Low molecular weight, non-peptide fibrinogen receptor antagonists

Abstract

The tetrapeptide H-Arg-Gly-Asp-Ser-OH (1) (RGDS), representing a recognition sequence of fibrinogen for its platelet receptor GP IIb-IIIa (integrin alpha IIb beta 3), served as lead compound for the development of highly potent and selective fibrinogen receptor antagonists. Replacement of the N-terminal arginine by p-amidinophenylalanine or the Gly moiety by m-aminobenzoic acid led to compounds which are superior to the lead peptide with regard to activity and selectivity for GP IIb-IIIa vs the closely related vitronectin receptor alpha v beta 3. By random screening [(p-amidinobenzenesulfonamido)ethyl]-p-phenoxyacetic acid derivatives have been identified as fibrinogen receptor antagonists. Further structure-activity relationship studies culminated in the preparation of N-[N-[N-(p-amidinobenzoyl)-beta-alanyl]-L-alpha-aspartyl]-3-phenyl-L- alanine (29h, Ro 43-5054) and [[1-[N-(p-amidinobenzoyl)-L-tyrosyl]-4-piperidinyl]oxy]acetic acid (37f, Ro 44-9883), which exhibit very high activity as platelet aggregation inhibitors (IC50s 0.06 and 0.03 microM, respectively, human PRP/ADP) as well as marked selectivity for GP IIb-IIIa vs alpha v beta 3. Since the activity of 37f in dogs declines according to a two-compartment model with an initial phase having a t1/2 of 8 min and a second phase with a t1/2 of 110 min, this compound is a suitable candidate for the development as iv platelet inhibitor.

Signaling through GP Ib-IX-V activates αIIbβ3 independently of other receptors

“…32 MRS-2216 and ARC-69931MX against the P2Y1 and P2Y12 receptors, respectively, were from Dr Kenneth Jacobson (National Institutes of Health [NIH], Bethesda, MD) 33 and Astra Zeneca (Wilmington, DE). 34 Inhibitors of ligand binding to ␣IIb␤3, Ro 44-9883 ((1-(N-p-amidinobenzoyl)-Ltyrosyl)-4-piperidinyl(oxy)acetic acid) and Integrilin, were from Dr Beat Steiner (Roche, Basel, Switzerland) 35 and Dr David Phillips (Cor Therapeutics, South San Francisco, CA), 36 respectively. Oregon Green, Fura Red, BAPTA-AM, and Alexa-488 were from Molecular Probes (Eugene, OR).…”

A Model of Platelet Aggregation Involving Multiple Interactions of Thrombospondin-1, Fibrinogen, and GPIIbIIIa Receptor

“…Peptide GRGDSP and fluorescein isothiocyanate (FITC) celite were from Calbiochem (La Jolla, CA). Ro 44 -9883, a nonpeptide analogue of the RGD peptide but 1000 times more potent and selective for ␣ IIb ␤ 3 (GPIIbIIIa) than for ␣ v ␤ 3 (32), was kindly provided by Dr. T. Weller (F. Hoffmann-La Roche, Basel, Switzerland). Dr. T. Krais (Schering Co., Berlin, Germany) generously provided ZK 36 374, a stable prostacyclin analogue.…”

“…Preparation of Fg-or TSP-coated Beads-Polystyrene latex beads were washed three times at ϳ0.5% solids and incubated with either 500 nM Fg in phosphate-buffered saline or 200 nM TSP in Tyrode buffer containing 2 mM Ca 2ϩ , pH 7.4, for 30 min at room temperature and processed as previously published for Fg (32). The beads were finally centrifuged and resuspended in distilled and deionized water (Fgbeads), or in Tyrode containing 2 mM Ca 2ϩ (TSP-beads) at a concentration of 250,000 beads/l and stored at 4°C.…”

Trans-dominant inhibition of integrin function.

“…Integrins often recognize small discrete peptide segments in their natural protein ligands . These recognition sites can be simulated by small peptide (Pierschbacher and Ruoslahti, 1984) or nonpeptide compounds (Alig et al, 1992) or by mAbs (Tomiyama et al, 1992a,b ligands or of ligand-mimetic peptides (Parise et al, 1987), small molecules (Kouns et al, 1992), or antibodies to integrins (Tomiyama et al, 1992a) induces conformational changes in their extracellular domains. These changes can be detected by conformation-dependent mAbs, termed antiligand-induced-binding sites (LIBS; Frelinger et al, 1988).…”