Spectroscopic and molecular docking investigation on the interaction of a water-soluble Cu(II) complex containing diethanolamine and dipicolinic acid ligands with human serum albumin.

Under physiological conditions, spectroscopic techniques as well as molecular docking simulation have been used to investigate the binding interaction mechanism between Cu(II) complex containing Pyridine-2,6-dicarboxylic acid (PDCA) and Diethanolamine (DEA) ligands, [Cu(DEA)(PDCA)] and human serum albumin (HSA). UV spectral changes of protein in the presence of the Cu(II) complex suggested the formation of a Protein-Cu(II) complex conjugate with specific new structure. The Cu(II) complex quenches the intrinsic fluorescence of the HSA via a static mechanism in which van der Waals interactions along with hydrogen bonds are fundamental binding forces. Displacement experiments performed by warfarin and ibuprofen site probes predict that the Cu(II) complex is located in subdomain IIA, Sudlow site 1 of HSA. Molecular docking results showed close resemblance with experimental data.Communicated by Ramaswamy H. Sarma.

Interaction studies of water-soluble Zn(II) complex with calf thymus DNA using biophysical and molecular docking methods".

The binding between a fluorescent water-soluble Zn(II) complex of {2-[N-(2-hydroxyethylammonioethyl) imino methyl] phenol} and calf thymus DNA (ct-DNA) was investigated using spectroscopic techniques. The complex was prepared and identified by FT-IR, and 1H NMR spectroscopies. The significant changes in the absorption and the circular dichroism spectra of ct-DNA in the presence of the Zn(II) complex implied the interaction between the Zn(II) complex and ct-DNA. Upon addition of ct-DNA, the fluorescence emission intensity of the Zn(II) complex was increased and indicated the interaction between the Zn(II) complex and ct-DNA was occurred. The binding constant values (Kb) resulted from fluorescence spectra clearly showed the Zn(II) complex affinity to ct-DNA. The fluorescence studies also approved the static enhancement mechanism in the Zn(II) complex-DNA complexation process. The thermodynamic profile exhibited the exothermic and spontaneous formation of ct-DNA-Zn(II) complex system via hydrogen bonds and van der Waals forces. The competitive fluorescence investigation by methylene blue (MB), and Hoechst 33258 demonstrated that the Zn(II) complex could replace the DNA-bound Hoechst and bind to the minor groove binding site in ct-DNA. The viscosity changes were negligible, representing the Zn(II) complex binding to DNA via the groove binding mode. Molecular docking simulation affirmed that the Zn(II) complex is located in the minor groove of ct-DNA near the DG12, DA17, DA18, and DG16 nucleobases.

Analysis of the binding mechanism for a water-soluble Pd(II) complex containing ß-amino alcohols with HSA applying experimental and computational methods.

In the study ahead, the binding interactions of the [Pd (HEAC) Cl2] complex with human serum albumin (HSA) protein have been assayed in vitro (pH= 7.40) utilizing computational and experimental procedures. The mentioned complex was synthesized as a water-soluble complex from {2-((2-((2-hydroxyethyl)amino)ethyl)amino) cyclohexanol} ligand = HEAC. The results of electronic absorption and circular dichroism investigations illustrated that the hydrophobicity of the Tryptophan microenvironment in HSA undergoes the changes by binding to the Pd(II) complex without substantial perturbations on the protein secondary structure. The fluorescence emission spectroscopy analysis revealed that with rising temperature, the quenching constant (Ksv) in the Stern-Volmer's relation decreases; so, it can be said that the interaction process is along with a static quenching mechanism. The values of 2.88 × 105 M-1, and 1.26 represent the binding constant (Kb) and the number of the binding sites (n), respectively. The Job graph showed the maximum point at χ = 0.5, which means organizing a new set with 1:1 stoichiometry. Thermodynamic profile (ΔH < 0, ΔS < 0, and ΔG < 0) has affirmed that van der Waals forces and hydrogen bonds have a basic function in the Pd(II) complex-albumin bindings. The ligand-competitive displacement studies utilizing warfarin and ibuprofen have represented that Pd(II) complex interacts with albumin by site II (subdomain IIIA). The computational molecular docking theory approved the results of the site-competitive tests; also, it indicated the existence of hydrogen bonds and van der Waals forces in Pd(II) complex-albumin interactions.Communicated by Ramaswamy H. Sarma.

