Probing the binding sites and the effect of berbamine on the structure of bovine serum albumin

Dual Antimicrobial-Anticancer Potential, Hydrolysis, and DNA/BSA Binding Affinity of a Novel Water-Soluble Ruthenium-Arene Ethylenediamine Schiff base (RAES) Organometallic

The need for a systematic approach in developing new metal-based drugs with dual anticancer-antimicrobial properties is emphasized by the vulnerability of cancer patients to bacterial infections. In this context, a novel organometallic assembly was designed, featuring ruthenium(II) coordination with p-cymene, one chlorido ligand, and a bidentate neutral Schiff base derived from 4-methoxybenzaldehyde and N,N-dimethylethylenediamine. The compound was extensively characterized in both solid-state and solution, employing single crystal X-ray diffraction, nuclear magnetic resonance, infrared, ultraviolet-visible spectroscopy, and density functional theory, alongside Hirshfeld surface analysis. The hydrolysis kinetic was thoroughly investigated, revealing the important role of the chloro-aqua equilibrium in the dynamics of binding with deoxyribonucleic acid and bovine serum albumin. Notably, the aqua species exhibited a pronounced affinity for deoxyribonucleic acid, engaging through electrostatic and hydrogen bonding interactions, while the chloro species demonstrated groove-binding properties. Interaction with albumin revealed distinct binding mechanisms. The aqua species displayed covalent binding, contrasting with the ligand-like van der Waals interactions and hydrogen bonding observed with the chloro specie. Molecular docking studies highlighted site-specific interactions with biomolecular targets. Remarkably, the compound exhibited wide spectrum moderate antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, coupled with low micromolar cytotoxic activity against human colorectal adenocarcinoma cells and significant activity against human leukemic monocyte lymphoma cells. The presented findings encourage further development of this compound, promising avenues for its evolution into a versatile therapeutic agent targeting both infectious diseases and cancer.

Multispectroscopic and computational study of interaction of the bovine serum albumin with atropine and atropine-loaded chitosan nanoparticles (synthesized and characterized)

Two different systems of bovine serum albumin (BSA) were used for multiple spectroscopic and computational studies to determine interaction of BSA and atropine (Atrop), that is, BSA-Atrop system and Atrop-loaded chitosan nanoparticles (Atrop@CS NPs), that is, BSA-Atrop@CS NPs system. The study suggests that BSA-Atrop system and BSA-Atrop@CS NPs system involve non-fluorescent complexes of Ksv = 3.2 × 103 Lmol-1 and 3.1 × 104 Lmol-1, kq = 3.2 × 1011 Lmol-1 s-1 and 3.1 × 1012 Lmol-1 s-1, the binding constant Kb = 1.4 × 103 Lmol-1, 2.0 × 102 Lmol-1, respectively, and number of binding sites n ∼ 1 for both the systems. The negligible conformational changes induced in BSA were also observed. Synchronous fluorescence spectroscopic study revealed that more quenching occurred in intrinsic fluorescence of tryptophan (Trp, W) than that in tyrosine residue (Tyr, Y). UV-vis spectroscopic study verified the presence of static quenching from the presence of BSA-Atrop and BSA-Atrop@CS NPs complexes. CD spectra confirmed the conformational changes induced in BSA upon increment of concentrations of Atrop and Atrop@CS NPs separately into the constant concentration of BSA. The coherent observations from various spectroscopic studies were in agreement with those of computational study, showing BSA-Atrop complex formation and other related details. The hydrogen bonds (H-bonds), van der Walls (vdW) interactions and π -type of interactions were mainly involved in stabilization of the formed BSA-Atrop complex.Communicated by Ramaswamy H. Sarma.

Anticancer Behavior of Pyrrolidine-Based Palladium(II) Complexes and Biophysical Approach on Their DNA, BSA Binding Activity, Molecular Docking, and DFT Study

