Flavonoids differentially inhibit guinea pig epidermal cytosolic phospholipase A2

초록

Cytosolic phospholipase A<inf>2</inf> (cPLA<inf>2</inf>) is believed to involve the regulation of essential cellular processes. Like other cell types, epidermal cPLA<inf>2</inf> may participate in various metabolic processes including eicosanoid generation. In this investigation, we demonstrated the presence of cPLA<inf>2</inf> in guinea pig epidermis. The epidermal cPLA<inf>2</inf> is Ca2+-dependent, active at micromolar concentration of Ca2+ and resistant to disulfide-reducing agents. Furthermore, it is inhibited by methyl arachidonyl fluorophosphonate (MAFP), a selective inhibitor of cPLA<inf>2</inf>, while 12-epi-scalardial (a sPLA<inf>2</inf> inhibitor) did not cause inhibition. A test of several flavonoids revealed that quercetin (flavonol) weakly inhibited cPLA<inf>2</inf>, while flavanone had negligible inhibitory activity. In contrast, amentoflavone and ginkgetin (biflavones) markedly inhibited cPLA<inf>2</inf> activity in the epidermis. These results underscore that different flavonoids do vary in their capability to exert differential effects on arachidonate metabolism in the skin via modulation of epidermal cPLA<inf>2</inf> activity. © 2001 Harcourt Publishers Ltd.