DNA interaction studies of a cobalt(III) complex containing ß-amino alcohol ligand by spectroscopic and molecular docking methods.

In the present research, the feasibility of a Cobalt(III) complex containing ß-amino alcohol ligands for affinity with the target calf thymus DNA is demonstrated. In the title complex, [Co(C11H15N2O2)2]Cl, the Co(III) atom is six-coordinated with four N atoms and two O atoms from (2-[(E)-({2-[(2-Hydroxyethyl) amino]ethyl}imino)methyl]phenol) ligand (L). To investigate the molecular interaction between the synthesized complex and DNA, some multi-spectroscopic approaches associated with molecular docking were employed in the physiological buffer (pH 7.4). The results indicated that the Co(III) complex proved to be a minor groove binder with a preference for the A-T region, which was substantiated by displacement studies with Hoechst33258 and Methylene blue (MB) as minor groove binder and intercalator. In addition, the results of the molecular docking study revealed that the Co(III) complex approached the gap between the DNA minor grooves near the spot where the Hoechst was. Furthermore, the results of the cytotoxicity and apoptosis tests for the MCF-7 cell line were also indicative of the positive effects of the complex on controlling the growth and viability of breast cancer.Communicated by Ramaswamy H. Sarma.

Green synthesized silver nanoparticles obtained from Stachys schtschegleevii extract: ct-DNA interaction and in silico and in vitro investigation of antimicrobial activity.

The aim of this study was the synthesis of Ag nanoparticles (AgNPs) by using Stachys schtschegleevii extract and checking the composition, morphology and size of the green synthesized AgNPs using the analytical techniques (UV-vis, DLS, zeta potential, SEM-EDX, FT-IR and TEM). The TEM images of AgNPs represent a smooth surface and are spherical in shape with an average particle size of 31.43 nm. The antioxidant activities of green synthesized AgNPs were appraised by radical scavenging 1, 1-diphenyl-2-picrylhydrazyl test and the green synthesized AgNPs showed a strong ability to scavenge free radicals. In addition, AgNPs displayed a remarkable antibacterial and antifungal activity against various microorganisms. We employed molecular docking to investigate the AgNPs interaction with Dihydrofolate reductase (DHFR) of Escherichia coli, Staphylococcus aureus, and Candida albicans and there is a good agreement between molecular docking and our experimental results. The result of ct-DNA-AgNPs interaction demonstrated that AgNPs can bind to ct-DNA through partial intercalation binding mode.Communicated by Ramaswamy H. Sarma.

In vitro cytotoxicity, antibacterial activity and HSA and ct-DNA interaction studies of chlorogenic acid loaded on γ-Fe2O3@SiO2 as new nanoparticles.

In this study, nanoparticles with both anticancer and antibacterial features were synthesized through loading chlorogenic acid (CGA) of essential oils on magnetic nanoparticles (MNPs). Characterization of γ-Fe2O3@SiO2-CGA MNPs was performed using Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) that show effective coating of the MNPs with SiO2 and CGA ligand and spherical shape of the nanoparticles with a mean diameter of 16 nm, respectively. The cytotoxicity study demonstrated that γ-Fe2O3@SiO2-CGA MNPs had fewer toxic effects on normal cells (Huvec) than on cancerous cells (U-87 MG, A-2780 and A-549), and could be a new potential candidate for use in biological and pharmaceutical applications. The interaction of calf thymus deoxyribonucleic acid (ct-DNA) with γ-Fe2O3@SiO2-CGA MNPs indicated that the anticancer activity might be associated with the DNA binding properties of γ-Fe2O3@SiO2-CGA MNPs. Moreover, the interaction of γ-Fe2O3@SiO2-CGA MNPs with human serum albumin (HSA) suggests that the native conformation of HSA was preserved at the level of secondary structure, indicating that the γ-Fe2O3@SiO2-CGA MNPs do not show any cytotoxicity effect when they are injected into the blood. Antibacterial tests were performed and represented γ-Fe2O3@SiO2-CGA MNPs attained better antibacterial function than CGA as free.

