Heme induced loss of renovascular endothelial protein C receptor promotes chronic kidney disease in sickle mice.

Chronic kidney disease (CKD) is a major contributor to morbidity and mortality in sickle cell disease (SCD). Anemia, induced by chronic persistent hemolysis, is associated with progressive deterioration of renal health resulting in CKD. Moreover, patients with SCD experience acute kidney injury (AKI), a risk factor for CKD, often during vasoocclusive crisis associated with acute intravascular hemolysis. However, the mechanisms of the hemolysis-driven pathogenesis of the AKI-to-CKD transition in SCD remain elusive. Here, we investigated the role of increased renovascular rarefaction and the resulting substantial loss of vascular endothelial protein C receptor (EPCR) on the progressive deterioration of renal function in transgenic SCD mice. Multiple hemolytic events raised circulating levels of soluble EPCR (sEPCR) indicating loss of EPCR from the cell surface. Using bone marrow transplantation and super-resolution ultrasound imaging, we demonstrated that SCD mice overexpressing EPCR were protective against heme-induced CKD development. In a cohort of SCD patients, plasma sEPCR was significantly higher in individuals with CKD than in those without CKD. This study concludes that multiple hemolytic events may trigger CKD in SCD through the gradual loss of renovascular EPCR. Thus, restoration of EPCR may be a therapeutic target, and plasma sEPCR can be developed as a prognostic marker for sickle CKD.

Environmentally relevant lead alters nuclear integrity in erythrocytes and generates oxidative stress in liver of Anabas testudineus: Involvement of Nrf2-Keap1 regulation and expression of biomarker genes.

Genotoxic and hepatotoxic effects of lead (Pb) on a freshwater fish, climbing perch (Anabas testudineus) were studied at an environmentally relevant concentration (43.3 ppm). The genotoxic potential of Pb was confirmed by micronucleus study, with increased frequencies of erythrocytic nuclear alterations like lobed, blebbed, notched, fragmented, and micronuclei were observed in erythrocytes in treated groups as compared to control. Inorganic Pb induces oxidative stress which is a consequence of elevated level of Reactive Oxygen Species. Hepatotoxicity was assessed both by the oxidative stress and cellular responses that emerged due to the toxic assault of Pb in the liver, the most important detoxifying organ. Upregulation of xenobiotic metabolizing enzyme like catalase was evident after 15, 30, and 90 days of exposure, and a profound effect was observed on 30th days. The level of lipid peroxidation and reduced glutathione was increased after Pb exposure. Histoarchitectural damages of liver were distinctly evident in treated fish. Western blot analysis confirmed the expressional alterations of stress-responsive marker proteins like Nrf2, Keap1, Hsp70, and Nqo1. Pb exposure resulted in increased expression of Hsp70, Nrf2, and Nqo1, whereas Keap1 was downregulated, suggesting the involvement of Nrf2-Keap1 regulation as a cytoprotective mechanism against Pb toxicity.

Environmentally Relevant Hexavalent Chromium Disrupts Elemental Homeostasis and Induces Apoptosis in Zebrafish Liver.

Although hexavalent chromium Cr [VI] is known as a toxicant in the aquatic environment, its effect in low, environmentally relevant concentration (ERC; 2 mg L-1) is less characterized. Against this backdrop, the effects of Cr [VI] in ERC on zebrafish liver has been investigated in this study. Fluorescence microscopy and gel electrophoresis detected excess DNA damage and cell death via apoptosis in 2 mg L-1 Cr [VI]-treated fish when compared with that of control. Besides, there were transcriptional activations of p53, Bax, Caspase 9 and Caspase 3 genes but downregulation of Bcl2 gene in the treated group, confirming the apoptotic pathway. Energy dispersive X-ray fluorescence (EDXRF) data showed significant (p < 0.05) increase in hepatic content of Cr, selenium, iron, manganese, calcium, sulfur and magnesium but depletion of zinc, copper and cobalt in the treated group. Collectively, the study shows that even a low, ERC of Cr [VI] is toxic to the zebrafish as it elicited marked apoptosis in the hepatocytes and altered the liver elemental profile.

A Density Functional Theory Study on Et-BAC-Catalyzed 1,6-Conjugate Addition of p-Chlorobenzaldehyde to p-Quinone Methide for the Synthesis of α,α'-Diarylated Ketones.

