omega-Transaminases as efficient biocatalysts to obtain novel chiral selenium-amine ligands for Pd-catalysis

omega-Transaminases have been evaluated as biocatalysts in the reductive amination of organoselenium acetophenones to the corresponding amines, and in the kinetic resolution of racemic organoselenium amines. Kinetic resolution proved to be more efficient than the asymmetric reductive amination. By using these methodologies we were able to obtain both amine enantiomers in high enantiomeric excess (up to 99%). Derivatives of the obtained optically pure o-selenium 1-phenylethyl amine were evaluated as ligands in the palladium-catalyzed asymmetric alkylation, giving the alkylated product in up to 99% ee.

Synthesis of selenium- and tellurium-containing nucleosides derived from uridine

The synthesis of selenium- and tellurium-containing nucleosides, derived from uridine is described herein. These compounds were prepared in a concise and short synthetic route in good yields, by nucleophilic substitution of a tosylate group by organoselenium nucleophiles. (C) 2009 Elsevier Ltd. All rights reserved.

Total synthesis of (+/-)-dihydroactinidiolide using selenium-stabilized carbenium ion

A new, short total synthesis of dihydroactinidiolide 1 is described using selenium carbenium ion-promoted carbon-carbon bond formation as the key step. Our synthetic strategy starts with a lactonization reaction between 1,3,3-trimethylcyclohexene 13 and alpha-chloro-alpha-phenylseleno ethyl acetate 14, affording the key intermediate, alpha-phenylseleno-gamma-butyro lactone 15, which reacted via a selenoxide elimination to the target compound 1. (C) 2009 Elsevier Ltd. All rights reserved.

Color of smoked loin from animals fed with bioactive compounds added to forage

The objective of this work was to evaluate the influence of the breed and of the addition of bioactive substances to forage on the color of smoked pork loin. Two pig breeds (Polish Landrace and the crossbreed Polish Landrace x Duroc), three types of bioactive components (organic selenium; 2% of canola oil and 1% of flaxseed oil; and 2% of flaxseed oil and 1% of canola oil), and a control treatment were evaluated. Computer image analysis included the color assessment of muscle, fat, connective tissues, and smoked loin surface. For Polish Landrace, selenium supplementation caused higher values of red, green, and blue color components of the muscle tissue, which were lower for the crossbreed. However, there was no difference in the color components of loin fat tissue of the Polish Landrace breed due to selenium supplementation. In the case of oil supplementation, values of the color components of the muscle tissue for the Polish Landrace x Duroc crossbreed were also lower. The color components of muscle, fat, connective tissues, and smoked loin surface depend on the pig breed and on the bioactive compounds added to the forage.

First dynamic kinetic resolution of selenium-containing chiral amines catalyzed by palladium (Pd/BaSO(4)) and Candida antartica lipase (CAL-B)

An efficient method for chemoenzymatic dynamic kinetic resolution of selenium-containing chiral amines (organoselenium-1-phenylethanamines) has been developed, leading to the corresponding amides in excellent enantioselectivities and high isolated yields. This one-pot procedure employs two different types of catalysts: Pd on barium sulphate (Pd/BaSO(4)) as racemization catalyst and lipase (CAL-B) as the resolution catalyst. (C) 2009 Elsevier Ltd. All rights reserved.

Lithium butylchalcogenolate induced Michael-aldol tandem sequence: easy and rapid access to highly functionalized organochalcogenides and unsaturated compounds

Lithium ""butylchalcogenolates are generated in situ by reacting the elements (S, Se, and Te) with (n)butyl-lithium at 0 degrees C. Reaction of the lithium alkylchalcogenolates with activated alkenes and aldehydes gives the corresponding aldol adducts. The selenium-containing products give Morita-Baylis-Hillman adducts after the oxidation/elimination of the selenoxide. The whole sequence can be performed in a one-pot procedure. (C) 2009 Elsevier Ltd. All rights reserved.

Studying the distribution of Selenium in buffalo and cow's milk whey

Neste estudo, a cromatografia por exclusão de tamanho (SEC) com detecção online ultravioleta (UV), espectrometria de absorção atômica em forno de grafite (GF AAS) e a espectrometria de massa por tempo de voo com dessorção/ionização de matriz assistida por laser (MALDI-TOF-MS) foram usadas para estudar a associação de selênio com macromoléculas e compostos presentes no soro de leite de búfala e bovino. Os perfis de SEC-UV obtidos para as amostras de soro de leite de búfala e soro de leite bovino indicaram a presença de espécies de alta e baixa massa molecular. A combinação das informações obtidas com SEC-UV, GF AAS e MALDI-TOF-MS para as frações < 10 kDa confirmou a associação de selênio com espécies de baixa massa molecular.

