Mechanism for antiplatelet effect of onion: AA release inhibition, thromboxane A(2)synthase inhibition and TXA(2)/PGH(2)receptor blockade.
Antiplatelet actions of aqueous extract of onion were investigated in rat and human platelet. IC(50)values of onion extract for collagen-, thrombin-, arachidonic acid (AA)-induced aggregations and collagen-induced thromboxane A(2)(TXA(2)) formation were 0.17 +/- 0. 01, 0.23 + 0.03, 0.34 +/- 0.02 and 0.12 +/- 0.01 g/ml, respectively. [(3)H]-AA release induced by collagen (10 microg/ml) in rat platelet was decreased by onion compared to control (22.1 +/- 2.13 and 5.2 +/- 0.82% of total [(3)H]-AA incorporated, respectively). In fura-2 loaded platelets, the elevation of intracellular Ca(2+)concentration stimulated by collagen was inhibited by onion. Onion had no cytotoxic effect in platelet. Onion significantly inhibited TXA(2)synthase activity without influence on COX activity. Platelet aggregation induced by U46619, a stable TXA(2)mimetic, was inhibited by onion, indicating its antagonism for TXA(2)/PGH(2)receptor. These results suggest that the mechanism for antiplatelet effect of onion may, at least partly, involve AA release diminution, TXA(2)synthase inhibition and TXA(2)/PGH(2)receptor blockade.
Moon
C H
CH
Honam University, Kwangjoo, South Korea.
Jung
Y S
YS
Kim
M H
MH
Lee
S H
SH
Baik
E J
EJ
Park
S W
SW
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020128:Inhibitory Concentration 50; D019697:Onions / Q000627:therapeutic use*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013928:Thromboxane A2 / Q000096:biosynthesis; D013929:Thromboxane B2 / Q000378:metabolism; D013930:Thromboxane-A Synthase / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D010936:Plant Extracts; D010975:Platelet Aggregation Inhibitors; D014662:Vasoconstrictor Agents; D013929:Thromboxane B2; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D011451:Prostaglandin-Endoperoxide Synthases; D013930:Thromboxane-A Synthase