High Binding Ability Research Articles

The effect of antibiotics and photodynamic therapy on extended-spectrum beta-lactamase (ESBL) positive of Escherichia coli and Klebsiella pneumoniae in urothelial cells.

Background/aimUrinary tract infections are commonly caused by the bacteria Escherichia coli and Klebsiella pneumoniae (UTI). The emergence of extended-spectrum -lactamase (ESBL)-producing bacteria strains has made UTI treatment more difficult.Materials and methodsThe aim of this study was to characterize E. coli and K. pneumoniae strains' cytotoxic effects, antibiotic sensitivity, interaction with urothelial cells, and reaction to photodynamic therapy.ResultsAs demonstrated by the higher number of colonies formed, the ESBL + E. coli and K. Pneumonia showed a higher degree of binding with human urothelial cells. With the urothelial cells, K. Pneumonia had the highest binding ability. The cytotoxicity of non-ESBL generating E. coli and K. Pneumonia, on the other hand, was higher. With longer incubation, the discrepancy between the cytotoxic effects of non-ESBL producer and ESBL + E. coli decreased. K. Pneumonia was the opposite. The concentration of ESBL-negative E. coli was easily decreased by photodynamic therapy; however, after a two-hour incubation period, the number of E. coli ESBL + colonies increased from 124 percent to 294 percent.ConclusionWith the duration of the incubation period, the number of non-ESBL-producing K. Pneumonia increased. Even with longer incubation times, the number of K. Pneumonia ESBL + colonies decreased, contrary to expectations. The findings show that the two bacterial species differed in terms of cytotoxicity, interaction with urothelial cells, and photodynamic therapy response.

Humidity sensor based on Gallium Nitride for real time monitoring applications

Gallium Nitride (GaN) remarkably shows high electron mobility, wide energy band gap, biocompatibility, and chemical stability. Wurtzite structure makes topmost Gallium atoms electropositive, hence high ligand binding ability especially to anions, making it usable as humidity sensor due to water self-ionization phenomenon. In this work, thin-film GaN based humidity sensor is fabricated through pulse modulated DC magnetron sputtering. Interdigitated electrodes (IDEs) with 100 μm width and spacing were inkjet printed on top of GaN sensing layer to further enhance sensor sensitivity. Impedance, capacitance, and current response were recorded for humidity and bio-sensing applications. The sensor shows approximate linear impedance response between 0 and 100% humidity range, the sensitivity of 8.53 nF/RH% and 79 kΩ/RH% for capacitance and impedance, and fast response (Tres) and recovery (Trec) time of 3.5 s and 9 s, respectively. The sensor shows little hysteresis of < 3.53% with stable and wide variations for accurate measurements. Especially, it demonstrates temperature invariance for thermal stability. Experimental results demonstrate fabricated sensor effectively evaluates plant transpiration cycle through water level monitoring by direct attachment onto leaves without causing any damage as well as freshness level of meat loaf. These properties of the proposed sensor make it a suitable candidate for future electronics providing a low-cost platform for real time monitoring applications.

Dragon Fruits as a Reservoir of Natural Polyphenolics with Chemopreventive Properties.

Dragon fruits are a valued source of bioactive compounds with high potential to become a functional food. The aim of the study was to evaluate and compare the chemopreventive potential and chemical composition of fruits harvested in Thailand and Israel. The amount of different compounds in water and methanol extracts and antioxidant activity was investigated. Moreover, cytotoxic activity against cancer and normal cells of skin, prostate, and gastrointestinal origin was performed, accompanied by anti-inflammatory assay based on NO production in RAW 264.7 macrophage model. Additionally, the quenching properties of polyphenols from fruits were determined by the interaction of the main drug carrier in blood human serum (HSA). The chemometric analysis was used to reveal the relationships between the determined parameters. Dragon fruits harvested in Israel revealed higher antioxidant properties and total content of polyphenols and betacyanins when compared to those from Thailand. The examined fruits of both origins showed significant cytotoxic activity toward colon and prostate cancer cells, with no toxic effect on normal cells, but also no anti-inflammatory effect. Moreover, a high binding ability to HSA was observed for water extracts of dragon fruits. All these predestine dragon fruits are the candidates for the attractive and chemopreventive elements of daily diet.

