Mechanism of action of an anti-allergic compound; 2,4-bis(2-acetoxybenzamido)benzoic acid (AB50): Inhibition of anaphylactic and non-anaphylactic histamine release from rat peritoneal mast cells.

Abstract
The mechanism of the inhibitory effect of the newly synthesized compounds AB-50 and 2,4-bis(2-hydroxybenzamido)benzoic acid (AB-23, an active form of Ab-50) on Ig[immunoglobulin]E-like antibody-mediated passive cutaneous anaphylaxis (PCA) was studied in comparison with disodium cromoglycate (DSCG). AB-50 had no anti-inflammatory activity in the carrageenan edema assay, nor did it inhibit dermal reactions elicited by local injection of histamine, serotonin or bradykinin. AB-23 markedly inhibited rat mast cell degranulation (RMCD) in vitro following IgE-anti-IgE interaction and antigen-induced histamine release in the rat peritoneal cavity. The inhibition of IgE-mediated PCA by AB-50 was based on prevention of degranulation and release of chemical mediators from mast cells without direct antagonism against chemical mediators of PCA. AB-23 also inhibited non-anaphylactic histamine release from rat peritoneal mast cells induced by compound 48/80 [p-methoxyphenethyl methylamine formaldehyde product] or dextran. While all of these activities were also shared by DSCG, AB-23 was more active than DSCG with respect to inhibition of RMCD and histamine release induced by compound 48/80.