Search results for: phenolic compounds
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 2524

Search results for: phenolic compounds

1654 Synthesis and Biological Evaluation of Some Benzoxazole Derivatives as Inhibitors of Acetylcholinesterase / Butyrylcholinesterase and Tyrosinase

Authors: Ozlem Temiz-Arpaci, Meryem Tasci, Fatma Sezer Senol, İlkay Erdogan Orhan

Abstract:

Alzheimer’s disease (AD), a neurodegenerative disorder characterized by a progressive deterioration of memory and cognition, occurs more frequently in elderly people. Current treatment approaches in this disease with the major therapeutic strategy are based on the AChE and BChE inhibition. On the other hand, tyrosinase inhibition has become a target for the treatment of Parkinson’s disease (PD) since this enzyme may play a role in neuromelanin formation in the human brain and could be critical in the formation of dopamine neurotoxicity associated with neurodegeneration linked to PD. Also benzoxazoles are structural isosteres of natural nucleotides that can interact with biopolymers so that benzoxazoles showed a lot of different biological activities. In this study, a series of 2,5-disubstituted-benzoxazole derivatives were synthesized and were evaluated as possible inhibitors of acetylcholinesterase (AChE) / butyrylcholinesterase (BChE) and tyrosinase. The results demonstrated that the compounds exhibited a weak spectrum of AChE / BChE inhibitory activity ranging between 3.92% - 54.32% except compound 8 which showed no activity against AChE and compound 4 which showed no activity against BChE at the specified molar concentrations. Also, the compounds indicated lower than tyrosinase inhibitory activity of ranging between 8.14% - 22.90% to that of reference (kojic acid).

Keywords: AChE and BChE inhibition, Alzheimer’s disease, benzoxazoles, tyrosinase inhibition

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1653 Synthesis, Characterization, and Quantum Investigations on [3+2] Cycloaddition Reaction of Nitrile Oxide with 1,5-Benzodiazepine

Authors: Samir Hmaimou, Marouane Ait Lahcen, Mohamed Adardour, Mohamed Maatallah, Abdesselam Baouid

Abstract:

Due to (3 + 2) cycloaddition and condensation reaction, a wide range of synthetic routes can be used to obtain biologically active heterocyclic compounds. Condensation and (3+2) cycloaddition reactions in heterocyclic syntheses are versatile due to the wide variety of possible combinations of several atoms of the reactants. In this article, we first outline the synthesis of benzodiazepine 4 with two dipolarophilic centers (C=C and C=N) by condensation reaction. Then, we use it for cycloaddition reactions (3+2) with nitrile oxides to prepare oxadiazole-benzodiazepines and pyrazole-benzodiazepine compounds. ¹H and ¹³C NMR are used to establish all the structures of the synthesized products. These condensation and cycloaddition reactions were then analyzed using density functional theory (DFT) calculations at the B3LYP/6-311G(d,p) theoretical level. In this study, the mechanism of the one-step cycloaddition reaction was investigated. Molecular electrostatic potential (MEP) was used to identify the electrophilic and nucleophilic attack sites of the molecules studied. Additionally, Fukui investigations (electrophilic f- and nucleophilic f+) in the various reaction centers of the reactants demonstrate that, whether in the condensation reaction or cycloaddition, the reaction proceeds through the atomic centers with the most important Fukui functions, which is in full agreement with experimental observations. In the condensation reaction, thermodynamic control of regio, chemo, and stereoselectivity is observed, while those of cycloaddition are subject to kinetic control.

Keywords: cycloaddition reaction, regioselectivity, mechanism reaction, NMR analysis

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1652 Synthesis, Density Functional Theory (DFT) and Antibacterial Studies of Highly Functionalized Novel Spiropyrrolidine 4-Quinolone-3-Carboxylic Acids Derived from 6-Acetyl Quinolone

Authors: Thangaraj Arasakumar, Athar Ata, Palathurai Subramaniam Mohan

Abstract:

A series of novel 4-quinolone-3-carboxylic acid grafted spiropyrrolidines as new type of antibacterial agents were synthesized via multicomponent 1,3-dipolar cycloaddition reaction of an azomethine ylides with a newly prepared (E)-4-oxo-6-(3-phenyl-acryloyl)-1,4-dihydro-quinoline-3-carboxylic acids in high regioselectivity with good yields. The structure of cycloadduct characterized by FT IR, mass, 1H, 13C, 2D NMR techniques and elemental analysis. Structure and spectrometry of compound 8a has been investigated theoretically by using HF and DFT approach at B3LYP, M05-2x/6-31G* levels of theories. The optimized geometries and calculated vibrational frequencies are evaluated via comparison with experimental values. A good agreement is found between the measured and calculated values. The DFT studies support the molecular mechanism of this cycloaddition reaction and determine the molecular electrostatic potential and thermodynamic properties. Furthermore, the antibacterial activities of synthesized compounds were evaluated against Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria strains (Escherichia coli, Klebsiella pneumoniae). Among 21 compounds screened, 8f and 8p were found to be more active against tested bacteria.

Keywords: antibacterial activity, azomethine ylide, DFT calculation, spirooxindole

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1651 Isolation and Characterization of Anti-melanoma (Skin Cancer) Compounds from Corchorus olitorius .L

Authors: Peramachi Sathiyamoorthy, Jacop Gopas, Avi Golan Goldhirsh

Abstract:

Corchorus olitorius is a leafy vegetable and an industrial crop. The herb has antioxidant, anti inflammatory, and anti-cancer properties. To assay the pharmaceutical properties, aqueous extracts of leaves and seeds from C. olitorius were tested against drug resistant melanoma cell line. The test showed LC50 of the extract was 0.08µg/ml. Aqueous seed extract exhibited higher melanoma inhibiting activity than leaf extract. Dialysis of seed extract showed that the active compound is less than 12 KDa. The compound with <3 KDa MW separated by microconcentration of seed extract showed 70.5 % inhibition of melanoma cell growth. Among the two fractions obtained by Gel filtration with G10 column, the first fraction at 1:2000 dilutions exhibited 100% inhibition of melanoma growth. The compound with Rf value 0.86 (MA4) isolated by TLC separation showed about 98% cytotoxicity against melanoma at 1: 1000 dilutions. Furthermore, HPLC separation of MA4 compound with Superdex 75 column resulted in 4 compounds. Out of 4, one compound showed melanoma inhibition. The active compound is identified by reagent methods as Strophanthidin. Further toxicological and clinical studies will lead to the development of a potential drug to treat drug resistant melanoma.

