Squalene: More than a Step toward Sterols.

Marco Micera,Giulia Querio,Cinzia Margherita Bertea,Renzo Levi,Susanna Antoniotti,Federica Geddo,Alfonso Botto,Maria Pia Gallo

doi:10.3390/antiox9080688

Abstract

Squalene (SQ) is a natural triterpene widely distributed in nature. It is a metabolic intermediate of the sterol biosynthetic pathway and represents a possible target in different metabolic and oxidative stress-related disorders. Growing interest has been focused on SQ’s antioxidant properties, derived from its chemical structure. Strong evidence provided by ex vivo models underline its scavenging activity towards free radicals, whereas only a few studies have highlighted its effect in cellular models of oxidative stress. Given the role of unbalanced free radicals in both the onset and progression of several cardiovascular diseases, an in depth evaluation of SQ’s contribution to antioxidant defense mechanisms could represent a strategic approach in dealing with these pathological conditions. At present experimental results overall show a double-edged sword role of squalene in cardiovascular diseases and its function has to be better elucidated in order to establish intervention lines focused on its features. This review aims to summarize current knowledge about endogenous and exogenous sources of SQ and to point out the controversial role of SQ in cardiovascular physiology.

Highlights

Squalene (SQ) is a lipophilic biomolecule that belongs to the chemical class of triterpenes
In eukaryotic cells SQ is a metabolic intermediate in the sterol biosynthetic pathway [5]; squalene synthase, an enzyme associated with the membrane of the endoplasmic reticulum, catalyzes the biosynthesis of SQ in a two-step reaction starting from two units of farnesyl diphosphate [6]
Squalene is a key metabolite in the sterol pathway and it is pivotal in regulating cellular and systemic physiology in eukaryotic organisms

Summary

Introduction

Squalene (SQ) is a lipophilic biomolecule that belongs to the chemical class of triterpenes. It is formed by six isoprene units, so, it is a 30-carbon isoprenoid compound with six double bonds (C30 H50 ). The molecule was named squalene because it was initially isolated by Tsujimoto from shark (Squalus milsukurii and other squaloids) liver oil [1,2,3], but subsequent studies have found this compound in several plant extracts [4]. In eukaryotic cells SQ is a metabolic intermediate in the sterol biosynthetic pathway [5]; squalene synthase, an enzyme associated with the membrane of the endoplasmic reticulum, catalyzes the biosynthesis of SQ in a two-step reaction starting from two units of farnesyl diphosphate [6]. SQ is the precursor of cholesterol in animal cells and the precursor of phytosterols in plant cells (Figure 1)

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