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arsenous acid

László Valkai, Attila K Horváth
It is clearly demonstrated that the arsenous acid-periodate reaction displays crazy-clock behavior when a statistically meaningful number of kinetic runs are performed under "exactly the same" conditions. Both extensive experimental and numerical simulation results gave convincing evidence that the stochastic feature of the title reaction originates from the imperfection of the mixing process, and neither local random fluctuation nor initial inhomogeneity alone is capable of explaining adequately the observed phenomena...
May 11, 2018: Physical Chemistry Chemical Physics: PCCP
Janina-Miriam Noy, Hongxu Lu, Philip J Hogg, Jia-Lin Yang, Martina Stenzel
PENAO (4-(N-(S-penicillaminylacetyl)amino) phenylarsonous acid), which is a mitochondria inhibitor that reacts with adenine nucleotide translocator (ANT), is currently being trialed in patients with solid tumors. To increase the stability of the drug, the formation of nanoparticles has been proposed. Herein, the direct synthesis of polymeric micelles based on the anticancer drug PENAO is presented. PENAO is readily available for amidation reaction to form PENAO MA (4-(N-(S-penicillaminylacetyl) amino) phenylarsonous acid methacrylamide) which undergoes RAFT (reversible addition-fragmentation chain transfer) polymerization with poly(ethylene glycol methyl ether methacrylate) as comonomer and poly(methyl methacrylate) (pMMA) as chain transfer agent, resulting in p(MMA)-b-p(PEG-co-PENAO) block copolymers with 3-15 wt % of PENAO MA...
February 21, 2018: Bioconjugate Chemistry
T Marino, A Parise, N Russo
Platinum(ii)-based molecules are the most commonly used anticancer drugs in the chemotherapeutic treatment of tumours but possess serious side effects and some cancer types exhibit resistance with respect to these compounds (e.g. cisplatin). For these reasons, the research of new compounds that can bypass this limitation is in continuous development. Recently, mixed Pt(ii)-As(iii) systems have been synthesized and tested as potential anticancer agents. The mechanism of action of these kinds of drugs is unclear...
January 4, 2017: Physical Chemistry Chemical Physics: PCCP
Adrienne S Ettinger, Tye E Arbuckle, Mandy Fisher, Chun Lei Liang, Karelyn Davis, Ciprian-Mihai Cirtiu, Patrick Bélanger, Alain LeBlanc, William D Fraser
Arsenic is a common environmental contaminant from both naturally-occurring and anthropomorphic sources and human exposure can be detected in various tissues. Its toxicity depends on many factors including the chemical form, valence state, bioavailability, metabolism and detoxification within the human body. Of paramount concern, particularly with respect to health effects in children, is the timing of exposure as the prenatal and early life periods are more susceptible to toxic effects. The Maternal-Infant Research on Environmental Chemicals (MIREC) cohort was established to obtain national-level biomonitoring data for approximately 2,000 pregnant women and their infants between 2008 and 2011 from 10 Canadian cities...
February 2017: Environmental Research
Qi Zhang, Mohammad Reza Vakili, Xing-Fang Li, Afsaneh Lavasanifar, X Chris Le
In this study, we developed a micellar platform composed of terpolymers for the encapsulation of inorganic arsenite or arsenous acid (AsIII ). For this purpose, a series of terpolymers composed of poly(ethylene oxide) (PEO, block A), poly(α-carboxylate-ε-carprolactone) (PCCL, block B), and poly(ε-caprolactone) (PCL, block C) with either a blocked, i.e., BC or CB, or random, i.e., (B/C)ran block copolymer sequence in the polyester segment was synthesized. The COOH groups on block B were further modified with mercaptohexylamine for AsIII encapsulation...
December 5, 2016: Molecular Pharmaceutics
Irene Navarro Serrano, María Teresa Llorente Ballesteros, Silvia Sánchez Fernández Pacheco, Silvia Izquierdo Álvarez, Jose Luis López Colón
BACKGROUND: Very few studies exist on urinary arsenic exposure in Spain. OBJECTIVE: To evaluate total and speciated urinary arsenic (As) levels in a Spanish population sample. METHODS: Demographic, lifestyle and dietary data was collected for 124 volunteers (aged 20-76years; 88 women and 36 men), who were tested for total arsenic and five arsenic species using high-performance liquid chromatography-inductively coupled plasma mass spectrometry...
