Investigation of Optical Spectroscopic and Computational Binding Mode of Bovine Serum Albumin with 1, 4‐Bis ((4‐((4‐Heptylpiperazin‐1‐yl) Methyl)‐1H‐1, 2, 3‐Triazol‐1‐yl) Methyl) Benzene

A newly synthesized 1, 4‐bis ((4‐((4‐heptylpiperazin‐1‐yl) methyl)‐1H‐1, 2, 3‐triazol‐1‐yl) methyl) benzene from the family of piperazine derivative has good anticancer activity, antibacterial and low toxic nature; its binding characteristics are therefore of huge interest for understanding pharmacokinetic mechanism of the drug. The binding of piperazine derivative to bovine serum albumin (BSA) was investigated using fluorescence spectroscopy. The molecular distance r between the donor (BSA) and acceptor (piperazine derivative) was estimated according to Forster's theory of nonradiative energy transfer. The physicochemical properties of piperazine derivative, which induced structural changes in BSA, have been studied by circular dichroism and those chemical environmental changes were probed using Raman spectroscopic analysis. Further, the binding dynamics was expounded by synchronous fluorescence spectroscopy and molecular modeling studies explored the hydrophobic interaction and hydrogen bonding results, which stabilize the interaction.     

Cobalt (II) complex with novel unsymmetrical tetradentate Schiff base (ON) ligand: in vitro cytotoxicity studies of complex,interaction with DNA/protein,molecular docking studies,and antibacterial activity

[C₂₀H₁₇N₃O₂] and cobalt (II) complex [Co(L²)(MeOH)₂].ClO₄, (L² = 4-((E)-1-((2-(((E)-pyridin-2-ylmethylene) amino) phenyl) imino) ethyl) benzene-1, 3-diol) novel Schiff base has been synthesiszed and chracterized by Fourier transform infrared, UV–vis, ¹H-NMR spectroscopy, and elemental analysis techniques. The interaction of Co(II) complex with DNA and BSA was investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism, and thermal denaturation studies. Our experiments indicate that this complex could strongly bind to CT-DNA via minor groove mechanism. In addition, fluorescence spectrometry of BSA with the complex showed that the fluorescence quenching mechanism of BSA was of static type. The complex exhibited significant in vitro cytotoxicity against three human cancer cell lines (JURKAT, SKOV3, and U87). The molecular docking experiment effectively proved the binding of complex to DNA and BSA. Finally, antibacterial assay over gram-positive and gram-negative pathogenic bacterial strains was studied.     

Combined multispectroscopic and molecular docking investigation on the interaction between delphinidin‐3‐O‐glucoside and bovine serum albumin

Anthocyanin is one of the flavonoid phytopigments with specific health benefits. The interaction between delphinidin‐3‐O‐glucoside (D3G) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, three‐dimensional fluorescence spectroscopy, ultraviolet‐visible absorption spectroscopy, circular dichroism spectroscopy and molecular modeling. D3G effectively quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites and binding constant K_a were determined, and the hydrogen bonds and van der Waals forces played major roles in stabilizing the D3G–BSA complex. The distance r between donor and acceptor was obtained as 2.81 nm according to Förster's theory. In addition, the effects of pH and metal ions on the binding constants were discussed. The results studied by synchronous fluorescence, three‐dimensional fluorescence and circular dichroism experiments indicated that the secondary structures of the protein has been changed by the addition of D3G and the α‐helix content of BSA decreased (from 56.1% to 52.4%). Furthermore, the study of site marker competitive experiments and molecular modeling indicated that D3G could bind to site I of BSA, which was in the large hydrophobic cavity of subdomain IIA. Copyright © 2014 John Wiley & Sons, Ltd.     

