Studies on Topical Antiinflammatory Agents. IV., : 21-(Alkylthio)acetates and (Methylthio)methoxides of Corticosteroids

A series of 21-(alkylthio)acetates and 21-(methylthio)methoxides of corticosteroids were synthesized and examined for vasoconstrictive activities. The activities of seven compounds were equal to or greater than that of 9α-fluoro-11β, 21-dihydroxy-16β-methyl-17α-valeryloxy-1, 4-pregnadiene-3, 20-dione (betamethasone 17-valerate, BV). Among them, betamethasone 21-(methylthio)acetate 17-propanoate (2Ca) was found to have the most potent activity, which is superior to that of BV. A structure-activity relationship study revealed that substitution of the 21-hydroxy group of corticosteroids with the (methylthio)acetate function is a useful approach for obtaining potent activity.