Bovine Serum Albumin Binding Research Articles

Mechanistic competitive binding interaction study between olmutinib and colchicine with model transport protein using spectroscopic and computer simulation approaches

Drug-drug interactions are due to the binding of a drug to plasma proteins displacing another plasma protein-bound drug. Two ligands, olmutinib (OLM) and colchicine (COL), were explored for their binding and displacement interaction with bovine serum albumin (BSA). Olmutinib is a 3rd-generation tyrosine kinase inhibitor (TKI), inhibits EGFR. COL is an anti-mitotic agent used in the treatment of gouty arthritis and has chemotherapeutic properties. The binding of BSA with OLM and COL was evaluated independently and in the presence of each other with spectroscopic and molecular docking and molecular dynamic simulation. Results based on quenching curves, displacement curves, binding constants, and docking results were evaluated. The presence of either drug (OLM or COL) influenced the binding of OLM and COL to BSA. The OLM had a higher binding capacity to BSA compared to COL. The presence of COL in the BSA-OLM system lowered the binding constants in comparison to its binary system. The OLM in the BSA-COL system increased the binding constant values for the system compared to the BSA-COL system. These findings are essential since increased non-bound fraction or reduced free drug fraction availability in the systemic circulation. The interference in the binding of drugs may lead to adverse events or subtherapeutic responses of the drugs.

Synthesis, characterization and biological activities of complexes CoII, NiII and CuII prepared using mixture of 2-hydroxy-1-naphthaldehyde and N, N′-dimethyl-1, 3-propanediamine

Copper-based compounds are promising entities for target-specific next-generation anticancer therapeutics. In lieu of this, 2-Hydroxy-1-Naphthaldehyde and N, N′-Dimethyl-1,3-Propanediamine scaffold plays an important role, because of their wide variety of potential (NCS) = Thiocynade and coordination modes. Herein, we report copper complexes 3 with a biocompatible molecule, and secondary ligands viz,. copper complexes have been designed, synthesized and adequately characterized using various spectroscopic techniques. In-vitro, DNA and Bovine serum albumin (BSA) binding was also carried out using fluorescence technique Furthermore, copper complexes 1–3 were tested for biological studies, i.e., anticancer as well as In vitro cytotoxicity results were carried out on cultured MCF-7 cell lines responsible for Moreover, and the copper complexes 3 were tested for potential to act cytotoxicity.

Schiff base containing pyridine groups functionalized water-soluble phthalocyanine: Synthesis, photo-physicochemical properties, and bovine serum albumin binding behavior.

The novel pyridine bearing schiff base substituted metal-free (9), zinc(II) phthalocyanine (10), and its quaternized derivative (11) were designed and synthesized. These phthalocyanines were fully characterized by spectroscopic methods (FT-IR, UV-Vis, MALDI-TOF, and 1H NMR). The photo-physicochemical properties of these phthalocyanines were investigated in both DMSO and DMF for 10 and in both DMSO and aqueous solution for 11. The addition of pyridine bearing Schiff base groups as peripheral ligands showed an improvement in the photophysical and photochemical properties. In addition, a spectroscopic investigation of the binding behavior of the water-soluble zinc (II) phthalocyanine complex to bovine serum albumin (BSA) was also studied in this work.

On the Effect of Soft Molecularly Imprinted Nanoparticles Receptors Combined to Nanoplasmonic Probes for Biomedical Applications.

Soft, deformable, molecularly imprinted nanoparticles (nanoMIPs) were combined to nano-plasmonic sensor chips realized on poly (methyl methacrylate) (PMMA) substrates to develop highly sensitive bio/chemical sensors. NanoMIPs (dmean < 50 nm), which are tailor-made nanoreceptors prepared by a template assisted synthesis, were made selective to bind Bovine Serum Albumin (BSA), and were herein used to functionalize gold optical nanostructures placed on a PMMA substrate, this latter acting as a slab waveguide. We compared nanoMIP-functionalized non-optimized gold nanogratings based on periodic nano-stripes to optimized nanogratings with a deposited ultra-thin MIP layer (<100 nm). The sensors performances were tested by the detection of BSA using the same setup, in which both chips were considered as slab waveguides, with the periodic nano-stripes allocated in a longitudinal orientation with respect to the direction of the input light. Result demonstrated the nanoMIP-non optimized nanogratings showed superior performance with respect to the ultra-thin MIP-optimized nanogratings. The peculiar deformable character of the nano-MIPs enabled to significantly enhance the limit of detection (LOD) of the plasmonic bio/sensor, allowing the detection of the low femtomolar concentration of analyte (LOD ∼ 3 fM), thus outpassing of four orders of magnitude the sensitivies achieved so far on optimized nano-patterned plasmonic platforms functionalized with ultra-thin MIP layers. Thus, deformable nanoMIPs onto non-optimized plasmonic probes permit to attain ultralow detections, down to the quasi-single molecule. As a general consideration, the combination of more plasmonic transducers to different kinds of MIP receptors is discussed as a mean to attain the detection range for the selected application field.