Design,Synthesis, and Insecticidal Activities of Novel meta-Diamide Compounds Containing Ethyl Acetate and Their Derivatives

In this study, a series of meta-diamide compounds containing ethyl acetate group and their derivatives were designed and synthesized. Their insecticidal activities against Plutella xylostella, Spodoptera frugiperda and Alfalfa sprouts were evaluated. Preliminary bioassays showed that some of the title compounds exhibited excellent insecticidal activities. Especially compound ethyl N-(3-((2-bromo-4-(perfluoropropan-2-yl)-6-(trifluoromethyl)phenyl)carbamoyl)-2-fluorophenyl)-N-(4-cyanobenzoyl)glycinate and ethyl N-(3-((2-bromo-4-(perfluoropropan-2-yl)-6-(trifluoromethyl)phenyl)carbamoyl)-2-fluorophenyl)-N-(6-fluoronicotinoyl)glycinate showed 100 % mortality at 0.1 mg/L against Plutella xylostella and Spodoptera frugiperda, same to broflanilide. Their LC₅₀ against Plutella xylostella is 0.286 mg/L and 0.0218 mg/L, respectively. Moreover, compound ethyl N-(3-((2-bromo-4-(perfluoropropan-2-yl)-6-(trifluoromethyl)phenyl)carbamoyl)-2-fluorophenyl)-N-(6-fluoronicotinoyl)glycinate displayed faster control efficacy than broflanilide at 0.1 mg/L. The results indicated that meta-diamide compounds containing ethyl acetate group could be developed as novel and promising insecticides.     

Homo‐C‐nucleoside analogs IV. Synthesis of 4‐(2,5‐anhydro‐D‐altro‐pentitol‐1‐yl)‐2‐phenyl‐2H‐1,2,3‐triazole homo‐C‐nucleoside. CD assignment of the absolute configuration of the carbon bridge

Dehydrative cyclization of 4‐(D‐altro ‐pentitol‐1‐yl)2‐phenyl‐2H ‐1,2,3‐triazole in basic medium with one moler equivalent of p‐toluene sulfonyl chloride in pyridine solution gave the homo‐C‐ nucleoside 4‐(2,5‐anhydro‐D‐altro ‐1‐yl)‐2‐phenyl‐2H ‐1,2,3‐triazole. The structure and anomeric configuration was determined by acylation, nuclear magnetic resonance (NMR), and mass spectroscopy. The stereochemistry at the carbon bridge of homo‐C‐ nucleoside 2‐phenyl‐2H ‐1,2,3‐triazoles was determined by circular dichroism (CD) spectroscopy.     

Explication of bovine serum albumin binding with naphthyl hydroxamic acids using a multispectroscopic and molecular docking approach along with its antioxidant activity

In the present investigation, the protein‐binding properties of naphthyl‐based hydroxamic acids (HAs), N‐1‐naphthyllaurohydroxamic acid ( 1 ) and N‐1‐naphthyl‐p‐methylbenzohydroxamic acid ( 2 ) were studied using bovine serum albumin (BSA) and UV–visible spectroscopy, fluorescence spectroscopy, diffuse reflectance spectroscopy–Fourier transform infrared (DRS–FTIR), circular dichroism (CD), and cyclic voltammetry along with computational approaches, i.e. molecular docking. Alteration in the antioxidant activities of compound 1 and compound 2 during interaction with BSA was also studied. From the fluorescence studies, thermodynamic parameters such as Gibb's free energy (ΔG), entropy change (ΔS) and enthalpy change (ΔH) were calculated at five different temperatures (viz., 298, 303, 308, 313 or 318 K) for the HAs–BSA interaction. The results suggested that the binding process was enthalpy driven with dominating hydrogen bonds and van der Waals’ interactions for both compounds. Warfarin (WF) and ibuprofen (IB) were used for competitive site‐specific marker binding interaction and revealed that compound 1 and compound 2 were located in subdomain IIA (Sudlow's site I) on the BSA molecule. Conclusions based on above‐applied techniques signify that various non‐covalent forces were involved during the HAs–BSA interaction. Therefore the resulted HAs–BSA interaction manifested its effect in transportation, distribution and metabolism for the drug in the blood circulation system, therefore establishing HAs as a drug‐like molecule.     

