Lutein is a competitive inhibitor of cytosolic Ca²+-dependent phospholipase A₂
Ho Sun Song1, Hee Rae Kim, Myung Cheul Kim
1College of Pharmacy, Chung-Ang University, 221 Huksuk-dong, Dongjak-gu, Seoul 156-756, Korea.
Objectives:
We have investigated the effect of lutein on phospholipase A₂ (PLA₂) isozymes.
Methods:
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.
Key Findings:
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.
Conclusions:
We suggest that lutein acted as a competitive inhibitor of cPLA₂ but did not affect sPLA₂.
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