Cholesterol Oxidation Products Research Articles

Assessment of lipid oxidation and microbial decontamination of sardine (Sardina pilchardus) fillets processed by plasma-activated water (PAW)

Plasma activated water (PAW) is emerging as a mild and environmentally friendly technology for microbial and chemical decontamination of food. The aim of this work was to evaluate the degree of oxidation of lipids of sardine tissue treated by PAW generated with a pulsed corona discharge. The effect of PAW on the natural microflora of the fish was also evaluated. Under the adopted experimental conditions, PAW was able to reduce the number of mesophilic aerobes and Pseudomonas spp. by 0.22 and 0.20 log units, respectively, but no increase in shelf life was observed at chilling temperatures compared to water washing. A loss of polyunsaturated fatty acids (PUFAs) and an increase in volatile oxidation products derived from the cleavage of PUFA hydroperoxides were observed at the longest treatment duration. Twelve cholesterol oxidation products (COPs) were identified in sardine lipids, but no significant differences in total COPs content were observed between PAW processed and control samples. Free radical mediated oxidation pathways led to the most abundant COPs, but a significant contribution of non-radical pathways was also observed. Further studies are needed to better understand the low efficiency of PAW in microbial decontamination of proteinaceous materials.

Concentrated Grape Powder Consumption Modulates Cholesterol Metabolism and Homeostasis in Healthy Subjects.

Four weeks' of concentrated grape powder (GP) consumption reduces circulating cholesterol in healthy free-living subjects consuming a low-fiber/low-polyphenol diet. Here, the study aims to investigate the underlying mechanisms for cholesterol reduction by evaluating biomarkers of cholesterol de novo biosynthesis, intestinal absorption, miRNA involved in transcriptional regulation of cholesterol metabolism, as well as cholesterol oxidation. Fasting plasma samples collected from 19 healthy free-living subjects at baseline and week 4 of GP consumption are used in this study. Gas chromatography-mass (GC-MS) analysis of plasma samples shows that lathosterol, a precursor of cholesterol synthesis, is significantly decreased after GP consumption indicating reduced cholesterol de novo biosynthesis. Markers of intestinal absorption, campesterol, and β-sitosterol are not changed. Realtime PCR shows that plasma exosomal miRNA-1 is increased after GP consumption. GC-MS also shows that GP consumption reduces the plasma cholesterol oxidation product 27-hydroxycholesterol (27-HC). This study enhances the understanding of the mechanisms of the cholesterol lowering effects of GP, and provides new insights into the potential health benefits of grape consumption.

Regulation of cholesterol homeostasis in osteoporosis mechanisms and therapeutics.

Osteoporosis is a metabolic bone disease that affects hundreds of millions of people worldwide and is characterized by excessive loss of bone protein and mineral content. The incidence and mortality of osteoporosis increase with age, creating a significant medical and economic burden globally. The importance of cholesterol levels has been reported in the development of diseases including osteoporosis. It is important to note that key enzymes and molecules involved in cholesterol homeostasis are closely related to bone formation. Excessive cholesterol may cause osteoporosis, cholesterol and its metabolites affect bone homeostasis by regulating the proliferation and stimulation of osteoblasts and osteoclasts. Therefore, antagonism of elevated cholesterol levels may be a potential strategy to prevent osteoporosis. There is sufficient evidence to support the use of bisphosphonates and statin drugs for osteoporosis in the clinic. Therefore, in view of the aggravation of the aging problem, we summarize the intracellular mechanism of cholesterol homeostasis and its relationship with osteoporosis (including cholesterol and cholesterol oxidation products (COPs) in osteoporosis). Furthermore, the current clinical cholesterol-lowering drugs for osteoporosis were also summarized, as are new and promising therapies (cell-based therapies (e.g., stem cells) and biomaterial-delivered target drug therapies for osteoporosis as well).

7-Ketocholesterol accelerates pancreatic β-cell senescence by inhibiting the SIRT1/CDK4–Rb–E2F1 signaling pathway

ABSTRACT Pancreatic β-cell dysfunction is a key factor in the development of type 2 diabetes. Pancreatic β-cell senescence accelerates abnormal glucose metabolism, which decreases insulin secretion and cell regeneration ability, eventually leading to diabetes. A cholesterol oxidation product, 7-ketocholesterol (7-KC) can affect pancreatic β-cell function. However, its role in pancreatic β-cell senescence has not been reported. We investigated the role of 7-KC in pancreatic β-cell senescence and its underlying molecular mechanism in MIN6 cells. MIN6 cells were treated with 25 μmol/L 7-KC for 24 h and the proportion of senescent cells was detected based on senescence-associated β-galactosidase (SA-β-gal) activity. The cell cycle, DNA damage, and the senescence-associate secretory phenotype (SASP) and protein expression were detected by flow cytometry, immunofluorescence, and western blotting, respectively. 7-KC can significantly increase SA-β-gal activity, promoted G0/G1 arrest, DNA damage, and interleukin-1β expression in MIN6 cells and significantly inhibited insulin synthesis. Further studies indicated that 7-KC induced β-cell senescence by inhibiting the SIRT1/CDK4–Rb – E2F1 signaling pathway.

