Mononuclear Nonheme High-Spin Iron(III)-Acylperoxo Complexes in Olefin Epoxidation and Alkane Hydroxylation Reactions

Wang, Bin,Lee, Yong-Min,Clé,mancey, Martin,Seo, Mi Sook,Sarangi, Ritimukta,Latour, Jean-Marc,Nam, Wonwoo American Chemical Society 2016 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.138 No.7

<P>Mononuclear nonheme high-spin iron(III)-acylperoxo complexes bearing an N-methylated cyclam ligand were synthesized, spectroscopically characterized, and investigated in olefin epoxidation and alkane hydroxylation reactions. In the epoxidation of olefins, epoxides were yielded as the major products with high stereo-, chemo-, and enantioselectivities; cis- and trans-stilbenes were oxidized to cis- and trans-stilbene oxides, respectively. In the epoxidation of cyclohexene, cyclohexene oxide was formed as the major product with a kinetic isotope effect (KIE) value of 1.0, indicating that nonheme iron(III)-acylperoxo complexes prefer C=C epoxidation to allylic C-H bond epoxidation by chiral iron(III)-acylperoxo complexes afforded epoxides with high enantioselectivity, suggesting that iron(III)acylperoxo species, not high-valent iron-oxo species, are the epoxidizing agent. In alkane hydroxylation reactions, iron(III)acylperoxo complexes hydroxylated C-H bonds as strong as those in cyclohexane at -40 degrees C, wherein (a) alcohols were yielded as the major products with high regio- and stereoselectivities, (b) activation of C-H bonds by the iron(III)-acylperoxo species was the rate -determining step with a large KIE value and good correlation between reaction rates and bond dissociation energies of alkanes, and (c) the oxygen atom in the alcohol product was from the iron(III)-acylperoxo species, not from molecular oxygen. In isotopically labeled water ((H2O)-O-13) experiments, incorporation of 180 from (H2O)-O-18 into oxygenated products was not observed in the epoxidation and hydroxylation reactions. On the basis of mechanistic studies, we conclude that mononuclear nonheme high-spin iron(III)-acylperoxo complexes are strong oxidants capable of oxygenating hydrocarbons prior to their conversion into iron-oxo species via O-O bond cleavage.</P>

A Mononuclear Nonheme Iron(IV)-Amido Complex Relevant for the Compound II Chemistry of Cytochrome P450

Lu, Xiaoyan,Li, Xiao-Xi,Seo, Mi Sook,Lee, Yong-Min,Clé,mancey, Martin,Maldivi, Pascale,Latour, Jean-Marc,Sarangi, Ritimukta,Fukuzumi, Shunichi,Nam, Wonwoo American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.1

<P>A mononuclear nonheme iron(IV)-amido complex bearing a tetraamido macrocyclic ligand, [(TAML)Fe<SUP>IV</SUP>(NHTs)]<SUP>−</SUP> (<B>1</B>), was synthesized via a hydrogen atom (H atom) abstraction reaction of an iron(V)-imido complex, [(TAML)Fe<SUP>V</SUP>(NTs)]<SUP>−</SUP> (<B>2</B>), and fully characterized using various spectroscopies. We then investigated (1) the p<I>K</I><SUB>a</SUB> of <B>1</B>, (2) the reaction of <B>1</B> with a carbon-centered radical, and (3) the H atom abstraction reaction of <B>1</B>. To the best of our knowledge, the present study reports for the first time the synthesis and chemical properties/reactions of a high-valent iron(IV)-amido complex.</P> [FIG OMISSION]</BR>

Effects of Anodic Potential and Chloride Ion on Overall Reactivity in Electrochemical Reactors Designed for Solar-Powered Wastewater Treatment

Cho, Kangwoo,Qu, Yan,Kwon, Daejung,Zhang, Hao,Cid, Clé,ment A.,Aryanfar, Asghar,Hoffmann, Michael R. American Chemical Society 2014 Environmental science & technology Vol.48 No.4

