Protective Effects of Brain Infarction by N -Acetylcysteine Derivatives

Background and Purpose— We recently found that acrolein (CH2 =CH-CHO) is more strongly involved in brain infarction compared with reactive oxygen species. In this study, we looked for acrolein scavengers with less side effects.Methods— Photochemically induced thrombosis model mice were prepared by injection of Rose Bengal. Effects ofN -acetylcysteine (NAC) derivatives on brain infarction were evaluated using the public domain National Institutes of Health image program.Results— NAC, NAC ethyl ester, and NAC benzyl ester (150 mg/kg) were administered intraperitoneally at the time of induction of ischemia, or these NAC derivatives (50 mg/kg) were administered 3× at 24-h intervals before induction of ischemia and 1 more administration at the time of induction of ischemia. The size of brain infarction decreased in the order NAC benzyl ester>NAC ethyl ester>NAC in both experimental conditions. Detoxification of acrolein occurred through conjugation of acrolein with glutathione, which was catalyzed by glutathioneS -transferases, rather than direct conjugation between acrolein and NAC derivatives. The level of glutathioneS -transferases at the locus of brain infarction was in the order of administration of NAC benzyl ester>NAC ethyl ester>NAC>no NAC derivatives, suggesting that NAC derivatives stabilize glutathioneS -transferases.Conclusions— The results indicate that detoxification of acrolein by NAC derivatives is caused through glutathione conjugation with acrolein catalyzed by glutathioneS -transferases, which can be stabilized by NAC derivatives. This is a new concept of acrolein detoxification by NAC derivatives.