Cineole

Cineole, also known as eucalyptol, is a natural organic compound that belongs to the class of monoterpene ethers. It has the chemical formula C10H18O and is a colorless, volatile liquid with a characteristic camphor-like, fresh odor. It exists as two enantiomers and is widely produced by plants, especially eucalyptus.

Natural occurrence and production: Cineole is a major component of eucalyptus oils, often comprising 60–90% depending on species and source. It is obtained commercially by steam distillation of eucalyptus leaves and other essential oils (for example, tea tree, bay laurel, and rosemary) and by fractional distillation of the resulting essential oils.

Properties: It is relatively insoluble in water but miscible with many organic solvents. Its boiling point is about 176 °C. It is a key flavor and fragrance compound and is used in foods, beverages, cosmetics, and perfumery.

Applications and effects: Cineole is used as a flavor and fragrance ingredient, and in medicines as a decongestant and cough suppressant in inhalants and topical preparations. It also appears in some topical analgesics. In essential oils, it contributes to their characteristic aromatic profiles.

Safety and regulation: In typical cosmetic and consumer product concentrations, cineole is considered safe when used according to guidelines, but high concentrations can irritate skin and mucous membranes and can be toxic if ingested in large amounts. It can cause allergic reactions in some individuals. It should be stored away from heat and oxidizing agents.

Research: Laboratory studies have shown antimicrobial, antifungal, and anti-inflammatory activity for cineole in vitro and in animal models; clinical evidence for cough relief or respiratory benefits is variable and dose-dependent. Quality and concentration are important, and potential interactions with medications should be considered.