- Novel thiocoumarins as inhibitors of TNF-α induced ICAM-1 expression on human umbilical vein endothelial cells (HUVECs) and microsomal lipid peroxidation
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Different coumarin/thiocoumarin derivatives, that is, 7-hydroxy-4- methylcoumarin, 7,8-dihydroxy-4-methylcoumarin, 7-acetoxy-4-methylcoumarin, 7,8-diacetoxy-4-methylcoumarin, 7-hydroxy-4-methylthiocoumarin, 7,8-dihydroxy-4-methylthiocoumarin, 7-acetoxy-4-methylthiocoumarin and 7,8-diacetoxy-4-methylthiocoumarin were synthesized and evaluated for their effects on TNF-α induced expression of intercellular adhesion molecule-1 (ICAM-1) on endothelial cells and on NADPH-catalyzed rat liver microsomal lipid peroxidation with a view to identify modulators for expression of cell adhesion molecules and to establish structure-activity relationship. We found that dihydroxy and diacetoxy derivatives of thiocoumarin were more potent in comparison to the corresponding coumarin derivatives in inhibiting TNF-α-induced expression of ICAM-1. However, coumarin derivatives were found to be more potent in comparison to the corresponding thiocoumarins in inhibiting microsomal lipid peroxidation. We have also tested the intermediate compounds 7,8-dibenzyloxy-4-methylcoumarin and 7,8-dibenzyloxy-4- methylthiocoumarin for their inhibitory activity on TNF-α-induced ICMA-1 expression. We found that dibenzyloxy-4-methylthiocoumarin is better than dibenzyloxy-4-methylcoumarin. The mechanisms underlying the observed activities of coumarins and thiocoumarins have been discussed with reference to their structures. Such structure-function relationship studies may help in developing molecules with better anti-inflammatory and anti-oxidant activities.
- Kumar, Sarvesh,Singh, Brajendra K.,Kalra, Neerja,Kumar, Vineet,Kumar, Ajit,Prasad, Ashok K.,Raj, Hanumantharao G.,Parmar, Virinder S.,Ghosh, Balaram
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- Mapping the catechol binding site in dopamine D1 receptors: Synthesis and evaluation of two parallel series of bicyclic dopamine analogues
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A novel class of isochroman dopamine analogues, originally reported by Abbott Laboratories, have >100-fold selectivity for D1-like over D2-like receptors. We synthesized a parallel series of chroman compounds and showed that repositioning the oxygen atom in the heterocyclic ring decreases potency and confers D2-like receptor selectivity to these compounds. Insilico modeling supports the hypothesis that the altered pharmacology for the chroman series is due to potential intramolecular hydrogen bonding between the oxygen in the chroman ring and the meta-hydroxy group of the catechol moiety. This interaction realigns the catechol hydroxy groups and disrupts key interactions between these ligands and critical serine residues in TM5 of the D1-like receptors. This hypothesis was tested by the synthesis and pharmacological evaluation of a parallel series of carbocyclic compounds. Our results suggest that if the potential for intramolecular hydrogen bonding is removed, D1-like receptor potency and selectivity are restored. What a difference an H bond makes: Structurally related chromans, isochromans, and their carbocyclic analogues were assessed for dopamine D1 and D2 receptor affinity. Isochromans and carbocyclic analogues had high D1 receptor affinity. Poor affinity for the chromans was attributed to an intramolecular hydrogen bond, which disrupts the ligand-receptor hydrogen bonding network.
- Bonner, Lisa A.,Laban, Uros,Chemel, Benjamin R.,Juncosa, Jose I.,Lill, Markus A.,Watts, Val J.,Nichols, David E.
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p. 1024 - 1040
(2012/01/06)
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