156291-94-0Relevant articles and documents
Sonochemical degradation of ethyl paraben in environmental samples: Statistically important parameters determining kinetics, by-products and pathways
Papadopoulos, Costas,Frontistis, Zacharias,Antonopoulou, Maria,Venieri, Danae,Konstantinou, Ioannis,Mantzavinos, Dionissios
, p. 62 - 70 (2016)
The sonochemical degradation of ethyl paraben (EP), a representative of the parabens family, was investigated. Experiments were conducted at constant ultrasound frequency of 20 kHz and liquid bulk temperature of 30 °C in the following range of experimental conditions: EP concentration 250-1250 μg/L, ultrasound (US) density 20-60 W/L, reaction time up to 120 min, initial pH 3-8 and sodium persulfate 0-100 mg/L, either in ultrapure water or secondary treated wastewater. A factorial design methodology was adopted to elucidate the statistically important effects and their interactions and a full empirical model comprising seventeen terms was originally developed. Omitting several terms of lower significance, a reduced model that can reliably simulate the process was finally proposed; this includes EP concentration, reaction time, power density and initial pH, as well as the interactions (EP concentration) × (US density), (EP concentration) × (pHo) and (EP concentration) × (time). Experiments at an increased EP concentration of 3.5 mg/L were also performed to identify degradation by-products. LC-TOF-MS analysis revealed that EP sonochemical degradation occurs through dealkylation of the ethyl chain to form methyl paraben, while successive hydroxylation of the aromatic ring yields 4-hydroxybenzoic, 2,4-dihydroxybenzoic and 3,4-dihydroxybenzoic acids. By-products are less toxic to bacterium V. fischeri than the parent compound.
Synthesis, characterisation of new derivatives with mono ring system of 1,2,4-triazole scaffold and their anticancer activities
Slaihim, Mukhlif Mohsin,Al-Suede, Fouad Saleih R.,Khairuddean, Melati,Khadeer Ahamed, Mohamed B.,Shah Abdul Majid, Amin Malik
, p. 78 - 87 (2019)
In the present study, two important starting materials and 18 new 1,2,4-triazole compounds with mono ring system have been synthesized and characterized. The mono system showed 16 compounds of a Schiff base moiety attached to the triazole ring which was prepared from the corresponding starting material 5(A–B) or piperidinium salt system 6(A–B). All these compounds were characterized using Fourier Transform Infrared (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy and carbon hydrogen nitrogen (CHN) elemental analysis. The compounds were selected for in vitro anticancer study to test the therapeutic cytotoxic potential against cancer cells. The MTT test was conducted against human breast (MCF-7) and colorectal (HCT-116) cancer cells. Among all the compounds tested, 7A-i demonstrated more pronounced in vitro anticancer effect against MCF-7 and HCT-116 cells with IC50 of 38 and 19.2 μM, respectively, comparable to that of the standard reference drugs, tamoxifen and 5-fluorouracil, respectively. Compound 7A-vi showed a considerable cytotoxic effect with IC50 53 and 41.2 μM against MCF-7 and HCT-116 cells, respectively. Compounds 7A-ii, 7A-iii and 7A-v exhibited moderate cytotoxicity with IC50 68, 91 and 85 μM, respectively against MCF-7 cells and also 59.3, 81.7 and 137.1 μM against HCT-116 cells, respectively. However, all other compounds tested in this study showed poor cytotoxicity against both the cell lines. Cellular morphological analysis revealed that the cytotoxicity induced by the compounds could probably due to autophagy. It can be concluded that 1,2,4-triazole derivatives can be promising therapeutic agents. Further studies will be done to investigate the antitumor efficacy of the 1,2,4-triazole derivatives using suitable preclinical models.
