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Maleic acid

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https://www.readbyqxmd.com/read/28732966/effect-of-ultrasonic-waves-on-the-water-turbidity-during-the-oxidation-of-phenol-formation-of-hydro-peroxo-complexes
#1
Natalia Villota, Jose M Lomas, Luis M Camarero
Analysis of the kinetics of aqueous phenol oxidation by a sono-Fenton process reveals that the via involving ortho-substituted intermediates prevails: catechol (25.0%), hydroquinone (7.7%) and resorcinol (0.6%). During the oxidation, water rapidly acquires color that reaches its maximum intensity at the maximum concentration of p-benzoquinone. Turbidity formation occurs at a slower rate. Oxidant dosage determines the nature of the intermediates, being trihydroxylated benzenes (pyrogallol, hydroxyhydroquinone) and muconic acid the main precursors causing turbidity...
November 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28719476/a-rare-case-of-contact-urticaria-and-allergic-contact-dermatitis-to-maleic-and-fumaric-acids
#2
Franziska Raessler, Sibylle Schliemann, Peter Elsner
No abstract text is available yet for this article.
July 2017: Dermatitis
https://www.readbyqxmd.com/read/28714596/multifunctional-nanotube-mucoadhesive-poly-methyl-vinyl-ether-co-maleic-acid-hydroxypropyl-methylcellulose-acetate-succinate-composite-for-site-specific-oral-drug-delivery
#3
Nattha Kerdsakundee, Wei Li, João Pedro Martins, Zehua Liu, Feng Zhang, Marianna Kemell, Alexandra Correia, Yaping Ding, Mikko Airavaara, Jouni Hirvonen, Ruedeekorn Wiwattanapatapee, Hélder A Santos
An advanced oral drug delivery system that can effectively deliver drugs with poor oral bioavailability is strongly desirable. Herein, a multifunctional nano-in-micro structured composite is developed by encapsulation of the mucoadhesive poly(methyl vinyl ether-co-maleic acid) modified halloysite nanotubes (HNTs) with the pH-responsive hydroxypropyl methylcellulose acetate succinate by the microfluidics to control the drug release, increase cell-particle interaction, and improve drug absorption. The microparticles show spherical shape, homogeneous particle size distribution (58 ± 1 µm), and pH-responsive dissolution behavior at pH > 6, and they prevent the premature release of curcumin in simulated pH conditions of the stomach and immediately release the curcumin in simulated pH conditions of the small intestine...
July 17, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28714233/bioinspired-size-tunable-self-assembly-of-polymer-lipid-bilayer-nanodiscs
#4
Thirupathi Ravula, Sudheer Ramadugu, Giacomo Di Mauro, Ayyalusamy Ramamoorthy
Polymer-based nanodiscs are valuable tools in biomedical research that can offer a detergent-free solubilization of membrane proteins maintaining their native lipid environment. Here, we introduce a novel ~1.6 kDa SMA-based polymer with styrene:maleic acid moieties that can form nanodiscs containing a planar lipid bilayer which are useful to reconstitute membrane proteins for structural and functional studies. The physicochemical properties and the mechanism of formation of polymer-based nanodiscs are characterized by light scattering, NMR, FT-IR, and TEM imaging experiments...
July 16, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28711707/protecting-group-free-radical-decarboxylation-of-bile-acids-synthesis-of-novel-steroidal-substituted-maleic-anhydrides-and-maleimides-and-evaluation-of-their-cytotoxicity-on-c6-rat-glioma-cells
#5
Mohammad Samadi, Thomas Nury, Ali Khalafi-Nezhad, Gérard Lizard
We report the first Barton radical decarboxylation of unprotected bile acids via in situ irradiation of their thiohydroxamic esters in the presence of citraconic anhydride and citracoimide, leading to the synthesis a series of steroidal maleic anhydrides and maleimides as novel hybrid bile acids. The cytotoxic activities were evaluated on C6 rat glioma cells.
July 12, 2017: Steroids
https://www.readbyqxmd.com/read/28691739/nuclear-magnetic-resonance-and-mass-spectometry-based-metabolomics-to-study-maleic-acid-toxicity-from-repeated-dose-exposure-in-rats
#6
Charlene Wu, Chi-Hung Chen, Hsin-Chang Chen, Hao-Jan Liang, Shu-Ting Chen, Wan-Yu Lin, Kuen-Yuh Wu, Su-Yin Chiang, Ching-Yu Lin
Maleic acid (MA), a chemical intermediate used in many consumer and industrial products, was intentionally adulterated in a variety of starch-based foods and instigated food safety incidents in Asia. We aim to elucidate possible mechanisms of MA toxicity after repeated exposure by (1) determining the changes of metabolic profile using (1) H nuclear magnetic resonance spectroscopy and multivariate analysis, and (2) investigating the occurrence of oxidative stress using liquid chromatography tandem mass spectrometry by using Sprague-Dawley rat urine samples...