A series of pyrrolidine-based Pd(II) complexes, [Pd(AEP)Cl2] (C-1), [Pd(AEP)(OH2)2]2+(C-2), [Pd(AEP)(L-cys)]+ (C-3), [Pd(AEP)(N-ac-L-cys)] (C-4), [Pd(AEP)(GSH)] (C-5), and [Pd(AEP)(DL-meth)]2+ (C-6) (where, AEP = 1-(2-aminoethyl)pyrrolidine, L-cys = l-cysteine, N-ac-L-cys = N-acetyl-l-cysteine, GSH = glutathione, and DL-meth = dl-methionine), as anticancer drug candidates have been synthesized and characterized. The DNA binding property of the complexes was executed by gel electrophoresis and spectrophotometric and viscometric methods, and their interaction with BSA was also investigated by various spectroscopic methodologies. The binding activity of the Pd(II) complexes with DNA and BSA were assessed to evaluate their binding mode and binding constants. Molecular docking was performed to correlate with the experimental results on the interaction of the complexes with DNA and BSA. The changes in the microenvironmental and structural properties of BSA are monitored by a synchronous and 3D fluorescence study. The structural properties were evaluated by DFT and TD-DFT studies. The anticarcinogenic activity of the Pd(II) complexes was assessed by PASS prediction software to corroborate with the experimental results of the anticancer activity of the complexes. The ROS generation in cancer cell lines has been investigated, and the cell death mechanism through apoptosis was confirmed by measuring the protein expression. All these complexes have excellent anticancer activity compared to ancillary ligands. The cancer cell line (HCT116) shows almost similar or better cell inhibition activity when treated with the Pd(II) complexes compared to cisplatin, whereas the adverse effect is minimum on a normal cell (NKE). Both the Pd(II) and Pt(II) complexes carrying the same ligands reveal almost similar antiproliferative activity.

Insights on the in-vitro binding interaction between donepezil and bovine serum albumin

In this work, the binding mechanism between donepezil (DNP) and bovine serum albumin (BSA) was established using several techniques, including fluorimetry, UV- spectrophotometry, synchronous fluorimetry (SF), fourier transform infrared (FTIR), fluorescence resonance energy transfer (FRET) besides molecular docking study. The fluorescence quenching mechanism of DNP-BSA binding was a combined dynamic and static quenching. The thermodynamic parameters, binding forces, binding constant, and the number of binding sites were determined using a different range of temperature settings. Van't Hoff's equation was used to calculate the reaction parameters, including enthalpy change (ΔH^ο) and entropy change (ΔS^ο). The results pointed out that the DNP-BSA binding was endothermic. It was shown that the stability of the drug-protein system was predominantly due to the intermolecular hydrophobic forces. Additionally, the site probing method revealed that subdomain IIA (Site I) is where DNP and BSA's binding occurs. This was validated using a molecular docking study with the most stable DNP configuration. This study might help to understand DNP's pharmacokinetics profile and toxicity as well as provides crucial information for its safe use and avoiding its toxicity.

Exploring the molecular interaction of mebendazole with bovine serum albumin using multi-spectroscopic approaches and molecular docking

This article presents the binding interaction between mebendazole (MBZ) and bovine serum albumin. The interaction has been studied using different techniques, such as fluorescence quenching spectroscopy, UV–visible spectroscopy, synchronous fluorescence spectroscopy, fourier transform infrared, and fluorescence resonance energy transfer in addition to molecular docking. Results from Stern Volmer equation stated that the quenching for MBZ-BSA binding was static. The fluorescence quenching spectroscopic study was performed at three temperature settings. The binding constant (k_q), the number of binding sites (n), thermodynamic parameters (ΔH^ο, ΔS^ο and ΔG^ο), and binding forces were determined. The results exhibited that the interaction was endothermic. It was revealed that intermolecular hydrophobic forces led to the stabilization of the drug-protein system. Using the site marker technique, the binding between MBZ and BSA was found to be located at subdomain IIA (site I). This was furtherly approved using the molecular docking technique with the most stable MBZ configuration. This research may aid in understanding the pharmacokinetics and toxicity of MBZ and give fundamental data for its safe usage to avoid its toxicity.

Systematic spectroscopic investigation of structural changes and corona formation of bovine serum albumin over magneto-fluorescent nanoparticles

Magneto-fluorescent nanoparticles have attracted great attention because of their dual nature as multimodal imaging probes in various biomedical applications. Particulary, it is desirable to understand how these nanoparticles interact with human serum proteins before they are used in biological systems. In this work, the physiological interactions between magneto-fluorescent nanoparticles (MFNPs) and bovine serum albumin (BSA) were systematically investigated. The present observations identified that the collision of MFNPs and BSA caused fluorescence quenching of BSA. Steady state fluorescence, lifetime and anisotropy measurements in the presence of MFNPs supported dynamic quenching of the BSA emission. Furthermore, in the presence of MFNPs, the conformation changes in the BSA structure indicate merely the secondary structural changes. The findings demonstrated that random interactions and hydrophobic forces play a major role in the dynamic quenching. Further, subsequent coating of BSA over MFNPs result in protein corona formation, as is evident through spectroscopic measurements. In light of the present work, MFNPs could serve a purpose in magnetic separation and optical detection of serum proteins from blood plasma in real-time disease diagnosis.

