α-Terpineol is a terpene alcohol that is found in natural oils such as pine oil and petitgrain (the oil from the bitter orange tree). It is the most common of four structural isomers; the others are β-, γ-, and 4-terpineol. It should not be confused with terpinol, the hydrate of terpin, a terpene diol.

α-Terpineol is a racemic mixture of (R)-(+)- and (S)-(–)-enantiomers. Both are found in nature; but the article of commerce, which is usually synthesized from α-pinene, is the racemate. In 1903, German chemists H. Waldbaum and O. Hüthig isolated the (+)-stereoisomer from petitgrain. Four years later, J. E. Teeple of New York City separated its enantiomer from long-leaf pine oil.

uses of α-Terpineol

(-)-alpha terpineol is the alpha form of terpineol, a naturally monoterpene alcohol that can be isolated from various kinds of sources such as cajuput oil, pine oil, and petitgrain oil. The alpha form is the major constituent of terpineol. It is a common component in perfumes, cosmetic and flavors.

It is also a kind of solvent used for extracting natural spices and as a kind of solvent of acetate fibers. Moreover, it exhibited strong and broad antimicrobial activity against fungi, bacteria and virus. Study has demonstrated that is antibacterial (bactericidal) effect originated from its destroying effect on the cell wall and cell membrane of bacteria. It also has certain anticonvulsant activity.

General Properties

Terpineol has a pleasant odour similar to lilac and is a common ingredient in perfumes, cosmetics, and flavours.  alpha-Terpineol is occasionally found as a volatile component in urine. It is a water-soluble component of Melaleuca alternifolia Cheel, the tea tree oil (TTO). alpha-Terpineol is a likely mediator of the in vitro and in vivo activity of the TTO as an agent that could control C. albicans vaginal infections.

Purified alpha-terpineol can suppress pro-inflammatory mediator production by activated human monocytes. alpha-Terpineol is able to impair the growth of human M14 melanoma cells and appear to be more effective on their resistant variants, which express high levels of P-glycoprotein in the plasma membrane, overcoming resistance to caspase-dependent apoptosis exerted by P-glycoprotein-positive tumour cells.