STUDY OF THE SORPTION ABILITY OF NATURAL SORBENTS ISOLATED FROM THE CAMPSIS RADICANS

Currently, more and more chemical additives are used in food products, which leads to the accumulation of harmful substances in the body. Therefore, it is relevant to search for new substances of natural origin with detoxification properties. The aim of the work was to determine the sorption ability of pectin substances and water-soluble polysaccharides isolated from the leaves and flowers of the campsis radicans. By the method of N.K. Kochetkova and M. Sinner isolated polysaccharides from water-borne campsis leaves and flowers: water-soluble polysaccharides, pectin, hemicellulose A and hemicellulose B. The adsorption capacity of pectins and water-soluble polysaccharides was studied on the basis of their complexing properties with respect to lead ions. The determination of their content in the raffinate was carried out by titration with a solution of sodium ethylenediaminetetraacetate disubstituted. To evaluate the nature of the sorbent, the calculated Langmuir and Freindlich equations were used. A study of the sorption ability of polysaccharides isolated from leaves of the campsis radicans showed the presence of a high binding ability of Pb2+ ions in pectin substances was associated with 54.2%, and in water-soluble polysaccharides – 37.5%. Polysaccharides isolated from the flowers of the campsis radicans showed sorption activity in the ratio: pectin substances – 32.6%, water-soluble polysaccharides – 80.1%.&#x0D; The expressed complexing ability of the studied polysaccharides with respect to lead ions was revealed. The ratio of the experimental and calculated data on the values of the adsorption of lead ions showed that the sorption process is largely subordinate to the Langmuir equation. Pectic substances and water-soluble polysaccharides obtained from the leaves and flowers of the campsis radicans can be considered as effective detoxifiers. Further study of the physicochemical properties will make it possible to assess the possibility of their biomedical use.

Screening of novel alkaloid inhibitors for vascular endothelial growth factor in cancer cells: an integrated computational approach.

Vascular endothelial growth factor (VEGF) is expressed at elevated levels by most cancer cells, which can stimulate vascular endothelial cell growth, survival, proliferation as well as trigger angiogenesis modulated by VEGF and VEGFR (a tyrosine kinase receptor) signaling. The angiogenic effects of the VEGF family are thought to be primarily mediated through the interaction of VEGF with VEGFR-2. Targeting this signaling molecule and its receptor is a novel approach for blocking angiogenesis. In recent years virtual high throughput screening has emerged as a widely accepted powerful technique in the identification of novel and diverse leads. The high-resolution X-ray structure of VEGF has paved the way to introduce new small molecular inhibitors by structure-based virtual screening. In this study using different alkaloid molecules as potential novel inhibitors of VEGF, we proposed three alkaloid candidates for inhibiting VEGF and VEGFR mediated angiogenesis. As these three alkaloid compounds exhibited high scoring functions, which also highlights their high binding ability, it is evident that these alkaloids can be taken to further drug development pipelines for use as novel lead compounds to design new and effective drugs against cancer.

Identification and functional characterization of odorant-binding proteins 69a and 76a of Drosophila suzukii

