Antiallergic and cytoprotective activity of new N-phenylbenzamido acid derivatives.

A series of new N-phenylbenzamido acid derivatives was synthesized and evaluated for their ability to inhibit the IgE-mediated passive cutaneous anaphylaxis in the rat (PCA), as well as for their capacity to inhibit gastric mucosal damage induced by the oral administration of absolute alcohol in the rat. Some of these new derivatives exhibit potent antiallergic and cytoprotective activity, 20-80 times higher than that of the reference, disodium cromoglycate (DSCG). Structure-activity relationships are discussed. The antiallergic activity of one of the more potent compounds of this series, i.e. 4-(1H-tetrazol-5-yl)-N-[4-(1H-tetrazol-5-yl)phenyl]benzamide (compound 44, CR 2039) was further evaluated in vivo. This compound antagonizes the bronchoconstriction induced by aerosolized ovalbumin in both anesthetized and conscious IgE sensitized guinea pigs with ID50 of 3.7 mg/animal (tracheal insufflation) and 20 mg/kg (im). Further cytoprotective effects were evaluated in gastric ulcer models induced by the acute oral administration of hypertonic sodium chloride solution or by acetic acid and by the subchronic administration of glucose in fasted animals. In the models used experimentally CR 2039 is effective, whereas DSCG seems to be devoid of any protective activity. Such a potent antiallergic and mucosal protectant could provide a new potential agent in the therapy of atopic allergic diseases.