July 10, 2017: Journal of Applied Toxicology: JAT
https://www.readbyqxmd.com/read/28660939/genetic-and-chemical-characterisation-of-the-cornexistin-pathway-provides-further-insight-into-maleidride-biosynthesis
#7
Katherine Williams, Agnieszka J Szwalbe, Claire Dickson, Tim R Desson, Nicholas P Mulholland, Jason L Vincent, John M Clough, Andrew M Bailey, Craig P Butts, Christine L Willis, Thomas J Simpson, Russell J Cox
The biosynthesis of the herbicide cornexistin in the fungus Paecilomyces variotii was investigated by full sequencing of its genome, knockout of key genes within its biosynthetic gene cluster and isolation and identification of intermediate compounds. The general biosynthetic pathway resembles that of byssochlamic acid and other nonadrides in the early stages, but differs in requiring fewer enzymes in the key nonadride dimerisation step, and in the removal of one maleic anhydride moiety.
June 29, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28658642/folic-acid-conjugated-polymeric-micelles-loaded-with-a-curcumin-difluorinated-analog-for-targeting-cervical-and-ovarian-cancers
#8
Duy Luong, Prashant Kesharwani, Hashem O Alsaab, Samaresh Sau, Subhash Padhye, Fazlul H Sarkar, Arun K Iyer
The current study utilizes folic acid conjugated poly(styrene-co-maleic anhydride) block copolymer (FA-SMA) to enhance the solubility of a hydrophobic but very potent synthetic curcumin-difluorinated (CDF) analog and its targeted delivery to folate receptor-alpha overexpressing cancers. The nanomicelles showed high aqueous solubility. Importantly, the encapsulation of CDF in nanomicelles resulted in high photo-stability of the otherwise photo-labile drug. When the nanomicelles were tested in folate-receptor overexpressing ovarian and cervical cancer cells they exhibited high anticancer activity causing significant cell population to undergo apoptosis due to upregulation of tumor suppressor phosphatase and tensin homolog (PTEN) and inhibition of nuclear factor kappa-B (NFκB), which further confirmed the targeting ability and anticancer potentials of folate-targeted formulations...
June 21, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28653931/impact-of-different-organic-acids-on-solubility-enhancement-of-cefpodxime-proxetil-immediate-release-tablet-and-its-stability-studies
#9
Sabahat Jabeen, Fouzia Hassan, Rabia Ismail Yousuf, Muhammad Harris Shoaib, Fozia Israr, S M Farid Hasan, Rehana Saeed, Sadaf Farooqi
Cefpodoxime proxetil is a third generation cephalosporin antibiotic demonstrates pH dependent solubility and is highly soluble only in acidic pH. The purpose of this investigation was to design and develop immediate release tablets of cefpodoxime proxetil by direct compression method and determine the effect of different solid buffers (organic acids) such as fumaric acid (formulations F1-F4), maleic acid (formulations M1-M4) and citric acid (formulations C1-C4) by using cefpodoxime and acid in the ratios of 4:1, 2:1, 1:1 and 1:2 to achieve pH-independent release of the drug...
May 2017: Pakistan Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28644059/carbonic-anhydrase-i-ii-iv-and-ix-inhibition-with-a-series-of-7-amino-3-4-dihydroquinolin-2-1h-one-derivatives
#10
Murat Bozdag, Silvia Bua, Sameh M Osman, Zeid AlOthman, Claudiu T Supuran
A series of new derivatives was prepared by derivatisation of the 7-amino moiety present in 7-amino-3,4-dihydroquinolin-2(1H)-one, a compound investigated earlier as CAI. The derivatisation was achieved by: i) reaction with arylsulfonyl isocyanates/aryl isocyanates; (ii) reaction with fluorescein isothiocyanate; (iii) condensation with substituted benzoic acids in the presence of carbodiimides; (iv) reaction with 2,4,6-trimethyl-pyrylium tetrafluoroborate; (v) reaction with methylsulfonyl chloride and (vi) reaction with maleic anhydride...
