Coumarin and Flavone Derivatives from Estragon and Thyme as Inhibitors of Chemical Mediator Release from RBL-2H3 Cells

Abstract

Estragon and thyme extracts showed potent inhibitory activities against chemical mediator release from rat basophilic leukemia RBL-2H3 cells. 7-Methoxycoumarin was isolated from estragon, and 5,4′-dihydroxy-6,7,3′-trimethoxyflavone, 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone, 5-hydroxy-6,7,8,3′,4′-pentamethoxyflavone and luteolin were isolated from thyme as active components. Structure-activity relationship studies among the active isolates and their related compounds indicated that the oxygen-containing functional group at the 7-position of the coumarin structure was advantageous for the inhibitory activity and that methylation of the hydroxyl group at the 4′-position of the flavone structure was disadvantageous. It was also found that coumarin derivatives inhibited an earlier step than intracellular calcium release and proteinkinase C activation, while flavones inhibited a later step or both earlier and later steps.

• anti-allergic effect
• coumarin
• flavone
• RBL-2H3 cell