Avena Rhealba® inhibits A23187-stimulated arachidonic acid mobilization, eicosanoid release, and cPLA2 expression in human keratinocytes: Potential in cutaneous inflammatory disorders

Abstract

The aim of the present study was to examine the effects of Avena Rhealba® (AR) oatmeal extract on the metabolism of arachidonic acid (AA) and eicosanoids as well as on the expression of cytosolic phospholipase A 2 (cPLA2) in the human keratinocyte cell line HaCaT. For this purpose, we examined the effects of AR on basal and A23187-triggered release of [3H]-AA from phospholipids and on the production of [ 1H]-labeled metabolites of the cyclooxygenase (CO) and 5-lipoxygenase (LO) pathways. AR was found to inhibit A23187-triggered [3H]-AA mobilization from phospholipids (p>0.05) and production of [ 3H]-labeled metabolites of CO (p<0.05) and LO (p<0.05) pathways. These results suggest AR decreases PLA2-dependent mobilization of AA from phospholipids. A closer examination of the effects of AR on prostaglandin 6KF1α (6KPGF1α), the stable metabolite of prostacyclin, revealed dose-dependent inhibition of this AA metabolite. AR also decreased A23187- and tumor necrosis factor α-induced cPLA2 overexpression, as shown by cPLA2 immunodetection and mRNA expression. These results demonstrate the high potential of AR in the treatment of inflammatory diseases of the skin. © 2005 Pharmaceutical Society of Japan.