The immune system is limited by oxidative stress: dietary selenium promotes optimal antioxidative status and greatest immune defense in pacu Piaractus mesopotamicus

Reactive oxygen species (ROS) are reactive molecules containing oxygen, that form as byproducts of aerobic metabolism, including immune system processes. Too much ROS may cause oxidative stress. In this study, we examined whether it can also limit the production of immune system compounds. To assess the relationship between antioxidant status and immunity we evaluated the effect of dietary supplementation with organic selenium, given at various levels for 10 days, on the antioxidant and immune system of the pacu fish (Piaractus mesopotamicus). Fish fed a diet containing 0.6 mg Se-yeast kg(-1) showed significant improvement in antioxidant status, as well as in hematological and immunological profiles. Specifically, they had the highest counts for catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), red blood cells, and thrombocytes; the highest leukocyte count (particularly for monocytes); and the highest serum lysozyme activity. There was also a positive correlation between GPx and lysozyme in this group of fish. These findings indicate that short-term supplementation with 0.6 mg Se-yeast kg(-1) reestablished the antioxidative status, allowing the production of innate components which can boost immunity without the risk of oxidative stress. This study shows a relationship between oxidative stress and immunity, and, from a practical perspective, shows that improving immunity and health in pacu through the administration of selenium could improve their growth performance.

Stable isotope fractionation of selenium by biomethylation in soil

Selen ist in geringen Mengen ein essentielles Nährelement, das aber in höheren Gehalten toxisch wird. Der Se-Kreislauf in der Umwelt ist eng mit Redoxreaktionen wie der Reduktion von Se-Oxyanionen zu Methylselenid verknüpft. Flüchtige Methylselenide sind weit verbreitet und stellen einen wichtigen Se-Fluss in der Umwelt dar. Das übergeordnete Ziel meiner Dissertation war, die Stabilisotopenfraktionierung von Se durch Biomethylierung verschiedener oxidierter Se-Spezies (Se[IV] und Se[VI]) im Boden aufzuklären. Zunächst wurde eine Methode entwickelt, die es erlaubte flüchte Methylselenide quantitativ zurückzuhalten. Es zeigte sich, dass alkalische Peroxid-Lösung dafür geeignet war. Mit alkalischer Peroxid-Lösung wurde eine Wiederfindung von 95,6 ± Standardabweichung 5,4% in Verflüchtigungsexperimenten mit Methylselenid-Standards erreicht. Bei Einsatz von alkalischer Peroxid-Lösung in geschlossenen Mikrokosmos-Experimenten kam es zu keinen Se-Verlusten und ausgeglichenen Se-Isotopenbilanzen. Die massengewichteten δ82/76Se-Werte lagen für Se(IV) und Se(VI) am Ende der Mikrokosmos-Inkubationen bei -0,31 ± 0,05‰ (n = 3) und -0,76 ± 0,07‰ (n = 3) verglichen mit -0,20 ± 0,05‰ und -0,69 ± 0,07‰ im jeweils zugegebenen Se. Im zweiten Teil meiner Dissertation wurde die Pilzart Alternaria alternata mit Se(VI) und Se(IV) in geschlossenen Mikrokosmen für 11-15 und Se(IV) zusätzlich für 3-5 Tage bei 30°C inkubiert. In 11-15 Tagen wurden 2,9-11% des Se(VI) und 21-29% des Se(IV) und in 3-5 Tagen, 3-5% des Se(IV) methyliert. Die anfänglichen δ82/76Se-Werte von Se(VI) und Se(IV) lagen bei -0,69 ± 0,07‰, und -0,20 ± 0,05‰. Die δ82/76Se-Werte der Methylselenide unterschieden sich nach 11-15 Tagen Inkubation signifikant zwischen Se(VI) (-3,97 bis -3,25 ‰) und Se(IV) (-1,44 bis -0,16‰) als Quellen. Die δ82/76Se-Werte der Methylselenide zeigen also die Quellen der Biomethylierung von Se an. Die kürzere Inkubation von Se(IV) für 3-5 Tage führte zu einer ausgeprägten Se-Isotopenfraktonierung von mindestens -6‰, bevor ein Fließgleichgewicht erreicht wurde. Im dritten Teil bestimmte ich die Bindungsformen von Se mit drei operativ definierten sequentiellen Extraktionen und die δ82/76S-Werte des gesamten Selens in zehn urbanen Oberböden mit 0,09-0,52 mg/kg Se, die fünf verschiedene Landnutzungstypen repräsentierten (Überschwemmungsgrünland, Garten, Park, Straßenrand und Wald). Nur ein kleiner Teil des Seleniums lag in austauschbarer und damit direkt bioverfügbarer und in residualer, wenig reaktiver Form vor. Das meiste Se war an die organische Substanz und Fe-(Hydr-)Oxide gebunden (42-77% des gesamten Selens). Der mittlere δ82/76Se-Wert des gesamten Selens in den Oberböden lag mit -0,03 ± 0,38‰ nahe beim Mittelwert der gesamten Erde. Geringfügig niedrigere Se-Isotopensignale von -0,59 bis -0,35‰ v.a. in Waldböden und geringfügig höhere von 0,26 to 0,45‰ in Überschwemmungsgrünland wurden vermutlich durch Boden-Pflanze-Recycling und Se-Kontaminationen durch das Flusswasser verursacht. Der vierte Teil umfasste ein “Natural Attenuation”-Experiment und Mikrokosmos-Inkubationen von Bodenproben mit A. alternata. Die Equilibrierung von zum Boden gegebenem Se(IV) und Se(VI) für drei Tage führte zu abnehmenden wasserlöslichen Se-Gehalten um 32-44% bzw. 8-14, die mit kleinen Isotopenfraktionierung (ε = -0,045 bis -0,12 ‰ and -0,05 to -0,07‰ verbunden waren. In zwei der inkubierten Böden mit mäßig sauren pH-Werten wurden zwischen 9,1 und 30% des zugefügten Se(IV) und 1,7% des zugefügten Se(VI) methyliert während in einem stark sauren Boden keine Methylierung auftrat. Das aus Se(IV) entstandene Methylselenid war deutlich gegenüber dem zugegebenen Se-Standard (0,20‰) an 82Se verarmt (δ82/76Se = -3,3 bis -4,5‰). Meine Ergebnisse zeigen, dass die stabilen Isotopenverhältnisse von Se neue Einblicke in Se-Transformationsprozesse erlauben.rn

