Novel Non-Peptide Fibrinogen Receptor Antagonists. 1. Synthesis and Glycoprotein IIb-IIIa Antagonistic Activities of 1,3,4-Trisubstituted 2-Oxopiperazine Derivatives Incorporating Side-Chain Functions of the RGDF Peptide

Abstract

Based on the lead tetrapeptide RGDF, two possible non-peptide glycoprotein (GP) IIb-IIIa antagonists possessing an (S)-2-oxopiperazine-3-acetic acid moiety as a scaffold incorporating the indispensable Asp fragment were prepared, and (S)-4-[[trans-[4-(guanidinomethyl)-cyclohexyl]carbonyl]glycyl]-2- oxopiperazine-1,3-diacetic acid, 1a, was identified as a potential lead. A series of 3-substituted 2-oxopiperazine-1-acetic acids bearing the Arg-Gly equivalent at the 4-position were prepared and evaluated for their ability to prevent platelet aggregation and for their binding affinity for the GP IIb-IIIa receptor purified from human HEL cells. (S)-4-[(4-Amidinobenzoyl)glycyl]-3-[(methoxycarbonyl)methyl]- 2-oxopiperazine-1-acetic acid, 9 (TAK-029), inhibited in vitro human platelet aggregation with an IC50 value of 0.03 microM and GP IIb-IIIa-fibrinogen binding with an IC50 value of 0.49 nM. The [4-(2-aminoethyl)benzoyl]glycyl derivative 26 showed activity comparable to that of 9 (IC50 = 0.093 microM, guinea pig platelet aggregation assay). Compound 9 dose-dependently inhibited ex vivo platelet aggregation in guinea pigs (0.03 and 0.1 mg/kg, i.v.), and long-lasting inhibition of platelet aggregation was observed upon oral administration of 9 (3 mg/kg) to guinea pigs. On the other hand, the activity of 26 disappeared within 1 h after a dose of 1 mg/kg (i.v.). Compound 9 may therefore be useful in the clinical treatment of arterial thrombotic diseases.

Rapid Platelet-Function Assay

“…6 It was also tested for its effects on platelet aggregometry and RPFA, and the results were correlated with those obtained with an assay to measure GP IIb/IIIa receptor occupancy by TAK-029. 14 C-TAK-029, diluted with 10 mmol/L HEPES, 150 mmol/L NaCl, pH 7.4, was added to 200 L of PRP to yield the concentrations noted in the figure legends.…”

Solid-Phase Synthesis of Amidine-Based GP IIb-IIIa Antagonists on Dendrimer Resin Beads

“…More recently the amidine moiety has been found as part of a number of pharmacologically active molecules such as fibrinogen receptor antagonists, [3] thrombin inhibitors, [4] factor Xa inhibitors, [5] and (S)-adenosylmethionine decarboxylase inhibitors. [6] Recent studies on the biochemical mechanisms of platelet activation [7] indicate that the interaction of the tissue-bound von Willebrand factor (vWF) with glycoprotein Ib-IX on the platelet surface is responsible for the adhesion of platelets to exposed subendothelium. This is thought to trigger the final and most critical step in aggregation, the crosslinking of the dimeric plasma protein fibrinogen between membrane glycoprotein IIb/IIIa (α II β 3 ) receptor complexes exposed on adjacent activated platelets, through stimulation of adhered platelets by locally generated agonists such as thrombin.…”

“…Moreover, it has been shown that the basic function can be either a guanidine, which is the natural function of the RGD sequence, or an amine such as piperidine or a benzamidine moiety. Some molecules with these features are currently in preclinical or clinical trials, like Lamifiban (Ro44-9883) (1), [3] TAK-029 (2), [7] or Ro43-5054 (3) [13] (Figure 1). …”

Synthesis of Components for the Generation of Constitutional Dynamic Analogues of Nucleic Acids

“…2), nucleobase acids 1 and 2 were synthesised as described in the literature [24b,c], while amine 3 was obtained by reductive amination of glyoxal dimethyl acetal with glycine methyl ester hydrochloride [28]. Coupling reactions of these nucleobase acids 1 and 2 with amine 3 were effected using diisopropylcarbodiimide/1-hydroxybenzotriazole (HOBt) in DMF to give the corresponding ester derivatives 4 and 5, respectively (Scheme 1).…”