The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform

Chunying Chen - One of the best experts on this subject based on the ideXlab platform.

  • Fullerene Derivatives protect endothelial cells against NO-induced damage
    Nanotechnology, 2009
    Co-Authors: Fang Lao, Dong Han, Ying Liu, Yuliang Zhao, Chunying Chen
    Abstract:

    Functional fullerene Derivatives have been demonstrated with potent antioxidation properties. Nitric oxide (NO) is a free radical that plays a part in leading to brain damage when it is accumulated to a high concentration. The possible scavenging activity of NO by the hydroxylated fullerene Derivative C60(OH)22 and Malonic Acid Derivative C60(C(COOH)2)2 was investigated using primary rat brain cerebral microvessel endothelial cells (CMECs). Results demonstrate that sodium nitroprusside (SNP), used as an NO donor, caused a marked decrease in cell viability and an increase in apoptosis. However, fullerene Derivatives can remarkably protect against the apoptosis induced by NO assault. In addition, fullerene Derivatives can also prevent NO-induced depolymerization of cytoskeleton and damage of the nucleus and accelerate endothelial cell repair. Further investigation shows that the sudden increase of the intercellular reactive oxygen species (ROS) induced by NO was significantly attenuated by post-treatment with fullerene Derivatives. Our results suggest that functional fullerene Derivatives are potential applications for NO-related disorders.

H. El-diwani - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of Novel 1-Substituted and 1,9-Disubstituted-1,2,3,4-tetrahydro-9H-Carbazole Derivatives as Potential Anticancer Agents
    Molecules, 2000
    Co-Authors: N. Shmeiss, M. Ismail, A. Soliman, H. El-diwani
    Abstract:

    Condensation of 1-acetyl-1,2,3,4-tetrahydro-9H-carbazole (2) with some amino compounds furnished the corresponding imino Derivatives 3a-e. Compound 3a reacted with chloroacetic Acid and underwent cyclization to give the thiazolidine Derivative 5. Also, treatment of 3c with thionyl chloride caused cyclization to yield the [1,2,6]thiadiazino Derivative 6, which gave the corresponding N-formyl Derivative 7 upon heating with ethyl formate. In addition, interaction of 3d with ethyl cyanoacetate yielded the monoamide of Malonic Acid Derivative 8. Acylation of carbazole 1 with succinoyl chloride or phenylacetyl choride produced the corresponding azepine (11) and 1,9-diphenyl acetyl Derivatives (14), respectively. Compounds 11, 14 were further reacted to give the carbazole Derivatives 12, 13 and 15a,b. The cytotoxic activity for some of the prepared compounds against breast cancer B20 is discussed

Luigi Toniolo - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of γ-keto carboxylic Acids from γ-keto-α-chloro carboxylic Acids via carbonylation—decarboxylation reactions catalysed by a palladium system
    Journal of Molecular Catalysis, 1993
    Co-Authors: Gianni Cavinato, Luigi Toniolo
    Abstract:

    Abstract A palladium-based catalytic system is highly active in the synthesis of γ-keto Acids of type ArCOCH 2 CH 2 COOH via carbonylation-decarboxylation of the corresponding α-chloride. Typical reaction conditions are: P (CO) = 20–30 atm; substrate/H 2 O/Pd = 100–400/800–1000/1 (mol); temperature: 100–110 °C; [Pd]=0.25 × 10 −2 −1 × 1O −2 M; solvent: acetone; reaction time: 1–2 h. A palladium(II) complex can be used as catalyst precursor. Under the reaction conditions above, reduction of the precursor to palladium metal occurs to a variable extent. High catalytic activity is observed when the precursor undergoes extensive decomposition to the metal. Pd/C is also highly active. Slightly higher yields are obtainable when the catalytic system is used in combination with a ligand such as PPh 3 . A mechanism for the catalytic cycle is proposed: (i) The starting keto chloride undergoes oxidative addition to reduced palladium with formation of a catalytic intermediate having a Pd-[CH(COOH)CH 2 COPh] moiety. The reduced palladium may be the metal coordinated by other atoms of palladium and/or by carbon monoxide and/or by a PPh 3 ligand when catalysis is carried out in the presence of this ligand. It is also proposed that the keto group in the β-position with respect to the carbon atom bonded to chlorine weakens the CCl bond, easing the oxidative addition step and enhancing the activity of the catalyst. (ii) Carbon monoxide ‘inserts’ into the PdC bond of the above intermediate to give an acyl catalytic intermediate having a Pd-[COCH(COOH)CH 2 COPh] moiety. (iii) Nucleophilic attack of H 2 O to the carbon atom of the carbonyl group bonded to the metal of the acyl intermediate yields a Malonic Acid Derivative as product intermediate. This, upon decarboxylation, gives the final product. Alternatively, the desired product may form without the Malonic Acid Derivative intermediate, through the following reaction pathway: the acyl intermediate undergoes decarboxylation with formation of a different acyl intermediate, having a Pd-[CO-CH 2 CH 2 COPh] moiety, which, upon nucleophilic attack of H 2 O on the carbon atom of the carbonyl group bonded to the metal, yields the final product.