Erratum: Site-Selective C-H Alkylation of Complex Arenes by a Two-Step Aryl Thianthrenation-Reductive Alkylation Sequence (J. Am. Chem. Soc. (2021) 143: 21 (7909?7914) DOI: 10.1021/jacs.1c03459)
Granatino, Paola,Lansbergen, Beatrice,Ritter, Tobias
, p. 10477 - 10478 (2021)
Page 7912. In our previous Communication, we inadvertently drew the substrates derived from the molecule pyriproxyfen with incorrect connectivity of the pyriproxyfen molecule (meta instead of para was drawn), omitted a methylene group from compound 13, and drew an epimer of compound 20 in Scheme 3. These drawing errors have been corrected in the corrected Scheme 3 shown here. As a further clarification, we have commented in the revised Supporting Information about the undefined stereocenter of compound 21. The findings and conclusions of the original communication remain unchanged. We apologize for the errors and for any inconvenience that this may have caused the readers of JACS.
C3N4-Photocatalyzed aerobic oxidative cleavage of CC bonds in alkynes with diazonium salts leading to two different aldehydes or esters in one pot
Wang, Jingjing,Ni, Bangqing,Niu, Tengfei,Ji, Fei
, p. 8458 - 8464 (2020)
A novel photocatalyzed radical addition/oxygen oxidation/cleavage of dioxetane/HAT domino process for cleavage of CC bonds has been described. This protocol used porous graphitic carbon nitrides (p-g-C3N4) as a metal-free recyclable photocatalyst for transformations of alkynes with diazonium salts to give two different aldehydes or esters, which enables the formation of multiple C-O bonds in a single reaction with operational simplicity. This reaction has an excellent substrate scope and gives the desired products in moderate to high yields. In addition, the heterogeneous semiconductor exhibits easy handling and excellent recyclability for at least 6 cycles without any apparent loss of activity. Furthermore, this reaction could be carried out under solar light irradiation and is applicable for the gram scale with satisfactory results.
The effect of meta versus para substitution on the efficiency of chemiexcitation in the chemically triggered electron-transfer-initiated decomposition of spiroadamantyl dioxetanes
Adam, Waldemar,Trofimov, Alexei V.
, p. 6474 - 6478 (2000)
A similar viscosity dependence of the CIEEL efficiencies for the para- and meta-substituted spiroadamantyl dioxetanes 1 has been observed, which implies that an electron-transfer mechanism operates through solvent-caged species for both regioisomers. The pronounced difference in the chemiexcitation yields for the meta- and para-substituted dioxetanes is rationalized in terms of the much larger (ca. 200-fold) rate constant for the electron back-transfer (BET) step to afford the excited meta CIEEL emitter. An in-depth kinetic analysis of the viscosity effect on the excited-state generation for the papa versus meta regioisomers supports this conclusion.
Solar photocatalytic decomposition of ethyl paraben in zinc oxide suspensions
Frontistis, Zacharias,Antonopoulou, Maria,Venieri, Danae,Dailianis, Stefanos,Konstantinou, Ioannis,Mantzavinos, Dionissios
, p. 139 - 148 (2017)
The photocatalytic degradation of ethyl paraben (EP) in zinc oxide (ZnO) suspensions under simulated solar radiation was investigated. The effect of EP concentration (500–1500 μg/L), ZnO concentration (100–500 mg/L), reaction time (3–9 min), initial pH (3–9), light intensity (7.3 10?7–1.1 10?6 einstein/(L.s)) and the water matrix (0–10 mg/L of humic acid) on degradation was evaluated implementing a factorial design methodology. Of the six variables tested, EP concentration, ZnO concentration, reaction time and the water matrix were found to be statistically significant variables, and also important was the second order interaction of EP concentration with reaction time. With the exception of the water matrix, all other effects were positive with respect to the concentration of EP removed. Experiments at increased EP concentration (20 mg/L) were performed to identify transformation products (TPs) and assess the extent of mineralization. LC-TOF-MS analysis revealed the formation of seven early-stage TPs through hydroxylation and dealkylation reactions and a plausible reaction pathway was proposed. Besides the identified TPs, other unidentified TPs were also formed as has been verified measuring the extent of mineralization and performing a carbon balance in the liquid phase. EP at 20 mg/L exhibited mild estrogenic activity, which was partially removed upon oxidation. The stability of ZnO was evaluated measuring the extent of zinc leaching, which was just 1.5%; moreover, ZnO was found to be more active than reference P25 TiO2 for EP degradation and mineralization.