Radioprotective Role of Vitamins C and E against the Gamma Ray-Induced Damage to the Chemical Structure of Bovine Serum Albumin.

Radioprotective effects of vitamin C and vitamin E as a water-soluble and a lipid-soluble agent, respectively, were investigated at the molecular level during the imposition of gamma radiation-induced structural changes to bovine serum albumin (BSA) at the therapeutic dose of 3 Gy. Secondary and tertiary structural changes of control and irradiated BSA samples were investigated using circular dichroism and fluorescence spectroscopy. The preirradiation tests showed nonspecific and reversible binding of vitamins C and E to BSA. Secondary and tertiary structures of irradiated BSA considerably changed in the absence of the vitamins. Upon irradiation, α-helices of BSA transitioned to beta motifs and random coils, and the fluorescence emission intensity decreased relative to nonirradiated BSA. In the presence of the vitamins C or E, however, the irradiated BSA was protected from these structural changes caused by reactive oxygen species (ROS). The two vitamins exhibited different patterns of attachment to the protein surface, as inspected by blind docking, and their mechanisms of protection were different. The hydrophilicity of vitamin C resulted in the predominant scavenging of ROS in the solvent, whereas hydrophobic vitamin E localized on the nonpolar patches of the BSA surface, where it did not only form a barrier for diffusing ROS but also encountered them as an antioxidant and neutralized them thanks to the moderate BSA binding constant. Very low concentrations of vitamins C or E (0.005 mg/mL) appear to be sufficient to prevent the oxidative damage of BSA.

Effect of Tetraphenylborate on Physicochemical Properties of Bovine Serum Albumin.

The binding interactions of bovine serum albumin (BSA) with tetraphenylborate ions ([B(Ph)4]−) have been investigated by a set of experimental methods (isothermal titration calorimetry, steady-state fluorescence spectroscopy, differential scanning calorimetry and circular dichroism spectroscopy) and molecular dynamics-based computational approaches. Two sets of structurally distinctive binding sites in BSA were found under the experimental conditions (10 mM cacodylate buffer, pH 7, 298.15 K). The obtained results, supported by the competitive interactions experiments of SDS with [B(Ph)4]− for BSA, enabled us to find the potential binding sites in BSA. The first site is located in the subdomain I A of the protein and binds two [B(Ph)4]− ions (logK(ITC)1 = 7.09 ± 0.10; ΔG(ITC)1 = −9.67 ± 0.14 kcal mol−1; ΔH(ITC)1 = −3.14 ± 0.12 kcal mol−1; TΔS(ITC)1 = −6.53 kcal mol−1), whereas the second site is localized in the subdomain III A and binds five ions (logK(ITC)2 = 5.39 ± 0.06; ΔG(ITC)2 = −7.35 ± 0.09 kcal mol−1; ΔH(ITC)2 = 4.00 ± 0.14 kcal mol−1; TΔS(ITC)2 = 11.3 kcal mol−1). The formation of the {[B(Ph)4]−}–BSA complex results in an increase in the thermal stability of the alfa-helical content, correlating with the saturation of the particular BSA binding sites, thus hindering its thermal unfolding.