November 15, 2016: Science of the Total Environment
Joel B Awuah, Nelson Y Dzade, Richard Tia, Evans Adei, Bright Kwakye-Awuah, C Richard A Catlow, Nora H de Leeuw
We present density functional theory calculations of the adsorption of arsenic acid (AsO(OH)3) and arsenous acid (As(OH)3) on the Al(III)-modified natural zeolite clinoptilolite under anhydrous and hydrated conditions. From our calculated adsorption energies, we show that adsorption of both arsenic species is favorable (associative and exothermic) under anhydrous conditions. When the zeolite is hydrated, adsorption is less favourable, with the water molecules causing dissociation of the arsenic complexes, although exothermic adsorption is still observed for some sites...
April 28, 2016: Physical Chemistry Chemical Physics: PCCP
László Valkai, Attila K Horváth
The iodine-arsenous acid (Roebuck), iodide-iodate (Dushman), and iodate-arsenous acid reactions have been studied simultaneously by a stopped-flow technique by monitoring the absorbance-time profiles at the isosbestic point of the I2/I3(-) system (468 nm). Using the well-accepted rate coefficients of iodine hydrolysis, we have proven that iodine is the kinetically active species of the iodine-arsenous acid reaction. Strong iodide inhibition of this system is explained by a rapidly established equilibrium between iodine and arsenous acid to produce an iodide ion, a hydrogen ion, and a short-lived intermediate H2AsO3I, which is shifted far to the left...
February 15, 2016: Inorganic Chemistry
György Csekő, László Valkai, Attila K Horváth
The autocatalytic iodate-arsenous acid reaction was investigated by a stopped-flow instrument under strongly acidic medium (pH ≤ 1) by monitoring the absorbance-time profiles at 468 nm. The kinetic traces were found to exhibit a perfect sigmoidal shape in stoichiometric excess of iodate with a well-defined and reproducible induction period that depends on the initial concentration of the reactants as well as on the pH. All the experimental curves can be globally fitted by a simple kinetic model involving the direct reaction between the reactants to produce iodide ion, the Dushman and the Roebuck reactions, and two rapid equilibria...
November 12, 2015: Journal of Physical Chemistry. A
Li-Juan Duan, Chao Li, Ru-Yu Yang
OBJECTIVE: To explore the clinical value of arsenious acid (H3AsO3) for treating patients with acute promyelocytic leukemia (APL). METHODS: A total of 86 patients with APL were randomly divided into experimental group (43 cases) and control group (43 cases). The control group was treated by all trans retinoic acid combined with chemotherapy, the experimental group were treated by arsenous acid on the basis of the control group. RESULTS: The overall response rate (ORR) in experimental group (100...
August 2015: Zhongguo Shi Yan Xue Ye Xue za Zhi
László Valkai, György Csekő, Attila K Horváth
It is unambiguously demonstrated that in the case of an autocatalytic reaction, initial inhomogeneities induced by the imperfectly mixed part of the overall volume may result in a serious irreproducibility of the individual kinetic runs. A statistically meaningful number of repetitions, however, gives rise to a reproducible cumulative probability distribution curve often referred to as a support of the stochastic feature. The iodate-arsenous acid reaction being autocatalytic with respect to both iodide and hydrogen ions displays clock behavior...
September 14, 2015: Physical Chemistry Chemical Physics: PCCP
Indranil Sen, Wei Zou, Josephine Alvaran, Linda Nguyen, Ryszard Gajek, Jianwen She
In order to better distinguish the different toxic inorganic and organic forms of arsenic (As) exposure in individuals, we have developed and validated a simple and robust analytical method for determining the following six As species in human urine: arsenous (III) acid (As-III), As (V) acid, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine (AsB), and arsenocholine. In this method, human urine is diluted using a pH 5.8 buffer, separation is performed using an anion exchange column with isocratic HPLC, and detection is achieved using inductively coupled plasma-MS...
March 2015: Journal of AOAC International
Bharathi Avula, Yan-Hong Wang, Ikhlas A Khan
The study involves the analysis of total arsenic (As) in metallic form, and organic and inorganic As species from seaweeds and dietary supplements. The analysis provides data for dietary exposure estimates of inorganic species that are considered more toxic to humans than organic and total As. Total As was determined by acid digestion followed by inductively coupled plasma (ICP)-MS. To characterize the As species, solvent extraction with sonication and microwave extraction using various aqueous and aqueous/organic solvent mixtures were initially evaluated...