The fruit fly Drosophila suzukii is a fruit crop pest that causes a severe economic threat to soft summer fruit worldwide. The male sex pheromone, cis-vaccenyl acetate (cVA) has multiple functions in intra-species communication in Drosophila melanogaster, which is required in male to suppress male-male courtship. D. suzukii males do not produce cVA; however, the odorant receptor for cVA (Or67d) is still functional. The lack of cVA in D. suzukii casts the question of whether this pheromone might have been replaced by another compound similar to cVA that disrupts mating in D. suzukii. In order to address this question, we cloned two D. suzukii adult antenna-specific odorant-binding proteins (OBPs) DsOBP69a and DsOBP76a and aligned with their D. melanogaster orthologues. Moreover, we examined the binding properties of the newly identified recombinant proteins against 26 potential ligands including cVA, using the fluorescence-based ligand binding assay. The alignment showed that DsOBP69a and DsOBP76a, have six conserved cysteines and belong to the classic OBP family. Furthermore, our results revealed that cVA did not bind to DsOBP69a or DsOBP76a proteins. Interestingly, the floral odorant β-ionone and the bitter substance berberine chloride and coumarin displayed high binding ability. It is also worth noting that DsOBP69a and DsOBP76a have different affinities to (Z)-7-Tricosene that may reflect different functional roles. These findings suggest that DsOBP69a and DsOBP76a are potentially involved in olfaction and gustation of D. suzukii.

Real-Time Quantification of Cartilage Degeneration by GAG-Targeted Cationic Nanoparticles for Efficient Therapeutic Monitoring in Living Mice.

One of the characterizations of degenerative cartilage disease is the progressive loss of glycosaminoglycans (GAGs). The real-time imaging method to quantify GAGs is of great significance for the biochemical analysis of cartilage and diagnosis and therapeutic monitoring of cartilage degeneration in vivo. To this end, a cationic photoacoustic (PA) contrast agent, poly-l-lysine melanin nanoparticles (PLL-MNPs), specifically targeting anionic GAGs was developed in this study to investigate whether it can image cartilage degeneration. PLL-MNP assessed GAG depletion by Chondroitinase ABC in vitro rat cartilage and intact ex vivo mouse knee joint. A papain-induced cartilage degenerative mice model was used for in vivo photoacoustic imaging (PAI). Oral cartilage supplement glucosamine sulfate was intragastrically administered for mice cartilage repair and the therapeutic efficacy was monitored by PLL-MNP-enhanced PAI. Histologic findings were used to further confirm PAI results. In vitro results revealed that the PLL-MNPs not only had a high binding ability with GAGs but also sensitively monitored GAG content changes by PAI. The PA signal was gradually weakened along with the depletion of GAGs in cartilage. Particularly, PLL-MNPs depicted the cartilage structure and the distribution of GAGs was demonstrated in PA images in ex vivo joints. Compared with the normal joint, a lower signal intensity was detected from degenerative joint at 3 weeks after papain injection, suggesting an early diagnosis of cartilage lesion by PLL-MNPs. Importantly, this PA-enhanced nanoprobe was suitable for monitoring in vivo efficacy of glucosamine sulfate, which effectively blocked cartilage degradation in a high dose manner. In vivo imaging findings correlated well with histological examinations. PLL-MNPs provided sensitive visualization of cartilage degeneration and promising monitoring of therapeutic response in living subjects.

Colorimetric determination of amyloid-β peptide using MOF-derived nanozyme based on porous ZnO-Co3O4 nanocages.

A sensitive and rapid colorimetric biosensor has been developed for determination of amyloid-β peptide (Aβ) and study ofamyloidogenesis based on the high peroxidase-like activity of porous bimetallic ZnO-Co3O4 nanocages (NCs). Due to the high binding ability of Aβ monomer to ZnO-Co3O4 NCs, the catalytic activity of ZnO-Co3O4 NCs can be significantly suppressed by Aβ monomer. This finding forms the basis for a colorimetric assay for Aβ monomer detection. The detection limit for Aβ monomer is 3.5nM with a linear range of 5 to 150nM (R2 = 0.997). The system was successfully applied to the determination of Aβ monomer in rat cerebrospinal fluid. Critically, the different inhibition effects of monomeric and aggregated Aβ species on the catalytic activity of ZnO-Co3O4 NCs enabled the sensor to be used for tracking the dynamic progress of Aβ aggregation and screening Aβ inhibitors. Compared with the commonly used thioflavin T fluorescence assay, this method provided higher sensitivity to the formation of Aβ oligomer at the very early assembly stage. Our assay shows potential application in early diagnosis and therapy of Alzheimer's disease (AD).