Cu(II) complex with auxin (3-indoleacetic acid) and an aromatic planar ligand: synthesis, crystal structure, biomolecular interactions and radical scavenging activity

A novel water soluble ternary copper(II) complex,-[Cu₂(phen)₂(3-IAA)₂(H₂O)](ClO₄)₂·H₂O-(phen: 1,10-phenanthroline, 3-IAA: 3-indoleacetic acid), has been synthesized and characterized by elemental CHN analysis, ESI-TOF, FTIR and single-crystal X-ray diffraction techniques. Interaction of the complex with calf thymus DNA (CT-DNA) has been investigated by absorption spectral titration, ethidium bromide (EB) and Hoechst 33258 displacement assay. The interactions between the complex and bovine serum albumin (BSA) were investigated by electronic absorption and fluorescence spectroscopy methods. The experimental results indicate that the fluorescence quenching mechanism between the complex and BSA is a static quenching process. The Stern-Volmer constants, binding constants, binding sites and the corresponding thermodynamic parameters (ΔG, ΔH, ΔS) of BSA + complex systems were determined at different temperatures. The binding distance between the complex and BSA was calculated according to Förster non-radiation energy transfer theory (FRET). The effect of the complex on the conformation of BSA was also examined using synchronous, two dimensional (2D) and three dimensional (3D) fluorescence spectroscopy. Furthermore, the oxygen radical scavenging activity of the complex was determined in terms of IC₅₀, using the DPPH and H₂O₂ method, to show that it particularly enables electron loss from radical species. This study highlights the importance of indole and moieties in the development of antioxidant agents. A potent drug candidate novel water soluble ternary copper(II) complex,-[Cu₂(phen)₂(3-IAA)₂(H₂O)] (ClO₄)₂·H₂O-(phen: 1,10-phenanthroline, 3-IAA: 3-indoleacetic acid), has been synthesized and characterized by elemental CHN analysis, FTIR, ESI-MS and single-crystal X-ray diffraction techniques. The complex has been tested for in vitro biomacromolecular interactions by spectroscopic methods. Furthermore, radical scavenging activities of the complex were also investigated.

Spectrofluorimetric analysis of the binding of a target molecule to serum albumin: tricky aspects and tips

Protein binding heavily modulates drug activity. Therefore, the binding features need to be elucidated when chemistry researchers study new molecules (metal complexes) to be used as drugs. This paper concerns the experimental and data treatment aspects of the mechanistic analysis of the binding to a fluorescent protein (the golden standard serum albumin) by using direct fluorescence titrations. Fluorescence data are not rarely only qualitatively used, neglecting further treatments which could offer a precious detailed picture of the behavior of the drug. We aim to spread a mechanistic approach, discussing the critical aspects for correctly designing the experiments and treating the data. The researcher may confirm adduct formation and evaluate binding constants (Stern-Volmer K_SV or other types of K). Also, we discuss here, with the help of literature examples, the correct use of temperature dependence of K to extract thermodynamic parameters, comment on enthalpy-entropy compensation, together with the use of synchronous spectra and exchange experiments to gain information on the binding type and site. We think that this tutorial/critical synopsis can be of help for the increasing community dealing with these experiments, which are valuable but often much more tricky than it might appear at first sight.

Physicochemical, in-vitro therapeutic activity and biomolecular interaction studies of Mn(II), Ni(II) and Cu(II) complexes tethered with O2N2 ligand backbone

Two major health crisis of today's world are antimicrobial drug resistance and type II diabetes. To tackle them, there is an immediate requirement for the development of new and safer drugs and the present work is one such quest for novel and efficient drug candidates. We have developed three trace metal coordination compounds tethered with a reduced salen ligand {H₂(hpdbal)₂-an} (L), namely, a manganese-salan complex, [Mn^II(H₂O)₂{(hpdbal)₂-an}] (1), a nickel-salan complex, [Ni^II{(hpdbal)₂-an}] (2) and a copper-salan complex, [Cu^II{(hpdbal)₂-an}] (3). The compounds were characterized by elemental analysis, vibrational spectroscopy, electronic spectroscopy, thermogravimetric analysis, nuclear magnetic resonance and electron-paramagnetic resonance techniques. The compounds were evaluated for antimicrobial activity against seven pathogens (Escherichia coli, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Cryptococcus neoformans) and antidiabetic activity by mimicking diabetic environment on the immortal human liver cancer cells, HepG2. Complexes 1 and 2 were additionally tested for their reactivity and stability in biological media mimic conditions. The nickel(II) salan complex (2) exhibited noteworthy antifungal activity against Candida albicans and the manganese(II) salan complex (1) induced increased glucose uptake by the insulin resistant cells. Both compounds were found to be stable when solution pH conditions were varied from 3 to 9. They exhibited strong affinity of binding towards a carrier protein, bovine serum albumin which was evaluated with the aid of multi-spectroscopic techniques.