Umpolung-based organocatalysis has made a remarkable breakthrough in the field of synthetic organic chemistry. Among a plethora of umpolung catalysts, bis(amino)cyclopropenylidenes (BACs) have emerged as efficient organocatalysts with potential applications in synthesizing numerous essential organic moieties. In this study, a plausible mechanism for bis(diethylamino)cyclopropenylidene (Et-BAC)-catalyzed synthesis of α,α'-diarylated ketones has been established using the density functional theory (DFT) method. The proposed catalytic cycle of the studied reaction initiates with the nucleophilic interaction of Et-BAC with p-chlorobenzaldehyde to form a zwitterionic intermediate, which is then transformed to a reactive Breslow intermediate. The Breslow intermediate further undergoes a chemoselective and stereoselective 1,6-conjugate addition reaction with p-quinone methide to form a new C-C bond connection. Finally, the generated adduct undergoes a proton shift reaction with the assistance of both 8-diazabicyclo(5.4.0)undec-7-ene (DBU) and protonated DBU to yield the desired product. Conceptual DFT-derived reactivity indices and frontier molecular orbital theory analysis have been successfully utilized to unravel the role of Et-BAC in this studied reaction. In addition to Et-BAC, DBU and protonated DBU also play a very important role in lowering the activation energy barrier of proton transfer steps. This investigation will help in the rational designing of simple nonheterocyclic carbene-mediated novel organic transformations.

Environmental exposure of arsenic and fluoride and their combined toxicity: A recent update.

Environmental exposure to arsenic (As) and fluoride (F) in the recent year has been increased because of excessive use of naturally contaminated ground water. Surface water is also regularly contaminated with these elements in various industrial areas. Arsenicosis and fluorosis upon individual exposure of As and F are reported in many studies. A syndrome of endemic As poisoning and fluorosis occurs during concurrent exposure of As and F. Previous reports showed synergistic, antagonistic and independent effects of these two compounds, although few recent reports also revealed antagonistic effects after co-exposure. Interaction during intestinal absorption and influence of F on As metabolism might be the cause of antagonism. The synergism/antagonism is thought to depend on the dose and duration of the co-exposure. However, the detailed mechanism is still not fully understood and needs further studies. Removal technologies of As and F from contaminated water is available but removal of such contaminants from food is yet to be developed. Antioxidants are useful to mitigate the toxic effects of As and F. This review focused on the effect of co-exposure, amelioration as well as removal techniques of As and F.

Chronic exposure to environmentally relevant concentration of fluoride alters Ogg1 and Rad51 expressions in mice: Involvement of epigenetic regulation.

Chronic exposure to fluoride (F) beyond the permissible limit (1.5 ppm) is known to cause detrimental health effects by induction of oxidative stress-mediated DNA damage overpowering the DNA repair machinery. In the present study, we assessed F induced oxidative stress through monitoring biochemical parameters and looked into the effect of chronic F exposure on two crucial DNA repair genes Ogg1 and Rad51 having important role against ROS induced DNA damages. To address this issue, we exposed Swiss albino mice to an environmentally relevant concentration of fluoride (15 ppm NaF) for 8 months. Results revealed histoarchitectural damages in liver, brain, kidney and spleen. Depletion of GSH, increase in lipid peroxidation and catalase activity in liver and brain confirmed the generation of oxidative stress. qRT-PCR result showed that expressions of Ogg1 and Rad51 were altered after F exposure in the affected organs. Promoter hypermethylation was associated with the downregulation of Rad51. F-induced DNA damage and the compromised DNA repair machinery triggered intrinsic pathway of apoptosis in liver and brain. The present study indicates the possible association of epigenetic regulation with F induced neurotoxicity.

Coumarin Based Fluorescent Probe for Colorimetric Detection of Fe3+ and Fluorescence Turn On-Off Response of Zn2+ and Cu2.

