Direct assessment of the antioxidant properties of midazolam by electron spin resonance spectroscopy.

Some antioxidant anesthetics directly inhibit lipid peroxidation mediated via the generation of reactive oxygen species (ROS). To date, the scavenging effects of midazolam on ROS have not been directly assessed. We investigated the inhibitory effect of midazolam on ROS [hydroxyl radical (HO(·)) and superoxide (O (2) (·-) )] by in vitro X-band electron spin resonance with the spin-trapping agent 5,5-dimethyl-1-pyrroline-N-oxide. Our results indicated that HO(·) and O (2) (·-) were not affected by midazolam at clinically relevant concentrations, but were directly scavenged by midazolam at high concentrations (i.e., >4.6 and >1.5 mM, respectively).