Carnosic acid is a natural benzenediol abietane diterpene found in rosemary and common sage. Dried leaves of rosemary or sage contain 1.5 to 2.5% carnosic acid. Carnosic acid is used as a preservative or antioxidant in food and nonfood products. CA decreased the cell viability in a dose-dependent manner. Further investigation in IMR-32 cells revealed that cell apoptosis following CA treatment is the mechanism as confirmed by flow cytometry, hoechst 33258, and caspase-3/-9 and poly(ADP-ribose) polymerase (PARP) activation. Immunoblotting suggested a down-regulation of anti-apoptotic Bcl-2 protein in the CA-treated cells. In flow cytometric analysis, CA caused the generation of reactive oxygen species (ROS); however, pretreatment with the antioxidant N-acetylcysteine (NAC) attenuated the CA-induced generation of ROS and apoptosis.
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