Squalene

Squalene is a natural 30-carbon organic compound originally obtained for commercial purposes primarily from shark liver oil (hence its name), although plant sources (primarily vegetable oils) are now used as well, including amaranth seed, rice bran, wheat germ, and olives. It is also found in high concentrations in the stomach oil of birds in the order Procellariiformes. All plants and animals produce squalene as a biochemical intermediate, including humans.

Squalene is a hydrocarbon and a triterpene, and is a natural and vital part of the synthesis of all plant and animal sterols, including cholesterol, steroid hormones, and vitamin D in the human body.

Squalene is used in cosmetics, and more recently as an immunologic adjuvant in vaccines. Squalene has been proposed to be an important part of the Mediterranean diet as it may be a chemopreventive substance that protects people from cancer.

Role in steroid synthesis

In animals, squalene is the biochemical precursor to the whole family of steroids. Oxidation (via squalene monooxygenase) of one of the terminal double bonds of squalene yields 2,3-squalene oxide, which undergoes enzyme-catalyzed cyclization to afford lanosterol, which is then elaborated into cholesterol and other steroids.