Keywords: corchorus olitorius, melanoma, drug development, strophanthidin

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1650 Catalytic Deoxygenation of Non-Edible Oil to Renewable Fuel by Using Calcium-Based Nanocatalyst

Authors: Hwei Voon Lee, N. Asikin-Mijana, Y. H. Taufiq-Yap, J. C. Juan, N. A. Rahman

Abstract:

Cracking–Deoxygenation process is one of the important reaction pathways for the production of bio-fuel with desirable n-C17 hydrocarbon chain via removal of oxygen compounds. Calcium-based catalyst has attracted much attention in deoxygenation process due to its relatively high capacity in removing oxygenated compounds in the form of CO₂ and CO under decarboxylation and decarbonylation reaction, respectively. In the present study, deoxygenation of triolein was investigated using Ca(OH)₂ nanocatalyst derived from low cost natural waste shells. The Ca(OH)₂ nanocatalyst was prepared via integration techniques between surfactant treatment (anionic and non-ionic) and wet sonochemical effect. Results showed that sonochemically assisted surfactant treatment has successfully enhanced the physicochemical properties of Ca(OH)₂ nanocatalyst in terms of nanoparticle sizes (∼50 nm), high surface area(∼130 m²g⁻¹), large porosity (∼18.6 nm) and strong basic strength. The presence of superior properties from surfactant treated Ca(OH)₂ nanocatalysts rendered high deoxygenation degree, which is capable of producing high alkane and alkene selectivity in chain length of n-C17(high value of C17/(n-C17+ n-C18)ratio = 0.88). Furthermore, both Ca(OH)₂–EG and Ca(OH)₂–CTAB nanocatalysts showed high reactivity with 47.37% and 44.50%, respectively in total liquid hydrocarbon content of triolein conversion with high H/C and low O/C ratio.

Keywords: clamshell, cracking, decarboxylation-decarbonylation, hydrocarbon

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1649 5-[Aryloxypyridyl (or Nitrophenyl)]-4H-1,2,4-Triazoles as Flexible Benzodiazepine Analogs: Synthesis, Receptor Binding Affinity and the Lipophilicity-Dependent Anti-Seizure Onset of Action

Authors: Latifeh Navidpour, Shabnam Shabani, Alireza Heidari, Manouchehr Bashiri, Azadeh Ebrahim-Habibi, Soraya Shahhosseini, Hamed Shafaroodi, Sayyed Abbas Tabatabai, Mahsa Toolabi

Abstract:

A new series of 5-(2-aryloxy-4-nitrophenyl)-4H-1,2,4-triazoles and 5-(2-aryloxy-3-pyridyl)-4H-1,2,4-triazoles, possessing C-3 thio or alkylthio substituents, was synthesized and evaluated for their benzodiazepine receptor affinity and anti-seizure activity. These analogues revealed similar to significantly superior affinity to GABAA/ benzodiazepine receptor complex (IC50 values of 0.04–4.1 nM), relative to diazepam as the reference drug (IC50 value of 2.4 nM). To determine the onset of anti-seizure activity, the time-dependent effectiveness of i.p. administration of compounds on pentylenetetrazole induced seizure threshold was studied and a very good relationship was observed between the lipophilicity (cLogP) and onset of action of studied analogues (r2 = 0.964). The minimum effective dose of the compounds, determined at the time the analogues showed their highest activity, was demonstrated to be 0.025–0.1 mg/kg, relative to diazepam (0.025 mg/kg).

Keywords: 1, 2, 4-triazole, flexible benzodiazepines, GABAA/bezodiazepine receptor complex, onset of action, PTZ induced seizure threshold

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1648 A New Method of Extracting Polyphenols from Honey Using a Biosorbent Compared to the Commercial Resin Amberlite XAD2

Authors: Farid Benkaci-Alia, Abdelhamid Neggada, Sophie Laurentb

Abstract:

A new extraction method of polyphenols from honey using a biodegradable resin was developed and compared with the common commercial resin amberlite XAD2. For this purpose, three honey samples of Algerian origin were selected for the different physico-chemical and biochemical parameters study. After extraction of the target compounds by both resins, the polyphenol content was determined, the antioxidant activity was tested, and LC-MS analyses were performed for identification and quantification. The results showed that physico-chemical and biochemical parameters meet the norms of the International Honey commission, and the H1 sample seemed to be of high quality. The optimal conditions of extraction by biodegradable resin were a pH of 3, an adsorption dose of 40 g/L, a contact time of 50 min, an extraction temperature of 60°C and no stirring. The regeneration and reuse number of both resins was three cycles. The polyphenol contents demonstrated a higher extraction efficiency of biosorbent than of XAD2, especially in H1. LC-MS analyses allowed for the identification and quantification of fifteen compounds in the different honey samples extracted using both resins and the most abundant compound was 3,4,5-trimethoxybenzoic acid. In addition, the biosorbent extracts showed stronger antioxidant activities than the XAD2 extracts.

Keywords: extraction, polyphénols, biosorbent, resin amberlite, HPLC-MS

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1647 Application of Nanoparticles on Surface of Commercial Carbon-Based Adsorbent for Removal of Contaminants from Water

Authors: Ahmad Kayvani Fard, Gordon Mckay, Muataz Hussien

Abstract:

Adsorption/sorption is believed to be one of the optimal processes for the removal of heavy metals from water due to its low operational and capital cost as well as its high removal efficiency. Different materials have been reported in literature as adsorbent for heavy metal removal in waste water such as natural sorbents, organic polymers (synthetic) and mineral materials (inorganic). The selection of adsorbents and development of new functional materials that can achieve good removal of heavy metals from water is an important practice and depends on many factors, such as the availability of the material, cost of material, and material safety and etc. In this study we reported the synthesis of doped Activated carbon and Carbon nanotube (CNT) with different loading of metal oxide nanoparticles such as Fe2O3, Fe3O4, Al2O3, TiO2, SiO2 and Ag nanoparticles and their application in removal of heavy metals, hydrocarbon, and organics from waste water. Commercial AC and CNT with different loadings of mentioned nanoparticle were prepared and effect of pH, adsorbent dosage, sorption kinetic, and concentration effects are studied and optimum condition for removal of heavy metals from water is reported. The prepared composite sorbent is characterized using field emission scanning electron microscopy (FE-SEM), high transmission electron microscopy (HR-TEM), thermogravimetric analysis (TGA), X-ray diffractometer (XRD), the Brunauer, Emmett and Teller (BET) nitrogen adsorption technique, and Zeta potential. The composite materials showed higher removal efficiency and superior adsorption capacity compared to commercially available carbon based adsorbent. The specific surface area of AC increased by 50% reaching up to 2000 m2/g while the CNT specific surface area of CNT increased by more than 8 times reaching value of 890 m2/g. The increased surface area is one of the key parameters along with surface charge of the material determining the removal efficiency and removal efficiency. Moreover, the surface charge density of the impregnated CNT and AC have enhanced significantly where can benefit the adsorption process. The nanoparticles also enhance the catalytic activity of material and reduce the agglomeration and aggregation of material which provides more active site for adsorbing the contaminant from water. Some of the results for treating wastewater includes 100% removal of BTEX, arsenic, strontium, barium, phenolic compounds, and oil from water. The results obtained are promising for the use of AC and CNT loaded with metal oxide nanoparticle in treatment and pretreatment of waste water and produced water before desalination process. Adsorption can be very efficient with low energy consumption and economic feasibility.

