Oxysterols formation: A review of a multifactorial process

Abstract

Highlights1-Heating sterols at 180 °C produced a high extent of oxidation.2-The presence and unsaturation degree of the surrounding lipids protected sterols from oxidation.3-Plant aqueous extracts protected cholesterol from oxidation.4-Greater amounts of campesterol-derived oxidation products were observed, followed by sitosterol, cholesterol and stigmasterol.5-In 5 out of 7 of our studies, 7-keto derivatives were the most abundant oxysterols formed. AbstractDietary sterols are nutritionally interesting compounds which can suffer oxidation reactions. In the case of plant sterols, they are being widely used for food enrichment due to their hypocholesterolemic properties. Besides, cholesterol and plant sterols oxidation products are associated with the development of cardiovascular and neurodegenerative diseases, among others. Therefore, the evaluation of the particular factors affecting sterol degradation and oxysterols formation in foods is of major importance. The present work summarizes the main results obtained in experiments which aimed to study four aspects in this context: the effect of the heating treatment, the unsaturation degree of the surrounding lipids, the presence of antioxidants on sterols degradation, and at last, oxides formation. The use of model systems allowed the isolation of some of these effects resulting in more accurate data. Thus, these results could be applied in real conditions.

Impact of Air Frying on Cholesterol and Fatty Acids Oxidation in Sardines: Protective Effects of Aromatic Herbs

“…As described in the literature the influence of cholesterol oxides on human health deserves some emphasis, because the exogenous cholesterol oxides formed during processing of foods can be potential harmful to health, affecting the cellular metabolism, changing the membrane composition and proprieties, and they are more cytotoxic than cholesterol and are associated with the development of cardiovascular and neurodegenerative diseases, among others, which can cause deleterious effects such as inflammation, atherosclerosis, mutagenic and carcinogenic, and cell death. (Thanan and others ; Laparra and others ; Barriuso and others ; Doria and others ; Kulig and others ).…”

“…However, some authors have demonstrated that sardines also contain high levels of cholesterol (Saldanha and others ; Scherr and others ). These 2 types of compounds, n ‐3 PUFAs and cholesterol, are not chemically stable and this instability is influenced by their chemical structure, the presence of oxygen, light, metal ions, and the processing techniques (heat) used, among other factors (Dantas and others ; Barriuso and others ).…”

“…These substances are structurally similar to cholesterol and are normally present in small quantities formed by endogenous metabolic processes. However, the exogenous cholesterol oxides formed during the processing of food can be potentially harmful to health (Dantas and others ) and these COPs are associated with the development of cardiovascular and neurodegenerative diseases, besides inflammation, atherosclerosis, mutagenesis, carcinogenesis, and cell death (Doria and others ; Barriuso and others ).…”

Use of Natural Antioxidants in the Inhibition of Cholesterol Oxidation: A Review

“…The presence of unsaturated fatty acids in the food matrix may accelerate the oxidation of cholesterol, as it generates a pro-oxidant environment, due to the presence of resonance zones, resulting in radicals such as hydroperoxides (Barnaba et al, 2016). However, lipids may compete for oxygen with sterols and reduce sterol oxidation by auto-oxidation (Barriuso, Ansorena, & Astiasarán, 2017).…”

The Effect of Diet Supplementation with Pomegranate and Bitter Melon on Lipidomic Profile of Serum and Cancerous Tissues of Rats with Mammary Tumours

“…Oxysterols are products of enzymatic and non-enzymatic oxidation of cholesterol, its precursors and phytosterols. They can be synthesised endogenously though different pathways, but they also are absorbed from diet, where their amount depends on temperature, oxygen, light exposure, lipid surrounding matrix and presence of antioxidants and water [14]. Oxysterols, which are present in physiological conditions in rather low amounts, are intermediates in cholesterol metabolism to bile acids and steroid hormones.…”