diseases. The interaction between PGL and ASP is one of the important medical issues to clarify the safety of co-administration of these drugs. In the present study, the effect of co-administered ASP with PGL was investigated on the structure and catalytic function of catalase as a potential target in the liver. Based on our data, co-administration of ASP-PGL significantly enhanced the catalase activity in comparison with PGL alone. However, ASP does not have any effects on the catalytic function of catalase. Moreover, the dialysis measurement and CD spectroscopy study revealed that binding of ASP to catalase could increase the stability of catalase-PGL complex. Based on the obtained data, it is shown that the binding of ASP to catalase led to increase the affinity of catalase to PGL. Binding analysis showed that the association constant of catalase-PGL was reduced considerably in the presence of ASP from 12.19 ±â€¯0.1 × 106 M-1 to 6.4 ±â€¯0.2 × 106 M-1 at 298 K. Multiple ligands simultaneous docking (MLSD) also confirmed an increase in the binding affinity of PGL to catalase.

The inhibitory effect of farnesiferol C against catalase; Kinetics, interaction mechanism and molecular docking simulation.

Farnesiferol C (FC) is a natural sesquiterpene coumarin, which includes a widely range of biological activities. In this work, effects of FC on the structure and catalytic function of bovine liver catalase (BLC) was assessed by various spectroscopic and theoretical methods. Kinetic studies showed that FC has a remarkable inhibitory activity on BLC via mixed-type inhibition. The IC50 value as the inhibitory strength of FC was evaluated 1.5µM. Fluorescence spectroscopy, synchronous fluorescence, CD spectroscopy and UV-vis absorption studies revealed conformational changes in the tertiary and secondary structure of BLC as well as the position of the heme group in the presence of different concentrations of FC. Fluorescence studies revealed that FC quenches intrinsic emission of catalase via static quenching process. The binding constants at 298 and 310K were calculated 1.17×105M-1 and 1.0×105M-1, respectively. Thermodynamic data suggested that hydrophobic interactions play a major role in the binding reaction of FC on BLC. Structural studies indicated that the binding FC to the enzyme is responsible for the changes of the percentage of secondary structures' elements especially α-helix. From the simulation data, the role of Arg353 residue in the mechanism of catalase inhibition has been recognized.