Platinum-group elements sorption by living macroalgae under different contamination scenarios

Increasing emissions of Platinum-Group Elements (PGE) into marine environments may negatively impact ecosystems services and organisms wellbeing. Removing PGE from contaminated systems using efficient and low-cost technologies can therefore provide a sustainable solution to aquatic systems remediation. Previous studies highlight algae’s high binding ability to metals in solution. Assessing the viability of various algae species to remove PGE from contaminated solutions, while identifying differences in performance among algae and among elements, was the purpose of this study. For this, six macroalgae species (Ulva lactuca, Ulva intestinalis, Fucus spiralis, Fucus vesiculosus, Osmundea pinnatifida and Gracilaria sp., 3 g L−1) were exposed to PGE (Palladium, Rhodium, Ruthenium, Iridium and Platinum)-spiked seawater (10 and 500 µg L−1) for 72 h. Removal rates varied with time and among macroalgae and elements. Palladium was easily removed by all species (up to 83 %), while other PGE showed lower affinity to macroalgae. Removal sequence was Pd > Rh > Ru > Ir > Pt. Initial concentration rise induced faster and higher removal. U. lactuca performed best for all elements, while brown macroalgae were the less effective. Macroalgae external area and chemical composition were considered major factors influencing sorption, although each element and macroalgae should be examined individually. Results evidence living macroalgae (particularly U. lactuca) as a promising alternative to remediate PGE contaminated waters.

Hydrophobic insertion-based engineering of tumor cell-derived exosomes for SPECT/NIRF imaging of colon cancer

BackgroundTumor cell-derived exosomes (TEx) have emerged as promising nanocarriers for drug delivery. Noninvasive multimodality imaging for tracing the in vivo trafficking of TEx may accelerate their clinical translation. In this study, we developed a TEx-based nanoprobe via hydrophobic insertion mechanism and evaluated its performance in dual single-photon emission computed tomography (SPECT) and near-infrared fluorescence (NIRF) imaging of colon cancer.ResultsTEx were successfully isolated from HCT116 supernatants, and their membrane vesicle structure was confirmed by TEM. The average hydrodynamic diameter and zeta potential of TEx were 110.87 ± 4.61 nm and –9.20 ± 0.41 mV, respectively. Confocal microscopy and flow cytometry findings confirmed the high tumor binding ability of TEx. The uptake rate of 99mTc-TEx-Cy7 by HCT116 cells increased over time, reaching 14.07 ± 1.31% at 6 h of co-incubation. NIRF and SPECT imaging indicated that the most appropriate imaging time was 18 h after the injection of 99mTc-TEx-Cy7 when the tumor uptake (1.46% ± 0.06% ID/g) and tumor-to-muscle ratio (8.22 ± 0.65) peaked. Compared with radiolabeled adipose stem cell derived exosomes (99mTc-AEx-Cy7), 99mTc-TEx-Cy7 exhibited a significantly higher tumor accumulation in tumor-bearing mice.ConclusionHydrophobic insertion-based engineering of TEx may represent a promising approach to develop and label exosomes for use as nanoprobes in dual SPECT/NIRF imaging. Our findings confirmed that TEx has a higher tumor-targeting ability than AEx and highlight the potential usefulness of exosomes in biomedical applications.

Renaturation of Lyophilized Concanavalin a Treated in Water Content Controlled Hydrated Ionic Liquids

A fraction of commercially available lyophilized concanavalin A (ConA) shows low mannose binding activity. In this study, we investigated the effects of the component ion and water content of hydrated ionic liquids (ILs) as treatment solvent on the mannose binding ability of lyophilized ConA. While high mannose binding ability was observed treated in hydrated ILs composed of dihydrogen phosphate anion with three water molecules per ion pair, it decreased with increase in water content. In contrast, no increase in mannose binding ability was observed after treatment with hydrated ILs composed of bromide anions. A steady response in mannose binding was observed after treatment with hydrated cholinium dihydrogen phosphate ([ch][dhp]). Following treatment with hydrated [ch][dhp] with three water molecules per ion pair, the mannose binding ability of lyophilized ConA increased twofold, while the low and high mannose binding ConA fraction showed an increase of 3.3 and 1.8 in the binding response, respectively.

