Novel 4-aryl-pyrido[1,2-c]pyrimidines with dual SSRI and 5-HT1A activity. Part 4

•A series of 2H-pyrido[1,2-c]pyrimidine derivatives was synthesized.•The most of tested compounds show dual affinity for 5-HT1A and SERT.•HHPI series exhibited a high degree of affinity for SERT and 5-HT1AR.•In vitro tests for metabolic stability in a first-pass test show that R1 and R2 substituents benefit stability.

This project describes the synthesis, pharmacological and pharmacodynamic tests on two series of novel derivatives of 2H-pyrido[1,2-c]pyrimidine with potential binary binding to 5-HT1A receptors and SSRI + serotonin transporters. The influence of piperidinyl-indole (8.1–8.7) and tetrahydropyridinyl-indole (8.8–8.32) residues and indole 5-position substituents (R3 = Br, Cl, F) present in the pharmacophore element of ligands on their binding to both molecular targets was tested.A considerable impact of piperidinyl-indole residue on binding to both targets was confirmed and compounds with a high binding affinity were identified: Ki 5-HT1A = 12.4 nM; Ki SERT = 15.6 nM 8.1; Ki 5-HT1A = 5.6 nM; Ki SERT = 20.7 nM 8.7, while the presence of a tetrahydropyridinyl-indole residue was found to reduce the affinity of ligands to 5-HT1AR. The presence of chlorine (R3) in this series resulted in a notable reduction in binding to both targets (5-HT1A and SERT). Selected compounds had their metabolic stability in a first-pass test (human liver microsomes, NADPH) determined in vitro, and R1 and R2 substituents present on the terminal residue of pyrido[1,2-c]pyrimidine were recognized as having an impact on stability.

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