A new coumarin based Schiff-base chemosensor-(E)-7-(((8-hydroxyquinolin-2-yl)methylene) amino)-4-methyl-2H-chromen-2-one (H 11 L) was synthesized and evaluated as a colorimetric sensor for Fe3+ and fluorescence "turn on-off" response of Zn2+ and Cu2+ using absorption and fluorescence spectroscopy. Upon treatment with Fe3+ and Zn2+, the absorption intensity as well as the fluorescence emission intensity increases drastically compared to other common alkali, alkaline earth and transition metal ions, with a distinct color change which provide naked eye detection. Formation of 1:1 metal to ligand complex has been evaluated using Benesi-Hildebrand relation, Job's plot analyses, 1H NMR titration as well as ESI-Mass spectral analysis. The complex solution of H 11 L with Zn2+ ion exhibited reversibility with EDTA and regenerate free ligand for further Zn2+ sensing. H 11 L exhibits two INHIBIT logic gates with two different chemical inputs (i) Zn2+ (IN1) and Cu2+ (IN2) and (ii) Zn2+ (IN1) and EDTA (IN2) and the emission as output. Again, an IMPLICATION logic gate is obtained with Cu2+ and EDTA as chemical inputs and emission as output mode. Both free ligand as well as metal-complexes was optimized using density functional theory to interpret spectral properties. The corresponding energy difference between HOMO-LUMO energy gap for H 11 L, H11L-Zn2+ and H11L-Cu2+ are 2.193, 1.834 and 0.172 eV, respectively.

Catalytic battle of activated carbon supported transition metal atom towards adsorption and dissociation of molecular hydrogen: Progress towards quantum chemical application on renewable energy resource.

Density functional theory (DFT) investigation has been done to unravel the adsorption and dissociation nature of hydrogen molecule on 3d, 4d and 5d transition metal (M = Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt or Au) atom doped activated carbon (AC) surface. Transition metal doped AC are found to be active catalyst for storage of hydrogen and also gives the stability of M - H bonds formed after bond breakage of H2 molecule. Transition metals are found to occupy the position on the five member ring rather than six member ring of the AC. Five member ring of the AC is seen to be more deformed than the six-member ring on metal doping. Higher values of LUMO-HOMO gap and vertical ionization potential and lower electron affinity signify the higher stability of hydrogen molecule adsorbed metal doped AC. Bond length and vibrational analysis of the adsorbed hydrogen molecule suggest the higher activation of hydrogen molecule on AC, where 4d and 5d metal doped ACs are found to be more efficient in comparison to 3d metal. Adsorbed hydrogen molecule on metal doped AC follows dissociation either via spill-over or via normal process. DFT evaluated rate constant and the transition states suggest that Ru, Rh, Os and Ir doped AC are found to be efficient in the dissociation of hydrogen molecule, while, Cu doped AC is seen to be worst in the same reaction. Deformed electron density, HOMO-LUMO isosurface, and density of states confirms the redistribution of electrons among H2 and metal doped AC surface. ΔGH values of Hydrogen evolution reaction also signifies the greater catalytic activities of Ru and Os supported activated carbon towards HER.

Tunable emissive lanthanidomesogen derived from a room-temperature liquid-crystalline Schiff-base ligand.

A novel photoluminescent room-temperature liquid-crystalline salicylaldimine Schiff base with a short alkoxy substituent and a series of lanthanide(III) complexes of the type [Ln(LH)3(NO3)3] (Ln = La, Pr, Sm, Gd, Tb, Dy; LH = (E)-5-(hexyloxy)-2-[{2-(2-hydroxyethylamino)ethylimino]methyl}phenol) have been synthesized and characterized by FTIR, (1)H and (13)C NMR, UV/Vis, and FAB-MS analyses. The ligand coordinates to the metal ions in its zwitterionic form. The thermal behavior of the compounds was investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The ligand exhibits an enantiotropic hexagonal columnar (Col(h)) mesophase at room temperature and the complexes show an enantiotropic lamellar columnar (Col(L)) phase at around 120 °C with high thermal stability. Based on XRD results, different space-filling models have been proposed for the ligand and complexes to account for the columnar mesomorphism. The ligand exhibits intense blue emission both in solution and in the condensed state. The most intense emissions were observed for the samarium and terbium complexes, with the samarium complex glowing with a bright-orange light (ca. 560-644 nm) and the terbium complex emitting green light (ca. 490-622 nm) upon UV irradiation. DFT calculations performed by using the DMol3 program at the BLYP/DNP level of theory revealed a nine-coordinate structure for the lanthanide complexes.

Quantum Chemical Investigation on Hydrolysis of Orally Active Organometallic Ruthenium(II) and Osmium(II) Anticancer Drugs and Their Interaction with Histidine.