Synthesis, structural characterization, and biological studies of ATBS–M complexes (M(II) = Cu, Co, Ni, and Mn): Access for promising antibiotics and anticancer agents

A new bidentate Schiff base ligand (ATBS [4-bromo-2-(thiazole-2-yliminomethyl)phenol]) was synthesized via the condensation reaction of 2-aminothiazole with 5-bromosalicylaldehyde in ethanol. The reaction of ATBS with transition metal salts of Cu(II), Co(II), Ni(II), and Mn(II) afforded the corresponding ATBS-M complexes. Results from physicochemical and spectral analyses, such as elemental analysis, infrared, UV-Vis spectroscopy, magnetic susceptibility, and molar conductance, revealed a nonelectrolytic nature with octahedral (Oh ) geometry and a metal/ligand ratio of 1:2 for Cu(II), Co(II), and Ni(II), but 1:1 for the Mn(II) complex. The density functional theory (DFT) calculations are correlated very well with the proposed structure and molecular geometry of the complexes as [M(ATBS)2 ] (M = Cu, Co, and Ni) and [Mn(ATBS)(H2 O)2 ]. Significantly, the prepared compounds showed strong inhibition activity for a wide spectrum of bacteria (Escherichia coli, Bacillus subtilis, and Staphylococcus aureus) and fungi (Candida albicans, Aspergillus flavus, and Trichophyton rubrum), with the ATBS-Ni complex being the most promising antibiotic agent. Molecular docking studies of the binding interaction between the title complexes with the bacterial protein receptor CYP51 revealed clear insights about the inhibition nature against the studied microorganisms, with the following order: ATBS-Cu > ATBS-Mn > ATBS-Ni > ATBS-Co for complex stability. Moreover, the cytotoxicity measurements of all prepared metal complexes against the colon carcinoma (HCT-116) and hepatocellular carcinoma (Hep-G2) cell lines showed exceptional anticancer efficacy of the complexes as compared with the free ATBS Schiff base ligand. Significantly, the results attested that ATBS-Cu is the most effective complex against HCT-116 cells, whereas ATBS-Mn has the highest cytotoxic efficiency against Hep-G2 cells. Furthermore, electronic spectra, viscosity measurements, and gel electrophoresis techniques were employed to probe the interaction of all prepared ATBS-metal complexes with calf thymus (CT)-DNA. Results confirmed that all complexes are strongly bound to CT-DNA via intercalation mode, with the ATBS-Co complex having the highest binding ability.

Bivalence metal complexes of antithyroid drug carbimazole; synthesis, characterization, computational simulation, and biological studies

New metal complexes of carbimazole (CMZ) were synthesized with a molar ratio of 1:2. The bivalence complexes were characterized by various techniques, such as elemental analyses and UV–visible spectra, magnetic, and thermal analysis. The metal-ligand stability constant obtained from the molar ratio experiment showed high copper complex stability among the prepared metal compounds at room temperature (Kf =6.6 × 105). The infrared spectra (IR) showed that the CMZ ligand coordinated to the metal through the sulfur atom and the oxygen ether group. The spectroscopic results suggested tetrahedral geometry for all complexes except Ni(II) and Zn(II) complexes with a square planar arrangement. The proposed structures were optimized using density functional theory (DFT/B3LYP) and 6–311G*(d,p) basis sets. The geometrical optimization parameters and molecular electrostatic potentials were calculated. Biological investigation started with DNA binding spectroscopy, which revealed a high binding ability of the Cu(II) and Ni(II) complexes to the CT-DNA. A docking study using different protein receptors was implemented to study the proposed drug's molecular behavior. The in vitro cytotoxicity evaluation of the complexes toward breast human cancer (Mcf7) and human colon cancer (CaCo-2) cell linesindicated that the Cu(II)-CMZ complex has high potential anticancer activities against those cell lines.