Keywords: carbon nanotube, activated carbon, adsorption, heavy metal, water treatment

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1646 Copper Related Toxicity of 1-Hydroxy-2-Thiopyridines

Authors: Elena G. Salina, Vadim A. Makarov

Abstract:

With the emergence of primary resistance to the current drugs and wide distribution of latent tuberculosis infection, a need for new compounds with a novel mode of action is growing steadily. Copper-mediated innate immunity and antibacterial toxicity propose novel strategies in TB drug discovery and development. Transcriptome of M. tuberculosis was obtained by RNA-seq, intracellular copper content was measured by ISP MS and complexes of 1-hydroxy-2-thiopyridines with copper were detected by HPLC.1-hydroxy-2-thiopyridine derivatives were found to be highly active in vitro against both actively growing and dormant non-culturable M. tuberculosis. Transcriptome response to 1-hydroxy-2-thiopyridines revealed signs of copper toxicity in M. tuberculosis bacilli. Indeed, Cu was found to accumulate inside cells treated with 1-hydroxy-2-thiopyridines. These compounds were found to form stable charged lipophylic complexes with Cu²⁺ ions which transport into mycobacterial cell. Subsequent metabolic destruction of the complex led to transformation of 1-hydroxy-2-thiopyridines into 2-methylmercapto-2-ethoxycarbonylpyridines, which did not possess antitubercular activity and releasing of free Cu²⁺ in the cytoplasm. 1-hydroxy-2-thiopyridines are a potent class of Cu-dependent inhibitors of M. tuberculosis which may control M. tuberculosis infection by impairment of copper homeostasis. Acknowledgment: This work was financially supported by the Ministry of Education and Science of the RussianFederation (Agreement No 14.616.21.0065; unique identifier RFMEFI61616X0065).

Keywords: copper toxicity, drug discovery, M. tuberculosis inhibitors, 2-thiopyridines

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1645 Synthesis of Erlotinib Analogues, Conjugation of BSA to Erlotinib Alcohol and Their Anti-Cancer Activity against NSCLC

Authors: Ramalingam Boobalan, Chinpiao Chen, Jui-I. Chiao

Abstract:

A series of erlotinib analogues that have structural modification at 6,7-alkoxyl positions is efficiently synthesized. The key reactions that involved in synthesis are one-pot oxime formation-dehydration for the formation of nitrile, quinazoline ring formation reaction between aniline and o-cyanoaniline via formamidine intermediate, Fe/NH4Cl catalyzed reduction-hetereocyclization-reductive ring opening reaction for the formation of o-aminobenzamide, high yielding seal tube reactions for O-demethylation, sodium iodide substitution, ammonia substitution. The in vitro anti-tumor activity of synthesized compounds is studied in two non-small cell lung cancer (NSCLC) cell lines (A549 and H1975). Among the synthesized compounds, the iodo compound 6 (ETN-6) exhibits higher anti-cancer activity compared to erlotinib. An efficient method is developed for the conjugation of erlotinib analogue-4, alcohol compound, with protein, bovine serum albumin (BSA), via succinic acid linker. The in vitro anti-tumor activity of the protein attached erlotinib analogue, 8 (ETN-4-Suc-BSA), showed stronger inhibitory activity in both A549 and H1975 NSCLC cell lines.

Keywords: anti-cancer, BSA, EGFR, Erlotinib

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1644 The Efficacy of Thymbra spicata Ethanolic Extract and its Main Component Carvacrol on In vitro Model of Metabolically-Associated Dysfunctions

Authors: Farah Diab, Mohamad Khalil, Francesca Storace, Francesca Baldini, Piero Portincasaa, Giulio Lupidi, Laura Vergani

Abstract:

Thymbra spicata is a thyme-like plant belonging to the Lamiaceae family that shows a global distribution, especially in the eastern Mediterranean region. Leaves of T. spicata contain large amounts of phenols such as phenolic acids (rosmarinic acid), phenolic monoterpenes (carvacrol), and flavonoids. In Lebanon, T. spicata is currently used as a culinary herb in salad and infusion, as well as for traditional medicinal purposes. Carvacrol (5-isopropyl-2-methyl phenol), the most abundant polyphenol in the organic extract and essential oils, has a great array of pharmacological properties. In fact, carvacrol is largely employed as a food additive and neutraceutical agent. Our aim is to investigate the beneficial effects of T. spicata ethanolic extract (TE) and its main component, carvacrol, using in vitro models of hepatic steatosis and endothelial dysfunction. As a further point, we focused on investigating if and how the binding of carvacrol to albumin, the physiological transporter for drugs in the blood, might be altered by the presence of high levels of fatty acids (FAs), thus impairing the carvacrol bio-distribution in vivo. For that reason, hepatic FaO cells treated with exogenous FAs such as oleate and palmitate mimic hepatosteatosis; endothelial HECV cells exposed to hydrogen peroxide are a model of endothelial dysfunction. In these models, we measured lipid accumulation, free radical production, lipoperoxidation, and nitric oxide release before and after treatment with carvacrol. The carvacrol binding to albumin with/without high levels of long-chain FAs was assessed by absorption and emission spectroscopies. Our findings show that both TE and carvacrol (i) counteracted lipid accumulation in hepatocytes by decreasing the intracellular and extracellular lipid contents in steatotic FaO cells; (ii) decreased oxidative stress in endothelial cells by significantly reducing lipoperoxidation and free radical production, as well as, attenuating the nitric oxide release; (ii) high levels of circulating FAs reduced the binding of carvacrol to albumin. The beneficial effects of TE and carvacrol on both hepatic and endothelial cells point to a nutraceutical potential. However, high levels of circulating FAs, such as those occurring in metabolic disorders, might hinder the carvacrol transport, bio-distribution, and pharmacodynamics.

