Inhibition of adenosine-3′, 5′-cyclic monophosphate phosphodiesterase by potential antiallergic compounds

The potential antiallergic compounds doxantrazole (3- (5-tetrazolyl)-thioxanthone 10, 10-dioxide) and CTD (3- carboxythioxanthone 10, 10-dioxide) are inhibitors of the phosphodiesterases of human and guinea pig lung and beef heart. Disodium cromoglycate is a weak inhibitor of all these enzymes. It is suggested that the antiallergic activity of doxantrazole and CTD is due, at least in part, to their ability to elevate intracellular cAMP levels by inhibiting phosphodiesterase activity.