Comparative Analysis of Microbial Consortiums and Nanoparticles for Rehabilitating Petroleum Waste Contaminated Soils

Nano-bioremediation application is an ecologically and environmentally friendly technique to overcome the catastrophic situation in soil because of petroleum waste contamination. We evaluated the efficiency of oil-degrading bacterial consortium and silver nanoparticles (AgNPs) with or without fertilizer to remediate soils collected from petroleum waste contaminated oil fields. Physicochemical characteristics of control soil and petroleum contaminated soils were assessed. Four oil-degrading strains, namely Bacillus pumilus ({"type":"entrez-nucleotide","attrs":{"text":"KY010576","term_id":"1248281175"}}KY010576), Exiguobacteriaum aurantiacum ({"type":"entrez-nucleotide","attrs":{"text":"KY010578","term_id":"1248281177"}}KY010578), Lysinibacillus fusiformis ({"type":"entrez-nucleotide","attrs":{"text":"KY010586","term_id":"1248281185"}}KY010586), and Pseudomonas putida ({"type":"entrez-nucleotide","attrs":{"text":"KX580766","term_id":"1159332275"}}KX580766), were selected based on their in vitrohydrocarbon-degrading efficiency. In a lab experiment, contaminated soils were treated alone and with combined amendments of the bacterial consortium, AgNPs, and fertilizers (ammonium nitrate and diammonium phosphate). We detected the degradation rate of total petroleum hydrocarbons (TPHs) of the soil samples with GC-FID at different intervals of the incubation period (0, 5, 20, 60, 240 days). The bacterial population (CFU/g) was also monitored during the entire period of incubation. The results showed that 70% more TPH was degraded with a consortium with their sole application in 20 days of incubation. There was a positive correlation between TPH degradation and the 100-fold increase in bacterial population in contaminated soils. This study revealed that bacterial consortiums alone showed the maximum increase in the degradation of TPHs at 20 days. The application of nanoparticles and fertilizer has non-significant effects on the consortium degradation potential. Moreover, fertilizer alone or in combination with AgNPs and consortium slows the rate of degradation of TPHs over a short period. Still, it subsequently accelerates the rate of degradation of TPHs, and a negligible amount remains at the end of the incubation period.     

Risedronate and Methotrexate Are High-Affinity Inhibitors of New Delhi Metallo-β-Lactamase-1 (NDM-1): A Drug Repurposing Approach

Bacteria expressing New Delhi metallo-β-lactamase-1 (NDM-1) can hydrolyze β-lactam antibiotics (penicillins, cephalosporins, and carbapenems) and, thus, mediate multidrug resistance. The worldwide dissemination of NDM-1 poses a serious threat to public health, imposing a huge economic burden in the development of new antibiotics. Thus, there is an urgent need for the identification of novel NDM-1 inhibitors from a pool of already-known drug molecules. Here, we screened a library of FDA-approved drugs to identify novel non-β-lactam ring-containing inhibitors of NDM-1 by applying computational as well as in vitro experimental approaches. Different steps of high-throughput virtual screening, molecular docking, molecular dynamics simulation, and enzyme kinetics were performed to identify risedronate and methotrexate as the inhibitors with the most potential. The molecular mechanics/generalized Born surface area (MM/GBSA) and molecular dynamics (MD) simulations showed that both of the compounds (risedronate and methotrexate) formed a stable complex with NDM-1. Furthermore, analyses of the binding pose revealed that risedronate formed two hydrogen bonds and three electrostatic interactions with the catalytic residues of NDM-1. Similarly, methotrexate formed four hydrogen bonds and one electrostatic interaction with NDM-1’s active site residues. The docking scores of risedronate and methotrexate for NDM-1 were –10.543 kcal mol⁻¹ and −10.189 kcal mol⁻¹, respectively. Steady-state enzyme kinetics in the presence of risedronate and methotrexate showed a decreased catalytic efficiency (i.e., kcat/Km) of NDM-1 on various antibiotics, owing to poor catalytic proficiency and affinity. The results were further validated by determining the MICs of imipenem and meropenem in the presence of risedronate and methotrexate. The IC₅₀ values of the identified inhibitors were in the micromolar range. The findings of this study should be helpful in further characterizing the potential of risedronate and methotrexate to treat bacterial infections.     

