Phytoremediation of landfill leachate waste contaminants through floating bed technique using water hyacinth and water lettuce

Abstract

In the present study, the effectiveness of water hyacinth and water lettuce was tested for the phytoremediation of landfill leachate for the period of 15?days. Fifteen plastic containers were used in experimental setup where aquatic plants were fitted as a floating bed with the help of thermo-pole sheet. It was observed that both plants significantly (p?<?0.05/p?<?0.01/p?<?0.001) reduce the physicochemical parameters pH, TDS, BOD, COD and heavy metals like Zn, Pb, Fe, Cu and Ni from landfill leachate. Maximum reduction in these parameters was obtained at 50% and 75% landfill leachate treatment and their removal rate gradually increased from day 3 to day 15 of the experiment. The maximum removal rate for heavy metals such as for Zn (80–90%), Fe (83–87%) and Pb (76–84%) was attained by Eichhornia crassipes and Pistia stratiotes. Value of bioconcentration and translocation factor was less than 1 which indicates the low transport of heavy metals from roots to the above-ground parts of the plants. Both these plants accumulate heavy metals inside their body without showing much reduction in growth and showing tolerance to all the present metals. Therefore, results obtained from the study suggest that these aquatic plants are suitable candidate for the removal of pollution load from landfill leachate.     

Binding Mode Analyses and Pharmacophore Model Development for Stilbene Derivatives as a Novel and Competitive Class of α-Glucosidase Inhibitors

Stilbene urea derivatives as a novel and competitive class of non-glycosidic α-glucosidase inhibitors are effective for the treatment of type II diabetes and obesity. The main purposes of our molecular modeling study are to explore the most suitable binding poses of stilbene derivatives with analyzing the binding affinity differences and finally to develop a pharmacophore model which would represents critical features responsible for α-glucosidase inhibitory activity. Three-dimensional structure of S. cerevisiae α-glucosidase was built by homology modeling method and the structure was used for the molecular docking study to find out the initial binding mode of compound 12, which is the most highly active one. The initial structure was subjected to molecular dynamics (MD) simulations for protein structure adjustment at compound 12-bound state. Based on the adjusted conformation, the more reasonable binding modes of the stilbene urea derivatives were obtained from molecular docking and MD simulations. The binding mode of the derivatives was validated by correlation analysis between experimental K_i value and interaction energy. Our results revealed that the binding modes of the potent inhibitors were engaged with important hydrogen bond, hydrophobic, and π-interactions. With the validated compound 12-bound structure obtained from combining approach of docking and MD simulation, a proper four featured pharmacophore model was generated. It was also validated by comparison of fit values with the K_i values. Thus, these results will be helpful for understanding the relationship between binding mode and bioactivity and for designing better inhibitors from stilbene derivatives.     

Finding off‐targets,biological pathways,and target diseases for chymase inhibitors via structure‐based systems biology approach

Off‐target binding connotes the binding of a small molecule of therapeutic significance to a protein target in addition to the primary target for which it was proposed. Progressively such off‐targeting is emerging to be regular practice to reveal side effects. Chymase is an enzyme of hydrolase class that catalyzes hydrolysis of peptide bonds. A link between heart failure and chymase is ascribed, and a chymase inhibitor is in clinical phase II for treatment of heart failure. However, the underlying mechanisms of the off‐target effects of human chymase inhibitors are still unclear. Here, we develop a robust computational strategy that is applicable to any enzyme system and that allows the prediction of drug effects on biological processes. Putative off‐targets for chymase inhibitors were identified through various structural and functional similarity analyses along with molecular docking studies. Finally, literature survey was performed to incorporate these off‐targets into biological pathways and to establish links between pathways and particular adverse effects. Off‐targets of chymase inhibitors are linked to various biological pathways such as classical and lectin pathways of complement system, intrinsic and extrinsic pathways of coagulation cascade, and fibrinolytic system. Tissue kallikreins, granzyme M, neutrophil elastase, and mesotrypsin are also identified as off‐targets. These off‐targets and their associated pathways are elucidated for the effects of inflammation, cancer, hemorrhage, thrombosis, and central nervous system diseases (Alzheimer's disease). Prospectively, our approach is helpful not only to better understand the mechanisms of chymase inhibitors but also for drug repurposing exercises to find novel uses for these inhibitors. Proteins 2015; 83:1209–1224. © 2014 Wiley Periodicals, Inc.     

