How a promising anti-cancer derivative of palladium consisting phen-imidazole ligand affects bovine liver catalase functionality

Effect of central metal ion on some pharmacological properties of new Schiff base complexes. Anticancer, antioxidant, kinetic/thermodynamic and computational studies

The biological capacities of Schiff Base complexes such as anti-cancer, anti-microbial and anti-oxidant properties have been widely studied in the scientific community. However, the effect of central metal ion in the occurrence of their biological properties should be paid more attention. With this aim, novel 2-(hydroxyimino)-1-phenylpropylidene)benzohydrazide (HIPB) Schiff base ligand, and C1/palladium(II), C2/platinum(II), and C3/zinc(II) complexes derived from it were synthesized and characterized. Theoretical studies showed that C2 is more reactive and also has a higher pharmacological affinity than C1 and C3. Experimental investigations were done to compare some biological properties of the complexes. The anticancer assay showed that C1-C3 have the ability to inhibit the growth of HCT116 colon cancer cell lines, but C2 shows a relatively better effect than other. Antioxidant studies using •DPPH (2,2-diphenyl-1-picrylhydrazyl) assay presented the following trend: C2 > C1 > C3 > HIPB. Considering the importance of the antioxidant enzyme catalase in removing reactive oxygen species (ROS), the interaction of C1-C3 with Bovine Liver Catalase (BLC) was evaluated. Kinetic studies showed that C1-C3 can inhibit the catalytic performance of BLC by a similar mechanism, i.e. mixed-type inhibition. Among them, C1 was the strongest inhibitor (Activity inhibition% = 82.2). The C1-C3 quenched the BLC fluorescence emission with dynamic quenching mechanism. The binding affinity to BLC was higher for C1 and C2 than C3. The most important forces in the interaction of C1-C3 with BLC were hydrophobic interactions, which was strongly confirmed by molecular docking data. Tracking the structural changes of catalase showed that BLC undergoes structural changes in the presence of C1 more than C2 and C3.

Experimental and Theoretical Approaches to Monitor the Behavior of Bovine Liver Catalase in Interaction with a Binuclear Bismuth Complex

Here, the antioxidant potency of a binuclear Bi(III) complex {[Bi2(μ-ox)(dipic)2(H2O)2 (taa)2].H2O, where ox2- = oxalato, dipic2- = pyridine 2,6-dicarboxylato, and taa = thiourea} was evaluated using the •DPPH assay. It was demonstrated that the Bi complex exhibited a high ability to inhibit DPPH free radicals. The binding mechanism of the complex with bovine liver catalase (BLC) was also investigated, revealing structural and activity changes in the enzyme in the presence of the complex. The catalase activity in the decomposition of hydrogen peroxide increased in the presence of the Bi complex, reaching 39.8% higher than its initial activity at a concentration of 7.77 × 10-6 M. The complex exhibited a relatively high affinity for BLC, with K b values of 3.98, 0.13, and 0.09 × 105 M-1 at 303, 310, and 317 K, respectively. The mechanisms involved in the interaction were hydrogen bonding and van der Waals interactions, as validated through molecular docking simulations. Synchronous fluorescence showed that tryptophan was more affected by enzyme-complex interactions than tyrosine. In addition, a cell viability test using the MTT method revealed that at its highest concentration, the Bi complex caused a decrease in the number of cells below 50% compared to the control, while cisplatin showed negative effects at all concentrations. These findings suggest that the Bi complex has the potential to be developed as a promising candidate for BLC-related therapeutic target therapy.

Unraveling the binding interactions between two Pt(II) complexes of aliphatic glycine derivatives with human serum albumin: A comprehensive computational and multi-spectral investigation

This article delves into the interaction between HSA protein and synthesized platinum complexes, with formula: [Pt(Propyl-NH2)2(Propylglycine)]NO3 and [Pt(Tertpentyl-NH2)2(Tertpentylglycine)]NO3, through a range of methods, including spectroscopic (UV-visible, fluorescence, synchronous fluorescence and CD) analysis and computational modeling (molecular docking and MD simulation). The binding constants, the number of binding sites, and thermodynamic parameters were obtained at 25 to 37 °C. The study found that both complexes could bind with HSA (moderate affinity for Tertpentyl and strong affinity for Propyl derivatives) and occupied one binding site in HSA (validated with, Stern-Volmer, Job-plots, and molecular docking investigations) located in subdomain IIA. The binding mechanisms of both mentioned Pt(II) agents were different, with the Propyl derivative predominantly using van der Waals forces and hydrogen bond interactions with a static quenching mechanism and the Tertpentyl derivative mainly utilizing hydrophobic force with a dynamic quenching mechanism. However, the two ligands affected protein differently; the Tertpentyl complex did not significantly alter the protein structure upon binding, as evidenced by synchronous fluorescence spectroscopy (SFS), CD spectroscopy, and MD analysis. The outcome helps in understanding the binding mechanisms and structural modifications induced by the ligands, which could aid in the innovation of more effective and stable Pt(II)-based drugs.