A potent drug candidature of Cu(II) pyrazino[2,3-f][1,10]phenanthroline complexes with bioactive ligands: synthesis, crystal structures, biomolecular interactions, radical scavenging and cytotoxicities

A novel ternary copper(II) complexes, - [Cu(py-phen)(asn)(NO₃)(H₂O)] (1) and [Cu(py-phen)(trp)(H₂O)]NO₃ (2)- (py-phen: pyrazino[2,3-f][1,10]phenanthroline, asn: asparagine, trp: tryptophan), have been synthesized and characterized by CHN analysis, ESI-MS, FTIR and single-crystal X-ray diffraction techniques. Interaction of the complexes 1 and 2 with CT-DNA has been investigated by absorption spectral titration, EB and Hoechst 33258 displacement assay. The interaction between the complexes 1 and 2 and BSA was investigated by electronic absorption and fluorescence spectroscopy methods. The experimental outcomes indicate that the fluorescence quenching mechanism between the complexes 1 and 2 and BSA is a static quenching process. The Stern-Volmer constants, binding constants, binding sites and the corresponding thermodynamic parameters (ΔG, ΔH, ΔS) of BSA + complex systems were determined at different temperatures. The binding distance between the complexes 1 and 2 and BSA was calculated according to FRET. The effect of the complexes 1 and 2 on the conformation of BSA was also examined using synchronous, two dimensional (2D) and three dimensional (3D) fluorescence spectroscopy. Radical scavenging activity of the complex was determined in terms of EC₅₀, using the DPPH and H₂O₂ method. The anticancer activities of the complexes 1 and 2 were investigated using an XTT assay against three cancer cell lines (MCF-7, Caco-2 and A549) and non-tumor cell line (BEAS-2B). Communicated by Ramaswamy H. Sarma.

Phytochemicals targeting matrix metalloproteinases regulating tissue degradation in inflammation and rheumatoid arthritis

PURPOSE

Matrix metalloproteinases, zinc dependent proteolytic enzymes, have significant implications in extracellular matrix degradation associated with tissue damage in inflammation and Rheumatoid arthritis. Numerous orchestrated pathways affects instigation and blockade of metalloproteinases as well as various factors that increase the expression of MMPs including inflammatory cytokines, hormones and growth factors. Direct inhibition of these proteolytic enzymes or modulation of these pathways can provide protection against tissue destruction in inflammation and rheumatoid arthritis. Inclination towards use of plant derived phytochemicals to prevent tissue damage has been increasing day by day. Diversity of phytochemicals have been known to directly inhibit metalloproteinases. Hence, thorough knowledge of phytochemicals is very important in novel drug discovery.

METHODS

Present communication evaluates various classes of phytochemicals, in effort to unveil the lead molecules as potential therapeutic agents, for prevention of MMPs mediated tissue damage in inflammation and rheumatoid arthritis. Data have been analyzed through different search engines.

RESULTS

Numerous phytochemicals have been studied for their role as MMPs inhibitors which can be processed further to develop into useful drugs for the treatment of inflammation and rheumatoid arthritis.

CONCLUSION

In search of new drugs, phytochemicals like flavonoids, glycosides, alkaloids, lignans & terpenes offer a wide canvas to develop into valuable forthcoming medicaments.

Coumarin tethered cyclic imides as efficacious glucose uptake agents and investigation of hit candidate to probe its binding mechanism with human serum albumin

