Rosmarinic acid (RA), a polyphenol found in Lamiaceae herbs, is a candidate of preventive ingredients against Alzheimer's disease (AD) as it potently suppresses the aggregation of amyloid β (Aβ); however, the effect of RA on tau phosphorylation and cognitive dysfunction remains unclear. This study revealed that RA intake inhibited the pathological hallmarks of AD, including Aβ and phosphorylated tau accumulation, and improved cognitive function in the 3 × Tg-AD mouse model. RA intake suppressed hippocampal inflammation and downregulated the JNK signaling pathway that induces tau phosphorylation. Downregulation of the hippocampal JNK signaling pathway may be a potential mechanism underlying the inhibition of disease progression and cognitive deficit by RA.
