Synthesis and in vitro antioxidant activity of some new fused pyridine analogs.

A new series of pyrano[3,2-c]pyridines, pyrazolo[4,3-c]pyridines, and pyrido[4,3-d]pyrimidines were synthesized and screened for their in vitro antioxidant activity. Compounds 13, 14, 15, 23, 29, 30, and 31 exhibited the most active oxygen free-radical scavenger activity with percentage inhibitions of 99.4, 99.6, 99.8, 97.3, 99.0, 99.3, and 99.5%; respectively, which is comparable to the curcumin potency. Most of the tested compounds proved to be safe towards peripheral multinuclear neutrophils (PMNs). The detailed synthesis and antioxidant activity data are reported.