Interaction of nitrobenzoxadiazole derivatives of piperazine and aniline with bovine serum albumine in silico and in vitro

Albumin is a globular protein of plasma of mammalian blood participating in transport of hydrophobic metabolites and drugs. Thus, studies devoted to its binding are valuable as a part of evaluation of new potential drugs or fluorescent probes for in vivo usage. Here we describe results concerning synthesis and bovine serum albumin binding assay both in silico (docking) and in vitro (spectrophotometric and spectrofluorimetric titrations) for four new 7-nitrobenzoxadiazol-4-yl (NBD) derivatives of aniline and piperazine. Experimental dissociation constant for NBD-ethynylaniline 4 was calculated to be about 10 µmol/L.

Floating terahertz metamaterials with extremely large refractive index sensitivities

In the diagnosis of severe contagious diseases such as Ebola, severe acute respiratory syndrome, and COVID-19, there is an urgent need for protein sensors with large refractive index sensitivities. Current terahertz metamaterials cannot be used to develop such protein sensors due to their low refractive index sensitivities. A simple method is proposed that is compatible with all geometrical structures of terahertz metamaterials to increase their refractive index sensitivities. This method uses patterned photoresist to float the split-ring resonators (SRRs) of a terahertz metamaterial at a height of 30 μm from its substrate that is deposited with complementary SRRs. The floating terahertz metamaterial has an extremely large refractive index sensitivity of 532 GHz/RIU because its near field is not distributed over the substrate and also because the complementary SRRs confine the field above the substrate. The floating terahertz metamaterial senses bovine serum albumin (BSA) and the protein binding of BSA and anti-BSA as BSA, and anti-BSA solutions with low concentrations that are smaller than 0.150 μmol/L are sequentially dropped onto it. The floating terahertz metamaterial is a great achievement to develop protein sensors with extremely large refractive index sensitivities, and has the potential to sense dangerous viruses.

A photoswitchable “turn-on” fluorescent chemosensor: Quinoline-naphthalene duo for nanomolar detection of aluminum and bisulfite ions and its multifarious applications

A quinoline-naphthalene duo-based Schiff base probe (R) was synthesized and characterized by the usual spectroscopic and single-crystal X-ray crystallographic techniques. Probe R detects Al3+ and HSO3− ions via the fluorescent turn-on approach by dual pathways i.e., i) when probe R interacts with Al3+, the restriction of CN single bond rotation, blocking of both photoinduced electron transfer (PET) and CN isomerization were observed, and ii) when the sensor R interacts with HSO3−, imine (CH = N) bond was cleaved via hydrolysis and produced the respective aldehyde and amine behaving as a chemodosimeter. The binding stoichiometric ratio of R + Al3+ (1:1) was confirmed by Job’s plot, emission titration profile, NMR, and mass spectrometric analyses. This probe R is highly selective to both Al3+ -ions and HSO3− -ions, without any interference of other potentially competing cations and anions. Limit of detection (LOD) and quantification (LOQ) of R with Al3+ and HSO3− were downed to nanomolar concentrations, which is much lower than the recommended level of drinking water/food fixed by the World Health Organization (WHO). Furthermore, probe R was utilized in the detection of Al3+ and HSO3− ions in highly contaminated real samples, bioimaging in E. coli cells, multiple-targeting molecular logic gate, and in bovine serum albumin (BSA) binding.

Synthesis, characterization, X-ray structural analysis, DFT and BSA binding study of a Zn(II) complex, [Zn(II)Cl2(nia)2].2nia

A Zn(II) complex with two nicotinamide (nia) ligands, two chloride ions, and two co-crystallized nicotinamide molecules, [ZnCl2(nia)2].2nia, was synthesized and characterized on the basis of elemental analysis, spectroscopic techniques (UV-vis, FT-IR, 1H and 13C NMR), conductivity measurements, DFT and single-crystal X-ray crystallography. The complex crystallized in orthorhombic crystal system with pccn space group and cell dimensions: a = 27.1852(2), b = 7.6705(4), c = 12.7502(8) Å and α = β = γ = 90°. Single-crystal structural analysis revealed the presence of a neutral complex having tetrahedral geometry. In this complex, Zn(II) is coordinated to two chloride and two nicotinamide ligands in the coordination sphere and two nicotinamide molecules are co-crystallized. Hydrogen bonding interactions (N-H…O, C-H…O, N-H…N, C-H…Cl) along with π…π bonding interactions (between the coordinated nicotinamide and free nicotinamide moiety) stabilize the crystal lattice. The DFT studies consolidated the experimental findings and provided deeper insight into vibrational spectra, excitation spectra and hydrogen bonding interactions between nicotinamide molecules. The interactions and binding parameters of this complex with bovine serum albumin (BSA) have been probed through absorption and fluorescence spectroscopy which revealed the presence of static quenching mechanism and good binding propensity of the Zn complex.

