Design, synthesis, and biological evaluation of novel catecholopyrimidine based PDE4 inhibitor for the treatment of atopic dermatitis

Selective inhibition of phosphodiesterase (PDE) 4B favorably suppresses the synthesis of inflammatory cytokines and subsequently arrest the development of atopic dermatitis via modulating the intracellular cAMP levels. Considering the side effects of corticosteroids, selective PDE4 inhibition could constitute an effective alternative therapy for the treatment of atopic dermatitis (AD). In this study, a series of novel catechol based compounds bearing pyrimidine as the core have been synthesized and screened for the PDE4 inhibitory properties. The PDE4 selectivity of the active compounds over other PDEs has been investigated. Compound 23 bearing pyrimidine core functionalized with catechol, pyridine and trifluoromethyl groups can effectively inhibit the PDE4B with IC50 value in nanomolar range (IC50 = 15 ± 0.4 nM). Compound 23 exhibited seven fold higher selectivity towards PDE4B over PDE4D. Molecular Docking study confirmed its stronger affinity towards catalytic domain of PDE4B. In-vivo analysis confirmed that compound 23 effectively alleviated the symptoms of atopic dermatitis in DNCB–treated Balb/c mice by suppressing the synthesis of inflammatory mediators such as TNF-α, and Ig-E. Taken together, this study suggested that compound 23 could be an effective PDE4 inhibitor for the potential treatment of AD.