DFT and PM3 Computational Studies of the Reaction Mechanism of the Oxidation of L-Tyrosine by Iodine in the Gas Phase

- The oxidation of L-Tyrosine by molecular iodine was studied using semi-empirical and density functional theory methods. Molecular information such as net charges, values of frontier orbital energies, composition, proportions and bonding contribution were obtained and analyzed. Thus, possible reactive sites were proposed and the reaction mechanism was postulated. The postulated transition states, intermediates and products were also computed using the PM3 and DFT methods. Computed enthalpies of the oxidation reaction at standard conditions for the PM3 and DFT calculation were 216.97 kJ/mol and -36327404.72 kJ/mol respectively. The calculated ΔGo andΔSo, for the transition states according to the DFT model were both large and negative indicating that the processes were exergonic associative substitution reactions

Assessment of trace metals in sewage water and sludge from River Kubanni drainage basin

The concentrations of trace metals in sewage water and sludge samples from River Kubanni drainage basin in Zaria City, Nigeria were investigated in this study. The drainage basin is utilized as a source for irrigation water, during dry seasons. The sewage water quality characteristics in three month sampling periods, that is, February - April, 2008 (peak of dry season and period of intensive usage of the sewage water), the speciation of metals in the sewage sludge from the drainage basin, and the risk to sewage water column contamination were evaluated. The sewage water quality characteristics were mostly beyond the recommended irrigation water standards by the food and agriculture organization (FAO) and United State environmental protection agency (USEPA) except for zinc and nickel. In addition, the average values of Cd, Cu, Pb, Cl- and NO3- in sewage water samples analyzed were higher than the respective reference values for irrigation water. To study the speciation of metals in sewage sludge, five metals (Zn, Ni, Cu, Pb and Cd) in the sludge were subjected to sequential extractions. The metals analyzed were distributed in both the non-residual and residual phases. Total extractable trace metals in sewage sludge were: Zn (403.3 mg/kg dry weight), Ni (184.2 mg/kg dry weight), Cu (303.4 mg/kg dry weight), Pb (129.0 mg/kg dry weight) and Cd (19.7 mg/kg dry weight). However, there was low risk to sewage water contamination based on the calculated individual contamination factors (ICF) obtained for sewage sludge from the trace metal sequential extractions. From the calculated individual contamination factors, Ni and Zn followed by Cd and Pb posed the highest risk to sewage water contamination. Based on this study, the human health is at risk, since sewage water from the drainage basin has been the source for irrigation water during dry seasons, which might lead to trace metal ingestion by soil and subsequently by vegetables. Thus, this might become important pathways of human exposure to metal contamination.Key words: Trace metals, speciation, contamination factor, sewage water and sludge

In silico Studies of some potential anti-cancer agents on M19-MEL cell line

The resistance of melanoma cancer cells to the known treatments has become a barrier to the success of chemotherapy.  In this research, a quantitative evaluation of the structure-activity relationship (QSAR) was carried out on 57 anti-cancer compounds and some selected potent compounds were screened through Lipinski’s rule and docked. Genetic function algorithm (GFA) was adopted in variables selection and Multiple linear regression (MLR) was used to generate the model. The built QSAR model showed good statistical parameters (( (0.904),  (0.885), Q2cv (0.873) and  (0.779)). The cR⁠2⁠P for Y-randomization is 0.749 and the applicability domain was also determined. The predictive ability of the model was found to be satisfactory and could be used to predict the anti-cancer activity of compounds on M19 MEL cell line. 4 most potent compounds were selected among the data set and screened through Lipinski's rule of five filters for oral bioavailability, ADMET risk filter for a drug like features. Later, V600E-BRAF, a known melanoma cancer target was used for docking. Based on the interaction energy and types of interactions involved, the selected compounds were identified as the best hits against V600E-BRAF. This research would help in the lead identification and design of novel drugs

Biosorption of zinc from aqueous solution by Penicillium sp immobilised in Calcium alginate

The biosorption of Zn (II) in aqueous solution by alginate- immobilised Penicillium sp was investigated. Parameters which are responsible for optimizing sorption such as: initial pH of the solution, contact time and initial Zn (II) concentrations were varied and observed. The results were fitted into Langmuir, Freundlich and Temkin Isotherms. Optimization parameters were focused on initial solution pH, contact time and initial Zn (II) concentrations. Results were fitted to Langmuir, Freundlich and Temkin isotherms. The maximum Zn (II) biosorption of 94.29 % in aqueous solution was achieved at pH of 6.0, contact time of 120 minutes and initial Zn (II) concentration of 1 mg/L. The experimental results showed the R2 values for the isotherms to be 0.7591, 0.7780 and 0.9552 respectively for the Langmuir, Freundlich and Temkin isotherms indicating that the results fitted the Temkin isotherm more than the other isotherms. The maximum biosorption capacity was 3.78 mgg-1 while the value of n, a measure of biosorption intensity, was 1.43 Lmg-1 showing a favorable adsorption. These results show that immobilized Penicillium sp is a good biosorbent for the removal of Zn (II) from waste water with minimal environmental impact

