Tricosanoic acid-d45 is the deuterium labeled Tricosanoic acid (HY-W009081). Tricosanoic acid is an endogenous agonist of long-chain saturated fatty acids and free fatty acid receptor FFAR1, which can activate hair growth. Tricosanoic acid (C23:0) has the activity of improving cognitive function by regulating neuronal membrane fluidity, inhibiting neuroinflammatory response, participating in myelination and neuronal energy metabolism. Tricosanoic acid expression levels are low in the prefrontal cortex of Alzheimers disease (AD) models, while better cognitive performance corresponds to higher serum concentration levels. Tricosanoic acid can be used as a biomarker for diseases related to cognitive decline[1].