Tricosanoic acid-d45 is a deuterium-labeled form of Tricosanoic acid. Tricosanoic acid (C23:0) is a long-chain saturated fatty acid and an endogenous agonist of the free fatty acid receptor FFAR1, known to promote hair growth. It contributes to enhanced cognitive function by regulating neuronal membrane fluidity, inhibiting neuroinflammatory responses, participating in myelination, and influencing neuronal energy metabolism. In Alzheimer's disease (AD) models, lower expression levels of Tricosanoic acid are observed in the prefrontal cortex, whereas higher serum concentrations correlate with improved cognitive performance. Tricosanoic acid can serve as a biomarker for conditions associated with cognitive decline.