Squalene is a biosynthetic precursor to all steroids and a terpene originally isolated from shark liver oil.1,2 Squalene is produced in mammals by condensation of two farnesyl diphosphate molecules by squalene synthase and then oxidized to squalene epoxide for use in the biosynthesis of lanosterol , cholesterol, and other steroids.1 An oil-in-water emulsion of squalene synergistically increases adaptive immune responses to glucopyranosyl lipid adjuvant (GLA), a toll-like receptor 4 (TLR4) agonist, compared with an aqueous formulation of GLA.3 Formulations containing squalene have been used as adjuvants in vaccines and as hair and skin conditioning agents.
1.Tansey, T.R., and Shechter, I.Structure and regulation of mammalian squalene synthaseBiochim. Biophys. Acta1529(1-3)49-62(2000) 2.Kubota, B.The chemical composition of squaleneTokyo Kagaku Kaishi39879-907(1918) 3.Seydoux, E., Liang, H., Dubois Cauwelaert, N., et al.Effective combination adjuvants engage both TLR and inflammasome pathways to promote potent adaptive immune responsesJ. Immunol.201(1)98-112(2018)