It has long been known that
singlet oxygen ((1)O2) is generated during inflammatory processes. Once formed in substantial amounts, (1)O2 may have an important role in mediating the destruction of infectious agents during host defense. On the other hand, (1)O2 is capable of damaging almost all
biological molecules and is particularly genotoxic, which gives a special relevance to the scavenging of this ROS throughout anti-inflammatory treatments. Considering that the use of non-steroidal anti-inflammatory drugs (
NSAIDs) constitutes a first approach in the treatment of persistent inflammatory processes (due to their ability to inhibit
cyclooxygenase), a putative scavenging activity of
NSAIDs for (1)O2 would also represent a significant component of their
therapeutic effect. The aim of the present study was to evaluate the scavenging activity for (1)O2 by several chemical families of
NSAIDs. The results suggested that the
pyrazole derivatives (
dipyrone and
aminopyrine) are, by far, the most potent scavengers of (1)O2 (much more potent compared to the other tested
NSAIDs), displaying IC(50)-values in the low micromolar range. There was a lack of activity for most of the arylpropionic
acid derivatives tested, with only
naproxen and
indoprofen displaying residual activities, as for the
oxazole derivative,
oxaprozin. On the other hand, the
pyrrole derivatives (
tolmetin and
ketorolac), the indolacetic
acid derivatives (
indomethacin, and
etodolac), as well as
sulindac and its metabolites (
sulindac sulfide and
sulindac sulfone) displayed scavenging activity in the high micromolar range. Thus, the scavenging effect observed for
dipyrone and
aminopyrine will almost certainly contribute to their healing effect in the treatment of prolonged or chronic
inflammation, while that of the other studied
NSAIDs may have a lower contribution, though these assumptions still require further in vivo validation.