  • Syntheses of gamma-keto carboxylic Acids from gamma-keto-alfa-chlorocarboxylic Acid via carbonylation decarboxylation reactions catalyzed by a palladium system
    'Elsevier BV', 1993
    Co-Authors: Cavinato Gianni, Luigi Toniolo
    Abstract:

    A palladium-based catalytic system is highly active in the synthesis of \u3b3-keto Acids of type ArCOCH2CH2COOH via carbonylation-decarboxylation of the corresponding \u3b1-chloride. Typical reaction conditions are: P(CO) = 20\u201330 atm; substrate/H2O/Pd = 100\u2013400/800\u20131000/1 (mol); temperature: 100\u2013110 \ub0C; [Pd]=0.25 7 10 122 121 7 1O 122 M; solvent: acetone; reaction time: 1\u20132 h. A palladium(II) complex can be used as catalyst precursor. Under the reaction conditions above, reduction of the precursor to palladium metal occurs to a variable extent. High catalytic activity is observed when the precursor undergoes extensive decomposition to the metal. Pd/C is also highly active. Slightly higher yields are obtainable when the catalytic system is used in combination with a ligand such as PPh3. A mechanism for the catalytic cycle is proposed: (i) The starting keto chloride undergoes oxidative addition to reduced palladium with formation of a catalytic intermediate having a Pd-[CH(COOH)CH2COPh] moiety. The reduced palladium may be the metal coordinated by other atoms of palladium and/or by carbon monoxide and/or by a PPh3 ligand when catalysis is carried out in the presence of this ligand. It is also proposed that the keto group in the \u3b2-position with respect to the carbon atom bonded to chlorine weakens the C-Cl bond, easing the oxidative addition step and enhancing the activity of the catalyst. (ii) Carbon monoxide \u2018inserts\u2019 into the Pd-C bond of the above intermediate to give an acyl catalytic intermediate having a Pd-[COCH(COOH)CH2COPh] moiety. (iii) Nucleophilic attack of H2O to the carbon atom of the carbonyl group bonded to the metal of the acyl intermediate yields a Malonic Acid Derivative as product intermediate. This, upon decarboxylation, gives the final product. Alternatively, the desired product may form without the Malonic Acid Derivative intermediate, through the following reaction pathway: the acyl intermediate undergoes decarboxylation with formation of a different acyl intermediate, having a Pd-[CO-CH2CH2COPh] moiety, which, upon nucleophilic attack of H2O on the carbon atom of the carbonyl group bonded to the metal, yields the final product

Fang Lao - One of the best experts on this subject based on the ideXlab platform.

  • Fullerene Derivatives protect endothelial cells against NO-induced damage
    Nanotechnology, 2009
    Co-Authors: Fang Lao, Dong Han, Ying Liu, Yuliang Zhao, Chunying Chen
    Abstract:

    Functional fullerene Derivatives have been demonstrated with potent antioxidation properties. Nitric oxide (NO) is a free radical that plays a part in leading to brain damage when it is accumulated to a high concentration. The possible scavenging activity of NO by the hydroxylated fullerene Derivative C60(OH)22 and Malonic Acid Derivative C60(C(COOH)2)2 was investigated using primary rat brain cerebral microvessel endothelial cells (CMECs). Results demonstrate that sodium nitroprusside (SNP), used as an NO donor, caused a marked decrease in cell viability and an increase in apoptosis. However, fullerene Derivatives can remarkably protect against the apoptosis induced by NO assault. In addition, fullerene Derivatives can also prevent NO-induced depolymerization of cytoskeleton and damage of the nucleus and accelerate endothelial cell repair. Further investigation shows that the sudden increase of the intercellular reactive oxygen species (ROS) induced by NO was significantly attenuated by post-treatment with fullerene Derivatives. Our results suggest that functional fullerene Derivatives are potential applications for NO-related disorders.

Natalia G. Vakhnina - One of the best experts on this subject based on the ideXlab platform.