Influence of the metal center on hydrolysis of organometallic anticancer complexes containing an N-phenyl-2-pyridinecarbothioamide (PCA) ligand, [M(η6-p-cymene)(N-phenyl-2-pyridinecarbothioamide)Cl]+ (M = RuII, 1A, and OsII, 2A), as well as their N-fluorophenyl derivatives [M(η6-p-cymene)(N-fluorophenyl-2-pyridinecarbothioamide)Cl]+ (M = RuII, 1B, and OsII, 2B) have been investigated using the DFT method in aqueous medium. The activation energy barriers for the hydrolysis of 1A (21.5 kcal/mol) and 1B (20.7 kcal/mol) are found to be significantly lower than those of their corresponding osmium analogs 2A (28.6 kcal/mol) and 2B (27.5 kcal/mol). DFT evaluated results reveal the inertness of Os(II)-PCA complex toward the hydrolysis that rationalizes the experimental observations. However, the incorporation of fluoride substituent slightly decreases the activation energy for the hydrolysis of Ru(II)- and Os(II)-PCA. In addition, the interaction of hydrolyzed Ru(II)-PCAs (1AH and 1BH) and Os(II)-PCAs (2AH and 2BH) complexes with the histidine (Hist) have also been investigated. The aquated 1BH and 2BH show an enhanced propensity toward the interaction with histidine, and their activation Gibbs free energies are calculated to be 15.9 and 18.9 kcal/mol, respectively. ONIOM (QM/MM) study of the resulting aquated complexes inside histone protein shows the maximum stability of the 2BH complex having a binding energy of -43.6 kcal/mol.

Quantum Chemical Investigations on the Hydrolysis of Gold(III)-Based Anticancer Drugs and Their Interaction with Amino Acid Residues.

A comprehensive hydrolysis mechanism of the promising class of Au(III) anticancer drugs [Au(DMDT)Cl2] (DMDT = N,N-dimethyldithiocarbamate) (R) and [Au(damp)Cl2] (damp = 2-[(dimethylamino)methyl]phenyl) (R') was done by means of density functional theory (DFT) in combination with the CPCM solvation model to explore the solution behavior and stability under physiological conditions. The activation free energies (ΔG) for the second hydrolysis, R (13.7 kcal/mol) and R' (10.0 kcal/mol) are found to be relatively lower in comparison to the first hydrolysis, and their rate constant values are computed to be 5.62 × 102 and 2.90 × 105 s-1, respectively. Besides these, the interaction mechanisms of aquated R and R' with the potential protein-binding sites cysteine (Cys) and selenocysteine (Sec) were also investigated in detail. The kinetic study and activation Gibbs free energy profiles reveal that the aquated complexes of R and R' bind more effectively to the Se site of Sec than to the S site of Cys. Intra- and intermolecular hydrogen bonding play a pivotal role in stabilizing the intermediates and transition states involved in the ligand substitution reactions of R and R'. Natural population analysis (NPA) was done to determine the charge distributions on important atoms during the hydrolysis and ligand substitution reactions.

Involvement of a unique chemodosimeter in the selective estimation of noxious cyanide in common water hyacinth (Eichhornia crassipes): an environmental refinement.

A naphthaldehyde-pyridoxal conjugated chemodosimeter (NPLC) was developed and employed for the sensitive and selective detection and estimation of cyanide in common water hyacinth (Eichhornia crassipes), a free floating macrophyte used in the phytoremediation process since ancient times. The non-fluorescent nature of the probe NPLC, directed by the possibility of excited state intramolecular proton transfer process (ESIPT), was promptly changed due to CN- induced di-deprotonation of the probe. The naked eye color change and turn on vivid fluorescent color of NPLC was attributed to the inhibition of the ESIPT mechanism in the deprotonated NPLC (NPLC-D). The selective detection of cyanide ion in the nanomolar range (81 nM), among other interfering anions, makes it exclusive. The involvement of the probe in a chemodosimetric fashion toward cyanide was elucidated by experimental and computational studies.

Calcium and Vitamin D Supplementation Effectively Alleviates Dental and Skeletal Fluorosis and Retain Elemental Homeostasis in Mice.