Repurposing FDA-approved drugs cetilistat, abiraterone, diiodohydroxyquinoline, bexarotene, and remdesivir as potential inhibitors against RNA dependent RNA polymerase of SARS-CoV-2: A comparative in silico perspective.

Vaccines are undoubtedly the most effective means of combating viral diseases like COVID-19. However, there are risks associated with vaccination, such as incomplete viral deactivation or potential adverse effects in humans. However, designing and developing a panel of new drug molecules is always encouraged. In an emergency, drug repurposing research is one of the most potent and rapid options. RdRp (RNA-dependent RNA polymerase) has been discovered to play a pivotal role in viral replication. In this study, FDA-approved drugs bexarotene, diiodohydroxyquinoline, abiraterone, cetilistat, and remdesivir were repurposed against the RdRp by molecular modeling, docking, and dynamic simulation. Furthermore, to validate the potency of these drugs, we compared them to the antiviral remdesivir, which inhibits RdRp. Our finding indicated that the selected drugs have a high potential to be developed as RdRp inhibitors and, with further validation studies, could serve as potential drugs for the treatment of COVID-19.

Synthesis, characterization, in vitro cytotoxicity and DNA interaction studies of antioxidant ferulic acid loaded on γ-Fe2O3@SiO2 nanoparticles.

In this investigation, Fe3O4 magnetic nanoparticles (MNPs) were prepared via a chemical coprecipitation reaction, and the surface of Fe3O4 MNPs was coated with silica by a sol-gel process. The surface of Fe3O4@SiO2 MNPs was modified by an antioxidant agent, trans-ferulic acid, to achieve water-soluble MNPs for biological applications. Fourier transform infrared spectroscopy (FT-IR) showed that the MNPs were successfully coated with SiO2 and ferulic acid (FA) ligand. The morphology of γ-Fe2O3@SiO2-FA MNPs was found to be spherical in images of transmission electron microscopy (TEM) and showed a uniform size distribution with an average diameter of 21 nm. The in vitro cytotoxic activity of γ-Fe2O3@SiO2-FA MNPs and FA were investigated against the human cancer cells (MCF-7, PC-3, U-87 MG, A-2780, and A-549) by MTT colorimetric assay. The cytotoxic effect of MNPs on all cancer cell lines was several times of magnitude higher compared to free FA except for A-549 cell lines. Furthermore, in vitro DNA binding studies were investigated by UV-vis and circular dichroism spectroscopies.

Can polyoxometalates (POMs) prevent of coronavirus 2019-nCoV cell entry? Interaction of POMs with TMPRSS2 and spike receptor domain complexed with ACE2 (ACE2-RBD): Virtual screening approaches.

The unexpected appearance and global spread of COVID-19 create significant difficulties for healthcare systems and present an unusual challenge for the fast discovery of medicines to combat this fatal disease. Screening metallodrugs libraries from the medicinal inorganic chemistry society may expand the studied 'chemical space' and improve the probability of discovering effective anti-COVID drugs, including polyoxometalates. POMs are an oxygen-rich family of inorganic cluster systems that have previously been tested for antiviral action against different types of viruses. Human angiotensin-converting enzyme 2 (ACE2), human transmembrane protease serine 2 (TMPRSS2), and the SARS-CoV-2 spike glycoprotein are required for host cell-mediated viral entrance. Targeting these proteins demonstrates potential possibilities for preventing infections and transmissions in the initial stage. As a result, POMs with known antiviral effects were investigated for this purpose using molecular docking and dynamic simulations. This research shows that POMs can prevent SARS CoV-2 from entering cells by blocking TMPRSS2, which SARS-CoV-2 uses for spike glycoprotein priming. They may also engage with ACE2 and the spike glycoprotein and disrupt their binding by blocking the active sites. We think that a thorough investigation of POMs as possible anti-COVID-19 drugs will provide significant opportunities.

Interaction of human hemoglobin (HHb) and cytochrome c (Cyt c) with biogenic chloroxine-conjugated silver nanoflowers: spectroscopic and molecular docking approaches.