Material basis and mechanism of Xiao'er Resuqing Oral Liquid on hand, foot and mouth disease based on network pharmacology and molecular docking

This paper aimed to investigate the active components and molecular mechanism of Xiao'er Resuqing Oral Liquid on hand, foot and mouth disease(HFMD) based on network pharmacology and molecular docking methods. The potential active components of 8 herbs in Xiao'er Resuqing Oral Liquid were selected through Traditional Chinese Medicine Systems Pharmacology Database(TCMSP), Batman database and relevant literature consultation. Then related targets for the medicine were analyzed through PubChem and Swiss Target Prediction database, while related targets for HFMD were analyzed through GeneCards platform. The common targets for medicine and disease were put into STRING database to obtain the potential targets of Xiao'er Resuqing Oral Liquid for treatment of HFMD. The Cytoscape software was used to establish the &quot;herbs-components-targets-disease&quot; network. The protein-protein interaction(PPI) network was constructed based on STRING platform and Cytoscape software to screen the core targets. Based on Metascape platform, GO function enrichment analysis and KEGG signal pathway enrichment analysis were carried out. The main active components and potential key targets of Xiao'er Resuqing Oral Liquid were verified by molecular docking with Autodock vina 1.1.2 software. A total of 118 potential active components and 123 potential targets for treatment of HFMD were collected. PPI network indicated a total of 23 key targets, such as AKT1, MAPK1, IL6, VEGFA, EGFR, TNF, HRAS, CCND1, and CXCL8. GO function enrichment analysis results showed that there were 381 GO biological processes, 127 GO cellular components, and 117 GO molecular functions(P&lt;0.01). KEGG enrichment analysis showed that 116 signal pathways were obtained(P&lt;0.01), and the results showed that it was mainly associated with TNF signal pathway, IL-17 signal pathway, inflammatory mediator regulation of TRP channels, and cytokine-cytokine receptor interaction. Molecular docking results showed that the main active components all had a high binding ability with the main potential key targets. This study preliminarily investigated the multi-pathways, multi-targets and multi-components molecular mechanism of Xiao'er Resuqing Oral Liquid for treatment of HFMD, providing theoretical references for further researches on its active components and action mechanism.

An Odorant Binding Protein (SaveOBP9) Involved in Chemoreception of the Wheat Aphid Sitobion avenae.

Odorant binding proteins play a key role in the olfactory system and are involved in the odor perception and discrimination of insects. To investigate the potential physiological functions of SaveOBP9 in Sitobion avenae, fluorescence ligand binding experiments, molecular docking, RNA interference, and behavioral tests were performed. Fluorescence binding assay results showed that SaveOBP9 had broad and high (Ki < 10 μM) binding abilities with most of the wheat volatiles, but was more obvious at pH 7.4 than pH 5.0. The binding sites of SaveOBP9 to the volatiles were predicted well by three-dimensional docking structure modeling and molecular docking. Moreover, S. avenae showed a strong behavioral response with the four compounds of wheat. The reduction in mRNA transcript levels after the RNA interference significantly reduced the expression level of SaveOBP9 and induced the non-significant response of S. avenae to the tetradecane, octanal, decanal, and hexadecane. This study provides evidence that SaveOBP9 might be involved in the chemoreception of wheat volatile organic compounds and can successfully contribute in the integrated management programs of S. avenae.

