Synthesis and structure–activity relationships of phenothiazine carboxylic acids having pyrimidine-dione as novel histamine H1 antagonists

A series of phenothiazine carboxylic acid derivatives, having 6-amino-pyrimidine-2,4(1H,3H)-dione moiety via a appropriate linker, were synthesized and evaluated for their affinity toward human histamine H1 receptor and Caco-2 cell permeability. Selected compounds were further evaluated for their oral anti-histaminic activity in mice and bioavailability in rats. Finally, promising compounds were examined for their anti-inflammatory potential in mice OVA-induced biphasic cutaneous reaction model. Among the compounds tested, phenothiazineacetic acid compound 27 showed both histamine H1-receptor antagonistic activity and anti-inflammatory activity in vivo model.

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