The active metabolite of Clopidogrel disrupts P2Y12 receptor oligomers and partitions them out of lipid rafts.

P2Y12, a G protein-coupled receptor that plays a central role in platelet activation has been recently identified as the receptor targeted by the antithrombotic drug, clopidogrel. In this study, we further deciphered the mechanism of action of clopidogrel and of its active metabolite (Act-Met) on P2Y12 receptors. Using biochemical approaches, we demonstrated the existence of homooligomeric complexes of P2Y12 receptors at the surface of mammalian cells and in freshly isolated platelets.

Structure and stereochemistry of the active metabolite of clopidogrel.

Clopidogrel (SR25990C, PLAVIX) is a potent antiplatelet drug, which has been recently launched and is indicated for the prevention of vascular thrombotic events in patients at risk. Clopidogrel is inactive in vitro, and a hepatic biotransformation is necessary to express the full antiaggregating activity of the drug. Moreover, 2-oxo-clopidogrel has been previously suggested to be the essential key intermediate metabolite from which the active metabolite is formed.

Identification and biological activity of the active metabolite of clopidogrel.

Like ticlopidine, the ADP receptor antagonist clopidogrel is inactive in vitro and must be administered i.v. or orally to exhibit antiaggregatory and antithrombotic activities.

Purification and characterization of a novel protease from culture filtrates of a Streptomyces sp.

A fibrinolytic protease has been isolated from Streptomyces sp. culture filtrate by successive chromatography on Mono S and Sephadex G50. The purified protease had a molecular mass of 33 kDa and had an isoelectric point of 6.

Echinomycin suppresses the pyrogenic effects of endotoxin and interleukin-1 beta in human endothelial cells and peripheral blood mononuclear cells.

Endotoxin (LPS) and interleukin-1 beta (IL-1 beta) increased in a dose-dependent manner the expression of tissue factor, an ubiquitous membrane-anchored glycoprotein that initiates blood coagulation at the surface of human umbilical vein endothelial cells (HUVEC and human peripheral blood mononuclear cells (PBMC). Echinomycin, a cyclic octapeptide of microbial origin strongly inhibited LPS- and IL-1 beta-induced tissue factor expression in HUVEC and PBMC with IC50 values in the subnanomolar range at the same time it reduced LPS and IL-1 beta-induced expression of intercellular adhesion molecule-1 (ICAM-1, CD54) on HUVEC (IC50 = 0.4 +/- 0.