In this research, the biological activity of the antibacterial drug Chloroxine-conjugated biogenic AgNPs (COX-AgNPs) was investigated in simulated physiological conditions (pH = 7.40). Different spectroscopic methods such as UV-visible, fluorescence, and circular dichroism spectroscopic and docking simulation were employed to evaluate the structural changes in the most important blood proteins (human hemoglobin (HHb) and Cytochrome c (Cyt c)) in the presence of COX-AgNPs. The results showed that the COX-AgNPs can bind to HHb and Cyt c and the secondary structure of these proteins remains unchanged, which is crucial in providing insights into the side effects of newly synthesized drugs on their carriers.Communicated by Ramaswamy H. Sarma.

In vitro cytotoxicity studies of smart pH-sensitive lamivudine-loaded CaAl-LDH magnetic nanoparticles against Mel-Rm and A-549 cancer cells.

In this study, an effective nano-drug delivery system was prepared by the co-precipitation method via two steps; the preparation of Fe3O4 magnetic nanoparticles and its surface modification with layered double hydroxide (LDH) and loading lamivudine on this nanocarrier (Fe3O4@CaAl-LDH@Lamivudine). The developed nanoparticles (NPs) were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, Fourier-transformed infrared spectroscopy, vibrating-sample magnetometry, thermogravimetric analysis, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller. The prepared system demonstrated an average size of 130 nm. Also, the drug entrapment efficiency was estimated at ∼70%. In vitro, drug release investigations showed a controlled and pH-dependent lamivudine release over 300 min. The in vitro cytotoxic activity of Fe3O4@CaAl-LDH@Lamivudine NPs was explored against Mel-Rm and A-549 cancer cell lines in comparison with lamivudine and nanocarrier using lactate dehydrogenase colorimetric and MTT assay. The results of the MTT assay revealed that the Fe3O4@CaAl-LDH@Lamivudine NPs significantly inhibited the proliferation of Mel-Rm and A-549 cells in a dose-dependent manner. The influences of Fe3O4@CaAl-LDH@Lamivudine on the cancer cell lines by different therapeutic investigation illustrated the remarkable effect in comparison with free drug. Finally, the achieved consequences confirm the anticancer properties of Fe3O4@CaAl-LDH@Lamivudine and indicate that they may be a cost-effective substitute in the treatment of lung and skin cancer.Communicated by Ramaswamy H. Sarma.

Antimicrobial, cytotoxicity, molecular modeling and DNA cleavage/binding studies of zinc-naproxen complex: switching DNA binding mode of naproxen by coordination to zinc ion.

The intercalation DNA binding mode of the naproxen, a non-steroidal anti-inflammatory drug, has been reported previously. In this study, calf thymus deoxyribonucleic acid (CT-DNA) binding of zinc-naproxen complex, [Zn(naproxen)2(MeOH)2], at physiological pH has been investigated by multi-spectroscopic techniques and molecular docking. Zinc-naproxen complex displays significant binding property to the CT-DNA (Kb = 0.2 × 105 L.mol-1). All of the experimental results; relative increasing in viscosity of CT-DNA and fluorimetric studies using ethidium bromide (EB) and Hoechst 33258 probes, are indicative of groove binding mode of zinc-naproxen complex to CT-DNA. These results show that the coordination of naproxen to zinc metal switches the mode of binding from intercalation to groove. The molecular modeling also shows that the complex binds to the AT-rich region of minor groove of DNA. Structural and topography changes of DNA in interaction with the complex by atomic force microscopy (AFM) indicated that CT-DNA becomes swollen after interaction. The pUC18 plasmid DNA cleavage ability of zinc-naproxen complex by gel electrophoresis experiments revealed that zinc-naproxen complex cleaved supercoiled pUC18 plasmid DNA to nicked DNA. The cytotoxicity of the zinc complex performed by MTT method on HT29 and MCF7 cancer cell lines and on HEK 293 normal cell lines indicates that zinc complex has no cytotoxic effect on both HT29 and MCF7 cell lines but has better cytotoxicity effect on HEK 293 cell lines compared to cisplatin standard drug. The antimicrobial activity of the complex against Staphylococcus aureus and Escherichia coli bacteria revealed the high antimicrobial activity of the complex.Communicated by Ramaswamy H. Sarma.