How Different Albumin-Binders Drive Probe Distribution of Fluorescent RGD Mimetics

The biodistribution of medical imaging probes depends on the chemical nature of the probe and the preferred metabolization and excretion routes. Especially targeted probes, which have to reach a certain (sub)cellular destination, have to be guided to the tissue of interest. Therefore, small molecular probes need to exhibit a well-balanced polarity and lipophilicity to maintain an advantageous bioavailability. Labelled antibodies circulate for several days due to their size. To alter the biodistribution behavior of probes, different strategies have been pursued, including utilizing serum albumin as an inherent transport mechanism for small molecules. We describe here the modification of an existing fluorescent RGD mimetic probe targeted to integrin αvβ3 with three different albumin binding moieties (ABMs): a diphenylcyclohexyl (DPCH) group, a p-iodophenyl butyric acid (IPBA) and a fatty acid (FA) group with the purpose to identify an optimal ABM for molecular imaging applications. All three modifications result in transient albumin binding and a preservation of the target binding capability. Spectrophotometric measurements applying variable amounts of bovine serum albumin (BSA) reveal considerable differences between the compounds concerning their absorption and emission characteristics and hence their BSA binding mode. In vivo the modified probes were investigated in a murine U87MG glioblastoma xenograft model over the course of 1 wk by fluorescence reflectance imaging (FRI) and fluorescence mediated tomography (FMT). While the unmodified probe was excreted rapidly, the albumin-binding probes were accumulating in tumor tissue for at least 5 days. Considerable differences between the three probes in biodistribution and excretion characteristics were proved, with the DPCH-modified probe showing the highest overall signal intensities, while the FA-modified probe exhibits a low but more specific fluorescent signal. In conclusion, the modification of small molecular RGD mimetics with ABMs can precisely fine-tune probe distribution and offers potential for future clinical applications.

Ruthenium(III) hydrazone complexes with triphenylphosphine/triphenylarsine co-ligands: Synthesis, DNA/BSA binding, antioxidative and cytotoxic activity

New ruthenium(III) complexes with (E)-3-methoxy-N'-(phenyl(pyridin-2-yl)methylene) benzohydrazide (HL) have been synthesized and characterized by various physico-chemical and spectroscopic methods. The ligand acted as a tridentate, monobasic chelating ligand with NNO donor sites in all the complexes. The X-ray crystal structure of one of the complexes, [RuIII(L)(PPh3)Cl2] (1) demonstrated a distorted octahedral coordination geometry around the metal centre. Interactions of these complexes with calf thymus-DNA (CT-DNA) assessed by absorption and emission spectroscopy revealed intercalative mode of binding. Bovine serum albumin (BSA) binding of the ligand and complexes investigated by absorption spectroscopy, fluorescence and synchronous spectroscopic methods revealed that the compounds bind to BSA via static binding. Antioxidant study of the ligand and complexes showed significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of the ligand and complexes against human breast cancer cell line (MCF-7) and human lung cancer cells (A-549) was assayed. The results showed higher cytotoxic activity with lower IC50 values indicating their efficiency in killing the cancer cells even at low concentrations.

Effects of alkyl side-chain length on binding with bovine serum albumin, cytotoxicity, and antibacterial properties of 1-alkyl-3-methylimidazolium dicyanamide ionic liquids

