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Propofol has free radical scavenging abilities

05/17/2012

tags: free radical, Propofol

Author: Michael J Avram

Propofol has been shown to have a variety of protective effects. For example, propofol has a neuroprotective effect on cerebral ischemia. There has been little study, though, of the drug’s free radical scavenging activity. Like the tocopherols (e.g., alpha-tocopherol, butylated hydroxytoluene), propofol is a substituted phenol with antioxidant and free radical scavenging activity. This activity is accomplished through electron and hydrogen transfer. In the article “In Vitro Kinetic Evaluation of the Free Radical Scavenging Ability of Propofol,” published in the June issue of Anesthesiology, Dr. Chenggang Zhang (Professor, Beijing Institute of Radiation Medicine, State Key Laboratory of Proteomics, Cognitive and Mental Health Research Center, Beijing, China) and coauthors used the synthetic stable free radical 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^—), which is dark green in solution, to probe the kinetics of free radical scavenging of propofol as it is converted to colorless ABTS compounds by antioxidants. Propofol covalently reduced ABTS^— to ABTS and several propofol-ABTS compounds in vitro. Its rate of ABTS^— consumption was rapid and stable. It was estimated that 10 propofol molecules could scavenge approximately 36 – 37 ABTS^—molecules when dissolved in methanol. The three clinical propofol formulations tested had similar free radical scavenging activity. These in vitro effects of propofol were observed at concentrations below clinically effective concentrations. In addition to its hypnotic effect, propofol has been reported to have a beneficial effect in ischemia reperfusion injury. These results suggest that the beneficial effects of propofol beyond hypnosis may be related, at least in part, to its free radical scavenging ability.