Synthesis, characterization and in vitro cytotoxicity studies of novel Cu(II) complex containing zonisamide drug: DNA interaction by multi spectroscopic and molecular docking methods.

In this study, the Cu(II) complex with Zonisamide (ZNS) and 1, 10-Phenanthroline (Phen) ligands as an anticancer metallodrug was synthesized and characterized successfully by FT-IR, mass spectrometry, TGA, XPS, AAS, CHNSO, magnetic susceptibility and electrical conductivity. The interaction of Cu(II) complex with DNA was explored through a multi-spectroscopic approach such as fluorescence, UV-vis spectrophotometry, CD spectroscopy, and viscosity measurements. Molecular docking simulation was carried out to gain a deeper insight into the target site of DNA which interacted with the mentioned complex. The competitive binding tests with Hoechst 33258 showed that [CuCl2(ZNS)(Phen)EtOH].H2O can bind to the groove site of DNA. The calculated thermodynamic parameters, ΔS° = +201.15 J mol-1K-1 and ΔH° = +41.32 kJ mol-1 confirm that the hydrophobic forces and hydrogen bonding play an essential role in the binding process. The experimental and molecular modeling results demonstrate that the Cu(II) complex binds to DNA through major groove binding. Moreover, the in vitro cytotoxic effects of [CuCl2(ZNS)(Phen)EtOH].H2O against B92 cancer cell lines showed better activity in Cu(II) complex in comparison to free ZNS. Therefore, [CuCl2(ZNS)(Phen)EtOH].H2O can open a new horizon in the treatment of glioma cancer by ZNS metallodrugs.Communicated by Ramaswamy H. Sarma.

Insight into the binding mechanism of macrolide antibiotic; erythromycin to calf thymus DNA by multispectroscopic and computational approaches.

In the present study, the interactions between Erythromycin drug and calf thymus deoxyribonucleic acid (ct-DNA) were explored by multi spectroscopic techniques (UV-Visible, fluorescence, circular dichroism spectroscopies), viscosity, molecular docking simulation, and atomic force microscopy (AFM). In addition, the values of binding constant were calculated by the UV-Visible and fluorescence spectroscopy. Competitive fluorescence study with methylene blue (MB), acridine orange (AO), and Hoechst 33258 were indicated that the Erythromycin drug could displace the DNA-bound Hoechst, which displays the strong competition of Erythromycin with Hoechst to interact with the groove binding site of DNA. In addition, the observed complexes in AFM analysis comprise the chains of ct-DNA and Erythromycin with an average size of 314.05 nm. The results of thermodynamic parameter calculations (ΔS° = -332.103 ± 14 J mol-1 K-1 and ΔH° = -115.839 ± 0.02 kJ mol-1) approved the critical role of van der Waals forces and hydrogen bonds in the complexation of Erythromycin-DNA. Fluorescence spectroscopy results demonstrate the existence of a static enhancement mechanism in the interaction of Erythromycin-DNA. According to the obtained results, Erythromycin drug interacts with the major groove of ct-DNA. These consequences were further supported by the molecular docking study, and it could be determined that DNA-Erythromycin docked model was in a rough correlation with our experimental results.Communicated by Ramaswamy H. Sarma.

Experimental and Molecular Docking Studies on the Interaction of a Water-Soluble Pd(II) Complex Containing ß-Amino Alcohol with Calf Thymus DNA.

