RESUMO
A series of 1-hydroxy-3-¿3-hydroxy-7-phenyl-1-hepten-1-yl cyclohexane acetic acid derivatives was designed based on postulated active conformation of leukotriene B(4) (LTB(4)) and evaluated as human cell surface LTB(4) receptor (BLTR) antagonists. Binding was determined through ¿(3)HLTB(4) displacement from human neutrophils and receptor antagonistic assays by in vitro measurements of inhibition of leukocyte chemotaxis induced by LTB(4). On the basis of these assays, a structure-affinity relationship was investigated. Optimization of the acid chain length and omega-substitution of a phenyl group on the lipophilic tail were shown to be critical for binding activity. These modifications led to the discovery of compounds with submicromolar potency and selective BLTR antagonism. The most potent compound 3balpha (IC(50) = 250 nM) was found to significantly inhibit oedema formation in a topical model of phorbolester-induced inflammation. Substantial improvement of in vitro potency was achieved by modification of the carboxylic acid function leading to the identification of the N,N-dimethylamide series. Compound 5balpha, free of agonist activity, displayed higher potency in receptor binding with an IC(50) of 40 nM. These results support the hypothesis that the spatial relationship between the carboxylic acid and allylic hydroxyl functions is crucial for high binding affinity with BLTR.
Assuntos
Cicloexanos/síntese química , Receptores do Leucotrieno B4/antagonistas & inibidores , Animais , Cicloexanos/química , Cicloexanos/farmacologia , Cobaias , Humanos , Leucotrieno B4/metabolismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas/métodos , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Ligação Proteica , Receptores do Leucotrieno B4/metabolismo , Espectrofotometria Infravermelho , Relação Estrutura-AtividadeRESUMO
A novel series of leukotriene B4 (LTB4) antagonists is reported. These compounds present a cyclohexane ring in their chemical structure, which mimics the three conjugated double bonds of LTB4. The biochemical/pharmacological profile of the leader compound, PH-163 (sodium (1S*,3S*)-1-hydroxy-3-[(3R*S,E)-3-hydroxy-7-phenyl-1-hepten-1-yl]- 1 -cyclohexane acetate, CAS 163251-41-0) is described. This compound competes with [3H]LTB4 binding to its receptor in human neutrophils and guinea pig lung membranes with IC50's of 0.8 mumol/l and 0.2 mumol/l, respectively, i.e. relative binding affinities of 1% as compared to LTB4. PH-163 does not elicit any agonist activity, but inhibits leucocyte chemotaxis induced by LTB4 (pKB = 6.57) and lung parenchymal strip contraction (IC50 = 0.1 mumol/l). In conclusion, PH-163 or derivatives could be useful in the treatment of inflammatory diseases where LTB4 seems to be involved.
Assuntos
Cicloexanóis/síntese química , Receptores do Leucotrieno B4/antagonistas & inibidores , Animais , Quimiotaxia de Leucócito/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Cicloexanóis/farmacologia , Cobaias , Humanos , Técnicas In Vitro , Leucotrieno B4/metabolismo , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Espectroscopia de Ressonância Magnética , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Espectrofotometria Infravermelho , Espectrofotometria Ultravioleta , EstereoisomerismoRESUMO
The synthesis and the binding affinities of new leukotriene B4 receptor photoaffinity probes, where a 1,3-disubstituted cyclohexane ring replaces the conjugated delta6,7 and delta8,9 double bonds of the natural eicosanoid, are described. One enantiomeric compound, 4b alpha, is specifically cross-linked upon photolysis to the recombinant leukotriene B4 receptor from human origin (h-BLTR) solubilized in a micellar medium. This probe appears as a good candidate for identifying the ligand binding site of this receptor.