In this study, the behavior of 1-alkyl-3-methylimidazolium dicyanamide ionic liquids (ILs) with ethyl, butyl, hexyl, octyl, and decyl side-chains was evaluated to gain a deeper insight into the potential hazards posed by ILs to the environment and organisms. The effects of the alkyl side-chain length on the interactions between the ILs and bovine serum albumin (BSA), the cytotoxicity and antibacterial performance of the ILs was evaluated. The BSA binding ability of the ILs increased with increasing alkyl side-chain length, and the binding constants of the ILs increased from 1.80 L/mol for 1-ethyl-3-methylimidazolium dicyanamide to 196 L/mol for 1-decyl-3-methylimidazolium dicyanamide. IL binding with BSA was a spontaneous process initiated by hydrophobic forces. This was confirmed using circular dichroism spectra, dynamic light scattering measurements and molecular docking simulations. The results of the cytotoxicity and antimicrobial activity of ILs demonstrated that the increase in alkyl side-chain length increased IL toxicity. The effects of the alkyl side-chain length of 1-alkyl-3-methylimidazolium tetrafluoroborate ILs on the interactions between ILs and BSA and cytotoxicity of the ILs were also evaluated. Furthermore, we demonstrated that tetrafluoroborate-based ILs were more toxic than dicyanamide-based ILs. Herein, we thoroughly describe the effects of the alkyl side-chain length on the properties of ILs and provide background information for future studies on the properties of carbon dots fabricated using ILs as precursors.

Protein Adsorption on Core-shell Particles: Comparison of Capto™ Core 400 and 700 Resins

Structural and functional characteristics of the two core-shell resins Capto™ Core 400 and 700, which are useful for the flow-through purification of bioparticles such as viruses, viral vectors, and vaccines, are compared using bovine serum albumin (BSA) and thyroglobulin (Tg) as models for small and large protein contaminants. Both resins are agarose-based and contain an adsorbing core surrounded by an inert shell. Although shell thicknesses are comparable (3.6 and 4.2 µm for Capto Core 400 and 700, respectively), the two resins differ substantially in pore size (pore radii of 19 and 50 nm, respectively). Because of the smaller pores and higher surface area, the BSA binding capacity of Capto Core 400 is approximately double that of Capto Core 700. However, for the much larger Tg, the attainable capacity is substantially larger for Capto Core 700. Mass transfer in both resins is affected by diffusional resistances through the shell and within the adsorbing core. For BSA, core and shell effective pore diffusivities are about 0.25 × 10−7 and 0.6 × 10−7 cm2/s, respectively, for Capto Core 400, and about 1.6 × 10−7 and 2.6 × 10−7 cm2/s, respectively, for Capto Core 700. These values decrease dramatically for Tg to 0.022 × 10−7 and 0.088 × 10−7 cm2/s and to 0.13 × 10−7 and 0.59 × 10−7 cm2/s for Capto Core 400 and 700, respectively. Adsorbed Tg further hinders diffusion of BSA in both resins. Column measurements show that, despite the higher static capacity of Capto Core 400 for BSA, the dynamic binding capacity is greater for Capto Core 700 as a result of its faster kinetics. However, some of this advantage is lost if the feed is a mixture of BSA and Tg since, in this case, Tg binding leads to greater diffusional hindrance for BSA.

Interaction of Differently Sized, Shaped, and Functionalized Silver and Gold Nanoparticles with Glycosylated versus Nonglycosylated Transferrin.

Exposure of nanomaterials (NMs) to biological medium results in their direct interaction with biomolecules and the formation of a dynamic biomolecular layer known as the biomolecular corona. Despite numerous published data on nano-biointeractions, the role of protein glycosylation in the formation, characteristics, and fate of such nano-biocomplexes has been almost completely neglected, although most serum proteins are glycosylated. This study aimed to systematically investigate the differences in interaction of metallic NPs with glycosylated vs nonglycosylated transferrin. To reach this aim, we compared interaction mechanisms between differently sized, shaped, and surface-functionalized silver NMs and gold NMs to commercially available human transferrin (TRF), a glycosylated protein, and to its nonglycosylated recombinant form (ngTRF). Bovine serum albumin (BSA) was also included in the study for comparative purposes. Characterization of NMs was performed using transmission electron microscopy and dynamic and electrophoretic light scattering techniques. Fluorescence quenching and circular dichroism methods were used to evaluate protein binding constants on the nanosurface and conformational changes after the protein-NM interactions, respectively. Competitive binding of TRF, ngTRF, and BSA to the surface of different NMs was evaluated by separating them after extraction from protein corona by gel electrophoresis following quantification with a commercial protein assay. The results showed that the binding strength between NMs and transferrin and the changes in the secondary protein structure largely depend not only on NM physicochemical properties but also on the protein glycosylation status. Data gained by this study highlight the relevance of protein glycosylation for all future design, development, and efficacy and safety assessment of NMs.

