Sesame oil: what is its phytochemical composition?

If the sesame oil is so widely used in cosmetics, it is due to the numerous benefits conferred by its biochemical composition. Indeed, the collective active molecules that make it up allow it to exert moisturising, nourishing, anti-inflammatory and antibacterial properties.

• Polyunsaturated fatty acids: 37 to 48% linoleic acid.

  Linoleic acid is a polyunsaturated fatty acid that belongs to the omega-6 family. It plays a significant role in the preservation of the skin barrier's integrity. Indeed, it is a constituent of cell membranes that helps combat skin dehydration by reducing transepidermal water loss. Linoleic acid also provides skin protection by creating a film on its surface, which shields it from external aggressors such as pollution, tobacco, and UV rays, factors that cause oxidative stress in cells. Moreover, the anti-inflammatory properties of linoleic acid allow it to soothe sensitive skin and alleviate tightness and irritation.

• Monounsaturated fatty acids: 35 to 50% oleic acid.

  Oleic acid is a monounsaturated fatty acid from the omega-9 family. It acts as a natural emollient that contributes to skin hydration. Indeed, like linoleic acid, it is capable of easily penetrating the superficial skin layers to help maintain their hydration. Oleic acid thus plays a role in the strengthening of the skin's barrier function and in preventing water loss. Moreover, studies suggest that oleic acid may have beneficial anti-inflammatory properties for the skin, particularly for individuals suffering from dermatoses such as eczema or psoriasis.

• Saturated fatty acids: 20 to 27% of palmitic acid.

  Palmitic acid is a saturated fatty acid that belongs to the omega-3 family. This molecule also promotes thehydration of the skin. Palmitic acid acts as an emollient and helps to hydrate the skin by forming a protective film on its surface, thus helping to reduce transepidermal water loss. It also has cleansing and emulsifying properties and imparts suppleness and softness to the skin.

• Saturated fatty acids: 4 to 7% stearic acid.

  Stearic acid is defined as a long-chain saturated fatty acid. In cosmetics, it is recognised for its emollient, nourishing, and protective properties. It is also capable of inducing the formation of a protective film on the skin's surface.

Sesame seed oil is a good source of vitamin E, present in the form of tocopherols. As a reminder, vitamin E is a natural antioxidant that protects cells from the harmful effects of free radicals. By neutralising these reactive species, it reduces skin damage caused by UV rays and other oxidative stress factors, playing a preventive role against skin ageing. Furthermore, vitamin E has interesting anti-inflammatory properties that complement the soothing effects of the fatty acids contained in sesame oil. At a lower concentration, this oil also contains vitamin B and provitamin A, which, like vitamin E, have an antioxidant role.

Sesame seeds contain lignans, polyphenols that accumulate in woody tissues. Indeed, they are found in the seeds and roots of many plants. The main lignans in sesame oil are sesamin and sesamolin, compounds with several interesting properties. These lignans not only have antioxidant effects, but they can also reduce inflammation, normalise blood pressure, and improve lipid levels.

The precise mechanisms of action of lignans remain unclear to this day. However, in terms of their antioxidant activity, it would be due to their protective action on tocopherols. Indeed, lignans could inhibit an enzyme involved in the degradation of vitamin E, thus allowing it to exert its anti-radical properties.

Sesame oil contains phytosterols, specifically β-sitosterol and campesterol, compounds that have anti-inflammatory and moisturising properties for the skin. Indeed, they contribute to the support of the hydrolipidic film and limit water loss. Moreover, they act to slow down inflammation by inhibiting the activity of two enzymes: cyclooxygenase (COX) and lipoxygenase (LOX). These enzymes play a major role in the production of inflammation factors such as prostaglandin. By inhibiting their activity, phytosterols help to reduce irritations, redness and itching associated with inflammatory processes.

Finally, sesame oil also contains a few phenolic compounds such as sesamol and sesamolinol, molecules that exert an antioxidant activity. This activity is carried out through interaction with free radicals via several mechanisms of electron and hydrogen atom transfer. Phenolic compounds also have beneficial anti-inflammatory properties for the skin. Similar to phytosterols, they work by inhibiting the production of pro-inflammatory factors.

• BAUGHMAN W. & al. The chemical composition of sesame oil. Journal of the American Chemical Society (1924).

• HWANG L. & al. Sesame Oil. Bailey's Industrial Oil and Fat Products (2005).

• YAGOUB A. & al. Chemical Composition and Oil Characteristics of Sesame Seed Varieties Cultivated in Sudan. Research Journal of Agriculture and Biological Sciences (2008).

• MOHITE N. & al. Sesame (Sesamum indicum L.) Significance and its High-Quality Seed Oil: A Review. Department of Plant Biotechnology, Tamil Nadu Agricultural University (2015).

• XIE M. & al. The correlation between antioxidant constituents and antioxidant activity of Sesame seed oil. Journal of the Science of Food and Agriculture (2015).