Fluoride (F) is an essential trace element, but chronic exposure beyond the permissible limit (1.5 ppm) effectuates dental and skeletal fluorosis. Although 200 million people across the world are suffering from toxic manifestations of F, till now proper treatment is not available. In this study, we assessed the effectiveness of calcium and vitamin D supplementation for alleviation of fluorosis. Swiss albino mice were divided into 6 groups; group I-control group (received drinking water ˂ 0.5 ppm F; within the permissible limit), group II-treated with 15 ppm of sodium fluoride (NaF) for 4 months, group III-treated with 15 ppm of NaF for 8 months through drinking water. Group IV-orally treated with 15 ppm NaF for 4 months, thereafter received only drinking water for next 4 months, group V-orally treated with 15 ppm NaF for 4 months, thereafter received drinking water supplemented with calcium and vitamin D (2.5-g calcium kg-1 diet and 1000 IU vitamin D kg-1 diet) for next 4 months, and group VI was treated with 15 ppm of NaF through drinking water as well as supplemented with calcium and vitamin D for 4 months. NaF treatment caused dental fluorosis, skeletal fluorosis, and alteration of bone's metal profile. Substitution of NaF-containing water with normal drinking water reduced the severity of fluorosis but supplementation of calcium and vitamin D effectively alleviated dental and skeletal fluorosis, reduced F deposition, and retained elemental homeostasis of the bone. Our findings strongly support that calcium and vitamin D act as redeemer of fluorosis. Graphical Abstract.

Combined effect of arsenic and fluoride at environmentally relevant concentrations in zebrafish (Danio rerio) brain: Alterations in stress marker and apoptotic gene expression.

Arsenic and fluoride are two naturally occurring toxicants to which various organisms including a major part of the human populations are co-exposed to. However, interactions between them inside body are quite complicated and needs proper evaluation. Inconclusive reports regarding their combined effects on brain prompted us to conduct this study where we investigated their individual as well as combined effects on female zebrafish brain at environmentally relevant concentrations (50 µgL-1 arsenic trioxide and 15 mgL-1 sodium fluoride) after different time intervals (15, 30 and 60 days). Persistent near-basal level of GSH, least increased MDA content and catalase activity portrayed arsenic and fluoride co-exposure as less toxic which was corroborated with far less damage caused in the histoarchitecture of optic tectum region in midbrain. Stress-responsive genes viz., Nrf2 and Hsp70 were overexpressed after individual as well as combined exposures, indicating a common cellular response to combat the formed oxidative stresses. Biphasic response of AChE upon individual exposure confirmed their neurotoxic effects too. Expression profile of p53 (unaltered), Bax (lower or near-basal) and Bcl2 (comparatively higher), along with absence of DNA fragmentation indicated no induction of apoptosis in the co-exposed group. Tissue accumulation of arsenic and fluoride was significantly less in the brain of co-exposed zebrafish when compared to their individual exposures. This preliminary study indicates an antagonistic effect of these two toxicants in zebrafish brain and needs further studies involving oxidative stress independent markers to understand the detailed molecular mechanism.

Environmentally relevant concentration of chromium induces nuclear deformities in erythrocytes and alters the expression of stress-responsive and apoptotic genes in brain of adult zebrafish.

Heavy metal contamination of water body has become a serious threat to aquatic life forms specially to fish. Hexavalent chromium (Cr [VI]) is one of the most potent heavy metal toxicant. It is present in aquatic environment at concentrations beyond permissible limit. Considering the fact that toxic effects are function of the exposure concentration, studies involving toxicological risk assessment should be done at environmentally relevant concentration. Therefore we studied the toxic effects of Cr [VI] to zebrafish at an environmentally relevant concentration (2 mg L-1). We monitored the genotoxic potential of Cr [VI] in erythrocytes through a simple reliable microscopic assay and found an increase in frequency of micronucleated erythrocytes along with erythrocytes with blebbed, lobed and notched nuclei. In addition, Cr [VI] induced neurotoxicity, being a least reported event was also investigated. Histological alterations in brain, elevated GSH and MDA content and increased catalase activity indicated oxidative stress-mediated damage. This was further confirmed through expressional alteration of Ucp2. Upregulation of Nrf2, Nqo1 and Ho1 clearly indicated the involvement of Nrf2-ARE system in stress response against Cr [VI] induced neurotoxicity. The transcriptional induction of apoptotic genes such as Bax, Caspase 9 and Caspase 3 along with downregulation of Bcl2 indicated that the cytoprotective system failed to counter the induced stress. Interestingly, there was upregulation of AChE gene, which could be correlated with the upregulated apoptotic genes. This study provides an insight on the neurotoxic stress of Cr [VI] on the zebrafish yet at an environmentally relevant concentration. Moreover the induction of nuclear anomalies in the erythrocytes can serve as extremely sensitive endpoints of toxicological stress indicators of aquatic contaminants like Cr [VI].