A europium (III) complex tested for deoxyribonucleic acid-binding, bovine serum albumin binding, and antibacterial activity

An original complex with europium is fabricated and characterized using infra-red spectroscopy, ultraviolet–visible spectroscopy, and elemental analysis as well as an Extended X-ray Absorption Fine Structure (EXAFS) for europium absorption edge at 6977 eV energy. The ligands were completely coordinated regarding the metal with four nitrogen sites for [Eu(dafone)2Cl2.(H2O)2]Cl·H2O, such that dafone is 4,5-diazafluoren-9-one. Close-neighbor correlations from nitrogen atoms on macrocyclic cages are evident within the EXAFS spectrum. Distorted octahedral structures of the europium (III) complex were examined by utilizing EXAFS and XANES methods. The final resulted bond-length for Eu atom with O, N, and Cl are 2.36±0.05Å, 2.52±0.08Å, and 2.76±0.06Å, respectively. The coordination number for O, N, and Cl atoms are 1.94, 4.48, and 1.89, where the total coordination number is 8.31 for the central Eu atom. The binding properties of the europium samples with bovine serum albumin (BSA) and deoxyribonucleic acid (DNA) were also evaluated. The interaction mode of DNA and the complex in this work was studied based on the UV–Vis absorption titration, fluorescence titration, circular dichroism spectroscopy, viscometric assessment, thermodynamic study, ionic strength measurement and competitive binding test. The outcomes show that the complex binds to fish salmon DNA at adequate intercalation. Also, this study reveals an excellent binding property of this complex with BSA proteins. The in vitro fish salmon DNA binding activity of the samples was studied to determine the antibacterial effect of the Eu-complex on an on several gram-negative and gram-positive bacteria.

Biological screening and docking studies of unique hybrids synthesized by conventional versus microwave assisted techniques

Purpose: To carry out the synthesis of various hybrids of 1,2,4-triazole in search of potential therapeutic enzyme inhibitory agents, and carry out docking and bovine serum albumin (BSA) binding studies on docking and bovine serum albumin (BSA) binding studies on the hybrids.&#x0D; Methods: The target compounds were synthesized by following a multistep protocol. Compound 1 was synthesized from 4-methoxybenzenesulfonyl chloride (a) and ethyl isonipecotate (b). Compound 1 was refluxed with hydrazine to synthesize compound 2, which was converted to compound 3 through two consecutive steps. Compound 4 and different amines (5a-5i), were utilized to synthesize an array of electrophiles (6a-6i). A series of 1,2,4-triazole hybrids (7a-7i) were synthesized at room temperature by stirring together 3 and 6a-6i. The final structures of 7a-7i were elucidated through 1H-NMR, 13C-NMR and EI-MS spectroscopy. The BSA binding studies were performed by fluorometric titration. Furthermore, antioxidant and enzyme inhibition activities were determined colorimetrically.&#x0D; Results: Compound 7d was the most active antioxidant agent, compared to butylated hydroxyanisole (BHA), while compounds 7d, 7e, 7f, 7g and 7i proved to be potent urease inhibitors with half-maximal inhibitory concentration (IC50) values of 19.5 ± 0.12, 21.1 ± 0.68, 18.2 ± 0.78, 19.9 ± 0.77 and 17.9 ± 0.10 µM, respectively, compared to thiourea with an IC50 of 24.3 ± 0.24 µM. Compounds 7a, 7b, 7d, and 7e exhibited high butyrylcholinesterase inhibition potential, compared to eserine.&#x0D; Conclusion: The synthesized compounds require studies further as potential therapeutic enzyme inhibitory agents in view of their urease inhibition as well as antioxidant activity.