A novel platform for peptide-mediated affinity capture and LC-MS/MS identification of host receptors involved in Plasmodium invasion

Successful Plasmodium falciparum invasion of red blood cells includes the orderly execution of highly specific receptor-ligand molecular interactions between the parasite's proteins and the red blood cell membrane proteins. There is a growing need for elucidating receptor-ligand pairings, which will help in understanding the parasite's biology and provide the fundamental basis for developing prophylactic or therapeutic alternatives leading to mitigating or eliminating this type of malaria.We have thus used Plasmodium falciparum RH5 - derived peptides and ghost red blood cell proteins in synthetic peptide affinity capture assays to identify important host receptors used by Plasmodium spp. in the invasion of red blood cells. LC-MS/MS analysis confirmed the extensively described interaction between PfRH5 and the basigin receptor on the red blood cell membrane.As shown here, tagged synthetic peptides displaying high binding ability to erythrocytes can be used to identify receptors present in protein extracts from ghost red blood cells via affinity capture and LC-MS/MS. SignificanceThe article describes a novel approach for identifying red blood cell receptors based on the ability of synthetic peptides having high red blood cell binding capacity to capture Plasmodium spp. receptors on proteins extracted from ghost red blood cells. Specifically, novel methods to identify Plasmodium falciparum reticulocyte binding protein homolog 5 PfRH5 and basigin interaction using a combination of affinity capture and LC-MS/MS assays is described. Identification of these host RBC receptors interacting with malarial parasite proteins is of utmost importance in studying the disease's pathogenesis and will provide crucial information in understanding the parasite's biology. In addition, data from these studies can be used to identify potential therapeutic target(s) to mitigate or eliminate this debilitating disease.

Antibacterial activity of Cu(II) and Co(II) porphyrins: role of ligand modification

In this study, we report antibacterial activity of metalloporphyrins; 5, 10, 15, 20-tetrakis (para-X phenyl)porphyrinato M (II) [where X = H, NH2 and COOMe for M = Cu and X = COOH and OMe for M = Co]. The activity study of the as-synthesized metalloporphyrins toward two Gram-positive (S. aureus and S. pyogenes) and two Gram-negative (E. coli and K. pneumoniae) bacteria showed a promising inhibitory activity. Among the complexes under study, the highest antibacterial activity is observed for 5, 10, 15, 20-tetrakis (p-carboxyphenyl)porphyrinato cobalt (II), with inhibition zone of 16.5 mm against Staphylococcus aureus (S. aureus). This activity could be attributed to the high binding ability of COOH group to cellular components, membranes, proteins, and DNA as well as the lipophilicity of the complex. Moreover, consistent with literature report, the study revealed that metalloporphyrins with electron withdrawing group at para-positions have better antibacterial activity than metalloporphyrin which possess electron donating group at para position.

Thermal and high‐pressure treatment stability of egg‐white avidin in aqueous solution

AbstractThe combined pressure (0.1 and 600 MPa) and thermal (30, 65, 75, 90, and 105°C) treatment effects on the binding properties of egg‐white avidin were investigated using fluorescence spectroscopy titrations with fluorescein‐labeled biotin for various holding times (up to 45 min). Pressure treatment was carried out in a high‐pressure kinetic tester whereas heat treatment was conducted using metal tubes in a temperature‐controlled oil bath. Avidin binding activity and strength decreased by approximately three orders of magnitude with increases in temperature and holding time, while the binding free energy (−52.3 ± 0.47 kJ/mol) remained unaffected by high‐pressure (600 MPa at 30°C) treatment. The thermal inactivation rate constant ranged from 0.009 to 0.793 per min at 65–105°C, 0.1 MPa. Combined pressure (600 MPa)–thermal (65–105°C) treatment reduced the corresponding values by a factor of two to nine, resulting in inactivation rates that ranged from 0.001 to 0.422 per min. Activation energies for avidin inactivation were 120 ± 10 and 149 ± 8 kJ/mol for thermal and combined pressure–thermal treatment, respectively. In conclusion, while heat treatment alone destroyed biotin binding strength of avidin, combined pressure, and heat exhibited antagonistic effects on avidin–biotin binding energies.Practical ApplicationsHeat and pressure can have synergistic, additive, or antagonistic effects on food components. The synergistic effect is important from food safety aspect whereas antagonistic effect is desirable to retain food quality attributes during food processing. The parameters of reaction kinetic models, more specifically rate constant and activation energy can be used to evaluate the interactions of heat and pressure during food processing. Egg‐white avidin has been selected in this study to evaluate the interaction between heat and pressure. Information obtained from this study can be used to preserve egg‐white avidin binding activity for various applications including food formulations, biochemical assays and preservation, due to its enormously high binding ability with biotin.

