In vitro kinetic evaluation of the free radical scavenging ability of propofol.

BACKGROUND Propofol is a widely used, short-acting, and intravenously administered hypnotic agent with notable antioxidant and free radical scavenging activities. However, there are relatively few kinetic studies on the free radical scavenging ability of propofol. The goal of this study is to evaluate the kinetics of propofol scavenging 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical (ABTS(·+)). METHODS The stock solution of ABTS(·+) was prepared by incubating 7 mM ABTS with 2.8 mM potassium persulfate in deionized water, and then diluted with 5 mM phosphate-buffered saline (pH 7.2) to get a working solution (36 μM ABTS(·+) and 18 μM ABTS). The reaction was monitored by measuring specific absorbance changes of ABTS and ABTS(·+) after adding 4 μM propofol (final concentration) to the working solution. The propofol-ABTS(·+) reaction products were analyzed by high-performance liquid chromatography and liquid chromatography mass spectrometry/mass spectrometry. RESULTS Wave scanning and kinetic evaluation demonstrated that the ABTS(·+) scavenging process of propofol is relatively fast. The ABTS(·+) consumption rate by propofol is greater than the rate of ABTS formation. The degradation products of reaction between propofol and ABTS(·+) were mainly ABTS-propofol, a part of the ABTS molecule, and a combination of propofol with a part of the ABTS molecule. CONCLUSIONS Propofol scavenges ABTS(·+) with a fast and stable kinetic feature in vitro, which is useful and important for understanding propofol's antioxidant properties. The kinetic process of the free radical scavenging activity of propofol may also play a role in dynamic protection in the body.