The interaction of water-soluble and fluorescent [Pd (HEAC) Cl2] complex, in which HEAC is 2-((2-((2-hydroxyethyl)amino)ethyl)amino) cyclohexanol, with calf thymus DNA (ct-DNA) has been studied. This study was performed using electronic absorption and fluorescence emission spectroscopies, cyclic voltammetry and circular dichroism analyses, dynamic viscosity measurements, and molecular docking theory. From hypochromic effect observed in ct-DNA absorption spectra, it was found that the Pd(II) complex could form a conjugate with ct-DNA strands through the groove binding mode. The Kb values obtained from fluorescence measurements clearly assert the Pd(II) complex affinity to ct-DNA. The fluorescence quenching of the DNA-Hoechst compound following the successive additions of the Pd(II) complex to the solution revealed that the Pd(II) complex is located in the ct-DNA grooves, and Hoechst molecules have been released into solution; moreover, the resulting measurements from relative viscosity authenticate the Pd(II) complex binding to the grooves. Negative quantities of thermodynamic parameters imply that the Pd(II) complex binds to ct-DNA mainly by the hydrogen bonds and van der Waals forces; also, the Gibbs-free energy changes show the exothermic and spontaneous formation of the Pd(II) complex-DNA system. The electrochemical behavior of the Pd(II) complex in the attendance of ct-DNA was investigated using the cyclic voltammetry method (CV). Several quasi-reversible redox waves were observed along with increasing the anodic/cathodic peak currents, as well as a shift in anodic/cathodic peak potentials. Circular dichroism (CD) observations suggested that the Pd(II)-DNA interaction could alter ct-DNA conformation. The results of molecular modeling confirmed that groove mechanism is followed by the Pd(II) complex to interact with ct-DNA.

Inhibitory activity of FDA-approved drugs cetilistat, abiraterone, diiodohydroxyquinoline, bexarotene, remdesivir, and hydroxychloroquine on COVID-19 main protease and human ACE2 receptor: A comparative in silico approach.

By September 1, 2021, SARS-CoV-2, a respiratory virus that prompted Coronavirus Disease in 2019, had infected approximately 218,567,442 patients and claimed 4,534,151 lives. There are currently no specific treatments available for this lethal virus, although several drugs, including remdesivir and hydroxychloroquine, have been tested. The purpose of this study is to assess the activity of FDA-approved drugs cetilistat, abiraterone, diiodohydroxyquinoline, bexarotene, remdesivir, and hydroxychloroquine as potential SARS-CoV-2 main protease inhibitors. Additionally, this study aims to provide insight into the development of potential inhibitors that may inhibit ACE2, thereby preventing SARS-CoV-2 entry into the host cell and infection. To this end, remdesivir and hydroxychloroquine were used as comparator drugs. The calculations revealed that cetilistat, abiraterone, diiodohydroxyquinoline, and bexarotene inhibit main protease and ACE2 receptors more effectively than the well-known drug hydroxychloroquine when used against COVID-19. Meanwhile, bexarotene and cetilistat bind more tightly to the SARS-CoV-2 main protease and the ACE2 receptor, respectively, than remdesivir, a potential treatment for COVID-19 that is the first FDA-approved drug against this virus. As a result, the molecular dynamic simulations of these two drugs in the presence of proteins were investigated. The MD simulation results demonstrated that these drugs interact to stabilize the systems, allowing them to be used as effective inhibitors of these proteins. Meanwhile, bexarotene, abiraterone, cetilistat, and diiodohydroxyquinoline's systemic effects should be further investigated in suitable ex vivo human organ culture or organoids, animal models, or clinical trials.

Selenium nanoparticles: Synthesis, in-vitro cytotoxicity, antioxidant activity and interaction studies with ct-DNA and HSA, HHb and Cyt c serum proteins.

The aim of this study was the synthesis of selenium nanoparticles (SeNPs) employing vitamin C as a biocompatible and low toxic reducing agent. The synthesized selenium nanoparticles were characterized by using UV-vis, FT-IR, SEM-EDX, TEM, DLS, and zeta potential measurements. The results of the DPPH free radical scavenging assay demonstrate that this synthesized nano-selenium has strong potentials to scavenge the free radicals and cytotoxicity against MCF-7 and Raji Burkitt's lymphoma cancer cell lines. The interaction of calf thymus DNA (ct-DNA) with SeNPs indicated that the anticancer activity might be associated with the DNA-binding properties of nano-selenium. Finally, it was found that the synthesized nano-selenium can bind to the most important blood proteins such as human serum albumin (HSA), human hemoglobin (HHb), and Cytochrome c (Cyt c). The results showed that the secondary structure of these proteins remains unchanged, suggesting that the synthesized nano-selenium could be employed as a carrier in the drug delivery system without any cytotoxicity effect.

