Produção Nacional
Revisado por pares
Yangambin: A New Naturally-Occurring Platelet-Activating Factor Receptor Antagonist: Binding and In Vitro Functional Studies
1995; Thieme Medical Publishers (Germany); Volume: 61; Issue: 02 Linguagem: Inglês
10.1055/s-2006-958025
ISSN1439-0221
AutoresHugo C. Castro‐Faria‐Neto, Patrı́cia T. Bozza, Hermenegildo N. Cruz, Cláudia Lúcia Martins Silva, Flávio A. Violante, José Maria Barbosa‐Filho, George Thomas, Marco A. Martins, Eduard Tibiriçá, François Noël, Renato S.B. Cordeiro,
Tópico(s)Phytochemistry and Biological Activities
ResumoThe effects of the furofuran lignan yangambin on rabbit platelet aggregation and binding of [3 H]-PAF to rabbit platelet plasma membranes were studied. Log concentration-response curves to PAF were obtained in the presence or absence of increasing concentrations of yangambin. This lignan dose-dependently inhibited PAF-induced platelet aggregation in platelet-rich plasma (PRP) and shifted PAF curves to the right without decreasing the maximal response. The Schild plot constructed from these data showed a slope of 1.17 and a pA2 of 6.45. Moreover, yangambin at 10-5 M did not inhibit the platelet aggregation induced by ADP (5 × 10-7 M), collagen (0.1 µg ml-1), or thrombin (0.05 U ml-1). Biochemical studies showed that [3 H]-PAF labelled in a saturable manner a single class of binding sites on platelet membranes with a Kd of 1.25 ± 0.24 nM and a maximal binding capacity (Bmax) of 14.9 ± 2.4 pmol mg protein-1. Both unlabelled PAF and yangambin competitively displaced [3 H]-PAF binding with an IC50 of 1.54 ± 0.37 nM and 1.93 ± 0.53 µM, respectively. The incubation of rabbit blood neutrophils with yangambin at 10-5 M did not prevent PAF-induced in vitro chemotaxis in conditions where the PAF antagonist SR 27417 at 10-5 A M abolished the phenomenon. These results indicate that yangambin is an antagonist that selectively blocks PAF receptors on platelets.
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