What is the composition of Italian Helichrysum essential oil?

The immortelle, or Italian helichrysum, is a yellow plant that blossoms on the rocky slopes of Corsica and Italy. It derives its name from its exceptional longevity after being picked. The immortelle essential oil is extracted from its flowers through hydrodistillation. Found in many oils and cosmetic creams under its INCI name Helichrysum Italicum Flower Oil, this botanical extract owes its numerous properties to its rich biochemical composition.

The essential oil of Italian Helichrysum is rich in neryl acetate (≈ 42%).

Neryl acetate forms the majority of the essential oil of immortelle and is responsible for its biological activities on the skin barrier. Indeed, studies have shown that this compound can stimulate epidermal differentiation as well as the synthesis of ceramides. As a reminder, ceramides are the main lipids of the stratum corneum and play a crucial role in the formation of the skin barrier and in skin protection.

Neryl acetate is also known for its vasoconstrictive and venotonic effects. These explain the frequent use of immortelle essential oil in cases of bruises or blood circulation disorders. Moreover, according to some studies, neryl acetate would play a role in wound healing and would possess anti-inflammatory and antioxidant properties.

The essential oil of immortelle contains curcumenes (≈ 18%).

Within the essential oil of Italian helichrysum, we find γ-curcumene (≈ 12%) and α-curcumene (≈ 2%), sesquiterpenes that possess antioxidant activity. The mechanisms involved are diverse and notably include the neutralisation of free radicals due to the double bonds found in their chemical structure, and the stimulation of antioxidant enzymes such as superoxide dismutase (SOD). The curcumenes present in the essential oil of immortelle also have antifungal properties, demonstrated particularly with Candida albicans and Saccharomyces cerevisiae.

The essential oil of Italian helichrysum, a source of italidiones (≈ 12%).

Italidiones, also known as betadiones and β-diketones, are ketones with anti-inflammatory properties. Indeed, they appear to be capable of inhibiting cyclooxygenase (COX) and lipoxygenase (LOX), key enzymes in the inflammatory process. By blocking these enzymes, italidiones reduce the production of inflammation mediators such as prostaglandins and leukotrienes, which are responsible for painful sensations and redness. Italidiones also protect the skin from oxidative stress. Indeed, through an electron donation, they can neutralise free radicals before they damage cellular constituents.

The essential oil of immortelle contains limonene (≈ 6%).

The essential oil of Italian helichrysum also contains limonene, a terpene renowned for its fresh and tangy scent, which often sees it used in perfumery. Limonene is also known for its antibacterial properties. Studies have indeed shown that it prevents the proliferation of certain bacteria, known as Gram-positive, such asEscherichia coli. Limonene works by causing the rupture of the bacterial membrane, which compromises the bacterial cell integrity. It can therefore be used as an antiseptic in case of injury, to prevent the risks of bacterial contamination.

The essential oil of immortelle, a source of linalool (≈ 6%).

One of the other ingredients found in Italian Helichrysum essential oil is linalool, which belongs to the family of monoterpenic alcohols. This anti-inflammatory active ingredient stimulates the production of HSP70 proteins (Heat Shock Protein), which ensure the correct conformation of proteins found in the body's cells. They also act to protect the organelles from external stresses that cause inflammation.

Furthermore, linalool is capable of limiting the proliferation of certain parasites, such as Leishmania amazonensis, which is responsible for leishmaniasis, and bacteria, like Cutibacterium acnes, involved in the development of acne. These antibacterial and anti-inflammatory properties of the essential oil of immortelle could enable it to prevent and alleviate skin imperfections.

The essential oil of Italian Helichrysum, a source of β-caryophyllene (≈ 5%).

Formerly known as α-caryophyllene, β-caryophyllene is frequently found in spices (cinnamon, pepper, black cumin...). Beyond its pronounced taste, β-caryophyllene possesses anti-inflammatory properties that allow it to reduce the production of pro-inflammatory cytokines in the body, including at the skin level. According to some sources, it also has bactericidal and antifungal activities. Finally, β-caryophyllene is believed to stimulate the re-epithelialisation of wounds in the healing process as well as the expression of filaggrin, a protein playing a key role in the integrity of the stratum corneum.

The essential oil of Italian Helichrysum contains neryl propionate (≈ 5%).

Neryl propionate is a terpene commonly used in the food industry for its flavour-enhancing properties. Although it is relatively significant in the composition of immortelle essential oil, its effects in topical application have, to date, been little studied. Some sources, however, report that it may have anti-inflammatory action, without specifying its mechanism of action. Further studies are still needed to better understand neryl propionate.

The essential oil of Italian helichrysum contains pinenes (≈ 3%).

The essential oil of immortelle contains pinenes, specifically α-pinene, at approximately 2%, and β-pinene, at around 1%. These active ingredients possess interesting antibacterial properties. Several studies have indeed shown that pinenes have a bacteriostatic action, meaning they inhibit the multiplication of bacteria, without necessarily killing them. It should be noted that this bacteriostatic activity of pinenes has only been demonstrated for Gram-positive bacteria, such as Staphylococcus aureus.

The essential oil of immortelle contains nerol (≈ 2%).

An isomer of geraniol, nerol is recognised for its anti-inflammatory virtues and its ability to inhibit the activation of the nuclear factor NF-κB, which triggers the release of inflammation molecules. It thus contributes to the soothing virtues of Italian helichrysum essential oil. It has also been shown that nerol possesses antimicrobial activity against certain bacteria, such as Escherichia coli or Salmonella enterica. Finally, it should be noted that geraniol has antioxidant properties and prevents the peroxidation of lipids in sebum and the corneal layer, compounds that contribute to the maintenance of the skin's protective barrier and the hydration of the skin.

The essential oil of immortelle contains eucalyptol (≈ 1%).

Eucalyptol, found in various plants, is generally appreciated for its refreshing and spicy scent, similar to camphor. It also has the ability to work in synergy with other compounds in Italian helichrysum essential oil and exert an anti-inflammatory activity. From a mechanistic perspective, this compound inhibits the transcription factor NF-κB, which regulates the expression of most of the body's pro-inflammatory proteins.

Depending on the origin of the Italian helichrysum essential oil and its extraction method, its biochemical composition may slightly vary.