Blockade of cytosolic phospholipase A(2) and 5-lipoxygenase activation in neutrophils by a natural isoflavanquinone abruquinone A.
Abruquinone A, a natural isoflavanquinone, suppressed A23187- and formyl-Met-Leu-Phe (fMLP)-induced production of thromboxane B(2) and leukotriene B(4) from rat neutrophils. This compound failed to inhibit the enzymatic activity of ram seminal vesicles cyclooxygenase (COX) and human recombinant 5-lipoxygenase (5-LO) in cell-free systems. Abruquinone A diminished the arachidonic acid release from [(3)H]arachidonic acid-loaded neutrophils stimulated with either fMLP or A23187, whereas it had no inhibitory effect on the cytosolic phospholipase A(2) (cPLA(2)) activity of neutrophil cytosolic fraction. Based on the Western blot analysis, the nuclear membrane recruitment of cPLA(2) and 5-LO was inhibited by abruquinone A in A23187- as well as in fMLP-stimulated cells. Moreover, the phosphorylation of both cPLA(2) and extracellular signal regulated kinases (ERKs) induced by fMLP and A23187 was attenuated by abruquinone A in a parallel concentration-dependent manner. Abruquinone A attenuated both fMLP- and ionomycin-mediated [Ca(2+)](i) elevation in a concentration range that inhibited the recruitment of cPLA(2) to nuclear membrane. These results indicate that the blockade of leukotriene B(4) production by abruquinone A implicates the attenuation of 5-LO membrane translocation. Inhibition of thromboxane B(2) production by abruquinone A is due to the attenuation of cPLA(2) membrane recruitment and/or cPLA(2) phosphorylation through the blockade of [Ca(2+)](i) elevation and ERK activation, respectively.
Hsu
Mei-Feng
MF
Department of Biochemistry, China Medical University, Taichung 404, Taiwan.
Chang
Ling-Chu
LC
Chen
Sheng-Chih
SC
Kuo
Sheng-Chu
SC
Lee
Hsiao-Yun
HY
Lu
Min-Chi
MC
Wang
Jih-Pyang
JP
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D001095:Arachidonic Acids / Q000378:metabolism; D001578:Benzopyrans / Q000494:pharmacology*; D016227:Benzoquinones / Q000494:pharmacology*; D015153:Blotting, Western; D000001:Calcimycin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology*; D015777:Eicosanoids / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D007975:Leukotriene B4 / Q000096:biosynthesis; D016859:Lipoxygenase Inhibitors; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D064801:Phospholipase A2 Inhibitors; D054467:Phospholipases A2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013929:Thromboxane B2 / Q000096:biosynthesis
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001095:Arachidonic Acids; D001578:Benzopyrans; D016227:Benzoquinones; D015777:Eicosanoids; D016859:Lipoxygenase Inhibitors; D064801:Phospholipase A2 Inhibitors; D007975:Leukotriene B4; D000001:Calcimycin; D013929:Thromboxane B2; D009240:N-Formylmethionine Leucyl-Phenylalanine; C093391:abruquinone A; D001094:Arachidonate 5-Lipoxygenase; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D054467:Phospholipases A2; D002118:Calcium