Caffeic acid-pYEEIE is a specialized synthetic compound consisting of caffeic acid conjugated to a phosphorylated tyrosine-containing peptide sequence (pYEEIE). It serves as a valuable tool in biochemical and pharmacological research, particularly for studying protein tyrosine phosphatases (PTPs) and kinases involved in signal transduction. This reagent is used to probe enzyme-substrate interactions, dephosphorylation kinetics, and cellular signaling pathways related to oxidative stress and inflammation. Its caffeic acid moiety imparts potential antioxidant properties, making it suitable for investigations into therapeutic applications for neurodegenerative diseases, inflammatory conditions, and as a component in advanced cosmetic formulations targeting free radical protection. As a niche research intermediate, it is not intended for general commodity use.