What are the properties of tea tree essential oil for the skin?

The Tea tree, also known as tea tree plant or alternatively melaleuca with alternate leaves, is a shrub native to New Caledonia and Madagascar, but the leading producer today is Australia.

The indigenous populations of the New Zealand archipelago used this plant, particularly the leaves, to create poultices and treat infections. However, it was not until 1922 that the antiseptic properties and antibacterial properties of the plant were demonstrated by the chemist Arthur DE RAMAN PENFOLD. An interesting fact, at the start of the Second World War, thetea tree essential oil was added to every first aid kit of thearmy and the Australian navy due to its anti-infectious virtues.

The essential oil of tea tree is extracted by hydrodistillation of the leaves, that is, by steam distillation. This method allows for the extraction of two substances, namely the hydrosol and the essential oil. The tea tree essential oil primarily contains monoterpenols (approximately 45% of terpinen-4-ol) and monoterpenes (gamma-terpinene, alpha terpinene, limonene). These compounds are responsible for its purifying and sanitising properties detailed below.

Due to its biochemical composition, this essential oil is primarily recognised for the following two actions.

• Limiting blemishes and regulating sebum.

  This essential oil regulates sebum production and mattifies oily skin that tends to shine. This sebum-regulating action also helps to prevent pore blockage and therefore the appearance of blackheads.

  Furthermore, when it is present at a level of 1% or more in a skincare product, this essential oil has demonstrated excellent bactericidal properties (kills bacteria) as well as bacteriostatic properties (inhibits bacterial growth). Thus, it helps to limit the proliferation of microorganisms involved in acne such as Staphylococcus aureus and Staphylococcus epidermidis.

  What is its anti-bacterial mode of action? Studies have shown that it works by depleting constituents of the bacterial cell membrane. More specifically, the hydrocarbon structure and lipophilicity (attraction to fats) of the terpenes present in this essential oil lead to lysis and thus the loss of functional integrity of bacterial membranes. This membrane destruction causes a leakage of potassium ions, thereby inhibiting cellular respiration. The compound 1,8-cineole present in this essential oil plays an important role in this phenomenon. It causes a permeabilisation of the bacterial membrane, thus facilitating the entry of more active bactericidal molecules such as terpinen-4-ol.

• Alleviate itching and certain skin conditions.

  The essential oil of tea tree is also recognised for its strong anti-inflammatory properties. It acts on patches, reducing itching and then redness. It is therefore recommended for certain skin conditions such aseczema or rosacea.

  What is its anti-inflammatory mode of action? Research over the past decade has shown that this essential oil affects a range of immune responses, both in vitro and in vivo. For instance, the water-soluble components of tea tree essential oil can inhibit the production of about 50% of certain inflammatory mediators such as tumour necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1) and IL-10, and about 30% of prostaglandin E2 after 40 hours. A more in-depth examination of the water-soluble fraction of this essential oil identified terpinen-4-ol, terpineol, and 1,8-cineole as the main components, but among these, only terpinen-4-ol was able to decrease the production of TNF-alpha, IL-1, IL-8, IL-10, and prostaglandin E2 by lipopolysaccharide-activated monocytes. Furthermore, studies have also shown that terpinen-4-ol, but not 1,8-cineole or terpineol, modulates the vasodilation and plasma extravasation associated with inflammation induced by histamine release in humans.