A series of novel coumarin-cyclic imide conjugates (1a-1j) were designed and synthesized to evaluate their glucose uptake activity by insulin resistant liver hepatocyte carcinoma (HepG2) cells through 2-NBDG uptake assay. Compounds (1a-1j) were characterised using various analytical methods such as ¹H NMR, ¹³C NMR, IR, GC-MS, elemental and single-crystal X-ray diffraction techniques. Compounds (1a-1j) exhibited 85.21 - 65.80% of glucose uptake and showed low level of cytotoxicity towards human embryonic kidney cells (HEK-293) indicating good selectivity and safety profile. Compound 1f was identified as a hit candidate exhibiting 85.21% of glucose uptake which was comparable with standard antidiabetic drug Metformin (93.25% glucose uptake). Solution stability study under physiological pH conditions ≈ (3.4 - 8.7), indicates that compound 1f is sufficiently stable at varied pH conditions and thereby compatible with bio-physiological environments. Interaction of 1f with human serum albumin (HSA) were also studied which quantifies that compound 1f binds with HSA efficiently through facile binding reaction in solution. Fluorescence, UV-vis spectrophotometry and molecular modeling methodologies were employed for studying the interaction mechanism of compound 1f with protein.

Potent drug candidature of an ONS donor tethered copper (II) complex: Anticancer activity, cytotoxicity and spectroscopically approached BSA binding studies

In our continued efforts to develop metal based therapeutic agents, we have synthesized a novel copper(II) complex, [{Cu(hpdbal-sbdt)}₂] (2) tethered with a biocompatible ONS^2- donor backbone [H₂hpdbal-sbdt] (1) [H₂hpdbal-sbdt is a tridentate ligand derived from S-benzyldithiocarbazate (Hsbdt) and 2-hydroxy-5-(phenyldiazenyl)benzaldehyde (Hhpdbal)]. The metal complex (2) was characterized using attenuated total reflection-infrared (ATR-IR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, thermogravimetry and differential scanning calorimetric (TG-DSC) analysis, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and elemental (CHNS) analysis. The antineoplastic ability of copper complex was evaluated in vitro against human cervical cancer (HeLa) cells. MTT assay results showed that the copper complex exhibited significant growth inhibition of HeLa cells with an IC₅₀ value of 4.46 μM and this value was compared with reported standards. Cytotoxicity of the copper complex towards human embryonic kidney cells (HEK-293) was also evaluated. The potentially active copper complex was studied for its solution state stability at a pH range of 3-9. Following this, the interactive behaviour of the bioactive copper complex with a drug transporter protein (BSA) was deciphered through multi-spectrosopic investigations like steady-state fluorescence, three-dimensional fluorescence, deconvoluted-IR and UV-Visible techniques.

In vitro apoptosis-induction, antiproliferative and BSA binding studies of a oxidovanadium(V) complex

In our ongoing efforts to develop novel trace metal complexes with therapeutically interesting properties, a neutral mono nuclear oxidomethoxidovanadium(V) complex, [V^VO(OCH₃)(hpdbal-sbdt)] (1) and a μ-O bridged dinuclear oxidovanadium(V) complex, [{V^VO(hpdbal-sbdt)}₂μ-O] (2) [H₂hpdbal-sbdt (I) is a tridentate and dibasic ONS^2- donor ligand obtained through the Schiff base reaction of 2-hydroxy-5-(phenyldiazenyl)benzaldehyde (Hhpdbal) and S-benzyldithiocarbazate (Hsbdt)] have been synthesized and characterized by various analytical techniques such as TGA, EDS, ATR-IR, UV-Vis, CV, ¹H NMR, ¹³C NMR and ⁵¹V NMR. Single-crystal X-ray diffraction analysis of 1 confirms the coordination of phenolate oxygen, imine nitrogen and thioenolate sulfur of the ligand to the vanadium center with a distorted tetragonal-pyramidal geometry. The compound 2 triggered apoptotic and reproductive death of the cancer cells in vitro with 76% and 62% growth inhibition of human breast adenocarcinoma (MCF-7) and human lung carcinoma cells (A549) respectively. The compound 2 was found to be sufficiently stable over a wide window of physiological pH. The complex 2 was studied further for its interaction with a drug carrier protein BSA with the aid of spectroscopic techniques viz. fluorescence, temperature controlled UV-vis and deconvoluted IR techniques.

Water-soluble binary and ternary palladium(ıı) complexes containing amino acids and intercalating ligands: synthesis, characterization, biomolecular interactions and cytotoxicities

Novel water soluble palladium(ii) complexes have been synthesized and characterized. Moreover, the cytotoxicities of these complexes against different human tumor and healthy cell lines were investigated by the XTT assay.

