Design and synthesis of azolopyrimidoquinolines, pyrimidoquinazolines as anti-oxidant, anti-inflammatory and analgesic activities

The 5,10-dihydro-2-thioxo-pyrimido[4,5-b]quinolines (2a–c) and its oxidized form 3 were prepared and used as key intermediates for the synthesis of thiazolo[3′,2′:1,2]pyrimido[4,5-b]-quinolines (5a–c), isoxazolo[5″,4″:4′,5′]thiazolo[3′,2′:1,2]pyrimido[4,5-b]quinolines (6a–c), 4-chloro-2-methylthio-pyrimido[4,5-b]quinoline, its amino derivatives (19–21) and 10,11,12,13-tetrahydro-5H-quino[2′,3′:4,5]pyrimido[6,1-b]quinazoline (22). The newly synthesized compounds were characterized by IR, NMR (1H, 13C) and mass spectral studies. Representative of the synthesized compounds was tested and evaluated for anti-oxidant, anti-inflammatory and analgesic activities. Compounds 2a–c showed the highest inhibitory anti-oxidant activity either using erythrocyte hemolysis or ABTS methods. Compounds 2a, 10b, 16, and 17a manifested the best protective effect against DNA damage induced by bleomycin. Compounds 2c, 5a, 20a, 2a, and 2b exhibited a potent anti-inflammatory activity using carrageenan-induced paw edema test in rats.

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