Novel thiocoumarins as inhibitors of TNF-α induced ICAM-1 expression on human umbilical vein endothelial cells (HUVECs) and microsomal lipid peroxidation Original Research Article

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.