- Study of synthesis and cardiovascular activity of some furoxan derivatives as potential NO-donors
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A series of hybrid molecules incorporating the furoxan and nicorandil moieties were designed as potential NO donors with cardiovascular and cerebrovascular activities. Thirty-six target molecules were successfully synthesized by conventional methods and characterized by infrared spectroscopy, 1H-NMR spectroscopy and high resolution mass spectra. The compounds were tested for their effects on KCl-induced contraction of rabbit thoracic aorta whose endothelium was denuded. Eight compounds were found to reduce KCl-induced contraction by more than 30% at 10 μM. All except one of these compounds are characterized by the presence of electron withdrawing groups in the phenyl ring attached via an amide or ester linkage to the furoxan moiety. The nature of the terminal carbonyl linkage (ester or amide) and the length or type of the alkyl chain bridging the two carbonyl functions have little effect on the activity. One of the active compounds, N-(4- methoxy-benzoyl)-N'-[3-methylfuroxanyl-4-carbonyl)piperazine (17i) was tested for hypotensive effects on anaesthetized rats at 1.5 mg/kg, and found to demonstrate a gradual and sustained hypotensive effect. The results suggest that the furoxannicorandil derivatives are a useful lead in the design of NO- donor compounds for hypertension.
- Mu, Li,Feng, Si-Shen,Go, Mei Lin
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p. 808 - 816
(2007/10/03)
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- Reaction enthalpy of nucleophilic substitution of ethyl iodide in acetonitrile and its mechanistic significance
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Enthalpies of reaction for nucleophilic substitution of ethyl iodide have systematically been determined in acetonitrile. Through the concurrent analysis of empirical correlations between the reaction enthalpies and the specific interaction enthalpies for relevant anions with those between the logarithmic rates and the specific interaction enthalpies, partial desolvation accompanying activation has been deduced to be the major contributor to activation thermodynamic parameters, while the propensity of the reacting central atom in the nucleophilic anion plays a crucial role in determining reaction thermodynamic parameters. Semi-empirical molecular orbital calculations have supported these ideas. The application of the Marcus equation to the analysis of reaction characteristics in these reactions is discussed.
- Kondo, Yasuhiko,Tsukamoto, Tamio,Kimura, Naoko
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p. 1765 - 1769
(2007/10/03)
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- Single-ion enthalpies of transfer as a scale of nucleophilic reactivity towards ethyl iodide in acetonitrile
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Logarithmic rates for nucleophilic substitution towards ethyl iodide in acetonitrile correlate well with the specific interaction enthalpies for the relevant nucleophile, ΔHt,SIAN->MeOH(Nu-).According to the correlation, the bromide ion reaction falls into the imidide ion reaction series, while the chloride ion reaction falls into the carboxylate ion reaction series.The partial desolvation accompanying activation is crucial in determining the reactivity behaviour of the nucleophile anions.Semi-empirical quantum mechanical calculations (MNDO/PM3 and MNDO/PM3/COSMO) give reasonable estimates for the enthalpies of activation as well as for reaction enthalpies in acetonitrile.The relative location of the transition state, estimated on the basis of empirical analysis, is in accord with the variation of electronic charges for the exposed atoms, which has been evaluated through semi-empirical quantum mechanical procedures.
- Kondo, Yasuhiko,Tsukamoto, Tamio,Moriguchi, Chika
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p. 1699 - 1704
(2007/10/03)
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