Multispectroscopic and molecular docking studies on DNA binding of guaifenesin drug.

The interaction mechanism of guaifenesin drug; (RS)-3-(2-methoxyphenoxy)propane-1,2-diol; and calf thymus DNA was characterized by multiple spectroscopic and molecular docking approaches. The changes in drug electronic absorption with increasing DNA concentration and also the observed significant quenching of guaifenesin emission in the presence of DNA proved the complex formation between guaifenesin and DNA during the interactions. Both the binding constant and thermodynamic parameters for the interaction have been calculated in 283, 298, and 310 K at pH 7.4. The results Δ H 0 = 17.87 kJ/mol and Δ S 0 = 143.31 J/mol.K confirmed the role of hydrophobic force in the guaifenesin-DNA interaction. Circular dichroism study showed that guaifenesin causes decrease in the negative band of CT-DNA and at the same time the positive band increases which indicated the transition of DNA conformation from B to A. KI quenching experiment specifies that guaifenesin binds to DNA via nonintercalative mode. The competitive studies based on known Hoechst 33258 and methylene blue probes proved the groove binding mode in guaifenesin-DNA adduct. Further, full agreement of molecular docking simulation with the experimental results of binding constant and interaction mode, support high accuracy of the results.

Direct effects of low-energy electrons on including sulfur bonds in proteins: a second-order Møller-Plesset perturbation (MP2) theory approach.

In an attempt to describe how low-energy electrons (LEEs) damage the polypeptide chain at disulfide bridges, ab initio electronic structure estimates on LEE interactions with cysteine-cysteine (Cys-Cys) disulfide bond model have been performed. Here, the fundamental mechanisms in LEE impression on S-S and C-S bond ruptures in the Cys-Cys model have been discussed. The electronic energy was calculated using the MP2 method with a Hartree-Fock exchange during the SCF and the Møller-Plesset correlation energy correction on the converged HF orbitals with 6-311++G(d,p) atomic orbital basis set. Further, six more sets of diffuse s and p functions with extra basis on the sulfur and relevant carbon atoms were used to describe the added electron to located away as much as possible from the nuclei in anions. The bonds rupture mechanisms involve the primary placement of LEEs to the π* orbital of the model to construct the shape-resonance state following by an adiabatic or nonadiabatic electron migration to either S-S or C-S bond σ* orbital. The formed radical anion undergoes S-S or C-S bonds cleavage by energy barriers of ca. 5.68 and 9.19 kcal/mol, respectively, to produce either (2-amino-2-carboxyethyl) sulfanyl (cysteine radical), aziridine-2-carboxylic acid or mercapto-L-cysteine lesions. In SMD solvent, calculations suggest electronically stable of the formed π* and σ* states by solvation, something that induces either S-S or C-S bond break even when the electron energy is near zero. The required barrier energy of only 0 to < 0.4 eV indicates a high kinetic favorable fragmentation for involved sulfur polypeptides with LEEs.Communicated by Ramaswamy H. Sarma.

Multispectroscopic analysis, atomic force microscopy, molecular docking and molecular dynamic simulation studies of the interaction between [SnMe2Cl2(Me2phen)] complex and ct-DNA in the presence of glucose.

In this study, the spectroscopic methods (UV-vis, fluorimetric), Atomic force microscopy, and computational studies (molecular docking and molecular dynamic simulation) were used to investigate the interaction of [SnMe2Cl2(Me2phen)] complex with CT-DNA in the presence of glucose. The results showed the complex in the medium containing glucose has less effect on calf thymus DNA (ct-DNA) than the medium without glucose. Cytotoxicity of [SnMe2Cl2(Me2phen)] complex on MCF-7 cells was examined and showed Sn(IV) complex possesses potential cytotoxicity against this cell line. Molecular docking study showed that Sn(IV) complex interacts with DNA by groove binding mode. Radius of gyration (Rg) was smaller upon binding of the Sn(IV) complex suggesting a more compact structure of DNA in the presence of Sn(IV) complex.Communicated by Ramaswamy H. Sarma.