Lutein is a competitive inhibitor of cytosolic Ca2+-dependent phospholipase A2

Abstract

We have investigated the effect of lutein on phospholipase A₂ (PLA₂) isozymes. We measured arachidonic acid release in [³H]arachidonic acid-labelled Raw 264.7 cells and PLA₂ activity using 1-palmitoyl-2-[¹⁴C]arachidonyl phosphatidylcholine ([¹⁴C]AA-PC) and 10-pyrene phosphatidylcholine in vitro. Lutein suppressed the release of arachidonic acid and inhibited Raw 264.7 cell-derived cytosolic Ca²+-dependent PLA₂ (cPLA₂-induced hydrolysis of [¹⁴C]AA-PC in a dose- and time-dependent manner. In contrast, lutein did not affect secretory Ca²+-dependent PLA₂ (sPLA₂)-induced hydrolysis of [¹⁴C]AA-PC. A Dixon plot showed that the inhibition by lutein on cPLA₂ appeared to be competitive with an inhibition constant, K(i) , of 13.6 µm. We suggest that lutein acted as a competitive inhibitor of cPLA₂ but did not affect sPLA₂.