Shinorine ameliorates chromium induced toxicity in zebrafish hepatocytes through the facultative activation of Nrf2-Keap1-ARE pathway.

Hexavalent chromium, a heavy metal toxicant, abundantly found in the environment showed hepatotoxic potential in zebrafish liver and instigated the Nrf2-Keap1-ARE pathway as a cellular stress response as reported in our previous studies. In the present study we have evaluated the ameliorating effect of shinorine, a mycosporine like amino acid (MAAs) and a mammalian Keap1 antagonist against chromium induced stress in zebrafish hepatocytes. Shinorine was found to be effective in increasing the cell viability of chromium treated hepatocytes through curtailing the cellular ROS content. Trigonelline, an Nrf2 inhibitor was found to reduce the viability of hepatocyte cultures co-exposed to shinorine and chromium. In other words, trigonelline being an Nrf2 blocker neutralised the alleviating effect of shinorine. This indicated that shinorine mediated cyto-protection in Cr [VI]-intoxicated cells is Nrf2 dependent. Further, qRT-PCR analysis revealed comparatively higher expression of nfe2l2 and nqo1 in shinorine + chromium treated hepatocytes than cells exposed to chromium alone indicating a better functioning of Nrf2-Keap1-Nqo1 axis. To further confirm if shinorine can lead to disruption of Nrf2-Keap1 interaction in zebrafish hepatocytes and render cytoprotection to chromium exposure, our in silico analysis through molecular docking revealed that shinorine could bind to the active amino acid residues of the DGR domain, responsible for Nrf2-Keap1 interaction of all the three Keap1s evaluated. This is the first report about shinorine that ameliorates chromium induced toxicity through acting as an Nrf2-Keap1 interaction disruptor. We additionally carried out in-silico pharmacokinetic and ADMET studies to evaluate druglikeness of shinorine whose promising results indicated its potential to be developed as an ideal therapeutic candidate against toxicant induced pathological conditions.

Environmentally relevant concentration of chromium activates Nrf2 and alters transcription of related XME genes in liver of zebrafish.

Fish is an excellent model to decipher the mechanism of toxicity of aquatic contaminants such as hexavalent chromium (Cr [VI]). The present study looked into the manifestation of stress in liver of zebrafish exposed to an environmentally relevant concentration (2 mgL-1), and the functioning of the cytoprotective machinery that pacifies the formed stress. The results lead us to hypothesize that oxidative stress plays a key role in chromium-induced toxicity resulting in lipid peroxidation and extensive changes in tissue ultrastructure. In treated fish, production of reactive oxygen species, increase in reduced glutathione content and increase in malondialdehyde content along with enhanced catalase activity were evident. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was found to increase both at transcriptional and translational level and its translocation into the nucleus was confirmed by fluorescence-based immunohistochemical studies. The mRNA levels of genes like Nqo1, Cyp1a and Cu/Zn Sod were found to increase whereas Ho1, Hsp70 and Ucp2 were down-regulated. The sensitivity of these genes towards Cr [VI] validates their candidature as important biomarkers of Cr [VI] exposure in zebrafish.

Mixture effect of arsenic and fluoride at environmentally relevant concentrations in zebrafish (Danio rerio) liver: Expression pattern of Nrf2 and related xenobiotic metabolizing enzymes.

