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Reaction mechanism for the synthesis of …

Initiate warfarin on day 1 or 2 of LMWH or unfractionated heparin therapy and .

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Jung HS(1 Kwon PS, Lee. mechanism for synthesis of coumarin.

This paper focuses on the examination of the Photoinduced Electron Transfer (PET) and Internal Charge Transfer (ICT) for two coumarin derivatives, namely 7-methoxycoumarin-4-methyl-1-aza-18-crown-6 and di(7-methoxycoumarin-4-methyl)-1,10-diaza-18-crown-6. The spectroscopic properties were investigated by UV-Vis and fluorescence spectroscopies. It was found that a dual mechanism explains the fluorescence enhancement and blue shift in the presence of a cationic species, namely saxitoxin. The ICT was elucidated by the polarity effect of methanol on the fluorescence of di(7-methoxycoumarin-4-methyl)-1,10-diaza-18-crown-6.

Organic Syntheses: One person to search for general preparations of coumarin and its derivatives.

In order to understand the pharmacokinetics and pharmacodynamics of the drugs, study of interaction between drugs and the plasma proteins is essential. Human serum albumin (HSA), the most abundant protein in the blood plasma, tends to have high affinity for variety of metabolites and drugs. HSA is used as a carrier to deliver various exogenous and endogenous substances including hormones, fatty acids and drugs to the target organs –. HSA is synthesized and secreted from liver cells. It is a 67 KDa protein having single chained non glycosylated polypeptide which folds into a heart shaped protein with approximately 67% α-helical content –.The globular protein of HSA comprises of three structurally similar α-helical domains (I–III) each consisting of subdomains (A and B), and stabilized by 17 disulphide bridges. Aromatic and heterocyclic ligands have been found to bind mainly within subdomains IIA and IIIA designated as site I and site II, respectively –. Also, seven binding sites are localized in sub-domains IB, IIIA and IIIB, and on the sub-domain interfaces , , . Many endogenous substances and drugs such as bilirubin, hemin, azapropazone, indomethacin, and tri-iodobenzoic acid (TIB) have been found to bind within IB domain and substances such as diflunisal, halothane, and ibuprofen bind to IIA–IIB domain . HSA contains a single intrinsic tryptophan residue at position 214 in domain IIA where its fluorescence is sensitive to the closely associated ligands , . Thus, fluorescence measurement is used as a probe for the drug binding studies with HSA and also used for differentiation of various fatty acid compositions in oils . Recently our group has shown that natural compounds like maslinic acid, trimethoxy-flavone, coumaroyltyramine, β-sitosterol, and betulinic acid binds strongly to HSA leading to a change in protein conformation –.

One of the most extended procedures for coumarin synthesis ..

Coumarin is a naturally occurring benzopyrone found in variety of plants. Coumarin and its derivatives have roles as anti-inflammatory, anti-coagulant, anti-retroviral, anti-arthritic, anti-herpes, anti-asthmatic, and antioxidant activities –.Their anti-retroviral activity is directly linked to their inhibitory effect on HIV-1 replication. The reduction in reverse transcriptase activity was observed when HIV infected ACH-2 lymphocytes were treated with warfarin, 4-hydroxycoumarin and umbelliferone . They were used as the anti-inflammatory agents as they inhibit the cyclooxygenase and 5-lipoxygenase activities which convert arachidonic acid to endoperoxides, precursors of prostaglandins and to leukotriene A4, respectively. Inhibition of prostaglandin synthesis accounts for their analgesic and antipyretic actions and inhibition of leukotriene accounts for their use in the treatment of asthma and mild arthritis . The anti-herpes simplex virus activity was identified in 7-(carboxymethoxy)-4-methyl coumarin designed by virtual combinatorial synthesis and selected by computational screening . It has also been used in the treatment of lymphedema . It also exhibits anticoagulant property when converted to dicoumarin by the strain of fungi Aspergillus fumigatus. Further, it inhibits the release of plasma clotting factor VII by vitamin K without inhibition of protein synthesis . Umbelliferone acts as a scavenger of reactive oxygen species which accounts for its antioxidant property .

AB - A novel coumarin-based fluorogenic probe bearing the 2-picoIyI unit (1) was developed as a fluorescent chemosensor with high selectivity and suitable affinity in biological systems toward Cu2+ over other cations tested. The fluorescence on-off mechanism was studied by femtosecond time-resolved fluorescence (TRF) upconversion technique and ab initio calculations. The receptor can be applied to the monitoring of Cu2+ ion in aqueous solution with a pH span 4-10. To confirm the suitability of 1 for biological applications, we also employed it for the fluorescence detection of the changes of intracellular Cu2+ in cultured cells. The results indicate that 1 should be useful for the fluorescence microscopic imaging and the study on the biological functions of Cu2+.

Mechanism of action of anticoagulants: correlation …

This is the first report of Biginelli adducts bearing a coumarin nucleus in the β-ketoester moiety and their MCR mechanism seems to pass through a Knoevenagel intermediate, which was considered as unlikely before.