THEORETICAL AND INSILCO PHARMACOKINETIC INVESTIGATIONS ON SOME PHENYL PIPERIDINE DERIVATIVES AS NOVEL ANTIDEPRESSANT AGENTS

A theoretical bioinformatic investigation was carried out on some Inhibitors of serotonin transporter (SERT) of Phenyl piperidine derivatives using Density Functional Theory (DFT/B3LYP/6-31G*) at ground state with Spartan 14 V1.1.4 software in modeling the antipsychotic activity of the compounds. The molecular descriptors were computed using the PaDEL-Descriptor software 2.20 version. Penta-parametric Multi-linear regression models were developed using the MLR-GFA for selecting the most important descriptors. The statistical parameters for the best model are; R2Train= 0.8572, R 2adj = 0.8274, R2Test = 0.678, Q2cv (LOO) = 0.7664, ?2= 0.0036, r2m (LOO)= 0.694 and Delta r2m (LOO)= 0.0051). Also, the estimated Chi-squared (?2= 0.0036), Root-mean squared error (RMSE= 0.168) and an

INVESTIGATION OF THE ACTIVITY OF 8- METHYLQUINOLONES AGAINST MYCOBACTERIUM TUBERCULOSIS USING THEORETICAL MOLECULAR DESCRIPTORS: A CASE STUDY

A quantitative structure-activity relationship (QSAR) study on a set of 36 structurally-similar 8-methylquinolones was performed using a large pool of theoretical molecular descriptors. The molecular structures of the compounds were pre-optimized using molecular mechanics (MM2). Full optimization was done with the density functional theory (DFT) using Becke’s three-parameter hybrid functional with LYP correlation functional in combination with the standard pople’s basis set 6311G*. HOMO and LUMO energies, dipole moment, total energy and many other properties served as quantum-chemical descriptors. The GA-MLRA technique was used to select the most significant descriptors and to generate a linear model for predicting the biological activity, Minimal Inhibitory Concentration (MIC), treated as negative decade logarithm, (pMIC). The best model was obtained with R2=0.90323 . The model was tested internally using the leave-one-out (LOO) cross validation procedure on the training set and validated against the external validation set (Q2 LOO = 0.83115 and R2 Pred = 0.78708 ). The Y-scrambling/randomization validation also confirmed the statistical significance of the model. Leverage approach was used to define the applicability domain of the model. This validated model could be used to design new potential drug candidates, within the 8-methylquinolone family, with high activity against tuberculosis

QSAR modeling of some anticonvulsant molecules as γ-aminobutyrate-aminotransferase inhibitors

Abstract Quantitative structure-activity relationship study was done on 62 compounds with anticonvulsant activity in maximal electroshock-induced seizures test. The molecular structure of the compounds was optimized with parametric semi-empirical PM3 method available in Spartan 14 software. Quantum mechanical descriptors were extracted from the property and output module of the software. Combination of activity based-clustering and genetic function algorithm chemo-metric techniques were used to map molecular descriptors to activity values. A well-validated and robust quantitative structure-activity model was obtained with R2 = 0.947, Q2= 0.924, F = 91.42 and R2pred(test) = 0.881. The descriptor contained in the model suggested an increase in the number of O and N atoms in the molecule augments the activity of the studied compounds. Also, the introduction of electron donating substituents is beneficial to the activity of the studied compounds. Armed with these, information, new hypothetical1H-pyrazole-5-carboxylic acid derivatives were designed using template approach and screened in silico. Compounds with hypothetic anticonvulsant activity better than the template were docked with γ-aminobutyrate-aminotransferase and their binding affinity was found to be comparable and even superior to that of 4-aminohex-5-enoic acid (vigabatrin), a known inhibitor of γ-aminobutyrate-aminotransferase

Seasonal Chemical Fractionation of Metals in Some Dumpsites Soils in Zaria Metropolis, Nigeria