The binding of bovine serum albumin with dye molecules at different pH values. Fluorescence lifetime studies

The spectral and kinetic characteristics of the fluorescence of the solutions of bovine serum albumin (BSA) and the dyes (N-(p-carboxyphenyl) imide of 4-(dimethylamino) naphthalic acid (CAPIDAN) and Bengal Rose (BR)) in BSA solutions were studied at 3.5 < pH < 8.0. It was discovered that the attenuation of CAPIDAN fluorescence at the studied pH region is described by the sum of three components (with the values of time constants: 6.0 ns < τ 1 < 8.5 ns, 1.8 ns < τ 2 < 2.2 ns, 0.4 ns < τ 3 < 0.6 ns), while it is described by two components for BR (0.33 ns < τ 1 < 0.4 ns, 2.0 ns < τ 2 < 3.1 ns). It is shown that the mechanisms of the binding of dye and protein molecules are different for CAPIDAN and BR. The binding process of CAPIDAN and BSA is regulated by the conformation of the binding center. The interaction between the BR and BSA molecules is electrostatic, the magnitude of this interaction is determined by the ratio of the charges of the dye and protein molecules. The dependence of the wavelength of the maximum of the spectra, the intensity of the glow and the efficiency of quenching of the fluorescence of the molecules of the studied dyes on the pH is analyzed. The parameters dμ, which characterizes the change in the dipole moment of the fluorophore during its excitation, and η, which characterizes the change in the intensity at the maximum of the fluorescence spectrum at different pH solutions, were also determined for BR. The following ratios were determined at the studied pH range: and η < 1. The changes of the characteristics of the stationary fluorescence of the studied dyes at different pH of BSA solutions confirm the mechanisms of the binding between CAPIDAN or BR molecules and protein molecules.

Synthesis, Characterization, and In Vitro Insulin-Mimetic Activity Evaluation of Valine Schiff Base Coordination Compounds of Oxidovanadium(V).

Type 2 diabetes became an alarming global health issue since the existing drugs do not prevent its progression. Herein, we aimed to synthesize and characterize a family of oxidovanadium(V) complexes with Schiff base ligands derived from L-/D-valine (val) and salicylaldehyde (sal) or o-vanillin (van) as insulin-mimetic agents and to assess their potential anti-diabetic properties. Two new oxidovanadium(V) complexes, [{VVO(R-salval)(H2O)}(μ2-O){VVO(R-salval)}] and [{VVO(R-vanval)(CH3OH)}2(μ2-O)], and their S-enantiomers were synthesized and characterized. The compounds exhibit optical activity as shown by crystallographic and spectroscopic data. The stability, the capacity to bind bovine serum albumin (BSA), the cytotoxicity against human hepatoma cell line, as well as the potential anti-diabetic activity of the four compounds are investigated. The synthesized compounds are stable for up to three hours in physiological conditions and exhibit a high capacity of binding to BSA. Furthermore, the synthesized compounds display cytocompatibility at biologically relevant concentrations, exert anti-diabetic potential and insulin-mimetic activities by inhibiting the α-amylase and protein tyrosine phosphatase activity, and a long-term increase of insulin receptor phosphorylation compared to the insulin hormone. Thus, the in vitro anti-diabetic potential and insulin-mimetic properties of the newly synthesized oxidovanadium(V) compounds, correlated with their cytocompatibility, make them promising candidates for further investigation as anti-diabetic drugs.

Low DNA and high BSA binding affinity of cationic ruthenium(II) organometallic featuring pyridine and 2’-hydroxychalcone ligands

The chiral-at-metal, piano-stool ruthenium(II) racemic organometallic [Ru(cymene)(chalconato)(pyridine)]PF6 was prepared by a multistep solution synthesis and its molecular and crystal structure was determined by single crystal X-ray diffraction. The compound crystallizes in a centrosymmetric triclinic P-1 space group with two molecules of opposite chirality within the asymmetric unit. Ruthenium is embedded in an octahedral half-sandwich coordination environment with four different donors, which generates the chirality of the metal centre. The formation of the organometallic was monitored ex-situ by infrared spectroscopy. The pyridine coordination to Ru(II) was particularly analysed to find its characteristic marker bands. The complex was also characterized by elemental analysis and NMR spectroscopy in solution. Its interaction with CT DNA and bovine serum albumin (BSA) was investigated by electron spectroscopy and spectrofluorimetry. The organometallic binds to DNA predominantly by electrostatic forces with low Kb value. On the contrary, its high affinity for BSA was confirmed by strong fluorescence quenching. The synchronous emission spectra revealed that the microenvironment of tryptophan is more affected compared to the environment of tyrosine.