Lead Evolution in Development of an Anti-allergic Agent ; Dimethyl(2-phenoxyethyl)sulfonium p-Toluenesulfonate as the Secondary Lead Compound

Derivatives of 2-hydroxyethyldimethylsulfonium p-toluenesulfonate (1) were evaluated for anti-allergic activity in order to develop the drug for treatment of type I allergic diseases. The IgE-induced rat homologous passive cutaneous anaphylaxis (PCA) was inhibited by some 2-alkoxy and 2-aryloxyethyl sulfonium p-toluenesulfonates. There were some correlations between hydrophobicity or electronic properties (HOMO or charge at the O atom) and anti-allergic activity or acute toxicity. Dimethyl(2-phenoxyethyl)sulfonium p-toluenesulfonate (5) was selected as a second lead compound in the next stage.