Keywords: carvacrol, endothelial dysfunction, fatty acids, non-alcoholic fatty liver diseases, serum albumin

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1643 Gold Nano Particle as a Colorimetric Sensor of HbA0 Glycation Products

Authors: Ranjita Ghoshmoulick, Aswathi Madhavan, Subhavna Juneja, Prasenjit Sen, Jaydeep Bhattacharya

Abstract:

Type 2 diabetes mellitus (T2DM) is a very complex and multifactorial metabolic disease where the blood sugar level goes up. One of the major consequence of this elevated blood sugar is the formation of AGE (Advance Glycation Endproducts), from a series of chemical or biochemical reactions. AGE are detrimental because it leads to severe pathogenic complications. They are a group of structurally diverse chemical compounds formed from nonenzymatic reactions between the free amino groups (-NH2) of proteins and carbonyl groups (>C=O) of reducing sugars. The reaction is known as Maillard Reaction. It starts with the formation of reversible schiff’s base linkage which after sometime rearranges itself to form Amadori Product along with dicarbonyl compounds. Amadori products are very unstable hence rearrangement goes on until stable products are formed. During the course of the reaction a lot of chemically unknown intermediates and reactive byproducts are formed that can be termed as Early Glycation Products. And when the reaction completes, structurally stable chemical compounds are formed which is termed as Advanced Glycation Endproducts. Though all glycation products have not been characterized well, some fluorescence compounds e.g pentosidine, Malondialdehyde (MDA) or carboxymethyllysine (CML) etc as AGE and α-dicarbonyls or oxoaldehydes such as 3-deoxyglucosone (3-DG) etc as the intermediates have been identified. In this work Gold NanoParticle (GNP) was used as an optical indicator of glycation products. To achieve faster glycation kinetics and high AGE accumulation, fructose was used instead of glucose. Hemoglobin A0 (HbA0) was fructosylated by in-vitro method. AGE formation was measured fluorimetrically by recording emission at 450nm upon excitation at 350nm. Thereafter this fructosylated HbA0 was fractionated by column chromatography. Fractionation separated the proteinaceous substance from the AGEs. Presence of protein part in the fractions was confirmed by measuring the intrinsic protein fluorescence and Bradford reaction. GNPs were synthesized using the templates of chromatographically separated fractions of fructosylated HbA0. Each fractions gave rise to GNPs of varying color, indicating the presence of distinct set of glycation products differing structurally and chemically. Clear solution appeared due to settling down of particles in some vials. The reactive groups of the intermediates kept the GNP formation mechanism on and did not lead to a stable particle formation till Day 10. Whereas SPR of GNP showed monotonous colour for the fractions collected in case of non fructosylated HbA0. Our findings accentuate the use of GNPs as a simple colorimetric sensing platform for the identification of intermediates of glycation reaction which could be implicated in the prognosis of the associated health risk due to T2DM and others.

Keywords: advance glycation endproducts, glycation, gold nano particle, sensor

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1642 Effects of Drying and Extraction Techniques on the Profile of Volatile Compounds in Banana Pseudostem

Authors: Pantea Salehizadeh, Martin P. Bucknall, Robert Driscoll, Jayashree Arcot, George Srzednicki

Abstract:

Banana is one of the most important crops produced in large quantities in tropical and sub-tropical countries. Of the total plant material grown, approximately 40% is considered waste and left in the field to decay. This practice allows fungal diseases such as Sigatoka Leaf Spot to develop, limiting plant growth and spreading spores in the air that can cause respiratory problems in the surrounding population. The pseudostem is considered a waste residue of production (60 to 80 tonnes/ha/year), although it is a good source of dietary fiber and volatile organic compounds (VOC’s). Strategies to process banana pseudostem into palatable, nutritious and marketable food materials could provide significant social and economic benefits. Extraction of VOC’s with desirable odor from dried and fresh pseudostem could improve the smell of products from the confectionary and bakery industries. Incorporation of banana pseudostem flour into bakery products could provide cost savings and improve nutritional value. The aim of this study was to determine the effects of drying methods and different banana species on the profile of volatile aroma compounds in dried banana pseudostem. The banana species analyzed were Musa acuminata and Musa balbisiana. Fresh banana pseudostem samples were processed by either freeze-drying (FD) or heat pump drying (HPD). The extraction of VOC’s was performed at ambient temperature using vacuum distillation and the resulting, mostly aqueous, distillates were analyzed using headspace solid phase microextraction (SPME) gas chromatography – mass spectrometry (GC-MS). Optimal SPME adsorption conditions were 50 °C for 60 min using a Supelco 65 μm PDMS/DVB Stableflex fiber1. Compounds were identified by comparison of their electron impact mass spectra with those from the Wiley 9 / NIST 2011 combined mass spectral library. The results showed that the two species have notably different VOC profiles. Both species contained VOC’s that have been established in literature to have pleasant appetizing aromas. These included l-Menthone, D-Limonene, trans-linlool oxide, 1-Nonanol, CIS 6 Nonen-1ol, 2,6 Nonadien-1-ol, Benzenemethanol, 4-methyl, 1-Butanol, 3-methyl, hexanal, 1-Propanol, 2-methyl- acid، 2-Methyl-2-butanol. Results show banana pseudostem VOC’s are better preserved by FD than by HPD. This study is still in progress and should lead to the optimization of processing techniques that would promote the utilization of banana pseudostem in the food industry.

Keywords: heat pump drying, freeze drying, SPME, vacuum distillation, VOC analysis

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1641 Arbuscular Mycorrhizal Symbiosis Modulates Antioxidant Capacity of in vitro Propagated Hyssop, Hyssopus officinalis L.

Authors: Maria P. Geneva, Ira V. Stancheva, Marieta G. Hristozkova, Roumiana D. Vasilevska-Ivanova, Mariana T. Sichanova, Janet R. Mincheva

Abstract:

Hyssopus officinalis L., Lamiaceae, commonly called hyssop, is an aromatic, semi-evergreen, woody-based, shrubby perennial plant. Hyssop is a good expectorant and antiviral herb commonly used to treat respiratory conditions such as influenza, sinus infections, colds, and bronchitis. Most of its medicinal properties are attributed to the essential oil of hyssop. The study was conducted to evaluate the influence of inoculation with arbuscular mycorrhizal fungi of in vitro propagated hyssop plants on the: activities of antioxidant enzymes superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase; accumulation of non-enzymatic antioxidants total phenols and flavonoid, water-soluble soluble antioxidant metabolites expressed as ascorbic acid; the antioxidant potential of hyssop methanol extracts assessed by two common methods: free radical scavenging activity using free stable radical (2,2-diphenyl-1-picrylhydrazyl, DPPH• and ferric reducing antioxidant power FRAP in flowers and leaves. The successfully adapted to field conditions in vitro plants (survival rate 95%) were inoculated with arbuscular mycorrhizal fungi (Claroideoglomus claroideum, ref. EEZ 54). It was established that the activities of enzymes with antioxidant capacity (superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase) were significantly higher in leaves than in flowers in both control and mycorrhized plants. In flowers and leaves of inoculated plants, the antioxidant enzymes activity were lower than in non-inoculated plants, only in SOD activity, there was no difference. The content of low molecular metabolites with antioxidant capacity as total phenols, total flavonoids, and water soluble antioxidants was higher in inoculated plants. There were no significant differences between control and inoculated plants both for FRAP and DPPH antioxidant activity. According to plant essential oil content, there was no difference between non-inoculated and inoculated plants. Based on our results we could suggest that antioxidant capacity of in vitro propagated hyssop plant under conditions of cultivation is determined by the phenolic compounds-total phenols and flavonoids as well as by the levels of water-soluble metabolites with antioxidant potential. Acknowledgments: This study was conducted with financial support from National Science Fund at the Bulgarian Ministry of Education and Science, Project DN06/7 17.12.16.

