The aim of this study was to investigate whether a total of twenty benzo[b]cyclohept[e][1,4]oxazines and their S-analogs, and 2-aminotropone derivatives affect the function of activated macrophages. These compounds inhibited the production of pro-inflammatory substances such as nitric oxide (NO) by lipopolysaccharide (LPS)-activated mouse macrophage-like RAW264.7 cells to different extents. Among them, benzo[b]cyclohept[e][1,4]oxazin-6(11H)-one [5] and 7-bromo-2-(4-hydroxyanilino)tropone [16] showed the highest inhibitory effects at concentrations that did not affect cellular viability (selectivity index=74.89 and 54.15, respectively). Western blot and RT-PCR analyses showed that [16] inhibited the expression of both inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 at both protein and mRNA levels, whereas [5] inhibited only iNOS protein expression. Electron-spin resonance (ESR) spectroscopy revealed that both [5] and [16] scavenged nitric oxide (generated from NOC-7) and superoxide anion (generated by HX-XOD reaction) only at much higher concentration. These data suggest that [16] but not [5] exerts its anti-inflammatory action against macrophages via the inhibition of iNOS and COX-2 protein expressions.