TETRAFIBRICIN, A NOVEL FIBRINOGEN RECEPTOR ANTAGONIST .1. TAXONOMY, FERMENTATION, ISOLATION, CHARACTERIZATION AND BIOLOGICAL-ACTIVITIES

Tetrafibricin is a novel fibrinogen receptor antagonist produced by St reptomyces neyagawaensis NR0577. It was isolated from the culture brot h by Diaion HP-21 adsorption, MeOH extraction, MCI GEL CHP-20P column chromatography, preparative HPLC and Toyopearl HW-40 SF column chromat ography. The physico-chemical properties of tetrafibricin indicated th at the structure of tetrafibricin is different from the known peptide fibrinogen receptor antagonists and closely related to the polyene mac rolide antibiotics. Tetrafibricin strongly inhibited the binding of fi brinogen to its receptors with an IC50 of 46 nm. It also inhibited ADP -, collagen-, and thrombin-induced aggregation of human platelets with IC50s of 5.6, 11.0 and 7.6 mum, respectively.