phosphite
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- MeSH
- fyziologie výživy zvířat MeSH
- krysa rodu rattus MeSH
- laboratorní zvířata MeSH
- styreny metabolismus toxicita MeSH
- Check Tag
- krysa rodu rattus MeSH
- Publikační typ
- srovnávací studie MeSH
Contrary to a previous report, the sulfurisation of phosphorus(III) derivatives by 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride) does not yield carbon disulfide and cyanamide as the additional reaction products. The reaction of xanthane hydride with triphenyl phosphine or trimethyl phosphite yields triphenyl phosphine sulfide or trimethyl thiophosphate, respectively, and thiocarbamoyl isothiocyanate which has been trapped with nucleophiles. The reaction pathway involves initial nucleophilic attack of the phosphorus at sulfur next to the thiocarbonyl group of xanthane hydride followed by decomposition of the phosphonium intermediate formed to products. The Hammett rho-values for the sulfurisation of substituted triphenyl phosphines and triphenyl phosphites in acetonitrile are approximately -1.0. The entropies of activation are very negative (-114+/-15 J mol-1 K-1) with little dependence on solvent which is consistent with a bimolecular association step leading to the transition state. The negative values of DeltaS(not equal) and rho values indicate that the rate limiting step of the sulfurisation reaction is formation of the phosphonium ion intermediate which has an early transition state with little covalent bond formation. The site of nucleophilic attack has been also confirmed using computational calculations. PMID: 17252130 [PubMed - indexed for MEDLINE]
- MeSH
- amitrol chemie MeSH
- chemické modely MeSH
- financování organizované MeSH
- fosfiny chemie MeSH
- fosfor chemie MeSH
- fosforitany chemie MeSH
- hydrolýza MeSH
- isothiokyanatany chemie MeSH
- kinetika MeSH
- kyanamid chemie MeSH
- síra chemie MeSH
- sirouhlík chemie MeSH
- termodynamika MeSH
- thiazoly chemie MeSH
- thioketony chemie MeSH
- triaziny chemie MeSH
- vodíková vazba MeSH
Two novel nonisosteric UDP-Gal analogues, (2-deoxy-2-fluoro- and 4-deoxy-4-fluoro-α-D-galactopyranosyl) phosphonoyl phosphates, were synthesized by optimized multistep procedures starting from 3,4,6-tri-O-benzyl-D-galactal and allyl 2,3,6-tri-O-benzyl-α-D-glucopyranoside, respectively. The key steps were a Michaelis-Arbuzov reaction of respective deoxy-fluoro-D-galactopyranosyl acetate with triethyl phosphite followed by a Moffatt-Khorana coupling reaction with UMP-morpholidate. The structure of all new compounds was confirmed by NMR and mass spectroscopies..
Syntheses of α-branched alkyl and aryl substituted 9-[2-(phosphonomethoxy)ethyl]purines from substituted 1,3-dioxolanes have been developed. Key synthetic precursors, α-substituted dialkyl [(2-hydroxyethoxy)methyl]phosphonates were prepared via Lewis acid mediated cleavage of 1,3-dioxolanes followed by reaction with dialkyl or trialkyl phosphites. The best preparative yields were achieved under conditions utilizing tin tetrachloride as Lewis acid and triisopropyl phosphite. Attachment of purine bases to dialkyl [(2-hydroxyethoxy)methyl]phosphonates was performed by Mitsunobu reaction. Final α-branched 9-[2-(phosphonomethoxy)ethyl]purines were tested for antiviral, cytostatic and antiparasitic activity, the latter one determined as inhibitory activity towards Plasmodium falciparum enzyme hypoxanthine-guanine-xanthine phosphoribosyltransfesase. In most cases biological activity was only marginal.
- MeSH
- antiparazitární látky chemická syntéza chemie farmakologie MeSH
- antivirové látky chemická syntéza chemie farmakologie MeSH
- dioxolany chemie MeSH
- DNA viry účinky léků MeSH
- inhibitory enzymů chemická syntéza chemie farmakologie MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- molekulární struktura MeSH
- myši MeSH
- nádorové buněčné linie MeSH
- pentosyltransferasy antagonisté a inhibitory metabolismus MeSH
- Plasmodium falciparum účinky léků enzymologie MeSH
- puriny chemická syntéza chemie farmakologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The development of novel inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) represents a viable approach to alleviate Alzheimer's disease. Thirty-six halogenated 2-hydroxy-N-phenylbenzamides (salicylanilides) with various substitution patterns and their esters with phosphorus-based acids were synthesized in yields of 72% to 92% and characterized. They were evaluated for in vitro inhibition of AChE from electric eel and BuChE from equine serum using modified Ellman's spectrophotometric method. The benzamides exhibited a moderate inhibition of AChE with IC50 values in a narrow concentration range from 33.1 to 85.8 µM. IC50 values for BuChE were higher (53.5-228.4 µM). The majority of derivatives inhibit AChE more efficiently than BuChE and are comparable or superior to rivastigmine-an established cholinesterases inhibitor used in the treatment of Alzheimer's disease. Phosphorus-based esters especially improved the activity against BuChE with 5-chloro-2-{[4-(trifluoromethyl)phenyl]carbamoyl}phenyl diethyl phosphite 5c superiority (IC50 = 2.4 µM). This derivative was also the most selective inhibitor of BuChE. It caused a mixed inhibition of both cholinesterases and acted as a pseudo-irreversible inhibitor. Several structure-activity relationships were identified, e.g., favouring esters and benzamides obtained from 5-halogenosalicylic acids and polyhalogenated anilines. Both 2-hydroxy-N-phenylbenzamides and esters share convenient physicochemical properties for blood-brain-barrier penetration and thus central nervous system delivery.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- benzamidy chemie farmakologie MeSH
- butyrylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory chemie farmakologie MeSH
- Electrophorus MeSH
- estery chemie farmakologie MeSH
- fosfor chemie MeSH
- inhibiční koncentrace 50 MeSH
- koně MeSH
- molekulární struktura MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Hlavním cílem této studie bylo ověření vhodnosti diagnostického nástroje Bruininks-Oseretzky Test of Motor Proficiency, Second Edition (BOT-2) v českých podmínkách u dětí ve věku 4 – 7 let pomocí konfirmativní faktorové analýzy. Výzkumný soubor tvořilo 88 probandů ve věku 4 – 7 let. Skupina byla tvořena dětmi ze dvou základních škol a dvou mateřských škol v Praze, jejichž výběr proběhl kvótně. Výsledky konfirmativní faktorové analýzy BOT-2 u české populace byly porovnány s výsledky originální předlohy podle Bruininks (2005). Sledovanými parametry byly výsledné hodnoty indexů fitu: TLI > 0,95, SRMR < 0,08, CFI > 0,95 nebo RMSEA < 0,08. V originální předloze BOT-2 pro věkovou kategorii 4 – 7 let dosahovala korelace mezi manifestními proměnnými rozpětí 0,57 až 0,91. U českého modelu činila nejvyšší korelace také 0,91 (mezi proměnnými „strenght & agility”). Fit model ukazatelů CFI > 0,95 a RMSEA < 0,08 byl jak u originální předlohy, tak u českého modelu totožný. Z výsledků byl indikován vhodný model BOT-2 pro věkovou kategorii 4 – 7 let u české populace.
The main aim of the study was to determine the suitability of diagnostic tools Bruininks-Oseretzky Test of Motor Proficiency Second Edition (BOT-2) using confirmatory factor analysis in children aged 4-7 years in the Czech Republic. The research group consisted of 88 probands aged 4-7 years. The group was made up of children from two primary schools and two kindergartens in Prague. The selectiom was held with the help of quota selection. The results of the confirmatory factor analysis BOT-2 in children in the Czech Republic were compared with the results of original artwork by Bruininks (2005). The monitored parameters were resulting index values phosphite: TLI > 0.95, SPDC < 0.08, CFI > 0.95, or RMSE < 0.08. In the original draft BOT-2 amounted the correlations between manifest variables range from 0.57 to 0.91 for the age group 4-7 years. In the Czech model was the highest correlation 0.91 (between variables ”Strength & Agility”). Fit model indicators CFI > 0.95 and RMSE < 0.08 was identical by original artwork and by the Czech model. The results indicated the appropriate model BOT-2 for the age group 4-7 years in the Czech Republic.
- MeSH
- dítě MeSH
- faktorová analýza statistická MeSH
- lidé MeSH
- motorické dovednosti fyziologie klasifikace MeSH
- předškolní dítě MeSH
- psychomotorický výkon * fyziologie klasifikace MeSH
- reprodukovatelnost výsledků MeSH
- tělesná výkonnost fyziologie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- předškolní dítě MeSH
- Publikační typ
- práce podpořená grantem MeSH
The sulfurization efficiency of 25 3-substituted-1,2,4-dithiazole-5-ones and 5-thiones towards triphenyl phosphite in acetonitrile, DCM, THF and toluene at 25 °C was evaluated. All the 1,2,4-dithiazoles are much better sulfurizing reagents than commercially available agents (PADS, TETD, Beaucage's reagent). The most efficient sulfurizing agents in all solvents are 3-phenoxy (4), 3-phenylthio (5) and 3-ethoxy-1,2,4-dithiazole-5-one (1) whose reactivity is at least two orders of magnitude higher than that of other 1,2,4-dithiazoles. Contrary to a previous report, the sulfurization with 1 does not yield carbonylsulfide and ethyl cyanate as the additional reaction products but unstable ethoxythiocarbonyl isocyanate which has been trapped with 4-methoxyaniline. Similar trapping experiments have proven that the site of attack is at the sulfur adjacent to the C=O group for compounds 4 and 5. The reaction pathway involves rate-limiting initial nucleophilic attack of the phosphorus at sulfur followed by decomposition of the phosphonium intermediate to the corresponding phosphorothioate and isocyanate/isothiocyanate species. The existence of the phosphonium intermediate during sulfurization of triphenyl phosphine with 3-phenyl-1,2,4-dithiazole-5-thione (7a) was proven using kinetic studies. From the Hammett and Brønsted correlations and from other kinetic measurements it was concluded that the transition-state structure is almost apolar for the most reactive 1,2,4-dithiazoles whereas a polar structure resembling a zwitter-ionic intermediate may be more appropriate for the least reactive 1,2,4-dithiazoles. The extent of P–S bond formation and S–S bond cleavage is very similar in all reaction series but it gradually decreases with the reactivity of the 1,2,4-dithiazole derivatives.
... Fellows hypo phosphites (152), Phosphor (153). Inhalt. ...
Specielle Pathologie und Therapie ; XII. Band, II. Theil
vii, 210 stran ; 25 cm
- MeSH
- neurastenie MeSH
- úzkost MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Psychiatrie
- NLK Obory
- psychiatrie