<P>We have investigated electrochemical treatment of real domestic wastewater coupled with simultaneous production of molecular H<SUB>2</SUB> as useful byproduct. The electrolysis cells employ multilayer semiconductor anodes with electroactive bismuth-doped TiO<SUB>2</SUB> functionalities and stainless steel cathodes. DC-powered laboratory-scale electrolysis experiments were performed under static anodic potentials (+2.2 or +3.0 V NHE) using domestic wastewater samples, with added chloride ion in variable concentrations. Greater than 95% reductions in chemical oxygen demand (COD) and ammonium ion were achieved within 6 h. In addition, we experimentally determined a decreasing overall reactivity of reactive chlorine species toward COD with an increasing chloride ion concentration under chlorine radicals (Cl·, Cl<SUB>2</SUB><SUP>–</SUP>·) generation at +3.0 V NHE. The current efficiency for COD removal was 12% with the lowest specific energy consumption of 96 kWh kgCOD<SUP>–1</SUP> at the cell voltage of near 4 V in 50 mM chloride. The current efficiency and energy efficiency for H<SUB>2</SUB> generation were calculated to range from 34 to 84% and 14 to 26%, respectively. The hydrogen comprised 35 to 60% by volume of evolved gases. The efficacy of our electrolysis cell was further demonstrated by a 20 L prototype reactor totally powered by a photovoltaic (PV) panel, which was shown to eliminate COD and total coliform bacteria in less than 4 h of treatment.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2014/esthag.2014.48.issue-4/es404137u/production/images/medium/es-2013-04137u_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es404137u'>ACS Electronic Supporting Info</A></P>

Healing Actions of Essential Oils from Citrus aurantium and d-Limonene in the Gastric Mucosa: The Roles of VEGF, PCNA, and COX-2 in Cell Proliferation

Thiago Mello Moraes,Ariane Leite Rozza,He´lio Kushima,Claudia Helena Pellizzon,Lucia Regina Machado Rocha,Cle´lia Akiko Hiruma-Lima 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.12

Previous studies have described the gastroprotective effects of essential oils that are derived from Citrus aurantium (OEC) and its main compound d-limonene (LIM) in a model of chemically induced ulcers in rats. However, these studies do not address the compound’s healing effects on the gastric mucosa. Thus, the aim of this work was to evaluate the healing activity of OEC and LIM in acetic acid-induced gastric ulcers in rats, a model that reproduces human chronic ulcers. The obtained results demonstrated that lower effective doses of OEC (250 mg/kg) and LIM (245 mg/kg) induced gastric mucosal healing with a cure rate of 44% and 56%, respectively, compared with the control group (P < .05). During the 14 days of OEC or LIM treatment, none of the groups demonstrated toxicity in terms of body and organ weight or serum biochemical parameters. Both OEC and LIM treatment promoted an increase in epithelial healing, as confirmed by immunohistochemistry, which was greater in the animals that were treated with the positive control. In addition, both treatments increased cellular proliferation as measured by proliferating cell nuclear antigen and cyclooxygenase 2 expression in the gastric mucosa, vascular endothelial growth factor-mediated blood vessel formation in the margin of the ulcer, and production of gastric mucus, which fortifies the gastric protective barrier. We concluded that OEC and LIM, two common flavoring agents, promote gastric mucosal healing without any apparent toxic effect, resulting in better gastric epithelial organization in the treated rats.

