3-N-butylphthalide is a natural phthalide derivative primarily found in celery (Apium graveolens) seed oil, responsible for its characteristic aroma and flavor. It is a colorless to pale yellow liquid used in food flavoring and traditional medicine. The compound exhibits potential antihypertensive, neuroprotective, and anti-inflammatory properties. It is lipophilic with low water solubility, contributing to its volatility and use in essential oils. Chemically, it features a fused benzene and gamma-lactone ring with a butyl side chain at the 3-position.