Effects of high selenium intake on selenium status, liver function and claw health of fattening bulls

The effects of three dietary selenium (Se) levels (0.15, 0.35 and 0.5 mg/kg dry matter (dm) and of two Se-compounds (sodium selenite and Se-yeast) on the Se-status, liver function and claw health were studied using 36 fattening bulls in a two-factorial feeding trial that lasted 16 weeks. The claw health was assessed macroscopically and microscopically. Compared to the two control diets containing 0.15 mg Se/kg dm, the intake of the diets containing 0.35 and 0.50 mg Se/kg dm significantly (P < 0.05) increased the Se-concentration in serum, hair, liver and skeletal muscle. Compared to sodium selenite the intake of Se-yeast resulted in significantly (P < 0.05) higher Se-concentration in serum, liver and hair. Concerning the claw horn quality, there was no significant difference between the different groups; the animals receiving organic Se tended to have a better histological score (P = 0.06) at the coronary band than the groups fed with sodium selenite. The serum vitamin E level decreased significantly (P < 0.05) with increasing Se-intake, which had no influence (P > 0.1) on growth and liver function parameters. With the exception of the decrease of the serum vitamin E level indicating an oxidative stress caused by a high Se-intake, no negative effects of dietary selenium exceeding recommended levels for 4 months were observed.

The co-ordination chemistry of tellurium and related selenium ligands

2-(2-pyridyl)phenyl(p-ethoxyphenyl)tellurium(II), (RR1Te) reacts with HgC12 at room temperature to give white HgCl2.RR1Te. On setting aside, or on warming the reaction mixture a yellow material, [R1HgCl.(RTeCl)2] is formed. Multinuclear NMR(125Te, 199Hg, 1H) and mass spectroscopy confirm the formulation, and confirm the ease of transfer of the p-ethoxyphenyl group (R1) between the metal centres. The crystal structure of the yellow material consists of two discrete RTeCl molecules together with a R1HgCl molecule. There is no dative bond formation between these species, hence the preferred description of the formation of an inclusion complex. The reaction of RR1Te with Copper(I) chloride in the cold gives an air sensitive yellow product Cu3Cl3(RR1Te)2(0.5CH3CN); under reflux in air changes to the green Cu2Cl(RR1Te)(0.5 EtOH). By contrast, the reaction of RR1Te with acetonitrile solution of Copper(II) salts under mild conditions affords the white materials CuCl(RR1Te) and CuBr(RR1Te)H2O. RR1Te reacts with PdCl2 and PtCl2 to give materials albeit not well defined, can be seen as intermediates to the synthesis of inorganic phase of the type M3XTe2XCl2X. Paramagnetism is associated with some of the palladium and platinum products. The 195Pt NMR measurement in DMSO establishes the presence of six platinum species, which are assigned to Pt(IV), Pt(III) or Pt(II). The reactions show that in the presence of PdCl2 or PtCl2 both R and R1 are very labile. The reaction of RHgCl(R= 2-(2-pyridyl)phenyl) with SeX4(X= Cl, Br) gives compounds which suggest that both Trans-metallation and redox processes are involved. By varying reaction conditions materials which appear to be intermediates in the trans-metallation process are isolated. Potentially bidentate tellurium ligands having molecular formula RTe(CH2)nTeR,Ln, (R= Ph,(t-Bu). C6H4, n = 5,10) are prepared. Palladium and Platinum complexes containing these ligands are prepared. Also complex Ph3SnC1L(L = p-EtO.C6H4) is prepared.