December 2017: Journal of Enzyme Inhibition and Medicinal Chemistry
https://www.readbyqxmd.com/read/28624590/maleic-acid-assisted-improvement-of-metal-chelation-and-antioxidant-metabolism-confers-chromium-tolerance-in-brassica-juncea-l
#11
Jubayer Al Mahmud, Mirza Hasanuzzaman, Kamrun Nahar, Anisur Rahman, Md Shahadat Hossain, Masayuki Fujita
Chromium (Cr) is a highly toxic environmental pollutant that negatively affects plant growth and development. Thus, remediating Cr from soil or increasing plant tolerance against Cr stress is urgent. Organic acids are recognized as agents of phytoremediation and as exogenous protectants, but using maleic acid (MA) to attain these results has not yet been studied. Therefore, our study investigated the effects of MA on Cr uptake and mitigation of Cr toxicity. We treated 8-d-old Indian mustard (Brassica juncea L...
June 15, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28606536/preparation-and-characterization-of-poly-maleic-acid-grafted-cross-linked-chitosan-microspheres-for-cd-ii-adsorption
#12
Zhenzhen Yu, Qifeng Dang, Chengsheng Liu, Dongsu Cha, Haifeng Zhang, Wenjing Zhu, Qianqian Zhang, Bing Fan
A novel adsorbent, composed of poly(maleic acid)-grafted cross-linked chitosan microspheres (PMACCMs), was prepared via cross-linking with glutaraldehyde and modification by grafting maleic acid. FTIR, zeta potential, elemental analysis, (13)C NMR, DTG, laser particle size analysis, SEM, and BET methods were applied to characterize PMACCMs, exhibiting a successful fabrication, good thermostability, and well-defined surface microstructure beneficial to Cd(II) adsorption. The effects of pH, contact time, and initial concentration on Cd(II) adsorption were also investigated, and the maximum adsorption capacity was 39...
September 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28606519/folate-conjugated-thermosensitive-o-maleoyl-modified-chitosan-micellar-nanoparticles-for-targeted-delivery-of-erlotinib
#13
Marziyeh Fathi, Parham Sahandi Zangabad, Ayuob Aghanejad, Jaleh Barar, Hamid Erfan-Niya, Yadollah Omidi
In the present work, new self-assembled nanoparticles (NPs) were engineered using biocompatible and biodegradable natural polymer, chitosan (CS). The complexation of CS with sodium dodecyl sulfate (SDS) facilitated the regioselective chemical modification of CS hydroxyl groups with maleic anhydride, and produced polymerizable precursor of CS that was further grafted with N-isopropylacrylamide (NIPAAm) as temperature-sensitive moiety and oleic acid (OA) as hydrophobic monomer. After removal of SDS complex, the free amino groups were functionalized with folic acid (FA) to form folate-(PNIPAAm-co-OA)-g-CS micellar NPs...
September 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28559897/the-influence-of-the-plant-growth-regulator-maleic-hydrazide-on-egyptian-broomrape-early-developmental-stages-and-its-control-efficacy-in-tomato-under-greenhouse-and-field-conditions
#14
Ariel Venezian, Evgenia Dor, Guy Achdari, Dina Plakhine, Evgeny Smirnov, Joseph Hershenhorn
Broomrapes (Phelipanche spp. and Orobanche spp.) are holoparasitic plants that cause tremendous losses of agricultural crops worldwide. Broomrape control is extremely difficult and only amino acid biosynthesis-inhibiting herbicides present an acceptable control level. It is expected that broomrape resistance to these herbicides is not long in coming. Our objective was to develop a broomrape control system in tomato (Solanum lycopersicum L.) based on the plant growth regulator maleic hydrazide (MH). Petri-dish and polyethylene-bag system experiments revealed that MH has a slight inhibitory effect on Phelipanche aegyptiaca seed germination but is a potent inhibitor of the first stages of parasitism, namely attachment and the tubercle stage...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28513723/amphiphilic-coatings-for-the-protection-of-upconverting-nanoparticles-against-dissolution-in-aqueous-media
#15
Olivija Plohl, Slavko Kralj, Boris Majaron, Eleonore Fröhlich, Maja Ponikvar-Svet, Darko Makovec, Darja Lisjak
Upconverting nanoparticles (UCNPs) of β-NaYF4, co-doped with Yb(3+) and Tm(3+) and 21-36 nm large, were synthesized using a modified thermal decomposition method. The as-synthesized UCNPs were coated with oleic acid and dispersed in nonpolar media. Their morphology, size and crystal structure were analysed with transmission electron microscopy and X-ray diffraction. The UCNPs showed a fluorescence emission spectrum characteristic of Tm(3+). Their dissolution in water (pH ∼ 4-5) and phosphate buffered saline (PBS, pH = 7...