Probing into the binding interaction between medroxyprogesterone acetate and bovine serum albumin (BSA): spectroscopic and molecular docking methods

To further understand the mechanism of action and pharmacokinetics of medroxyprogesterone acetate (MPA), the binding interaction of MPA with bovine serum albumin (BSA) under simulated physiological conditions (pH 7.4) was studied using fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, circular dichroism and molecular docking methods. The experimental results reveal that the fluorescence of BSA quenches due to the formation of MPA–BSA complex. The number of binding sites (n) and the binding constant for MPA–BSA complex are ~1 and 4.6 × 10³ M^?1 at 310 K, respectively. However, it can be concluded that the binding process of MPA with BSA is spontaneous and the main interaction forces between MPA and BSA are van der Waals force and hydrogen bonding interaction due to the negative values of ΔG⁰, ΔH⁰ and ΔS⁰ in the binding process of MPA with BSA. MPA prefers binding on the hydrophobic cavity in subdomain IIIA (site II′′) of BSA resulting in a slight change in the conformation of BSA, but BSA retaining the α‐helix structure. Copyright © 2016 John Wiley & Sons, Ltd.     

Studies on binding interactions between clenbuterol hydrochloride and two serum albumins by multispectroscopic approaches in vitro

In this study, binding properties of clenbuterol hydrochloride (CL) with human serum albumin (HSA) and bovine serum albumin (BSA) were examined using constant protein concentrations and various CL contents under physiological conditions. The binding parameters were confirmed using fluorescence quenching spectroscopy at various temperatures. The experimental results confirmed that the quenching mechanisms of CL and HSA/BSA were both static quenching processes. The thermodynamic parameters, namely, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to the van't Hoff equation, which suggested that the electrostatic interactions were the predominant intermolecular forces in stabilizing the CL–HSA complex, and hydrogen bonds and van der Waals force were the predominant intermolecular forces in stabilizing the CL–BSA complex. Furthermore, the conformational changes of HSA/BSA in the presence of CL were determined using the data obtained from three‐dimensional fluorescence spectroscopy, ultraviolet‐visible absorption spectroscopy and circular dichroism spectroscopy. Copyright © 2013 John Wiley & Sons, Ltd.     

Different spectroscopic and molecular modeling studies on the interaction between cyanidin‐3‐O‐glucoside and bovine serum albumin

Anthocyanin is one of the flavonoid phytopigments that shows strong antioxidant activity. The cyanidin‐3‐O‐glucoside (C3G) is one of the principal types of anthocyanins. To understand the interaction between C3G and bovine serum albumin (BSA), fluorescence spectroscopy, ultraviolet–visible absorption, Fourier transform infrared spectroscopy, circular dichroism and molecular modeling techniques were used. Binding constant (K_a) and the number of binding sites (n) were calculated. The quenching mechanism of fluorescence of BSA by C3G was discussed. The results studied by Fourier transform infrared spectroscopy and circular dichroism experiments indicate that the secondary structures of the protein have been changed by the interaction of C3G with BSA. The result of molecular modeling confirmed that the C3G bound to the site I (sub‐domain IIA) of BSA, and that the hydroxyl groups in the B ring of C3G took part in the binding with BSA. Copyright © 2013 John Wiley & Sons, Ltd.     

Combined spectroscopies and molecular docking approach to characterizing the binding interaction of enalapril with bovine serum albumin

The binding interaction between bovine serum albumin (BSA) and enalapril (ENPL) at the imitated physiological conditions (pH = 7.4) was investigated using UV–vis absorption spectroscopy (UV–vis), fluorescence emission spectroscopy (FES), synchronous fluorescence spectroscopy (SFS), Fourier transform infrared spectroscopy (FT‐IR), circular dichroism (CD) and molecular docking methods. It can be deduced from the experimental results from the steady‐state fluorescence spectroscopic titration that the intrinsic BSA fluorescence quenching mechanism induced by ENPL is static quenching, based on the decrease in the BSA quenching constants in the presence of ENPL with increase in temperature and BSA quenching rates >10¹⁰ L mol^?1 sec^?1. This result indicates that the ENPL–BSA complex is formed through an intermolecular interaction of ENPL with BSA. The main bonding forces for interaction of BSA and ENPL are van der Waal's forces and hydrogen bonding interaction based on negative values of Gibbs free energy change (ΔG ⁰), enthalpic change (ΔH ⁰) and entropic change (ΔS ⁰). The binding of ENPL with BSA is an enthalpy‐driven process due to |ΔH °| > |T ΔS °| in the binding process. The results of competitive binding experiments and molecular docking confirm that ENPL binds in BSA sub‐domain IIA (site I) and results in a slight change in BSA conformation, but BSA still retains its α‐helical secondary structure.     