A novel biocompatible NiII tethered moiety as a glucose uptake agent and a hit against methicillin-resistant Staphylococcus aureus

In the efforts to develop a biocompatible transition metal complex as a drug alike for some of the prevailing non-communicable diseases (NCDs) and communicable diseases (CDs), a novel binuclear Ni^II compound [{Ni^II(hpdbal-sbdt)}₂] (2) has been synthesized by the reaction of Ni(OAc)₂.4H₂O and H₂hpdbal-sbdt (1) [1 is a dibasic tridentate ONS^2- donor Schiff base ligand obtained by the condensation of 2-hydroxy-5-(phenyldiazenyl)benzaldehyde (Hhpdbal) and S-benzyldithiocarbazate (Hsbdt)]. Both ligand 1 and compound 2 were structurally characterized in the solid and solution state using various spectroscopic techniques like ATIR, ¹H NMR, ¹³C NMR, TGA, FESEM, EDS and CHNS analysis. The antidiabetic activity of H₂hpdbal-sbdt (1) and [{Ni^II(hpdbal-sbdt)}₂] (2) were assessed using 2-NBDG uptake assay. The assay results showed 85% and 95% of fluorescent glucose uptake by insulin resistant HePG2 cells treated with compounds 1 and 2 respectively. The 2-NBDG uptake by the cells treated with the compound 2 was observed to be comparable to the standard antidiabetic drug metformin. Compounds 1 and 2 were also tested against five bacterial and two fungi strains in order to evaluate pathogen killing activity. Compound 2 showed significant inhibitory action towards the methicillin-resistant Staphylococcus aureus (MRSA) strain with an MIC value of 2 μg/mL whereas the ligand 1 was found to be inactive. Furthermore, the interactive nature of compound 2 with a model serum carrier protein bovine serum albumin (BSA) was studied using a multi-spectroscopic approach which provided an insight into the nature and extent of binding, conformational changes and the quenching of amino acid residues of the protein.

The potential impact of carboxylic-functionalized multi-walled carbon nanotubes on trypsin: A Comprehensive spectroscopic and molecular dynamics simulation study

In this study, we report a detailed experimental, binding free energy calculation and molecular dynamics (MD) simulation investigation of the interactions of carboxylic-functionalized multi-walled carbon nanotubes (COOH-f-MWCNTs) with porcine trypsin (pTry). The enzyme exhibits decreased thermostability at 330K in the presence of COOH-f-MWCNTs. Furthermore, the activity of pTry also decreases in the presence of COOH-f-MWCNTs. The restricted diffusion of the substrate to the active site of the enzyme was observed in the experiment. The MD simulation analysis suggested that this could be because of the blocking of the S1 pocket of pTry, which plays a vital role in the substrate selectivity. The intrinsic fluorescence of pTry is quenched with increase in the COOH-f-MWCNTs concentration. Circular dichroism (CD) and UV–visible absorption spectroscopies indicate the ability of COOH-f-MWCNTs to experience conformational change in the native structure of the enzyme. The binding free energy calculations also show that electrostatics, π-cation, and π-π stacking interactions play important roles in the binding of the carboxylated CNTs with pTry. The MD simulation results demonstrated that the carboxylated CNTs adsorb to the enzyme stronger than the CNT without the–COOH groups. Our observations can provide an example of the nanoscale toxicity of COOH-f-MWCNTs for proteins, which is a critical issue for in vivo application of COOH-f-MWCNTs.

Syntheses, crystal structures, DFT calculations, protein interaction and anticancer activities of water soluble dipicolinic acid-imidazole based oxidovanadium(iv) complexes

Three novel water soluble neutral mononuclear oxidovanadium(iv) complexes 1-3, [VOLB₂] (where H₂L = dipicolinic acid (DPA) and B = imidazole (1)/1-methylimidazole (2)/1-allylimidazole (3)), were synthesized by the reaction of [VOL(H₂O)₂] with imidazole/1-methylimidazole/1-allylimidazole in ethanol. The complexes were thoroughly characterized by elemental analysis, IR, UV-Vis and EPR spectroscopy, magnetic susceptibility, cyclic voltammetry and single crystal X-ray diffraction techniques. In all the complexes the vanadium(iv) centre assumes a distorted octahedral environment. All the three complexes have similar structures and contain a range of intramolecular interactions such as hydrogen bonding, C-Hπ, and ππ stacking dominating their supramolecular architectures. A thermal study of the complexes was carried out to analyze their stability. The energy of non-covalent interactions and frontier orbitals for the complexes were also calculated by DFT. In order to investigate the binding interactions and conformational changes of the secondary structure of bovine serum albumin (BSA) with the complexes, absorption, fluorimetric titration and circular dichroism measurements in aqueous medium were carried out. Molecular docking studies have also been carried out to understand the binding modes and interaction patterns of the oxidovanadium(iv) complexes with BSA. The anticancer activities of the ligand and complexes 1-3 were tested against the human hepatic carcinoma cell line Hep3B. The complexes showed prominent cytotoxicity towards cancer cells.