Stereoselective synthesis of C-glycosides from carboxylic acids: the tandem Tebbe-Claisen approach

A variety of beta- or alpha-C-glycosides may be readily accessed in an entirely stereoselective fashion from esters derived from the reaction of carboxylic acids and 3-hydroxy glycals, by way of a tandem reaction sequence of Tebbe methylenation and Claisen rearrangement. Though of wide scope, for example allowing the synthesis of 1-6 linked C-disaccharides, the methodology does not currently allow the synthesis of C-glycosyl alpha-amino acids.     

Mass spectrometric detection of protein, lipid and heme components of cytochrome c oxidase from R. sphaeroides and the stabilization of non-covalent complexes from the enzyme

The cytochrome c oxidase enzyme from the Rhodobacter sphaeroides bacteria exists as a complex of four peptide subunits, two hemes, and a variety of lipids and metal ions held together by non-covalent forces. While the native enzyme functions as an associated unit, this complex usually dissociates during MALDI- TOF analysis. Through the use of matrix additives such as sucrose, the complete complex and partial complexes can be stabilized in the MALDI-TOF experiment. The dissociation of the complex allows for the detection of the components of the enzyme. The direct detection of associated lipids from an aqueous solution of the intact enzyme may eliminate the need for enzyme disruption and lipid extraction. The partial dissociation of multisubunit enzymes in such experiments may allow for the determination of subunit-subunit and subunit-lipid interactions     

Development of some important nitrogen donor ligands for transition metal homogeneous catalysis

This review provides a broad overview of the literature related to the importance of ligands in homogeneous catalysis. In particular, it describes the types of nitrogen donor ligands that have typically been used for homogeneous catalysis. We surveyed the important transition metal homogenous catalysts explicitly from 2011 up to early 2014 and summarize their comparative catalytic activities. Generally, the main factors observed are the ligand structure, electron donor property and steric bulk which can affect the catalytic activity. Electron count and inductive effect can also influence the efficiency of homogeneous catalyst.     

The coordination chemistry of perfluorovinyl substituted phosphine ligands, a crystallographic and spectroscopic study. Co-crystallisation of both cis- and trans-isomers of [PtCl2{P(i)pr2(CF=CF2)}2] within the same unit cell

The coordination chemistry of the perfluorovinyl phosphines PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy,(CF=CF2) and PPh(CF=CF2)2 to rhodium(I), palladium(II), and platinum(II) centres has been investigated. The electronic properties of the ligands are estimated based on v(CO) and 1J(Rh-P) values. X-Ray diffraction data for the square-planar Pd(II) and Pt(II) perfluorovinyl-phosphine containing complexes allow estimates of the steric demand for the series of ligands PPh2(CF=CF2), PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy2(CF=CF2) and PPh(CF=CF2)2 to be determined. The (CF=CF2) fragment is found to be more electron withdrawing than (C6F5) yet sterically less demanding. These ligands therefore provide a range of electron-neutral to phosphite-like electronic properties combined with a range of steric demands. This study also reveals that short intramolecular interactions from the metal centre to the beta-fluorine atom cis to phosphorus of the CF=CF2 groups are observed in all-trans square planar complexes of the ligands. Unusually, the complex [PtCl2{P(i)Pr2(CF=CF2)}2] crystallises with both cis- and trans-isomers present in the unit cell. It appears that co-crystallisation of both isomers occurs in order to maximise fluorous regions in the crystal packing, and the extended structure displays short fluorine-fluorine contacts. The generation of mixed geometries seems to be a phenomenon of crystallisation, as solution phase NMR studies reveal the presence of only the trans-isomer.     