May 30, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28512283/unusual-root-canal-irrigation-solutions
#16
Zahed Mohammadi, Hamid Jafarzadeh, Sousan Shalavi, Jun-Ichiro Kinoshita
Microorganisms and their by-products play a critical role in pulp and periradicular pathosis. Therefore, one of the main purposes of root canal treatment is disinfection of the entire system of the canal. This aim may be obtained using mechanical preparation, chemical irrigation, and temporary medication of the canal. For this purpose, various irrigation solutions have been advocated. Common root canal irrigants, such as sodium hypochlorite, chlorhexidine, and a mixture of tetracycline, acid, and detergent have been extensively reviewed...
May 1, 2017: Journal of Contemporary Dental Practice
https://www.readbyqxmd.com/read/28482555/octreotide-conjugated-fluorescent-pegylated-polymeric-nanogel-for-theranostic-applications
#17
Vineeth M Vijayan, Sachin J Shenoy, Jayabalalan Muthu
Targeted nanocarriers can significantly increase the efficiency of therapeutic formulations by ensuring the site specific delivery of the cargo. Here in, we report a novel actively targeted fluorescent nanogel, PMB-OctN, based on photoluminescent comacromer [PEG-maleic acid-4 aminobenzoic acid], diethylene glycoldimethacrylate and octreotide. The nanogel has spherical morphology with average particle size around 40nm. The PMB-OctN can load 78% of anticancer drug and release for 5days and beyond in a sustained way...
July 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28481255/in-vitro-anticancer-activity-and-structural-characterization-of-ubiquinones-from-antrodia-cinnamomea-mycelium
#18
I-Chuan Yen, Shih-Yu Lee, Kuen-Tze Lin, Feng-Yi Lai, Mao-Tien Kuo, Wen-Liang Chang
Two new ubiquinones, named antrocinnamone and 4-acetylantrocamol LT3, were isolated along with six known ubiquinones from Antrodia cinnamomea (Polyporaceae) mycelium. The developed HPLC analysis methods successfully identified eight different ubiquinones, two benzenoids, and one maleic acid derivative from A. cinnamomea. The ubiquinones 1-8 exhibited potential and selective cytotoxic activity against three human cancer cell lines, with IC50 values ranging from 0.001 to 35.883 μM. We suggest that the different cytotoxicity levels were related to their chemical structures, especially the 4-hydroxycyclohex-2-enone ring and the presence of a free hydroxyl group in the side chain...
May 6, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28472686/adsorptive-removal-of-copper-ii-and-lead-ii-using-chitosan-g-maleic-anhydride-g-methacrylic-acid-copolymer
#19
R Lavanya, T Gomathi, K Vijayalakshmi, M Saranya, P N Sudha, Sukumaran Anil
In the present work, the maleic anhydride and methacrylic acid monomers were grafted one after another onto chitosan by using ceric ammonium nitrate as the initiator. The optimum conditions for grafting were studied by varying the initiator concentration, monomer concentration and reaction temperature. The synthesized grafted samples were subjected to various analytical techniques such as FTIR, XRD, TGA and DSC methods The proof of formation of graft copolymer was ascertained from the results of FTIR analysis and XRD studies...
May 1, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28452481/reactions-of-three-lactones-with-cl-od-and-o3-atmospheric-impact-and-trends-in-furan-reactivity
#20
S Ausmeel, C Andersen, O J Nielsen, F F Østerstrøm, M S Johnson, E J K Nilsson
Lactones, cyclic esters of hydroxycarboxylic acids, are interesting biofuel candidates as they can be made from cellulosic biomass and have favorable physical and chemical properties for distribution and use. The reactions of γ-valerolactone (GVL), γ-crotonolactone (2(5H)-F), and α-methyl-γ-crotonolactone (3M-2(5H)-F) with Cl, OD, and O3 were investigated in a static chamber at 700 Torr and 298 ± 2 K. The relative rate method was used to determine kGVL+Cl = (4.56 ± 0.51) × 10(-11), kGVL+OD = (2.94 ± 0...
May 22, 2017: Journal of Physical Chemistry. A
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