Ciprostene is the 9β-methyl analog of carbaprostacyclin and a stable analog of PGI2. Ciprostene exhibits biological activity similar to PGI2, but is 30-fold less potent. In patas monkeys, ciprostene induces hypotension and causes tachycardia when administered at a dose of 0.16 μg/kg/min. In addition, ciprostene inhibits ADP-induced platelet aggregation ex vivo and in vitro with ID50 values of 9.1 μg/kg/min and 60 ng/ml, respectively.
Protein tyrosine phosphatases (PTPs) remove phosphate from tyrosine residues of cellular proteins. Reversible phosphorylation catalyzed by the coordinated actions of protein tyrosine kinases and phosphatases is key to the regulation of the signaling events that control cell growth and proliferation, differentiation, and survival or apoptosis, as well as adhesion and motility. RK-682, a bioactive compound originally isolated from the fermentation of Streptomyces sp. 88-682, is an inhibitor of the PTPs. It inhibits the phosphorylation of CD45 and VHR with IC50 values of 54 and 2 μM, respectively, and arrests cell cycle progress at the G1/S transition. It is also reported to inhibit heparanase (IC50 = 17 μM), an endo-β-D-glucuronidase involved in tumor cell invasion and angiogenesis. RK-682 (calciumsalt) is a less soluble version of the free acid.
4-hydroxy Atorvastatin is a metabolite of atorvastatin , an HMG-CoA reductase inhibitor present in formulations that have been used to treat hypercholesterolemia and certain dyslipidemias. Atorvastatin is metabolized by the cytochrome P450 (CYP) isoform CYP3A4 to form 4-hydroxy atorvastatin.