Novel (Azolo)Pyrimidine Derivatives as Dual Modulators of NO and IL-6 in Murine Macrophages and Human Monocytes.

Small molecules that simultaneously suppress nitric oxide (NO) and interleukin‑6 (IL‑6) offer a strategy to alleviate pathological inflammation. Building on our previous work with aryl‑substituted azaheterocycles, we synthesized 33 new pyrimidine and azolopyrimidine derivatives bearing amino, amide, hydroxyl, or halide groups to enhance hydrogen‑bonding capacity and improve inhibitory activity against both mediators. Screening in C57BL/6J mouse peritoneal macrophages identified nine compounds that markedly inhibited NO production at 50 µM. Two leads-triazolo[1,5‑a]pyrimidine 12bc and dihydropyrimidine carboxamide 7a-emerged as potent dual inhibitors. Compound 7a showed IC50 values of 0.47 µM (NO) and 0.1 µM (IL‑6); 12bc gave 8.66 µM (NO) and 0.85 µM (IL‑6), both with acceptable cytotoxicity. In human PBMC‑derived monocytes, both compounds dose‑dependently suppressed LPS‑induced IL‑6 secretion; 12bc was slightly more potent, reducing IL‑6 to near‑baseline at 100 µM, comparable to dexamethasone. In an LPS/ATP pyroptosis model, they protected monocytes from inflammatory death, with 12bc nearly restoring normal cell morphology. Docking studies into mouse iNOS and IL‑6 suggested plausible binding modes and structure-activity relationships. These (azolo)pyrimidine scaffolds represent promising leads for safe, dual‑acting anti‑inflammatory agents.