Direct and simultaneous profiling of epoxyeicosatrienoic acid enantiomers by capillary tandem column chiral-phase liquid chromatography with dual online photodiode array and tandem mass spectrometric detection

Despite first evidence for the cytochrome P450-mediated enantioselective biosynthesis and activity of cis-epoxyeicosatrienoic acids (EETs), as yet little is known about the stereospecifity of EET generation and physiology, because the existing chiral methods are time consuming, labor intensive, and not sensitive enough. We present a method for highly sensitive, direct, and simultaneous chiral analysis of all eight EET enantiomers consisting of (i) solid-phase extraction, (ii) reversed-phase high-performance liquid chromatographic purification followed by (iii) consecutive regio- and enantiomeric separation of the four underivatized EET regioisomers within one chromatographic run employing capillary tandem column chiral-phase liquid chromatography with (iv) reliable dual online photodiode array and gentle electrospray ionization tandem mass spectrometric identification and quantitation of the eluting optical antipodes. This one-step, simple, expeditious, and highly sensitive measurement allows profiling of all eight EET enantiomers at once, thus avoiding substance loss and enabling high sample throughput. Limits of quantification in the low picogram range were achieved by the use of capillary columns with typical high quantitative sensitivity instead of conventional columns with low chromatographic signal intensity employed by previous methods. Application to tissue homogenates demonstrated the suitability of this approach for routine and reliable “enantioprofiling” of free endogenous EETs, i.e., EETs not esterified into cellular membrane phospholipids, typically occurring at very low concentrations. The technique can readily be employed for preparative purification of enantiomers in the microgram range using large-inner-diameter columns. Figure Direct and simultaneous enantioprofiling of the four free endogenous epoxyeicosatrienoic acids (EETs) from a complex biological matrix, like the cardiopulmonary system, within one chromatographic run by highly sensitive, one-step capillary tandem column chiral-phase liquid chromatography with dual online photodiode array and tandem mass spectrometric detection (CapTC-CP-LC-PDAD-ESI-MS²) enables accurate, systematic, and routine correlation between the absolute configuration of EETs and their physiological actions Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The absolute configuration of streptonigrin

A theoretical study of the molecular circular dichroism (CD) of the antitumor antibiotic natural product streptonigrin is described, aiming at the secure assignment of its absolute configuration by comparison of the CD spectra predicted for M and P, with the experimental one. The stereostructure of streptonigrin was previously investigated by two other groups, yet leading to two different attributions. Although streptonigrin possesses two biaryl axes, only the ‘southern’ one is configurationally stable and thus responsible for the chiroptical properties, since the ‘northern’ AB-ring system of the molecule is kept in plane with ring C by hydrogen bonding. All computational methods applied within this work to simulate the CD spectrum—semiempirical approaches and time-dependent density functional theory (TDDFT)—consistently attribute the M-configuration to streptonigrin.     

Quantitative Analysis of Nicorandil in Commercial Tablets by Spectrophotometry

The main aim of this work is to develop and validate a spectrophotometric method for the determination of nicorandil in commercial tablets. The method is based on the reduction of the nitroxy ethyl group of nicorandil into carbonyl compound and nitrite ion by NH₄Cl and Zn dust. The nitrite ion thus formed reacts with potassium iodide and starch in dilute HCl medium to form a blue product, which absorbs maximally at 550 nm. Beer's law is obeyed in the concentration range 0.4‐4.0 μg mL^?1 with molar absorptivity of 7.92 × 10⁴L mol^?1 cm^?1. The detection limit is 0.017 μg mL^?1. The reaction conditions are optimized and validated as per the International Conference on Harmonisation guidelines (USA). The proposed method has been applied successfully for the determination of nicorandil in commercial tablets. The results of analyses are compared statistically with those of the author's spectrophotometric method, which confirmed that there is no significant difference between the methods compared.     

Solute–Solvent Interactions of Methyl Violet in Different Solvents on Spectral Data

Spectroscopic studies of Methyl violet in protic (water, methanol, ethanol, isopropanol and n-butanol) and aprotic solvents (acetone, DMF) were carried out. UV-Visible absorption spectra of Methyl violet in protic solvents showed a hypsochromic shift, as the solvent polarity was changed from less polar to more polar, while a bathochromic shift was observed for aprotic solvents. Transition energy of Methyl violet in different solvents was correlated with solvatochromic parameters to study solute–solvents interactions. The Kamlet–Taft, Catalan and unified scale models were applied to investigate interactions between Methyl violet and solvents. The best agreement is found for the Catalan model.