Perillaldehyde (also known as perilla aldehyde or perillyl aldehyde) is a monocyclic monoterpenoid aldehyde widely found in the essential oil of Perilla frutescens, as well as in several other aromatic plants and certain cannabis chemotypes. Structurally, it belongs to the p-menthane family of monoterpenes and is characterized by a conjugated aldehyde group and an isopropenyl side chain. This compound is recognized for its distinctive minty-cinnamon aroma with slightly spicy and cherry-like notes, along with a broad spectrum of biological activities including antimicrobial, antioxidant, anti-inflammatory, bronchodilatory, and neuroprotective effects.

Chemical Structure and Properties

Perillaldehyde has the molecular formula C₁₀H₁₄O and a molar mass of 150.22 g·mol⁻¹. Its structure corresponds to a p-menth-1-ene-8-al system, consisting of a six-membered cyclohexene ring bearing a double bond between C1 and C2, an isopropenyl substituent at C4, and an aldehyde function located at C8. The molecule is chiral and exists as two enantiomers, (R)-(+) and (S)-(−), with the (S)-(−) form being predominant in natural sources such as perilla.

Physicochemical Characteristics

In its pure form, perillaldehyde appears as a colorless to pale yellow volatile liquid with a characteristic fresh, minty-cinnamon and slightly spicy-cherry odor. It exhibits a boiling point in the range of 210–220 °C and a density of approximately 0.92–0.93 g·cm⁻³. The compound is practically insoluble in water but shows high solubility in organic solvents such as ethanol, diethyl ether, and chloroform. Its relatively high lipophilicity (logP ~2.5–3) facilitates its interaction with lipid membranes, a property that is closely associated with many of its biological activities.