High-affinity binding site for leukotriene C4 in human erythrocytes.

A specific, high-affinity binding site for leukotriene C4 was identified in human erythrocyte particulate fraction and in vesicle preparation. The binding was saturable, reversible and specific. Vesicle preparations showed that binding sites were localized on the outside of the plasma membrane. The dissociation constant and site density were found to be Kd = 15.9 +/- 3.2 nmol X 1(-1) and N = 152 +/- 35 sites per cell, respectively, as calculated from Scatchard analysis. The effect of leukotriene C4 did not modify the calcium influx and did not inhibit the ATPase-dependent calcium efflux. In this paper, the physiological significance of these sites is discussed.

Dual inhibition of cyclooxygenase and lipoxygenase by 2-acetylthiophene 2-thiazolylhydrazone (CBS-1108) and effect on leukocyte migration in vivo.

CBS-1108, 2- acetylthiophene 2- thiazolyhydrazone , inhibits 5-lipoxygenase activity in polymorphonuclear leukocytes (PMNs) (IC50 = 2 X 10(-6) M), 12-lipoxygenase (IC50 = 9 X 10(-6) M) and cyclooxygenase (IC50 = 2 X 10(-6) M) in platelets. Inhibition of the two pathways of arachidonic acid cascade could lead to additional beneficial anti-inflammatory activity by comparison with classical aspirin-like drugs. In fact, only inhibitors of both cyclooxygenase and lipoxygenase such as NDGA and CBS-1108 inhibit leukocyte migration in an animal model of acute inflammatory response.

Anti-inflammatory activity of a dual inhibitor of cyclooxygenase and lipoxygenase pathways, CBS-1108 (2-acetylthiophene-2-thiazolylhydrazone).

Anti-inflammatory therapy is actually devolved to glucocorticoids which prevent the release of arachidonic acid from phospholipids and consequently its subsequent transformation into prostaglandins and leukotrienes. This activity explains in part why steroids are better anti-inflammatory agents than acetylsalicylic acid (ASA)-like drugs which only reduce prostaglandin production. Despite their superior therapeutic actions, there are many side effects associated with corticosteroids. Therefore in recent years, research of non-steroid dual inhibitors of prostaglandin and leukotriene production has been developed. The present paper investigates the pharmacological activity of such a new compound, CBS-1108 (2-acetylthiophene-2-thiazolylhydrazone), in comparison with dexamethasone, cyclooxygenase inhibitors (ASA and indomethacin) and reference dual inhibitors (nordihydroguaiaretic acid (NDGA) and 3-amino-1-(m-trifluoromethylphenyl)-2-pyrazoline (BW-755 C]. The two-pathway inhibitors and ASA-like drugs are similarly effective on paracentesis-induced disruption of the blood-aqueous barrier and on croton oil-induced ear edema. On the contrary in an animal model of leukocyte migration and on mast cell degranulation, NDGA and CBS-1108 are very active when the other tested compounds are inefficient.

Specific binding of leukotriene C4 to endothelial cell membranes.

Vascular endothelium is a target for leukotriene C4 (LTC4) as demonstrated by previous in vivo and culture experiments. Binding assays were carried out at 0 degrees C on membrane fraction obtained from bovine aortic endothelial cells in culture. Specific binding sites (Kd = 49.9 +/- 6.3 nmol X 1(-1), N = 1.2 X 10(6) sites per cell) for LTC4 were demonstrated in this preparation. Competition studies showed that LTB4, LTD4 and LTE4 did not displace LTC4 from its binding sites. FPL 55712, a sulfidopeptide antagonist, was seen to be a weak competitor and reduced glutathione exhibited a significant affinity for the binding site. The possible receptor role of this site is discussed.