Doehlert Design-desirability Function Multi-criteria Optimal Separation Of 17 Phenolic Compounds From Extra-virgin Olive Oil By Capillary Zone Electrophoresis.

In Brazil, the consumption of extra-virgin olive oil (EVOO) is increasing annually, but there are no experimental studies concerning the phenolic compound contents of commercial EVOO. The aim of this work was to optimise the separation of 17 phenolic compounds already detected in EVOO. A Doehlert matrix experimental design was used, evaluating the effects of pH and electrolyte concentration. Resolution, runtime and migration time relative standard deviation values were evaluated. Derringer's desirability function was used to simultaneously optimise all 37 responses. The 17 peaks were separated in 19min using a fused-silica capillary (50μm internal diameter, 72cm of effective length) with an extended light path and 101.3mmolL(-1) of boric acid electrolyte (pH 9.15, 30kV). The method was validated and applied to 15 EVOO samples found in Brazilian supermarkets.

Intensification Of Bioactive Compounds Extraction From Medicinal Plants Using Ultrasonic Irradiation.

Extraction processes are largely used in many chemical, biotechnological and pharmaceutical industries for recovery of bioactive compounds from medicinal plants. To replace the conventional extraction techniques, new techniques as high-pressure extraction processes that use environment friendly solvents have been developed. However, these techniques, sometimes, are associated with low extraction rate. The ultrasound can be effectively used to improve the extraction rate by the increasing the mass transfer and possible rupture of cell wall due the formation of microcavities leading to higher product yields with reduced processing time and solvent consumption. This review presents a brief survey about the mechanism and aspects that affecting the ultrasound assisted extraction focusing on the use of ultrasound irradiation for high-pressure extraction processes intensification.

Influence Of The Stage Of Ripeness On The Composition Of Iridoids And Phenolic Compounds In Genipap (genipa Americana L.).

Genipap fruits, native to the Amazon region, were classified in relation to their stage of ripeness according to firmness and peel color. The influence of the part of the genipap fruit and ripeness stage on the iridoid and phenolic compound profiles was evaluated by HPLC-DAD-MS(n), and a total of 17 compounds were identified. Geniposide was the major compound in both parts of the unripe genipap fruits, representing >70% of the total iridoids, whereas 5-caffeoylquinic acid was the major phenolic compound. In ripe fruits, genipin gentiobioside was the major compound in the endocarp (38%) and no phenolic compounds were detected. During ripening, the total iridoid content decreased by >90%, which could explain the absence of blue pigment formation in the ripe fruits after their injury. This is the first time that the phenolic compound composition and iridoid contents of genipap fruits have been reported in the literature.

Anthocyanin And Other Phenolic Compounds In Ceylon Gooseberry (dovyalis Hebecarpa) Fruits.

Ceylon gooseberry is a deep-purple exotic berry that is being produced in Brazil with great market potential. This work aimed to determine major phenolic compounds in this specie by HPLC-PDA-ESI/MS. Samples were collected in two different seasons. Pulp and skin were analyzed separately. Non-acylated rutinoside derivatives of delphinidin (∼60-63%) and cyanidin (∼17-21%) were major anthocyanins tentatively identified. All anthocyanins had higher concentration in skin than in pulp (64-82 and 646-534mg of cyaniding-3-glucoside equivalents/100g skin and pulp, respectively). Moreover, anthocyanin profile changed between sampling dates (p<0.05). Mainly for delphinidin-3-rutinoside which could be a result of season variation. In this specie, non-anthocyanin polyphenols represent less than 35% of total extracted polyphenols. The tentative identification proposed a flavonol and three ellagitannins as major compounds of the non-anthocyanin phenolics fraction. Finally, anthocyanin is the major phenolic class in this fruit and its composition and content are significantly affected by season.