Multivalency Increases the Binding Strength of RGD Peptidomimetic-Paclitaxel Conjugates to Integrin αVβ3
Raposo Moreira Dias, André,Pina, Arianna,Dal Corso, Alberto,Arosio, Daniela,Belvisi, Laura,Pignataro, Luca,Caruso, Michele,Gennari, Cesare
, p. 14410 - 14415 (2017)
This work reports the synthesis of three multimeric RGD peptidomimetic-paclitaxel conjugates featuring a number of αVβ3 integrin ligands ranging from 2 to 4. These constructs were assembled by conjugation of the integrin αV/sub
Solar light-induced degradation of ethyl paraben with CuOx/BiVO4: Statistical evaluation of operating factors and transformation by-products
Petala, Athanasia,Bontemps, Remi,Spartatouille, Antoine,Frontistis, Zacharias,Antonopoulou, Maria,Konstantinou, Ioannis,Kondarides, Dimitris I.,Mantzavinos, Dionissios
, p. 122 - 131 (2017)
In this work, the solar light-induced photocatalytic degradation of ethyl paraben (EP) was studied using CuOx/BiVO4 with 0.75 wt.% copper loading, a relatively new photocatalyst that can exploit a large portion of the solar spectrum. The synthesized catalyst had a primary crystallite size of ca 37 nm, a specific surface area of 1 m2/g and a direct bandgap of 2.3 eV. A factorial design methodology was implemented to evaluate the importance of EP concentration (500–1500 μg/L), catalyst concentration (100–500 mg/L), reaction time (10–60 min), the presence of radical scavengers (pure water or 500 mg/L bicarbonates) and initial solution pH (3–9) on EP removal. All individual effects were statistically significant and so was the second-order interaction of EP concentration with reaction time. Interestingly and differently from the majority of photocatalytic studies, the presence of bicarbonates promotes the photocatalytic degradation of ethyl paraben. The photocatalytic activity drops from 98% to 79% after five consecutive runs, possibly due to accumulation of oxidation by-products. Liquid chromatography-time of flight mass spectrometry (LC-TOF-MS) revealed that EP degradation occurs mainly via dealkylation followed by hydroxylation reactions and the formation of methyl paraben, 4-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid as primary transformation by-products.
Chemical Synthesis and Evaluation of a Disialic Acid-Containing Dextran Polymer as an Inhibitor for the Interaction between Siglec 7 and Its Ligand
Yamaguchi, Sho,Yoshimura, Atsushi,Yasuda, Yu,Mori, Airi,Tanaka, Hiroshi,Takahashi, Takashi,Kitajima, Ken,Sato, Chihiro
, p. 1194 - 1203 (2017)
A new sialic acid (Sia)-containing glycopolymer—a fluorescent probe with high-density disialic acid (diSia) on the surface of polysaccharide dextran (diSia-Dex)—was synthesized as a key molecule to regulate the Sia recognition lectins, Siglecs, that are involved in the immune system. According to our original methods, diSia was synthesized by α-selective sialylation, and a dextran template possessing terminal acetylenes and amino groups was prepared. A diSia and a fluorescent molecule were subsequently introduced to surface-modified dextran by Hüisgen reaction and amidation, respectively. The modulatory activity of Siglec7 was evaluated by using synthetic probes. DiSia-Dex showed high binding avidity toward Siglec7, with a KD value of 5.87×10?10 m, and a high inhibitory activity for the interaction between Siglec7 and a ligand (GD3), with a IC50 value of 1.0 nm. Notably, diSia-Dex was able to release Siglec7 from the pre-existing Siglec7–GD3 complex, possibly due to its unique properties of a slow dissociation rate and a high association rate. Together, these data show that diSia-Dex can be widely applicable as a modulator of Siglec7 functions.
Enzymatically cleavable traceless biotin tags for protein PEGylation and purification
Wawro, Adam M.,Aoki, Yusuke,Muraoka, Takahiro,Tsumoto, Kouhei,Kinbara, Kazushi
, p. 1913 - 1916 (2018)
Here we report an example of a protein-PEG conjugate with a biotin tag cleavable by lipase-catalyzed hydrolysis. Very mild cleavage conditions, heterogeneous, easily separable catalysts, and traceless design make this method attractive for the preparation and purification of PEGylated proteins.
