4-Nitrophenyl stearate is an ester formed from the condensation of stearic acid and 4-nitrophenol. It is commonly used as a substrate in enzymatic assays, where the hydrolysis of the ester bond by esterases and lipases can be monitored through absorbance or colorimetric changes. Additionally, 4-Nitrophenyl stearate serves as a model compound to study the enzymatic activity and selectivity of lipases and esterases from various sources. Its long hydrophobic tail enhances solubility in lipophilic environments, making it a valuable probe for researching lipid metabolism.