Spectroscopic exploration and thermodynamic characterization of desvenlafaxine interacting with fluorescent bovine serum albumin

The mechanism of the interaction between bovine serum albumin (BSA) and desvenlafaxine was studied using fluorescence, ultraviolet absorption, 3‐dimensional fluorescence spectroscopy, circular dichroism, synchronous fluorescence spectroscopy, cyclic voltametry, differential scanning calorimetry, and attenuated total reflection–Fourier transform infrared spectroscopic techniques under physiological condition at pH 7.4. Stern‐Volmer calculations authenticate the fluorescence of BSA that was quenched by desvenlafaxine in a collision quenching mode. The fluorescence quenching method was used to evaluate number of binding sites “n” and binding constant K _A that were measured, and various thermodynamic parameters were evaluated at different temperatures by using the van't Hoff equation and differential scanning calorimetry technique, which indicated a spontaneous and hydrophobic interaction between BSA and desvenlafaxine. According to the Förster theory we calculate the distance between the donor, BSA and acceptor, desvenlafaxine molecules. Furthermore, circular dichroism and attenuated total reflection–Fourier transform infrared spectroscopy indicate nominal changes in the secondary structure of the protein.     

Insights into the binding interaction between copper ferrite nanoparticles and bovine serum albumin: An effect on protein conformation and activity

The binding affinity between bovine serum albumin (BSA) and copper ferrite (CuFe₂O₄) nanoparticles in terms of conformation, stability and activity of protein was studied using various spectroscopic methods. The quenching involved in BSA–CuFe₂O₄ NP interaction was static quenching as analysed by different techniques (steady‐state and time‐resolved fluorescence along with temperature‐dependent fluorescence measurements). Among all types of possible interactions, it was revealed that the major binding forces were van der Waals interaction and hydrogen bonding, which were explored from negative values of enthalpy change (?H = ?193.85 kJ mol^?1) and entropy change (?S = ?588.88 J mol^?1 K^?1). Additionally, synchronous, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy measurements confirmed the conformational changes in BSA upon the addition of CuFe₂O₄ NP. Furthermore, thermal denaturation observations were consistent with the circular dichroism results. The interaction of CuFe₂O₄ NP with BSA decreased the esterase activity in the BSA assay, revealing the affinity of copper ferrite towards the active site of BSA.     

Study on the interactions of mapenterol with serum albumins using multi‐spectroscopy and molecular docking

The interactions of mapenterol with bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated systematically using fluorescence spectroscopy, absorption spectroscopy, circular dichroism (CD) and molecular docking techniques. Mapenterol has a strong ability to quench the intrinsic fluorescence of BSA and HSA through static quenching procedures. At 291 K, the binding constants, K_a, were 1.93 × 10³ and 2.73 × 10³ L/mol for mapenterol–BSA and mapenterol–HAS, respectively. Electrostatic forces and hydrophobic interactions played important roles in stabilizing the mapenterol–BSA/has complex. Using site marker competitive studies, mapenterol was found to bind at Sudlow site I on BSA/HSA. There was little effect of K⁺, Ca²⁺, Cu²⁺, Zn²⁺ and Fe³⁺ on the binding. The conformation of BSA/HSA was changed by mapenterol, as seen from the synchronous fluorescence spectra. The CD spectra showed that the binding of mapenterol to BSA/HSA changed the secondary structure of BSA/HSA. Molecular docking further confirmed that mapenterol could bind to Sudlow site I of BSA/HSA. According to Förster non‐radiative energy transfer theory (FRET), the distances r₀ between the donor and acceptor were calculated as 3.18 and 2.75 nm for mapenterol–BSA and mapenterol–HAS, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of Morin–Zinc(II) Complex and its Interaction with Serum Albumin