Achieving One-Electron Oxidation of a Mononuclear Nonheme Iron(V)-Imido Complex

Hong, Seungwoo,Lu, Xiaoyan,Lee, Yong-Min,Seo, Mi Sook,Ohta, Takehiro,Ogura, Takashi,Clé,mancey, Martin,Maldivi, Pascale,Latour, Jean-Marc,Sarangi, Ritimukta,Nam, Wonwoo American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.41

<P>A mononuclear nonheme iron(V)-imido complex bearing a tetraamido macrocyclic ligand (TAML), [Fe<SUP>V</SUP>(NTs)(TAML)]<SUP>−</SUP> (<B>1</B>), was oxidized by one-electron oxidants, affording formation of an iron(V)-imido TAML cation radical species, [Fe<SUP>V</SUP>(NTs)(TAML<SUP>+•</SUP>)] (<B>2</B>); <B>2</B> is a diamagnetic (<I>S</I> = 0) complex, resulting from the antiferromagnetic coupling of the low-spin iron(V) ion (<I>S</I> = 1/2) with the one-electron oxidized ligand (TAML<SUP>+•</SUP>). <B>2</B> is a competent oxidant in C–H bond functionalization and nitrene transfer reaction, showing that the reactivity of <B>2</B> is greater than that of <B>1</B>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2017/jacsat.2017.139.issue-41/jacs.7b08161/production/images/medium/ja-2017-081612_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja7b08161'>ACS Electronic Supporting Info</A></P>

Prolonged Ingestion of Prehydrolyzed Whey Protein Induces Little or No Change in Digestive Enzymes, but Decreases Glutaminase Activity in Exercising Rats

Ana Cláudia C. Nery-Diez,Iara R. Carvalho,Jaime Amaya-Farfa´,Maria Ine´s Abecia-Soria,Ce´lio K. Miyasaka,Cle´cio da S. Ferreira 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.4

Because consumption of whey protein hydrolysates is on the increase, the possibility that prolonged ingestion of whey protein hydrolysates affect the digestive system of mammals has prompted us to evaluate the enzymatic activities of pepsin, leucine-aminopeptidase, chymotrypsin, trypsin, and glutaminase in male Wistar rats fed diets containing either a commercial whey isolate or a whey protein hydrolysate with medium degree of hydrolysis and to compare the results with those produced by physical training (sedentary, sedentary-exhausted, trained, and trained-exhausted) in the treadmill for 4 weeks. The enzymatic activities were determined by classical procedures in all groups. No effect due to the form of the whey protein in the diet was seen in the activities of pepsin, trypsin, chymotrypsin, and leucine-aminopeptidase. Training tended to increase the activity of glutaminase, but exhaustion promoted a decrease in the trained animals, and consumption of the hydrolysate decreased it even further. The results are consistent with the conclusion that chronic consumption of a whey protein hydrolysate brings little or no modification of the proteolytic digestive system and that the lowering of glutaminase activity may be associated with an antistress effect, counteracting the effect induced by training in the rat.

Differentiated Troy⁺ Chief Cells Act as Reserve Stem Cells to Generate All Lineages of the Stomach Epithelium

Stange, Daniel E.,Koo, B.K.,Huch, M.,Sibbel, G.,Basak, O.,Lyubimova, A.,Kujala, P.,Bartfeld, S.,Koster, J.,Geahlen, Jessica H.,Peters, Peter J.,van Es, Johan H.,van de Wetering, M.,Mills, Jason C.,Cle Cell Press ; MIT Press 2013 Cell Vol.155 No.2

Proliferation of the self-renewing epithelium of the gastric corpus occurs almost exclusively in the isthmus of the glands, from where cells migrate bidirectionally toward pit and base. The isthmus is therefore generally viewed as the stem cell zone. We find that the stem cell marker Troy is expressed at the gland base by a small subpopulation of fully differentiated chief cells. By lineage tracing with a Troy-eGFP-ires-CreERT2 allele, single marked chief cells are shown to generate entirely labeled gastric units over periods of months. This phenomenon accelerates upon tissue damage. Troy<SUP>+</SUP> chief cells can be cultured to generate long-lived gastric organoids. Troy marks a specific subset of chief cells that display plasticity in that they are capable of replenishing entire gastric units, essentially serving as quiescent ''reserve'' stem cells. These observations challenge the notion that stem cell hierarchies represent a ''one-way street.''