N2 - A novel coumarin-based fluorogenic probe bearing the 2-picoIyI unit (1) was developed as a fluorescent chemosensor with high selectivity and suitable affinity in biological systems toward Cu2+ over other cations tested. The fluorescence on-off mechanism was studied by femtosecond time-resolved fluorescence (TRF) upconversion technique and ab initio calculations. The receptor can be applied to the monitoring of Cu2+ ion in aqueous solution with a pH span 4-10. To confirm the suitability of 1 for biological applications, we also employed it for the fluorescence detection of the changes of intracellular Cu2+ in cultured cells. The results indicate that 1 should be useful for the fluorescence microscopic imaging and the study on the biological functions of Cu2+.

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  • for the synthesis of coumarin with pyrazole nucleus ..

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    Reaction mechanism for 7-hydroxy-4-methylcoumarin synthesis with an iodine ..

  • Pechmann Condensation - Organic chemistry

    What is the mechanism of the fluorescein synthesis performed by von Baeyer?

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Alkene synthesis by isomerization - Organic chemistry

It inhibits hepatic synthesis of vitamin K dependent coagulation 26 Apr 2003 Warfarin acts by inhibiting the synthesis of active vitamin K dependent proteins involved in blood coagulation, principally factors II (prothrombin) Warfarin (Coumadin®, Jantoven®) Considerations for Use*.

10.1021/ja0749993 - American Chemical Society

N2 - The metabolism of arylhydrazines by cytochromes P450 (P450s) has previously been shown to yield aryl-iron complexes that inhibit P450 enzymes as a result of heme modification. These modifications of the heme have been used to probe the topology of the active site of several P450s. Therefore, diaziridines containing one or more substitutions on the phenyl ring were synthesized and evaluated as potential mechanism-based inactivators of P450 2B enzymes that could be used to elucidate the active site topology. Five of the six trifluoroaryldiaziridines tested selectively inactivated P450 2B6 in the reconstituted system in a time-, concentration-, and NADPH-dependent manner as measured using the 7-ethoxy-4-(trifluoromethyl)coumarin O-deethylation assay. The kinetic parameters for P450 2B6 inactivation by the five compounds were calculated. Analysis of the P450 heme from P450s inactivated by the five substituted diaziridines suggested that the activity loss was not due to heme destruction as measured by the reduced-CO spectrum or high-performance liquid chromatography of the P450 heme. Dialysis experiments indicated the irreversible nature of the inactivation and the reaction between the diaziridine compounds and the P450 enzyme. Interestingly, a thiomethyl-substituted phenyl diaziridine had no effect on the activity of P450 2B6 in the reconstituted system, but competitively inhibited the O-debenzylation activity of P450 3A4 with 7-benzyloxy-4-(trifluoromethyl)coumarin as substrate. Binding spectra suggest that this compound bound reversibly to P450 2B6, and preliminary results indicate that 3-(4-methylthiophenyl)-3-(trifluoromethyl)diaziridine is metabolized by P450 2B6.

Low-Molecular-Weight Heparin versus a Coumarin for …

COUMADIN and other coumarin anticoagulants act by inhibiting the synthesis Coumadin is a potent drug with a half-life of 2½ days; therefore its effects may.

General & Introductory Chemistry

The metabolism of arylhydrazines by cytochromes P450 (P450s) has previously been shown to yield aryl-iron complexes that inhibit P450 enzymes as a result of heme modification. These modifications of the heme have been used to probe the topology of the active site of several P450s. Therefore, diaziridines containing one or more substitutions on the phenyl ring were synthesized and evaluated as potential mechanism-based inactivators of P450 2B enzymes that could be used to elucidate the active site topology. Five of the six trifluoroaryldiaziridines tested selectively inactivated P450 2B6 in the reconstituted system in a time-, concentration-, and NADPH-dependent manner as measured using the 7-ethoxy-4-(trifluoromethyl)coumarin O-deethylation assay. The kinetic parameters for P450 2B6 inactivation by the five compounds were calculated. Analysis of the P450 heme from P450s inactivated by the five substituted diaziridines suggested that the activity loss was not due to heme destruction as measured by the reduced-CO spectrum or high-performance liquid chromatography of the P450 heme. Dialysis experiments indicated the irreversible nature of the inactivation and the reaction between the diaziridine compounds and the P450 enzyme. Interestingly, a thiomethyl-substituted phenyl diaziridine had no effect on the activity of P450 2B6 in the reconstituted system, but competitively inhibited the O-debenzylation activity of P450 3A4 with 7-benzyloxy-4-(trifluoromethyl)coumarin as substrate. Binding spectra suggest that this compound bound reversibly to P450 2B6, and preliminary results indicate that 3-(4-methylthiophenyl)-3-(trifluoromethyl)diaziridine is metabolized by P450 2B6.

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