Keywords: antioxidant enzymes, antioxidant metabolites, arbuscular mycorrhizal fungi, Hyssopus officinalis L.

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1640 Analysis of Cannabinoid and Cannabidiol Affinity with GABRA1

Authors: Hamid Hossein Khezri, Afsaneh Javdani-Mallak

Abstract:

Fast inhibitory neurotransmission in the mammalian nervous system is largely mediated by GABAA receptors, chloride-selective members of the superfamily of pentameric Cys-loop receptors. Cannabidiol (CBD) is one of the members of cannabinoid compounds found in cannabis. CBD and Cannabinol (CBN), as the other extract of plant Cannabis, were able to reduce myofascial pain in rats with immunosuppressive and anti-inflammatory activities. In this study, we accomplished protein-protein BLAST and the sequence was found to be for Gamma-aminobutyric acid receptor subunit alpha-1 (GBRA1) chain A and its 3D structure was subsequently downloaded from Protein Data Bank. The structures of the ligands cannabinol and cannabidiol were obtained from PubChem. After a necessary process of the obtained files, AutoDock Vina was used to performing molecular docking. Docking between the ligands and GBRA1 chain A revealed that cannabinol has a higher affinity to GBRA1 (binding energy = -7.5 kcal/mol) compared to cannabidiol (binding energy = -6.5 kcal/mol). Furthermore, cannabinol seems to be able to interact with 10 residues of the protein, out of which 3 are in the neurotransmitter-gated ion-channel transmembrane domain of GBRA1, whereas cannabidiol interacts with two other residues. Although the results of this project do not indicate the activating /or inhibitory capability of the studied compounds, it suggests that cannabinol can act as a relatively strong ligand for GBRA1.

Keywords: protein-ligand docking, cannabinol, cannabidiol, GBRA1

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1639 An Antifungal Peptide from Actinobacteria (Streptomyces Sp. TKJ2): Isolation and Partial Characterization

Authors: Abdelaziz Messis, Azzeddine Bettache, Nawel Boucherba, Said Benallaoua, Mouloud Kecha

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Actinobacteria are of special biotechnological interest since they are known to produce chemically diverse compounds with a wide range of biological activity. This distinct clade of Gram-positve bacteria include some of the key antibiotic producers and are also sources of several bioactive compounds, established commercially a newly filamentous bacteria was recovered from Tikjda forest soil (Algeria) for its high antifungal activity against various pathogenic and phytopathogenic fungi. The nucleotide sequence of the 16S rRNA gene (1454 pb) of Streptomyces sp. TKJ2 exhibited close similarity (99 %) with other Streptomyces16S rRNA genes. Antifungal metabolite production of Streptomyces sp TKJ2 was evaluated using six different fermentation media. The extracellular products contained potent antifungal agents. Antifungal protein produced by Streptomyces sp. TKJ2 on PCA medium has been purified by ammonium sulfate precipitation, SPE column chromatography and high-performance liquid chromatography in a reverse-phase column. The UV chromatograms of the active fractions obtained at 214 nm by NanoLC-ESI-MS/MS have different molecular weights. The F20 Peptidic fraction obtained from culture filtrat of Streptomyces sp. TKJ2 precipitated at 30% of ammonium sulfate was selected for analysis by infusion ESI-MS which yielded a singly charged ion mass of 437.17 Da.

Keywords: actinobacteria, antifungal protein, chromatography, Streptomyces

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1638 The Study of Natural Synthetic Linalool Isolated from Ginger (Zingiber officinale) Using Photochemical Reactions

Authors: Elgendy M. Eman, Sameeh Y. Manal

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Ginger (Zingiber officinale) is so important plant for its medicinal properties from ancient time and used as a spicy herb all over the world. This study was designed to examine the chemical composition of the essential oil and various crude extracts (n-hexane, chloroform and ethanol) of Zingiber officinale as well. GC–MS analyses of the essential oil resulted in the identification of 68 compounds,; 1,8-cineole (8.9%) and linalool (15.1%) were the main components in the essential oil .The crude extracts were analyzed with TLC plates and revealed several spots under UV light; however the hexane extract exhibited the highest number of spots compared to the other extracts. Hexane extract was selected for GC-MS profile, and the results revealed the presence of several volatile compounds and linalool was the major component with high percentage (11.4 %). Further investigation on the structure elucidation of the bioactive compound (linalool) using IR, GC-MS and NMR techniques compared to authenticated linalool then subjected to purification using preparative and column chromatography. Linalool has been epoxidized using m-chloroperbenzoicacid (mcpba) at room temperature in the presence of florescent lamps to give two cyclic oxygenated products (furan epoxide & pyran epoxide) as a stereospecific product.it is concluded that, oxidation process is enhanced by irradiation to form epoxide derivative, which acts as the precursor of important products.

Keywords: epoxide, ginger, irradiation, linalool

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1637 Structural and Functional Comparison of Untagged and Tagged EmrE Protein

Authors: S. Junaid S. Qazi, Denice C. Bay, Raymond Chew, Raymond J. Turner

Abstract:

EmrE, a member of the small multidrug resistance protein family in bacteria is considered to be the archetypical member of its family. It confers host resistance to a wide variety of quaternary cation compounds (QCCs) driven by proton motive force. Generally, purification yield is a challenge in all membrane proteins because of the difficulties in their expression, isolation and solubilization. EmrE is extremely hydrophobic which make the purification yield challenging. We have purified EmrE protein using two different approaches: organic solvent membrane extraction and hexahistidine (his6) tagged Ni-affinity chromatographic methods. We have characterized changes present between ligand affinity of untagged and his6-tagged EmrE proteins in similar membrane mimetic environments using biophysical experimental techniques. Purified proteins were solubilized in a buffer containing n-dodecyl-β-D-maltopyranoside (DDM) and the conformations in the proteins were explored in the presence of four QCCs, methyl viologen (MV), ethidium bromide (EB), cetylpyridinium chloride (CTP) and tetraphenyl phosphonium (TPP). SDS-Tricine PAGE and dynamic light scattering (DLS) analysis revealed that the addition of QCCs did not induce higher multimeric forms of either proteins at all QCC:EmrE molar ratios examined under the solubilization conditions applied. QCC binding curves obtained from the Trp fluorescence quenching spectra, gave the values of dissociation constant (Kd) and maximum specific one-site binding (Bmax). Lower Bmax values to QCCs for his6-tagged EmrE shows that the binding sites remained unoccupied. This lower saturation suggests that the his6-tagged versions provide a conformation that prevents saturated binding. Our data demonstrate that tagging an integral membrane protein can significantly influence the protein.