The study was aimed at investigating the chemical fractionation, bioaccumulation and bioavailability of Hg, Cd, Cu, Pb and Zn in the refuse waste soils of some dumpsites across the seasons (wet and dry) in Zaria metropolis. The heavy metals in the waste soils were sequentially extracted and measured using atomic absorption spectrophotometry. The results revealed that high concentrations of metal in dry season. The non-residual fraction was found to be the most abundant pools for all the metals across the seasons (wet and dry). Also, significant amounts of Hg, Cd and Cu were mostly found in the bioavailable fractions across the sites in the seasons. Thus, these metals would readily be bioavailable to the environment. Overall, the order of mobility and bioavailability of these metals across the seasons (dry and wet) followed the pattern; Hg > Cd > Pb > Zn > Cu and Hg > Cd > Cu > Zn > Pb respectively. Tendencies of health risk for human and livestock due to the spread of the metal pollution from waste dumpsites to agricultural areas is high. Bioaccumulation of cadmium and mercury cause liver, brain and intestinal disorders, irreversible damage to nervous system and brain, protoplasmic poisoning etc. Keywords: Metals, Bioavailability, Dumpsites, Human Toxicity, Soil

Quantum Mechanics Calculation of Molybdenum and Tungsten Influence on the CrM-oxide Catalyst Acidity

Semi-empirical calculations were employed to understand the effects of introducing promoters such as molybdenum (Mo) and tungsten (W) on chromium (III) oxide catalyst for the dehydrogenation of propane into propylene. For this purpose, we investigated CrM-oxide (M = Cr, Mo, and W) catalysts. In this study, the Lewis acidity of the catalyst was examined using Lewis acidity parameters (Ac), including ammonia and pyridine adsorption energy. The results obtained from this study of overall acidity across all sites of the catalysts studied reveal Mo-modified catalyst as the one with the least acidity while the W-modified catalyst was found to have shown the highest acidity signifies that the introduction of Mo would reduce acidity while W accelerates it. The finding, therefore, confirms tungsten (W) to be more influential and would be more promising when compared to molybdenum (Mo) due to the better avenue that is offered by W for the promotion of electron exchange and its higher acidity(s). The suitability of some molecular descriptors for acidity prediction as a potential alternative to the current use of adsorption energies of the probes was also reported

Utjecaj Mo i W na katalitička svojstva CrXO3 (X = Cr, Mo, W) u procesu neoksidativne dehidrogenacije propana

The impact of molybdenum (Mo) and tungsten (W) on improving the catalytic characteristics of the chromium-based catalyst, Cr2O3, was explored in this study. The use of semi-empirical and density functional theory computational methods was deployed to understand the impact of the substitution of the chromium (Cr) with Mo and W on the catalyst, CrXO3 (where X = Cr, Mo, W) in the production of propylene from propane. Findings from the investigation confirmed that the surface modified with Mo showed better potential for improving the catalyst selectivity, retarding propylene dehydrogenation, cracking, and coking path than W, which offered a lower selectivity. The use of Mo was found to have better facilitated the propylene production due to its lower affinity for coke and cracking promoting adsorbates accounted for its sites, including easier desorption of propylene and higher barrier of deep dehydrogenation for preventing the production of undesired products, unlike the use of W. This study, therefore, recommends the use of Mo for the improvement of the catalyst that could result in better propylene yield, which could aid in meeting its rising market demand.S ciljem poboljšanja karakteristika katalizatora na bazi kroma, u ovom su se istraživanju kombinirano primijenile poluempirijske računalne metode i metode temeljene na teoriji funkcionala gustoće. Nastojao se dobiti uvid u katalitički potencijal izmjene kroma molibdenom i volframom u katalizatoru CrXO3 (gdje X označava krom, molibden i volfram) za dehidrogeniranje propana pri proizvodnji propilena. Rezultati su potvrdili da površina modificirana molibdenom pokazuje bolju selektivnosti u usporedbi s površinom modificiranom volframom, usporavajući dehidrogenaciju, pucanje i koksiranje propilena. Utvrđeno je da upotreba molibdena olakšava proizvodnju propilena zbog njegova nižeg afiniteta prema adsorbatima koji potiču pucanje i koksiranje, uključujući i lakšu desorpciju propilena te višu barijeru potpune dehidrogenacije što sprječava nastanak neželjenih produkata; to nije bio slučaj kod volframa. Ovo istraživanje stoga preporučuje upotrebu molibdena za poboljšanje svojstava katalizatora, što bi moglo rezultirati većim iskorištenjem u proizvodnji propilena te pomoći zadovoljavanju rastuće tržišne potražnje za propilenom