The Biochemical Composition of Melaleuca Alternifolia Leaf (Tea Tree) Oil.

The tea tree plant, or melaleuca alternifolia, is native to New Caledonia and Madagascar, but whose first producing country today is Australia. The tea tree essential oil is extracted from the leaves of the Melaleuca alternifolia tree. According to the INCI classification, it is called “Melaleuca Alternifolia Leaf Oil”.

It is obtained by hydrodistillation from the leaves. The principle consists in heating a mixture of water and leaves in order to evaporate the volatile molecules and to collect them following a condensation. This method makes it possible to obtain two extracts, namely the hydrolat and the essential oil. The essential oil of tea tree is a clear colorless to pale yellow liquid. It has a powerful, herbaceous and fresh smell.

This essential oil has many benefits. In particular, it reduces symptoms due to inflammation, fights bacteria and treats infections. It is for this reason that it has gained a certain reputation in aromatherapy as well as in dermocosmetics.

Depending on the method of extraction but also the conditions of cultivation of the plants, the biochemical composition of tea tree essential oils can vary from one to another. In this article, we chose to focus on the main molecules present in oil of Melaleuca alternifolia that we incorporate in some of our care products. According to chromatographic analysis, the four species present in majority are the following:

• Terpinen-4-ol (30 – 48%)

From the monoterpene alcohol family, this molecule brings a characteristic floral and spicy smell. This compound is a recognized bactericide, particularly effective against two bacteria involved in acne, S. Aureus and S. epidermidis. It is also a fungicide, virucide and immunomodulator.

• Gamma-terpinene (18 to 28%) and alpha-terpinene (7 – 8%) 

These monoterpenes are antioxidants that inhibit the oxidation of low-density lipoproteins (LDL) and lipid peroxidation. As a reminder, lipid peroxidation is a chain mechanism of degradation of the constituents of cell membranes leading to the formation of unstable compounds called hydroperoxides, which then attack the constituents of the skin accelerating its aging.

• Eucalyptol (about 15%)

Also called 1,8 cineole, this colorless natural compound has a refreshing and spicy odor similar to camphor. It is known for its antifungal, anti-infectious, bactericidal, antiviral and expectorant properties. To fight against the bacteria involved in acne, this compound plays an important role. It causes a permeabilization of bacterial membranes, thus facilitating the entry of the more active bactericidal molecules of the essential oil such as terpinene-4-ol, described above.

• P-Cymene (≤ 12%)

This organic compound with a benzene structure (consisting of a 6-carbon ring) with a spicy, herbaceous odor is also a recognized antibacterial.

In addition, tea tree essential oil contains 1 to 2% limonene, a terpene with a lemon and orange scent. This molecule with anti-inflammatory properties soothes redness and also fights against the bacteria involved in acne. Nevertheless, it is a recognized allergen.