Oxysterols as Reliable Markers of Quality and Safety in Cholesterol Containing Food Ingredients and Products

Abstract

Cholesterol is a lipid of high nutritional value that easily undergoes oxidation through enzymatic and non-enzymatic pathways, leading to a wide variety of cholesterol oxidation products (COPs), more commonly named oxysterols. The major oxysterols found in animal products are 7α-hydroxycholesterol, 7β-hydroxycholesterol, 7-ketocholesterol, 5α,6α-epoxycholesterol, 5β,6β-epoxycholesterol, cholestan-3β,5α,6β-triol, and 25-hydroxycholesterol. They are all produced by cholesterol autoxidation, thus belonging to the non-enzymatic oxysterol subfamily, even if 7α-hydroxycholesterol and 25-hydroxycholesterol are, in part, generated enzymatically as well. A further oxysterol of the full enzymatic origin has recently been detected for the first time in milk of both human and bovine origin, namely 27-hydroxycholesterol. Nowadays, gas or liquid chromatography combined to mass spectrometry allows to measure all these oxysterols accurately in raw and in industrially processed food. While non-enzymatic oxysterols often exhibited in vitro relevant cytotoxicity, above all 7β-hydroxycholesterol and 7-ketocholesterol, 27-hydroxycholesterol, as well as 25-hydroxycholesterol, shows a broad spectrum in vitro antiviral activity, inhibition of SARS-CoV-2 included, and might contribute to innate immunity. Quantification of oxysterols was afforded over the years, almost always focused on a few family's compounds. More comprehensive COPs measurements, also including oxysterols of enzymatic origin, are, nowadays, available, which better display the many advantages of systematically adopting this family of compounds as markers of quality, safety, and nutritional value in the selection of ingredients in processing and storage. Regarding foodstuff shelf life, COPs monitoring already provided useful hints for more suitable packaging. The identification of a subset of non-enzymatic and enzymatic oxysterols to be routinely assessed in food production and storage is proposed.

Development of a Mucoadhesive Vehicle Based on Lyophilized Liposomes for Drug Delivery through the Sublingual Mucosa

“…After freeze-drying, amorphous components remain vitrified only if the storage temperature is well below the transition temperature. As a rule of thumb, a difference of 45–50 °C between storage temperature and Tm has been proposed for sample preservation [ 41 ]. According to this rule, our lyophilized samples should not be stored at room temperature, but refrigeration under 10 °C would be required for appropriate preservation.…”

Propagation of age‐related diseases due to the changes of lipid peroxide and antioxidant levels in elderly people: A narrative review

“… 70 Some of the notable oxysterols are 7‐KC, 7α‐hydroxycholesterol (7α‐OHC), 7β‐OHC, 25‐hydroxycholesterol (25‐OHC), 27‐hydroxycholesterol (27‐OHC), 5α,6α‐epoxycholesterol (5α,6α‐EC), 5β,6β‐epoxycholesterol (5β,6β‐EC), and cholestan‐3β,5α,6β‐triol, all produced by autoxidation of cholesterols. 71 Oxysterols have been studied extensively for their role in vascular aging due to a few crucial properties such as proapoptosis, proinflammation, and pro‐oxidation. Increasing evidence showed the impact of different oxysterols in the age‐associated intimal stiffening, endothelial dysfunction, smooth muscle cell migration, and arterial thickening.…”

“… 76 , 77 So far, the toxicity of two common oxysterols, 7β‐OHC and 7‐KC, has been analyzed in the heart, brain, and gut, showing oxiapoptophagy leading to major elderly diseases, including cardiovascular disease and cancer, diabetes, and aging. 71 …”

“…Oxysterols are generally lipid peroxidation products, more specifically, cholesterol metabolites that are generated via enzymatic or nonenzymatic (radical) pathways 70 . Some of the notable oxysterols are 7‐KC, 7α‐hydroxycholesterol (7α‐OHC), 7β‐OHC, 25‐hydroxycholesterol (25‐OHC), 27‐hydroxycholesterol (27‐OHC), 5α,6α‐epoxycholesterol (5α,6α‐EC), 5β,6β‐epoxycholesterol (5β,6β‐EC), and cholestan‐3β,5α,6β‐triol, all produced by autoxidation of cholesterols 71 . Oxysterols have been studied extensively for their role in vascular aging due to a few crucial properties such as proapoptosis, proinflammation, and pro‐oxidation.…”

“…While oxysterols such as 25‐OHC and 27‐OHC have shown notable broad‐spectrum antiviral actions, only their toxicologic properties have been demonstrated so far for radically produced oxysterols when present excessively in the human body and ingested foods (milk‐derived products like chocolate) 76,77 . So far, the toxicity of two common oxysterols, 7β‐OHC and 7‐KC, has been analyzed in the heart, brain, and gut, showing oxiapoptophagy leading to major elderly diseases, including cardiovascular disease and cancer, diabetes, and aging 71 …”