Squalene

Squalene (from lat. squalus the shark) is a naturally occurring, unsaturated, slightly oxidizing hydrocarbon from the group of triterpenes with the molecular formula C30H50. The compound is a colourless, unsaponifiable, oily liquid at room temperature. It is almost insoluble in water, but readily soluble in acetone or ether.

Squalene is formed in all higher organisms. The synthesis of squalene starts with isopentenyl pyrophosphate. Thereby farnesyl pyrophosphate is formed via geranyl pyrophosphate. Two molecules of farnesyl pyrophosphate are finally combined to squalene under NADPH consumption. This reaction is catalysed by a synthetase (squalene synthase).

Squalene is an important starting product/intermediate for the synthesis of cholesterol, steroid hormones (e.g. estrogens, testosterone, cortisol) and vitamin D. Squalene is first activated by a monooxygenase under NADPH consumption, squalene epoxide (2,3-oxidosqualene) is formed. This is finally cyclized into lanosterol by the oxidosqualene cyclase. A series of subsequent reactions produces either cholesterol or ergosterol.

In humans, squalene with 12-15% is one of the main components of skin lipids (Pham DM et al.). It is synthesized in sebaceous glands in a day-to-day rhythm and hormone-triggered manner and is primarily excreted via the hair follicle apparatus (Pierard GE et al. 1987b). The substance is evaluated as the lead substance of the sebum (sebum). Thus, squalene is a potential marker for acne tendency and is significantly more elevated in patients with acne vulgaris than the other sebum lipids (Pappas et al. 2009).

Squalene plays an essential role in the biomembrane protection of immune cells against oxidative stress. By neutralizing excessive free radicals, squalene allows immune cells to function more efficiently without disruption. Squalene plays a role in the natural light protection of the skin.

General occurrence: In high concentration in fish liver oil, in vegetable oils like olive oil.

Medicine: Squalene is important as an adjuvant in some adjuvant vaccines, approved in Europe.

Cosmetics: Squalene is used for the production of liposomes and is applied accordingly. In cosmetic formulations, squalene acts as an antistatic agent (reduces static electricity by neutralising the electrical charge on the surface, for example of hair), emollient (makes the skin smooth and supple), hair conditioner (makes the hair easy to comb, soft, smooth and shiny and gives it volume), refatting agent and as a skin care product (keeps the skin in good condition).

1. Ammon HPT et al (2014) Hunnius Pharmaceutical Dictionary 11th Edition Walter de Gruyter Berlin-New York p. 1345
2. Otberg N et al (2004) Variations of hair follicle size and distribution in different body sites. J Invest Dermatol 122:14-19.
3. Pappas A , Joet al. (2009) Sebum analysis of individuals with and without acne. Dermatoendocrinol 1:157-161.
4. Pham DM et al (2015) Oxidization of squalene, a human skin lipid: a new and reliable marker of environmental pollution studies.Int J Cosmet Sci 37:357-365.
5. Pierard GE et al (1987b) Patterns of follicular sebum excretion rate during lifetime. Arch Dermatol Res 279 Suppl: 104-107.