Investigation on the Phytochemical Composition,Antioxidant and Enzyme Inhibition Potential of Polygonum Plebeium R.Br: A Comprehensive Approach to Disclose New Nutraceutical and Functional Food Ingredients

The present work describes medicinal potential and secondary metabolic picture of the methanol extract (PP-M) of Polygonum plebeium R.Br. and its fractions; hexane (PP-H), ethyl acetate (PP-E) and water (PP-W). In total bioactive component estimation, highest contents of phenolic (89.38±0.27 mgGAE/g extract) and flavonoid (51.21±0.43 mgQE/g extract) were observed in PP-E, and the same fraction exhibited the highest antioxidant potential in DPPH (324.80±4.09 mgTE/g extract), ABTS (563.18±11.39 mgTE/g extract), CUPRAC (411.33±15.49 mgTE/g extract) and FRAC (369.54±1.70 mgTE/g extract) assays. In Phosphomolybdenum activity assay, PP-H and PP-E showed nearly similar potential, however, PP-H was the most active (13.54±0.24 mgEDTAE/g extract) in metal chelating activity assay. PP-W was the stronger inhibitor (4.03±0.05 mgGALAE/g extract) of the enzyme AChE, while PP-H was potent inhibitor of BChE (5.62±0.27 mg GALAE/g extract). Interestingly, PP-E was inactive against BChE. Against tyrosinase activity, PP-E was again the most active fraction with inhibitory value of 71.89±1.44 mg KAE/g extract, followed by the activity of PP-M and PP-W. Antidiabetic potential was almost equally distributed among PP-M, PP-H and PP-E. For mapping the chemodiversity of P. plebeium, PP-M was analyzed through UHPLC/MS, which led to the identification of more than 50 compounds. Flavonoids were the main components derived from isovitexin, kaempferol and luteolin however, gallic acid, protocatechuic acid, gingerols and lyoniresinol 9′-sulfate were among important bioactive phenols. These findings prompted to conclude that Polygonum plebeium can be a significant source to offer new ingredient for nutraceuticals and functional foods.     

A Combination of Receptor-Based Pharmacophore Modeling & QM Techniques for Identification of Human Chymase Inhibitors

Inhibition of chymase is likely to divulge therapeutic ways for the treatment of cardiovascular diseases, and fibrotic disorders. To find novel and potent chymase inhibitors and to provide a new idea for drug design, we used both ligand-based and structure-based methods to perform the virtual screening(VS) of commercially available databases. Different pharmacophore models generated from various crystal structures of enzyme may depict diverse inhibitor binding modes. Therefore, multiple pharmacophore-based approach is applied in this study. X-ray crystallographic data of chymase in complex with different inhibitors were used to generate four structure–based pharmacophore models. One ligand–based pharmacophore model was also developed from experimentally known inhibitors. After successful validation, all pharmacophore models were employed in database screening to retrieve hits with novel chemical scaffolds. Drug-like hit compounds were subjected to molecular docking using GOLD and AutoDock. Finally four structurally diverse compounds with high GOLD score and binding affinity for several crystal structures of chymase were selected as final hits. Identification of final hits by three different pharmacophore models necessitates the use of multiple pharmacophore-based approach in VS process. Quantum mechanical calculation is also conducted for analysis of electrostatic characteristics of compounds which illustrates their significant role in driving the inhibitor to adopt a suitable bioactive conformation oriented in the active site of enzyme. In general, this study is used as example to illustrate how multiple pharmacophore approach can be useful in identifying structurally diverse hits which may bind to all possible bioactive conformations available in the active site of enzyme. The strategy used in the current study could be appropriate to design drugs for other enzymes as well.     