Elucidating the binding interaction of andrographolide with the plasma proteins: biophysical and computational approach

A phytochemical andrographolide is an anticancer agent with a stable conformation that strongly binds to the plasma proteins.

The anticancer effect related to disturbances in redox balance on Caco-2 cells caused by an alkynyl gold(I) complex

The alkynyl gold(I) derivative [Au(C≡CPh)(PTA)] (PTA=1,3,5-triaza-7-phosphaadamantane) induces apoptosis in colorectal carcinoma tumour cells (Caco-2) without affecting to normal enterocytes. [Au(C≡CPh)(PTA)] is a slight lipophilic drug, stable in PBS (Phosphate Buffered Saline) and able to bind BSA (Bovin Serum Albumin) by hydrophobic interactions. Once inside the cell, [Au(C≡CPh)(PTA)] targets seleno proteins such as Thioredoxin Reductase 1, increasing ROS (Reactive Oxygen Species) levels, reducing cell viability and proliferation and inducing mitochondrial apoptotic pathway, pro-apoptotic and anti-apoptotic protein imbalance, loss of mitochondrial membrane potential, cytochrome c release and activation of caspases 9 and 3. Moreover, unlike other metal-based drugs such as cisplatin, [Au(C≡CPh)(PTA)] does not target nucleic acid, reducing the risk of side mutation in the DNA. In consequence, our results predict a promising future for [Au(C≡CPh)(PTA)] as a chemotherapeutic agent for colorectal carcinoma.

Systematic elucidation of interactive unfolding and corona formation of bovine serum albumin with cobalt ferrite nanoparticles

Nanoparticles (NPs) are extensively being used in modern nano-based therapies and nano-protein formulations.

Surface patch binding induced interaction of anisotropic nanoclays with globular plasma proteins

Morphology dependent interaction of model anisotropic nanoparticles with globular plasma proteins.

Influence of the Surface Functional Group Density on the Carbon-Nanotube-Induced α-Chymotrypsin Structure and Activity Alterations

Because of the special properties of carbon nanotubes (CNTs), their applications have been introduced to many fields. The biosafety of these emerging materials is of high concern concomitantly. Because CNTs may initially bind with proteins in biofluids before they exert biological effects, it is of great importance to understand how the target proteins interact with these exogenous nanomaterials. Here we investigated the interaction between α-chymotrypsin (α-ChT) and carboxylized multiwalled CNTs in a simulated biophysical environment utilizing the techniques of fluorescence, UV-vis, circular dichroism spectroscopy, ζ potential, atomic force microscopy, and bicinchoninic acid analysis. It was demonstrated that CNTs interacted with α-ChT through electrostatic forces, causing a decrement in the α-helix and an increment in the β-sheet content of the protein. The protein fluorescence was quenched in a static mode. The increase in the surface modification density of CNTs enhanced the protein absorption and decreased the enzymatic activity correspondingly. α-ChT activity inhibition induced by CNTs with low surface modification density exhibited noncompetitive characteristics; however, a competitive feature was observed when CNTs with high surface modification density interacted with the protein. An increase of the ionic strength in the reaction buffer may help to reduce the interaction between CNTs and α-ChT because the high ionic strength may favor the release of the protein from binding on a CNT surface modified with functional groups. Accordingly, the functionalization density on the CNT surface plays an important role in the regulation of their biological effects and is worthy of concern when new modified CNTs are developed.

Study on the interaction between 21-(Ph-NN)-NCTPP and bovine serum albumin by spectroscopic techniques

The interaction between 21-(Ph-NN)-NCTPP and bovine serum albumin (BSA) was investigated by fluorescence and ultraviolet-visible (UV-Vis) spectroscopy under imitated physiological conditions. The results showed that the intrinsic fluorescence of BSA was quenched strongly by 21-(Ph-NN)-NCTPP. The binding constants (Ka) and the binding sites (n) were obtained at three different temperatures (298, 304, and 310K). The thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated, the results indicated that the binding process was spontaneous and the hydrophobic interaction played a major role in [21-(Ph-NN)-NCTPP]-BSA binding process. Based on the Förster non-radiation energy transfer theory, the binding distance from 21-(Ph-NN)-NCTPP to BSA was estimated to be about 3.51nm. What's more, the synchronous fluorescence spectra indicated that the conformation of BSA has not been changed.