A morin–zinc(II) complex (MZ) was synthesized and its interaction with bovine serum albumin (BSA) were studied by molecular spectroscopy including fluorescence emission spectra, UV-visible spectra, circular dichroism (CD) spectra, three-dimensional fluorescence spectra, and synchronous fluorescence spectra. The interaction mechanism of BSA and MZ was discussed by fluorescence quenching method and Förster non-radiation energy transfer theory. The thermodynamic parameters ΔH ^θ, ΔG ^θ, ΔS ^θ at different temperatures were calculated and the results indicate the interaction is an exothermic as well as entropy-driven process. Hydrogen bond forces played the most important role in the reaction. The fluorescence probe experiment showed that the binding site of MZ is in subdomain IIA of BSA and the distance between BSA and MZ is 3.17 nm at normal body temperature. The conformation changes of BSA in presence of MZ were investigated by CD spectra and three-dimensional fluorescence spectra.     

Combined spectroscopies and molecular docking approach to characterizing the binding interaction between lisinopril and bovine serum albumin

To further understand the mode of action and pharmacokinetics of lisinopril, the binding interaction of lisinopril with bovine serum albumin (BSA) under imitated physiological conditions (pH 7.4) was investigated using fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD) and molecular docking methods. The results showed that the fluorescence quenching of BSA near 338 nm resulted from the formation of a lisinopril–BSA complex. The number of binding sites (n) for lisinopril binding on subdomain IIIA (site II) of BSA and the binding constant were ~ 1 and 2.04 × 10⁴ M^–1, respectively, at 310 K. The binding of lisinopril to BSA induced a slight change in the conformation of BSA, which retained its α‐helical structure. However, the binding of lisinopril with BSA was spontaneous and the main interaction forces involved were van der Waal's force and hydrogen bonding interaction as shown by the negative values of ΔG⁰, ΔH⁰ and ΔS⁰ for the binding of lisinopril with BSA. It was concluded from the molecular docking results that the flexibility of lisinopril also played an important role in increasing the stability of the lisinopril–BSA complex. Copyright © 2015 John Wiley & Sons, Ltd.     

Spectroscopic study of the interaction between lycopene and bovine serum albumin

The interaction of lycopene with bovine serum albumin (BSA) in aqueous solution was studied by fluorescence quenching, three‐dimensional fluorescence and circular dichroism spectroscopy. The data showed that the fluorescence of BSA was quenched by lycopene at different temperatures through a dynamic mechanism. The evaluation of three‐dimensional fluorescence spectra revealed a conformational modification of BSA induced by coupling with lycopene and an increase in protein diameter as a consequence of the ligand–protein interaction. Moreover, the information obtained from evaluation of the effect of lycopene on BSA conformation by circular dichroism strongly supported the existence of a slight unfolding of BSA induced by coupling to lycopene. Copyright © 2012 John Wiley & Sons, Ltd.     

Fluorescence spectroscopic studies on the interaction of Gemini surfactant 14‐6‐14 with bovine serum albumin

The interaction of the cationic Gemini surfactant hexamethylene‐1,3‐bis (tetradecyldimethylammonium bromide) (14‐6‐14) with bovine serum albumin (BSA) has been investigated by fluorescence quenching spectra and three‐dimensional (3D) fluorescence spectra. The Stern–Volmer quenching constants K_SV and the corresponding thermodynamic parameters ΔH, ΔG and ΔS have been estimated by the fluorescence quenching method. The results indicated that hydrophobic forces were the predominant intermolecular forces between BSA and the surfactant. Competitive experiments and the number of binding sites calculation show that 14‐6‐14 can be inserted in site‐II (in subdomain IIIA) of BSA. The effect of 14‐6‐14 on the conformation of BSA was evaluated by synchronous fluorescence spectroscopy and 3D fluorescence spectral methods. The results show that the conformation of BSA was changed dramatically in the presence of 14‐6‐14, by binding to the Trp and Try residues of BSA. The investigation provides interaction between BSA and 14‐6‐14 as a model for molecular design and industrial research. Copyright © 2011 John Wiley & Sons, Ltd.     