March 2015: Journal of AOAC International
Paul Wilson, Athina Anastasaki, Matthew R Owen, Kristian Kempe, David M Haddleton, Sarah K Mann, Angus P R Johnston, John F Quinn, Michael R Whittaker, Philip J Hogg, Thomas P Davis
The entropy-driven affinity of trivalent (in)organic arsenicals for closely spaced dithiols has been exploited to develop a novel route to peptide/protein-polymer conjugation. A trivalent arsenous acid (As(III)) derivative (1) obtained from p-arsanilic acid (As(V)) was shown to readily undergo conjugation to the therapeutic peptide salmon calcitonin (sCT) via bridging of the Cys(1)-Cys(7) disulfide, which was verified by RP-HPLC and MALDI-ToF-MS. Conjugation was shown to proceed rapidly (t < 2 min) in situ and stoichiometrically through sequential reduction-conjugation protocols, therefore exhibiting conjugation efficiencies equivalent to those reported for the current leading disulfide-bond targeting strategies...
April 1, 2015: Journal of the American Chemical Society
Lenora K Harper, Sonia Antony, Craig A Bayse
The reactivity of arsenite and selenite with biological thiols plays an important role in the toxicity of these elements. However, toxic effects are eliminated when the species are coadministered, due to the antagonistic relationship between selenium and arsenic. The reduction of arsenous acid and selenious acid by thiol and the formation of an As-Se species have been modeled using density functional theory (DFT) and solvent-assisted proton exchange (SAPE), a microsolvation technique that uses a network of water molecules to mimic the participation of bulk solvent in proton transfer processes...
December 15, 2014: Chemical Research in Toxicology
Lorenz R Canaval, Oliver M D Lutz, Alexander K H Weiss, Christian W Huck, Thomas S Hofer
This work presents a hybrid ab initio quantum mechanical/molecular mechanical simulation at the RI-MP2 level of theory investigating the hydrolysis process of arsenic(III), ultimately leading to arsenous acid (H3AsO3). A newly implemented dissociative water model has been applied to treat the interactions in the classical region, which is capable of describing non-neutral water species such as hydroxide and oxonium ions. Three stages of hydrolysis have been observed during the simulation and besides profound dynamical considerations, detailed insights into structural changes and atomic partial charge shifts are presented...
November 17, 2014: Inorganic Chemistry
Eva Pópity-Tóth, Gábor Pótári, István Erdős, Dezső Horváth, Agota Tóth
Horizontally propagating chemical fronts leading to the formation of a single stable convection roll are investigated in the iodate-arsenous acid reaction with arsenous acid stoichiometrically limiting, leaving the surface active iodine present in the product mixture. In sufficiently thin solution layers with open upper surface, the contribution of Marangoni instability is significantly enhanced. Acting in the same direction as buoyancy driven instability, it distorts the entire tilted reaction front that becomes 50% more elongated...
July 28, 2014: Journal of Chemical Physics
Koji Baba, Tomohito Arao, Noriko Yamaguchi, Eiki Watanabe, Heesoo Eun, Masumi Ishizaka
Arsenic species, including arsenous acid, arsenic acid, methylarsonic acid, and dimethylarsinic acid, were determined using HPLC-ICPMS. The species were separated with a Discovery HS F5 column and a simple, volatile, and isocratic mobile phase of 0.1% (v/v) formic acid and 1% (v/v) methanol. The Discovery HS F5 column with a pentafluorophenyl (PFP) stationary phase gave sharp peaks and full separation of the arsenic species in 5min, and other PFP columns showed lower performance. This separation method was applied to arsenic species analysis in rice...
August 8, 2014: Journal of Chromatography. A
Qi Zhang, Mohammad Reza Vakili, Xing-Fang Li, Afsaneh Lavasanifar, X Chris Le
Arsenic trioxide (ATO), dissolved in water as arsenous acid or inorganic arsenite (As(III)), is an effective chemotherapeutic agent against acute promyelocytic leukemia (APL). It has been under investigation as a potential treatment for a variety of solid tumors although with much poorer efficacy than for APL. The toxicity of As(III) and its derivatives is a common concern that has limited its use. The objective of the current study was to develop a polymeric micelle drug delivery system for efficient and controlled delivery of trivalent arsenicals to solid tumor cells...
August 2014: Biomaterials
Sergio S C D C Rubin, Pradeep Alava, Ivar Zekker, Gijs Du Laing, Tom Van de Wiele
BACKGROUND: Arsenic (As) toxicity is primarily based on its chemical speciation. Although inorganic and methylated As species are well characterized in terms of metabolism and formation in the human body, the origin of thiolated methylarsenicals is still unclear. OBJECTIVES: We sought to determine whether sulfate-reducing bacteria (SRB) from the human gut are actively involved in the thiolation of monomethylarsonic acid (MMAV). METHODS: We incubated human fecal and colon microbiota in a batch incubator and in a dynamic gut simulator with a dose of 0...
August 2014: Environmental Health Perspectives
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