Biophysical study on the interaction of etomidate and the carrier protein in vitro

Etomidate is a unique drug used for induction of general anesthesia and sedation, and is usually used through intravenous injection clinically. Before targeting to the receptor, etomidate binds proteins in blood when it comes into veins. Thus to study the interaction of etomidate and serum albumin would be of great toxicological and pharmacological importance. In this study, the interaction between etomidate and human serum albumin (HSA) was studied using fluorescence spectroscopy, UV-vis absorption spectroscopy, Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD) spectroscopy, site maker displacement and molecular modeling methods. Investigations of the binding constant (K = 3.55 × 10(5 )M(-1), 295 K), the number of binding sites (n = 1.16), thermodynamic parameters (ΔG = 3.13 × 10(4 )J·mol(-1), ΔS = 364 J·mol(-1)·K(-1) and ΔH = -6.85 × 10(5 )J·mol(-1)) for the reaction and changes to the binding sites and conformation in HSA in response to etomidate were presented. Results show that etomidate can bind HSA tightly through electrostatic forces, and the protein skeleton conformation and secondary structure changes thereby. This is the first spectroscopic report for etomidate-HSA interactions which illustrates the complex nature of this subject.

Spectroscopic and molecular modeling study on the separate and simultaneous bindings of alprazolam and fluoxetine hydrochloride to human serum albumin (HSA): with the aim of the drug interactions probing

The objective of the present research is to study the interaction of separate and simultaneous of alprazolam (ALP) and fluoxetine hydrochloride (FLX) with human serum albumin (HSA) in phosphate buffer (pH 7.4) using different kinds of spectroscopic, cyclic voltammetry and molecular modeling techniques. The absorbance spectra of protein, drugs and protein-drug showed complex formation between the drugs and HSA. Fluorescence analysis demonstrated that ALP and FLX could quench the fluorescence spectrum of HSA and demonstrated the conformational change of HSA in the presence of both drugs. Also, fluorescence quenching mechanism of HSA-drug complexes both separately and simultaneously was suggested as static quenching. The analysis of UV absorption data and the fluorescence quenching of HSA in the binary and ternary systems showed that FLX decreased the binding affinity between ALP and HSA. On the contrary, ALP increased the binding affinity of FLX and HSA. The results of synchronous fluorescence and three-dimensional fluorescence spectra indicated that the binding of drugs to HSA would modify the microenvironment around the Trp and Tyr residues and the conformation of HSA. The distances between Trp residue and the binding sites of the drugs were estimated according to the Förster theory, and it was demonstrated that non-radiative energy transfer from HSA to the drugs occurred with a high probability. Moreover, according to CV measurements, the decrease of peak current in the cyclic voltammogram of the both drugs in the presence of HSA revealed that they interacted with albumin and binding constants were calculated for binary systems which were in agreement with the binding constants obtained from UV absorption and fluorescence spectroscopy. The prediction of the best binding sites of ALP and FLX in binary and ternary systems in molecular modeling approach was done using of Gibbs free energy.

Comprehensive spectroscopic studies on the interaction of biomolecules with surfactant detached multi-walled carbon nanotubes

This paper investigates the interaction of ten diverse biomolecules with surfactant detached Multi-Walled Carbon Nanotubes (MWCNTs) using multiple spectroscopic methods. Declining fluorescence intensity of biomolecules in combination with the hyperchromic effect in UV-Visible spectra confirmed the existence of the ground state complex formation. Quenching mechanism remains static and non-fluorescent. 3D spectral data of biomolecules suggested the possibilities of disturbances to the aromatic microenvironment of tryptophan and tyrosine residues arising out of CNTs interaction. Amide band Shifts corresponding to the secondary structure of biomolecules were observed in the of FTIR and FT-Raman spectra. In addition, there exists an increased Raman intensity of tryptophan residues of biomolecules upon interaction with CNTs. Hence, the binding of the aromatic structures of CNTs with the aromatic amino acid residues, in a particular, tryptophan was evidenced. Far UV Circular spectra have showed the loss of alpha-helical contents in biomolecules upon interaction with CNTs. Near UV CD spectra confirmed the alterations in the tryptophan positions of the peptide backbone. Hence, our results have demonstrated that the interaction of biomolecules with OH-MWCNTs would involve binding cum structural changes and alteration to their aromatic micro-environment.

Interactions in globular proteins with polyampholyte: coacervation route for protein separation

Representative model of protein–protein separation in a BSA–GB–β-Lg aqueous solution.