Keywords: small multidrug resistance (SMR) protein, EmrE, integral membrane protein folding, quaternary ammonium compounds (QAC), quaternary cation compounds (QCC), nickel affinity chromatography, hexahistidine (His6) tag

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1636 Bioremediation as a Treatment of Aromatic Hydrocarbons in Wastewater

Authors: Hen Friman, Alex Schechter, Yeshayahu Nitzan, Rivka Cahan

Abstract:

The treatment of aromatic hydrocarbons in wastewater resulting from oil spills and chemical manufactories is becoming a key concern in many modern countries. Benzene, ethylbenzene, toluene and xylene (BETX) contaminate groundwater as well as soil. These compounds have an acute effect on human health and are known to be carcinogenic. Conventional removal of these toxic materials involves separation and burning of the wastes, however, the cost of chemical treatment is very high and energy consuming. Bioremediation methods for removal of toxic organic compounds constitute an attractive alternative to the conventional chemical or physical techniques. Bioremediation methods use microorganisms to reduce the concentration and toxicity of various chemical pollutants Toluene is biodegradable both aerobically and anaerobically, it can be growth inhibitory to microorganisms at elevated concentrations, even to those species that can use it as a substrate. In this research culture of Pseudomonas putida was grown in bath bio-reactor (BBR) with toluene 100 mg/l as a single carbon source under constant voltage of 125 mV, 250 mV and 500 mV. The culture grown in BBR reached to 0.8 OD660nm while the control culture that grown without external voltage reached only to 0.6 OD660nm. The residual toluene concentration after 147 h, in the BBR operated under external voltage (125 mV) was 22 % on average, while in the control BBR it was 81 % on average.

Keywords: bioremediation, aromatic hydrocarbons, BETX, toluene, pseudomonas putida

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1635 Qsar Studies of Certain Novel Heterocycles Derived From bis-1, 2, 4 Triazoles as Anti-Tumor Agents

Authors: Madhusudan Purohit, Stephen Philip, Bharathkumar Inturi

Abstract:

In this paper we report the quantitative structure activity relationship of novel bis-triazole derivatives for predicting the activity profile. The full model encompassed a dataset of 46 Bis- triazoles. Tripos Sybyl X 2.0 program was used to conduct CoMSIA QSAR modeling. The Partial Least-Squares (PLS) analysis method was used to conduct statistical analysis and to derive a QSAR model based on the field values of CoMSIA descriptor. The compounds were divided into test and training set. The compounds were evaluated by various CoMSIA parameters to predict the best QSAR model. An optimum numbers of components were first determined separately by cross-validation regression for CoMSIA model, which were then applied in the final analysis. A series of parameters were used for the study and the best fit model was obtained using donor, partition coefficient and steric parameters. The CoMSIA models demonstrated good statistical results with regression coefficient (r2) and the cross-validated coefficient (q2) of 0.575 and 0.830 respectively. The standard error for the predicted model was 0.16322. In the CoMSIA model, the steric descriptors make a marginally larger contribution than the electrostatic descriptors. The finding that the steric descriptor is the largest contributor for the CoMSIA QSAR models is consistent with the observation that more than half of the binding site area is occupied by steric regions.

Keywords: 3D QSAR, CoMSIA, triazoles, novel heterocycles

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1634 Automated Resin Transfer Moulding of Carbon Phenolic Composites

Authors: Zhenyu Du, Ed Collings, James Meredith

Abstract:

The high cost of composite materials versus conventional materials remains a major barrier to uptake in the transport sector. This is exacerbated by a shortage of skilled labour which makes the labour content of a hand laid composite component (~40 % of total cost) an obvious target for reduction. Automation is a method to remove labour cost and improve quality. This work focuses on the challenges and benefits to automating the manufacturing process from raw fibre to trimmed component. It will detail the experimental work required to complete an automation cell, the control strategy used to integrate all machines and the final benefits in terms of throughput and cost.

Keywords: automation, low cost technologies, processing and manufacturing technologies, resin transfer moulding

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1633 Azaridachta Indica (Neem) Seed Oil Effect in Experimental Arthritis – Biochemical Parameters Assessment

Authors: Sasan Khademnematolahi, Kevine Kamga Silihe, Katarína Pružinská, Martina Chrastina, Elisabeth Louise Ndjengue Mindang, František Dráfi, Katarína Bauerová

Abstract:

Background: In ethnomedicine, plant parts and compounds are traditionally utilized to treat many disorders. Azadirachta indica, known as Neem, has been traditionally used in medicinal practices. Neem has various pharmaceutical activities, such as antioxidant and anti-inflammatory, due to the content of bioactive compounds like nimbolide, azadirachtin, and gedunin.Through its effect on pathological inflammatory processes, supplementation with it could alleviate the symptoms of rheumatoid arthritis (RA). Methods: This research aimed to assess Neem seed oil's impact on rats with adjuvant arthritis. Three doses in monotherapy and two in combination with methotrexate (MTX) have been studied and their effect was compared. Neem p.o. doses of 100, 200, and 300 mg/kg and MTX p.o. doses of 0.3 mg/kg were examined. After clinical parameters assessment, biochemical analysis was performed in plasma. Results: During the acute phase of the experimental arthritis (Day21), levels of MMP-9, MCP-1 and cytokines IL-1beta and IL-17A were measured. The positive results of inflammatory mediators evaluation in plasma encourage additional analysis also in related tissues to prove if Neem seed oil can be used as an adjuvant therapy for RA. Conclusion: In this study, the combination therapy of Neem with MTX was most effective from all therapies investigated.

Keywords: adjuvant, neem, methotrexate, arthritis

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1632 Influence of Cation Substitution on Magnetic Transitions and Ordering in La2NixCo1-xMnO6 Compounds (x = 0.2 - 0.8)

Authors: Amine.Harbia, Hicham. Moutaabbidb, Yann. Le Godecb, Said. Benmokhtara, Mouhammed. Moutaabbida

Abstract:

This study explores the structural and magnetic characteristics of newly synthesized double perovskite oxides, La₂NiₓCo1-xMnO₆, with x ranging from 0.2 to 0.8. Utilizing X-ray powder diffraction and SQUID magnetometry, we analyzed the compounds that consistently exhibit a monoclinic structure with the P21/n space group at ambient temperature. it findings reveal that as Ni2+ is progressively substituted by Co2+, there is a corresponding decrease in cell parameters, attributable to the smaller ionic radius of Ni2+ (0.69 Å) compared to Co2+ (0.74 Å). The crystal structure features octahedrally coordinated (Co/Ni)2+ and Mn4+ cations with oxygen, forming (Co/Ni)O6 and MnO6 octahedra linked via oxygen atoms along different crystallographic axes. Magnetic characterization conducted over a temperature range of 2 to 300 K in both DC and AC magnetic fields, showed a predominant paramagnetic to ferromagnetic transition between 232 K and 260 K, with the Curie temperature notably increasing with higher x values. Samples with x=0.2, 0.25, and 0.5 exhibited a secondary PM-FM transition between 200 K and 208 K. Cation ordering was quantitatively assessed, indicating a higher ordering in Ni2+-rich samples (x=0.75 and 0.8) at over 96%, whereas the sample with x=0.25 showed minimal ordering. Furthermore, the out-of-phase component of the AC susceptibility displayed frequency-dependent transitions between 65 K and 110 K, suggesting the presence of superparamagnetic domains across all samples.

