Compound found in common herbs inspires potential anti-inflammatory drug for Alzheimer’s disease
Scripps Research scientists created a stable form of carnosic acid, observing greater memory function and other disease improvements in mice.

March 10, 2025

LA JOLLA, CA—The herb rosemary has long been linked with memory: “There’s rosemary, that’s for remembrance,” says Ophelia in Shakespeare’s Hamlet. So it is fitting that researchers would study a compound found in rosemary and sage—carnosic acid—for its impact on Alzheimer’s disease. In the disease, which is the leading cause of dementia and the sixth leading cause of death in the US, inflammation is one component that often leads to cognitive decline.

Carnosic acid is an antioxidant and anti-inflammatory compound that works by activating enzymes that make up the body’s natural defense system. While pure carnosic acid is too unstable to be used as a drug, scientists at Scripps Research have now synthesized a stable form, diAcCA. This compound is fully converted to carnosic acid in the gut before being absorbed into the bloodstream.

The research, published in Antioxidants on February 28, 2025, showed that when diAcCA was used to treat mouse models of Alzheimer’s disease, it achieved therapeutic doses of carnosic acid in the brain and led to enhanced memory and synaptic density, or more synapses (representing the connections between nerve cells), in the brain. Because the decline of neuronal synapses is also closely correlated to dementia in Alzheimer’s disease, this approach could counteract the progression of cognitive decline.

Analysis of tissue samples showed the drug also markedly decreased inflammation in the brain. This unique drug is activated by the very inflammation that it then combats and thus is only active in areas of the brain undergoing inflammatory damage. This selectivity limits the potential side effects of carnosic acid, which is on the US Food and Drug Administration’s “generally regarded as safe” (GRAS) list, easing the way for clinical trials.

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diAcCA, a Pro-Drug for Carnosic Acid That Activates the Nrf2 Transcriptional Pathway, Shows Efficacy in the 5xFAD Transgenic Mouse Model of Alzheimer’s Disease
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