Di-acetylated carnosic acid (DiAcCA) is a rosemary-derived investigational compound designed to activate the Nrf2 antioxidant pathway selectively in oxidatively stressed brain tissue. Rather than acting as a simple antioxidant, it amplifies intrinsic cellular defense systems. Preclinical data suggest potential applications in Alzheimer’s disease, Parkinson’s disease, and traumatic brain injury, though human trials remain limited.