Keywords: double perovskite oxides, magnetic transitions, cation ordering, squid magnetometry

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1631 Tungsten-Based Powders Produced in Plasma Systems

Authors: Andrey V. Samokhin, Nikolay V. Alekseev, Mikhail A. Sinaiskii

Abstract:

The report presents the results of R&D of plasma-chemical production of W, W-Cu, W-Ni-Fe nanopowders as well as spherical micropowders of these compounds for their use in modern 3D printing technologies. Plasma-chemical synthesis of nanopowdersis based on the reduction of tungsten oxide compounds powders in a stream of hydrogen-containing low-temperature thermal plasma generated in an electric arc plasma torch. The synthesis of W-Cu and W-Ni-Fe nanocompositesiscarried out using the reduction of a mixture of the metal oxides. Using the synthesized tungsten-based nanocomposites powders, spherical composite micropowders with a submicron structure canbe manufactured by spray dryinggranulation of nanopowder suspension and subsequent densification and spheroidization of granules by melting in a low-temperature thermal plasma flow. The DC arc plasma systems are usedfor the synthesis of nanopowdersas well as for the spheroidization of microgranuls. Plasma systems have a capacity of up to 1 kg/h for nanopowder and up to 5 kg/h for spheroidized powder. All synthesized nanopowders consist of aggregated particles with sizes less than 100 nm, and nanoparticles of W-Cu and W-Ni-Fe composites have core (W) –shell (Cu or Ni-Fe) structures. The resulting dense spherical microparticles with a size of 20-60 microns have a submicron structure with a uniform distribution of metals over the particle volume. The produced tungsten-based nano- and spherical micropowderscan be used to develop new materials and manufacture products using advanced modern technologies.

Keywords: plasma, powders, production, tungsten-based

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1630 Oxidative Stability of Corn Oil Supplemented with Natural Antioxidants from Cypriot Salvia fruticosa Extracts

Authors: Zoi Konsoula

Abstract:

Vegetable oils, which are rich in polyunsaturated fatty acids, are susceptible to oxidative deterioration. The lipid oxidation of oils results in the production of rancid odors and unpleasant flavors as well as the reduction of their nutritional quality and safety. Traditionally, synthetic antioxidants are employed for their retardation or prevention of oxidative deterioration of oils. However, these compounds are suspected to pose health hazards. Consequently, recently there has been a growing interest in the use of natural antioxidants of plant origin for improving the oxidative stability of vegetable oils. The genus Salvia (sage) is well known for its antioxidant activity. In the Cypriot flora Salvia fruticosa is the most distributed indigenous Salvia species. In the present study, extracts were prepared from S. fruticosa aerial parts using various solvents and their antioxidant activity was evaluated by the 1,1-diphenyl-2-picrylhydrazine (DPPH) radical scavenging and Ferric Reducing Antioxidant Power (FRAP) method. Moreover, the antioxidant efficacy of all extracts was assessed using corn oil as the oxidation substrate, which was subjected to accelerated aging (60 °C, 30 days). The progress of lipid oxidation was monitored by the determination of the peroxide, p-aniside, conjugated dienes and trienes value according to the official AOCS methods. Synthetic antioxidants (butylated hydroxytoluene-BHT and butylated hydroxyanisole-BHA) were employed at their legal limit (200 ppm) as reference. Finally, the total phenolic (TPC) and flavonoid content (TFC) of the prepared extracts was measured by the Folin-Ciocalteu and aluminum-flavonoid complex method, respectively. The results of the present study revealed that although all sage extracts prepared from S. fruticosa exhibited antioxidant activity, the highest antioxidant capacity was recorded in the methanolic extract, followed by the non-toxic, food grade ethanol. Furthermore, a positive correlation between the antioxidant potency and the TPC of extracts was observed in all cases. Interestingly, sage extracts prevented lipid oxidation in corn oil at all concentrations tested, however, the magnitude of stabilization was dose dependent. More specifically, results from the different oxidation parameters were in agreement with each other and indicated that the protection offered by the various extracts depended on their TPC. Among the extracts, the methanolic extract was more potent in inhibiting oxidative deterioration. Finally, both methanolic and ethanolic sage extracts at a concentration of 1000 ppm exerted a stabilizing effect comparable to that of the reference synthetic antioxidants. Based on the results of the present study, sage extracts could be used for minimizing or preventing lipid oxidation in oils and, thus, prolonging their shelf-life. In particular, given that the use of dietary alcohol, such as ethanol, is preferable than methanol in food applications, the ethanolic extract prepared from S. fruticosa could be used as an alternative natural antioxidant.

Keywords: antioxidant activity, corn oil, oxidative deterioration, sage

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1629 The Spatial and Temporal Distribution of Ambient Benzene, Toluene, Ethylbenzene and Xylene Concentrations at an International Airport in South Africa

Authors: Ryan S. Johnson, Raeesa Moolla

Abstract:

Airports are known air pollution hotspots due to the variety of fuel driven activities that take place within the confines of them. As such, people working within airports are particularly vulnerable to exposure of hazardous air pollutants, including hundreds of aromatic hydrocarbons, and more specifically a group of compounds known as BTEX (viz. benzene, toluene, ethyl-benzene and xylenes). These compounds have been identified as being harmful to human and environmental health. Through the use of passive and active sampling methods, the spatial and temporal variability of benzene, toluene, ethyl-benzene and xylene concentrations within the international airport was investigated. Two sampling campaigns were conducted. In order to quantify the temporal variability of concentrations within the airport, an active sampling strategy using the Synspec Spectras Gas Chromatography 955 instrument was used. Furthermore, a passive sampling campaign, using Radiello Passive Samplers was used to quantify the spatial variability of these compounds. In addition, meteorological factors are known to affect the dispersal and dilution of pollution. Thus a Davis Pro-Weather 2 station was utilised in order to measure in situ weather parameters (viz. wind speed, wind direction and temperature). Results indicated that toluene varied on a daily, temporal scale considerably more than other concentrations. Toluene further exhibited a strong correlation with regards to the meteorological parameters, inferring that toluene was affected by these parameters to a greater degree than the other pollutants. The passive sampling campaign revealed BTEXtotal concentrations ranged between 12.95 – 124.04 µg m-3. From the results obtained it is clear that benzene, toluene, ethyl-benzene and xylene concentrations are heterogeneously spatially dispersed within the airport. Due to the slow wind speeds recorded over the passive sampling campaign (1.13 m s-1.), the hotspots were located close to the main concentration sources. The most significant hotspot was located over the main apron of the airport. It is recommended that further, extensive investigations into the seasonality of hazardous air pollutants at the airport is necessary in order for sound conclusions to be made about the temporal and spatial distribution of benzene, toluene, ethyl-benzene and xylene concentrations within the airport.