Nrf2 is a crucial transcription factor that regulates the expression of cytoprotective enzymes and controls cellular redox homeostasis. Both arsenic and fluoride are potent toxicants that are known to induce Nrf2. They are reported to coexist in many areas of the world leading to complex mixture effects in exposed organisms. The present study investigated the expression of Nrf2 and related xenobiotic metabolizing enzymes along with other stress markers such as histopathological alterations, catalase activity, reduced glutathione content and lipid peroxidation in zebrafish liver as a function of combined exposure to environmentally relevant concentrations of arsenic (37.87 µgL-1 or 5.05 × 10-7 M) and fluoride (6.8 mg L-1 or 3.57 × 10-4 M) for 60 days. The decrease in the total reduced glutathione level was evident in all treatment conditions. Hyperactivity of catalase along with conspicuous elevation in reactive oxygen species, malondialdehyde content and histo-architectural anomalies signified the presence of oxidative stress in the treatment groups. Nrf2 was seen to be induced at both transcriptional and translational levels in case of both individual and co-exposure. The same pattern was observed in case of its nuclear translocation also. From the results of qRT-PCR it was evident that at each time point co-exposure to arsenic and fluoride seemed to alter the gene expression of Cu/Zn Sod, Mn Sod, Gpx and Nqo1 just like their individual exposure but at a very low magnitude. In conclusion, this study demonstrates for the first time the differential expression and activity of Nrf2 and other stress response genes in the zebrafish liver following individual and combined exposure to arsenic and fluoride.

Quantum Chemical Studies on Detail Mechanism of Nitrosylation of NAMI-A-HSA Adduct.

Hydrolysis of NAMI-A in NAMI-A-HSA (HSA = human serum albumin) and nitrosylation of hydrolyzed NAMI-A-HSA adduct have been studied in detail using density functional theory method. It has been observed that the chloride exchange reaction with water in the NAMI-A-HSA adduct follows an interchange dissociative mechanism passing through an unstable heptacoordinated activated complex. The computed free energy of activation (ΔG) and rate constant (k) for the hydrolysis process in aqueous medium are observed to be 24.85 kcal mol(-1) and 3.81 × 10(-6) s(-1), respectively. Nitrosylation of hydrolyzed NAMI-A-HSA adduct with nitric oxide is found to be thermodynamically more favorable with the incorporation of solvent effect and provides a detailed understanding related to the antimetastatic activity of the NAMI-A drug. This investigation shows that nitric oxide coordinates linearly to NAMI-A-HSA adduct leading to the reduction of ruthenium(III) to more active ruthenium(II), with the reduction potential of -2.32 V. Negative relative solvation and relative binding free energies suggest that the hydrolysis and nitrosylation reactions are found to be thermodynamically favorable and faster. Our computed results provide a detailed thermodynamics and kinetics which may be highly beneficial for understanding antimetastatic activity as well as the nitric oxide scavenging ability of NAMI-A.

Novel water soluble neutral vanadium(IV)-antibiotic complex: Antioxidant, immunomodulatory and molecular docking studies.

A novel water soluble five coordinate oxovanadium(IV) complex, [VO(C16H15N4O8S)HSO4] incorporating cefuroxime, a cephalosporin group of antibiotic have been prepared from an interaction of vanadyl sulfate and cefuroxime in aqueous solution. The compound was characterized by Fourier transform infrared spectroscopy (FTIR), CHN microanalyses, ultraviolet-visible spectroscopy (UV-Vis), fast atom bombardment (FAB) mass spectrometry and thermogravimetric analysis (TGA). Density Functional Theory (DFT) computation using Gaussian 09 program at B3LYP level revealed a distorted square pyramidal energy optimized geometry for the vanadyl(IV) complex. The molecular docking studies show that the interaction between the vanadium complex and protein receptor, clathrin is dominated by hydrophobic forces. The experimental (1)H nuclear magnetic resonance (NMR) features of the analogous Zn(II) complex matched well with the theoretically computed values further affirming the distorted square pyramidal geometry for the vanadyl(IV) complex. Cyclic voltammetry revealed a metal centered single-electron oxidation-reduction response for VO(IV)/VO(V) couple. The antioxidant activity of the vanadium(IV)-complex vis-à-vis the antibiotic has been assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The vanadium complex showed comparatively better radical scavenging ability compared to the antibiotic cefuroxime. The antimicrobial activity of the compound has been assayed for five different microbial strains using minimum inhibitory concentration (MIC) method. Immunomodulatory studies carried out using phagocytosis index, myeloperoxidase release and cytokine assay indicated the vanadium(IV)-complex to be immunosuppressant. The cytotoxicity of the compound was evaluated by MTT (3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) reduction assay.