Correction to: Characterization,the Antioxidant and Antimicrobial Activity of Exopolysaccharide Isolated from Poultry Origin Lactobacilli

Probiotics and Antimicrobial Proteins - The original version of this article unfortunately contained mistakes. Replacements are needed on the following figures and captions:     

Molecular dynamics simulation study and hybrid pharmacophore model development in human LTA4H inhibitor design

Human leukotriene A4 hydrolase (hLTA4H) is a bi-functional enzyme catalyzes the hydrolase and aminopeptidase functions upon the fatty acid and peptide substrates, respectively, utilizing the same but overlapping binding site. Particularly the hydrolase function of this enzyme catalyzes the rate-limiting step of the leukotriene (LT) cascade that converts the LTA4 to LTB4. This product is a potent pro-inflammatory activator of inflammatory responses and thus blocking this conversion provides a valuable means to design anti-inflammatory agents. Four structurally very similar chemical compounds with highly different inhibitory profile towards the hydrolase function of hLTA4H were selected from the literature. Molecular dynamics (MD) simulations of the complexes of hLTA4H with these inhibitors were performed and the results have provided valuable information explaining the reasons for the differences in their biological activities. Binding mode analysis revealed that the additional thiophene moiety of most active inhibitor helps the pyrrolidine moiety to interact the most important R563 and K565 residues. The hLTA4H complexes with the most active compound and substrate were utilized in the development of hybrid pharmacophore models. These developed pharmacophore models were used in screening chemical databases in order to identify lead candidates to design potent hLTA4H inhibitors. Final evaluation based on molecular docking and electronic parameters has identified three compounds of diverse chemical scaffolds as potential leads to be used in novel and potent hLTA4H inhibitor design.     

Production, purification and characterization of beta-1,4-endoglucanase from a novel bacterial strain CTP-09 of a Bacillus sp

Bacillus strain CTP-09 yielded maximum productivity (1120 IU/L.h) of extracellular endoglucanase (CMCase) on 0.5% cellobiose after 10 h fermentation at 55 degrees C. The purified enzyme is mono-meric in nature and exhibits stability up to 80 degrees C and over a pH range (6.0-9.0). Activation energy, enthalpy and entropy of catalysis, and inactivation indicated that this CMCase is highly thermos-table. Purified enzyme possessed high power of defibrillation of textile and was minutely inhibited by anionic detergent and oxidizing agent comparable with inhibition by commercial enzyme. This polypeptide could be exploited for mass production and application in local industries.     

Calcium alginate–starch hybrid support for both surface immobilization and entrapment of bitter gourd (Momordica charantia) peroxidase

Calcium alginate–starch hybrid gel was employed as an enzyme carrier both for surface immobilization and entrapment of bitter gourd peroxidase. Entrapped crosslinked concanavalin A–bitter gourd peroxidase retained 52% of the initial activity while surface immobilized and glutaraldehyde crosslinked enzyme showed 63% activity. A comparative stability of both forms of immobilized bitter gourd peroxidase was investigated against pH, temperature and chaotropic agent; like urea, heavy metals, water-miscible organic solvents, detergent and inhibitors. Entrapped peroxidase was significantly more stable as compared to surface immobilized form of enzyme. The pH and temperature-optima for both immobilized preparations were the same as for soluble bitter gourd peroxidase. Entrapped crosslinked concanavalin A–bitter gourd peroxidase showed 75% of the initial activity while the surface immobilized and crosslinked bitter gourd peroxidase retained 69% of the original activity after its seventh repeated use.     

A bioconvection model for viscoelastic nanofluid confined by tapered asymmetric channel: implicit finite difference simulations

As part of the growing evolution in nanotechnology and thermal sciences, nanoparticles are considered as an alternative solution for the energy depletion due to their ultra-high thermal effectives. Nanofluids reflect inclusive and broad-spectrum significances in engineering, industrial and bio-engineering like power plants, energy source, air conditioning systems, surface coatings, evaporators, power consumptions, nano-medicine, cancer treatment, etc. The present study describes the bio-convective peristaltic flow of a third-grade nanofluid in a tapered asymmetric channel. Basic conservation laws of mass, momentum, energy, and concentration as well as the microorganism diffusion equation are utilized to model the problem. The simplified form of the modeled expressions is accounted with long wavelength assumptions. For solving the resulting coupled and nonlinear equations, a well-known numerical method implicit finite difference scheme has been utilized. The graphical results describe the velocity, temperature and concentration profiles, and the density of motile microorganisms at the nanoscale. Furthermore, microorganism concentration lines are analyzed.