Keywords: airport, air pollution hotspot, BTEX concentrations, meteorology

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1628 Cellulose Containing Metal Organic Frameworks in Environmental Applications

Authors: Hossam El-Sayed Emam

Abstract:

As an essential issue for life, water while it’s important for all living organisms. However, the world is dangerously facing the serious problem for the deficiency of the sources of drinking water. Within the aquatic systems, there are various gases, microbes, and other toxic ingredients (chemical compounds and heavy metals) occurred owing to the draining of agricultural and industrial wastewater, resulting in water pollution. On the other hand, fuel (gaseous, liquid, or in solid phase) is one of the extensively consumable energy sources, and owing to its origin from fossil, it contains some sulfur-, nitrogen- and oxygen-based compounds that cause serious problems (toxicity, catalyst poisoning, corrosion, and gum formation andcarcinogenic effects), to be ascribed as undesirable pollutants.MOFs as porous coordinating polymers are superiorly exploited in the adsorption and separationof contaminants for wastewater treatment and fuel purification. The inclusion of highly adsorbent materials like MOFs to be immobilized within cellulosic materialscould be investigated as a new challenge for the separation of contaminants with high efficiency and opportunity for recyclability. Therefore, the current approach ascribes the exploitation of different MOFsimmobilized within cellulose (powder, films, and fabrics)for applications in environmental. Herein, using cellulose containing MOFs in dye removal (degradation and adsorption), pharmaceutical intermediates removal, and fuel purification were summarized.

Keywords: cellulose, MOFs, dye removal, pharmaceutical intermediates, fuel purification

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1627 Synergistic Studies of Multi-Flame Retarders Using Silica Nanoparticles, and Nitrogen and Phosphorus-Based Compounds for Polystyrene Using Response Surface Methodology

Authors: Florencio D. De Los Reyes, Magdaleno R. Vasquez Jr., Mark Daniel G. De Luna, Peerasak Paoprasert

Abstract:

The effect of adding silica nanoparticles (SiNPs) obtained from rice husk, and phosphorus and nitrogen based compounds namely 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide (DOPO) and melamine, respectively, on the flammability of polystyrene (PS) was studied using response surface methodology (RSM). The flammability of PS was reduced as the limiting oxygen index (LOI) values increased when the flame retardant additives were added. DOPO exhibited the best retarding property increasing the LOI value of PS by 42.4%. A quadratic model for LOI was obtained from the RSM results, with percent loading of SiNPs, DOPO, and melamine, as independent variables. The observed increase in the LOI value as the percent loading of the flame retardant additives is increased, was attributed both to the main effects and synergistic effects of the parameters, as the LOI response of SiNPs is greatly enhanced by the addition of DOPO and melamine, as shown by the response surface plots. This indicates the potential of producing a cheaper, effective, and non-toxic multi-flame retardant system for the polymeric system via different flame retarding mechanisms.

Keywords: flame retardancy, polystyrene, response surface methodology, rice husk, silica nanoparticle

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1626 Theoretical Study of Structural and Electronic Properties of Matlockite CaFX (X = I and Br) Compounds

Authors: Meriem Harmel, Houari Khachai

Abstract:

The full potential linearized augmented plane wave (FP-LAPW)method within density functional theory is applied to study, for the first time, the structural and electronic properties of CaFI and to compare them with CaFCl and CaFBr, all compounds belonging to the tetragonal PbFCl structure group with space group P4/nmm. We used the generalized gradient approximation (GGA) based on exchange–correlation energy optimization to calculate the total energy and also the Engel– Vosko GGA formalism, which optimizes the corresponding potential for band structure calculations. Ground state properties such as the lattice parameters, c/a ratio, bulk modulus, pressure derivative of the bulk modulus and cohesive energy are calculated, as well as the optimized internal parameters, by relaxing the atomic position in the force directions. The variations of the calculated interatomic distances and angles between different atomic bonds are discussed. CaFCl was found to have a direct band gap at whereas CaFBr and BaFI have indirect band gaps. From these computed bands, all three materials are found to be insulators having band gaps of 6.28, 5.46, and 4.50 eV, respectively. We also calculated the valence charge density and the total density of states at equilibrium volume for each compound. The results are in reasonable agreement with the available experimental data.

Keywords: DFT, matlockite, structural properties, electronic structure

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1625 Role of Fish Hepatic Aldehyde Oxidase in Oxidative In Vitro Metabolism of Phenanthridine Heterocyclic Aromatic Compound

Authors: Khaled S. Al Salhen

Abstract:

Aldehyde oxidase is molybdo-flavoenzyme involved in the oxidation of hundreds of endogenous and exogenous and N-heterocyclic compounds and environmental pollutants. Uncharged N-heterocyclic aromatic compounds such phenanthridine are commonly distributed pollutants in soil, air, sediments, surface water and groundwater, and in animal and plant tissues. Phenanthridine as uncharged N-heterocyclic aromatic compound was incubated with partially purified aldehyde oxidase from rainbow trout fish liver. Reversed-phase HLPC method was used to separate the oxidation products from phenanthridine and the metabolite was identified. The 6(5H)-phenanthridinone was identified the major metabolite by partially purified aldehyde oxidase from fish liver. Kinetic constant for the oxidation reactions were determined spectrophotometrically and showed that this substrate has a good affinity (Km = 78 ± 7.6 µM) for hepatic aldehyde oxidase, coupled with a relatively high oxidation rate (0.77± 0.03 nmol/min/mg protein). In addition, the kinetic parameters of hepatic fish aldehyde oxidase towards the phenanthridine substrate indicate that in vitro biotransformation by hepatic fish aldehyde oxidase will be a significant pathway. This study confirms that partially purified aldehyde oxidase from fish liver is indeed the enzyme responsible for the in vitro production 6(5H)-phenanthridinone metabolite as it is a major metabolite by mammalian aldehyde oxidase.

Keywords: aldehyde oxidase, fish, phenanthridine, specificity

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