2,1,3-Benzothiadiazine derivatives: synthesis and screening versus PDE4 enzyme

A series of N-1,3 disubstituted 2,1,3-benzothiadiazine derivatives (BTDs) were synthesized and evaluated for their inhibitory activity versus enzymatic isoform PDE4 extracted from U937 cell line. Some of the tested compounds showed a high PDE4 inhibitory activity at 100 μM and the IC50 value of the most interesting terms were evaluated. The structure–activity relationships of these compounds showed that the 3,5-di-tert-butyl-4-hydroxybenzyl moiety at N-1 position is important to obtain activity at micromolar level as previously reported. For the same compounds the antioxidant activity were evaluated highlighting 14 as the most significative one. The introduction of other bulky substituents in N-1 position is detrimental