Tracking the binding site of anticancer drug fluxoridin with Fe-related proteins to achieve intelligent drug delivery

In cancer cells that need a lot of iron for growth and metastasis, halo-transferrin (TF-containing iron) enters the cell with the help of the transferrin receptor 1 (TFR1) protein. If the anticancer drug can bind to the iron site by interacting with apo-transferrin (iron-free FT), it can enter the cancer cell by the same mechanism. Two iron-related proteins, Bovine liver catalase (BLC) and apo-Transferrin (TF), that are important in cancer patients were selected and their interaction with the anti-cancer drug Floxuridine (FUDR) was investigated. Here, the protective role of FUDR was evaluated by several variables such as drug concentration, interaction time, and temperature-induced degradation of enzyme function. The results showed that the protective effect of the FUDR is greater in high concentrations (in 5 × 10-5 M:1.78 % and 2.59 % after 24 and 48 h). The interaction of the FUDR with both proteins can reduce the intensity of the fluorescence emission by a static mechanism. The binding strength of the FUDR with both proteins was almost similar and with the order of 104 M-1 (Kb = 3.90 ± 0.41 × 104 M-1 for BLC-FUDR and 5.01 ± 0.36 × 104 M-1 for TF-FUDR at 310 K). The thermodynamic calculations (in agreement with the docking results) indicated that FUDR-protein complex formation was exothermic and the main binding forces in the binding process were van der Waals interactions and hydrogen bonds. Both fluorophores tryptophan (Trp) and tyrosine (Tyr) of both proteins had significant roles in fluorescence quenching and the interaction process, the polarity of their microenvironment changed. CD results showed that the secondary structure changes of TF are slightly more than BLC. Molecular docking showed that the binding of the FUDR to TF is very close to the Fe-specific site and is placed in the cavity among the wrapping domain, N-Terminal arm, and β-barrel in BLC.

Biological interaction of Pt complex with imidazole derivative as an anticancer compound with DNA: Experimental and theoretical studies

This investigation is applied to find out interesting information on DNA binding mode with Pt(II) derivative of two N, N bidentate ligands in treating cancer. Thus, one new water-soluble platinum complex with FIP and phen with a new formula of [Pt(phen)(FIP)](NO3)2 was prepared and specified. DFT data can be used to evaluate geometry parameters. Based on the ADMET prediction, this complex can be considered a drug-like agent. Cytotoxicity property was evaluated against some human cancerous MCF7, A549, and HCT116 cell lines. Accumulation of Pt complex, cisplatin, and oxaliplatin in each cancerous cell was determined, which is probably related to their lipophilicity and solubility properties. The binding mode of the complex to ct-DNA was investigated by fluorescence spectroscopy, circular dichroism, and molecular docking simulation. The viscosity of DNA by different concentrations of EB and Pt complex titration shows Pt complex interacts with DNA via groove binding like the spectroscopic binding result. In the MD study, DNA helix, RMSD, and RMSF analysis showed that DNA stability decreased and that the majority of residues left the initial state. DNA increased residual deviations and flexibility are linked to an increase in its gyratory radius, which is consistent with the findings of the experiments.

Molecular docking and spectroscopic study of bovine serum albumin interaction with new anticancer Pt complex with isopentyl dithiocarbamate ligand

Although cisplatin is useful in the treatment of cancer, it has a series of side effects that limit its use. Dithiocarbamates reduce the toxicity of platinum due to their structure and the presence of S, and N donating groups. In this article, the interaction of [Pt(bpy)(isopentyl.dtc)]NO3, where bpy is bipyridine and isopentyl.dtc is isopentyl-dithiocarbamate, with BSA, bovine serum albumin has been studied. The molecular binding method, including UV-Vis and fluorescence titration, was carried out in conditions including pH = 7.4 and temperatures of 27 and 37 °C. The negative values of enthalpy (ΔH°b) and entropy (ΔS°b) show that the driving forces of this interaction are hydrogen and van der Waals, and the negative value of the Gibbs free energy, ΔG°b indicates that the interaction proceeds spontaneously. The fluorescence results showed that the quenching mechanism is the static type and the Stern Volmer constant, KSV, was also obtained. The fluorescence titration method data displayed that the quenching mechanism is static. Binding constant (Kb), binding point (n), Hill coefficients, nH, Hill constant, KH, number of binding sites, g, BSA melting temperature, Tm, were also obtained. Finally, the molecular docking method result shows the binding constant, Ki and binding free energy for the platinum complex are -6.53 and 16.39 kcal mol-1, respectively, and also the proper position of binding on BSA can be considered the site I in the subdomain IIA.

Structural and functional changes of catalase through interaction with Erlotinib hydrochloride. Use of Chou's 5-steps rule to study mechanisms

Erlotinib hydrochloride (Erlo) is used in the treatment of non-small cell lung cancer, pancreatic cancer and other types of cancer. Interaction of small molecules with bio-macromolecules can lead to changes in the structure and function of them which is one of the possible side effects of the drugs. In this study, the interaction of Erlo with bovine liver catalase (BLC) using spectroscopic and computational methods is presented in detail. The enzymatic function of BLC decreased to 58.7% when the concentration of the Erlo was 0.5 × 10^-7 M. Fluorescence results revealed that the combination of BLC with Erlo undergoes static quenching mechanism (K_b = 1.15 × 10⁴ M^-1 at 300 K). The interaction process was spontaneous, exothermic and enthalpy-driven and Van der Waals and hydrogen bonds forces played major roles in the this process. UV-Vis, CD, 3D, and synchronous fluorescence measurements indicated the changes in the microenvironment residues and α-helix contents of BLC in the presence of Erlo. Docking and molecular dynamics presented a stable binding configuration and their results were perfectly consistent with the spectroscopic results. Theoretical calculations and experimental analysis help to fully understand of drug interaction with important biological molecules such as enzymes.