Photochemical studies on the binding of an organic fluoride to bovine serum albumin

The interaction of fipronil (FPN), a pesticide containing fluorine, to bovine serum albumin (BSA) was studied by spectroscopy including fluorescence spectra, UV–Visible absorption, scattering spectra, circular dichroism (CD) spectra, synchronous and three-dimensional fluorescence spectra. The number of binding sites n and observed binding constant Kb was measured by fluorescence quenching method. The thermodynamic parameters ΔH, ΔG, ΔS at different temperatures were calculated and the results indicate that hydrophobic forces played major role in the reaction. The distance r between donor (BSA) and acceptor (FPN) was obtained according to the Förster theory of non-radiation energy transfer. The structural change of BSA molecules with addition of FPN was analyzed and the results may be helpful to biologists, chemists and therapeutists.     

Spectroscopic and molecular modelling analysis of the interaction between ethane‐1,2‐diyl bis(N,N‐dimethyl‐N‐hexadecylammoniumacetoxy)dichloride and bovine serum albumin

Several spectroscopic approaches namely fluorescence, time‐resolved fluorescence, UV‐visible, and Fourier transform infra‐red (FT‐IR) spectroscopy were employed to examine the interaction between ethane‐1,2‐diyl bis(N,N‐dimethyl‐N‐hexadecylammoniumacetoxy)dichloride (16‐E2‐16) and bovine serum albumin (BSA). Fluorescence studies revealed that 16‐E2‐16 quenched the BSA fluorescence through a static quenching mechanism, which was further confirmed by UV–visible and time‐resolved fluorescence spectroscopy. In addition, the binding constant and the number of binding sites were also calculated. The thermodynamic parameters at different temperatures (298 K, 303 K, 308 K and 313 K) indicated that 16‐E2‐16 binding to BSA is entropy driven and that the major driving forces are electrostatic interactions. Decrease of the α‐helix from 53.90 to 46.20% with an increase in random structure from 22.56 to 30.61% were also observed by FT‐IR. Furthermore, the molecular docking results revealed that 16‐E2‐16 binds predominantly by electrostatic and hydrophobic forces to some residues in the BSA sub‐domains IIA and IIIA. Copyright © 2015 John Wiley & Sons, Ltd.     

Multispectroscopic exploration and molecular docking analysis on interaction of eriocitrin with bovine serum albumin

Eriocitrin is a flavanone glycoside, which exists in lemon or lime citrus fruits. It possesses antioxidant, anticancer, and anti‐allergy activities. In order to investigate the pharmacokinetics and pharmacological mechanisms of eriocitrin in vivo, the interaction between eriocitrin and bovine serum albumin (BSA) was studied under the simulated physiological conditions by multispectroscopic and molecular docking methods. The results well indicated that eriocitrin and BSA formed a new eriocitrin‐BSA complex because of intermolecular interactions, which was demonstrated by the results of ultraviolet‐visible (UV‐vis) absorption spectra. The intrinsic fluorescence of BSA was quenched by eriocitrin, and static quenching was the quenching mechanism. The number of binding sites (n) and binding constant (K_b) at 310 K were 1.22 and 2.84 × 10⁶ L mol^?1, respectively. The values of thermodynamic parameters revealed that the binding process was spontaneous, and the main forces were the hydrophobic interaction. The binding distance between eriocitrin and BSA was 3.43 nm. In addition, eriocitrin changed the conformation of BSA, which was proved by synchronous fluorescence and circular dichroism (CD) spectra. The results of site marker competitive experiments suggested that eriocitrin was more likely to be inserted into the subdomain IIA (site I), which was further certified by molecular docking studies.