Novel thiol-functionalized covalent organic framework as adsorbent for simultaneous removal of BTEX and mercury (II) from water

A novel thiol-functionalized covalent organic framework (COF-S-SH) was prepared as an adsorbent for the simultaneous removal of BTEX (benzene, toluene, ethyl benzene and xylenes) and Hg(II) ion from water. The COF-S-SH was obtained via a Schiff-base reaction between a new triamino-monomer (TABPB) and 2,5-divinylterephthalaldehyde, followed by the thiol-ene “click” reaction between 1,2-ethanedithiol and the vinyl groups. The COF-S-SH was characterized by FT-IR spectrum, energy-dispersive X-ray spectrum, 13C MAS NMR spectrum, nitrogen adsorption–desorption isotherms, thermo-gravimetric analysis, scanning electron microscope, X-ray diffraction, and zeta potential. The new adsorbent showed high binding ability with the maximum adsorption capacities (Qmax) of 150.2–255.8 mg/g for BTEX and 588.2 mg/g for Hg(II). The adsorbent also presented fast adsorption kinetics with rate constants of 0.01043–0.05002 g/mg/min for BTEX and 7.254 × 10−4 g/mg/min for Hg(II). Moreover, the adsorbent had good binding selectivity for Hg(II) against common metal ions in water. The adsorbent also showed good simultaneous uptake ability and good reusability for BTEX and Hg(II), and it has been applied to simultaneously removing BTEX and Hg(II) in the simulated sewage with the removal efficiencies of 63.6, 82.1, 94.6, 95.3 and 94.1% for benzene, toluene, ethyl benzene, m-xylene and Hg(II), respectively. Especially, it can reduce the low-concentration Hg(II) in the simulated sewage to a level lower than the drinking water limit. Therefore, COF-S-SH can be used as an excellent adsorbent material for simultaneously removing BTEX and Hg(II) in from the produced water and wastewater in petroleum chemistry industries.

Detoxification of Aflatoxin B1 by Probiotic Yeasts and Bacteria Isolated From Dairy Products of Iran.

Purpose: The present study was conducted to assess the ability of probiotic bacteria and yeasts strains to reduce aflatoxin B1 (AFB1) in gastrointestinal simulated conditions. Aflatoxins are potent carcinogenic and immunosuppressive agents. Acute exposure to a high level of aflatoxins leads to aflatoxicosis, which cause rapid death due to liver failure. It is anticipated that consumption of probiotic microorganisms capable of binding aflatoxins can reduce the risk of AFB1 on human health to a certain extent. Methods: For this purpose, the bacteria (1 × 1010 cfu/mL) and yeasts count (2 × 108 cells/mL) and AFB1 concentration (10 ppb) were adjusted. Then, the samples were incubated in the simulated medium, human gastric secretions and small intestine. The concentration of residual AFB1 was determined using enzyme-linked immunosorbent assay (ELISA). The results were statistically analyzed by SPSS 16 software. Results: The native isolated bacteria and yeasts in the simulated gastrointestinal tract condition showed a significant effect on AFB1 reduction (P <0.05). The AFB1 reduction ability of native probiotic microorganisms was strain dependent. The highest binding ability in bacteria belonged to Lactobacillus rhamnosus (31.14%) and at yeasts belonged to Saccharomyces cerevisiae (30.46%). Conclusion: The use of probiotic strains is the appropriate biological method to reduce AFB1 in the human gastrointestinal tract. Probiotic bacteria could help to decrease the harmful effects of AFB1 in humans through enhancing the food safety.