The CH24H metabolite, 24HC, blocks viral entry by disrupting intracellular cholesterol homeostasis

Cholesterol-24-hydroxylase (CH24H or Cyp46a1) is a reticulum-associated membrane protein that plays an irreplaceable role in cholesterol metabolism in the brain and has been well-studied in several neuro-associated diseases in recent years. In the present study, we found that CH24H expression can be induced by several neuroinvasive viruses, including vesicular stomatitis virus (VSV), rabies virus (RABV), Semliki Forest virus (SFV) and murine hepatitis virus (MHV). The CH24H metabolite, 24-hydroxycholesterol (24HC), also shows competence in inhibiting the replication of multiple viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). 24HC can increase the cholesterol concentration in multivesicular body (MVB)/late endosome (LE) by disrupting the interaction between OSBP and VAPA, resulting in viral particles being trapped in MVB/LE, ultimately compromising VSV and RABV entry into host cells. These findings provide the first evidence that brain cholesterol oxidation products may play a critical role in viral infection.

Effect of packaging in preventing cholesterol autoxidation in milk chocolates for a higher quality and safer shelf-life.

Non-enzymatic cholesterol oxidation products (COPs) are nowadays receiving increasing attention in food technology for their potential use as biomarkers of freshness and safety in raw materials and complex food matrices, as well as markers of cholesterol oxidation during the production and shelf-life of end products. Here reported is the investigation of how long three prototype milk chocolates containing whole milk powders (WMPs) of increasing shelf-lives (i.e. 20, 120, and 180 days), could be safely stored in the market by adopting the non-enzymatic COPs as a quality markers. In addition, the protective effect of two different primary packaging, sealed and unsealed ones, in mitigating the generation of non-enzymatic COPs in three prototype milk chocolates after 3, 6, 9, 12 months of shelf-life was assessed to simulate two real storage conditions. Quantifying oxysterols' levels by mass spectrometry, the oxygen impermeable packaging (PLUS) resulted to significantly quench the non-enzymatic COPs production up to 34% as to that found in the same product but with unsealed standard packaging (STD). This study represents one practical application of non-enzymatic COPs as a reliable tool for corrective strategies to prevent food oxidation.

Single-Cell Transcriptomics Reveals the Difference of Aortic Atherosclerosis Response to Phytosterols and Oxidation Products of Sterols.

Phytosterols (PS) and sterol oxidation products are key dietary factors influencing atherosclerosis besides cholesterol, although the mechanisms remain elusive. Recently, single-cell RNA sequencing (scRNA-seq) has revealed the heterogeneity of multiple cell types associated with complex pathogenesis in atherosclerosis development. Here, scRNA-seq is performed to investigate the alterations in the aortic cells from ApoE-/- mice induced by diet-derived PS or two sterol oxidation products, phytosterols oxidation products (POPs), and cholesterol oxidation products (COPs). The study identifies four fibroblast subpopulations with different functions, and immunofluorescence demonstrates their spatial heterogeneity, providing evidence that suggests the transformation of smooth muscle cells (SMCs) and fibroblasts in atherosclerosis. The composition and gene expression profiles of aortic cells change broadly in response to PS/COPs/POPs exposure. Notably, PS exhibits an atheroprotective effect where different gene expressions are mainly found in B cells. Exposure to COPs accelerates atherosclerosis and results in marked alternations in myofibroblast subpopulations and T cells, while POPs only alter fibroblast subpopulations and B cells. The data elucidate the effects of dietary PS/COPs/POPs on aortic cells during atherosclerosis development, especially on the newly identified fibroblast subpopulations.

Replacement of soybean oil by Hermetia illucens larvae fat in broiler diets alters the breast muscle lipidome and reduces lipid oxidation of the breast muscle during heat-processing

ABSTRACT Replacement of soybean oil by insect fat from Hermetia illucens (HI) has been reported to increase the proportions of saturated fatty acids (SFA) and decrease those of polyunsaturated fatty acids (PUFA) in total lipids of breast and thigh meat in broilers. Since the susceptibility of meat to oxidation is strongly dependent on its PUFA content, the present study hypothesised that replacement of soybean oil by HI larvae fat in broiler diets reduces the formation of lipid oxidation products, including oxidation products of cholesterol and phytosterols, in heat-processed breast muscle of broilers. To test this hypothesis, 100 male, 1-day-old Cobb 500 broilers were assigned to three groups and fed three different nutrient adequate diets, which varied only in the fat source (group HI-0: 0% HI larvae fat and 5% soybean oil; group HI-2.5: 2.5% HI larvae fat and 2.5% soybean oil; group HI-5.0: 5.0% HI larvae fat and 0% soybean oil), in a three-phase feeding system for 35 days. While the growth performance of the broilers was not different, the absolute and relative breast muscle weights were higher in group HI-5.0 than in group HI-0 (p < 0.05). The proportions of C12:0, C14:0, C14:1, C16:0, C16:1 and total SFA were higher and those of C18:1, C18:2 n-6, C18:3 n-3 and total PUFA were lower in breast muscle total lipids of group HI-5.0 than in groups HI-2.5 and HI-0 (p < 0.05). Lipidomic analysis of breast muscle revealed that the concentration of triacylglycerols was 46% and 53% lower in groups HI-2.5 and HI-5.0, respectively, than in group HI-0 (p < 0.05), whereas all other lipid classes detected did not differ among groups. Concentrations of thiobarbituric acid-reactive substances, 7α-hydroxycholesterol, 7β-hydroxycholesterol and total cholesterol oxidation products in heat-processed breast muscle were lower in group HI-5.0 than in group HI-0 (p < 0.05). Concentrations of oxidation products of phytosterols in heat-processed breast muscle were generally much lower than those of cholesterol oxidation products and did not differ between the three groups of broilers. In conclusion, complete replacement of soybean oil with HI larvae fat in broiler diets strongly alters the fatty acid composition of breast muscle total lipids and reduce lipid oxidation of the breast muscle during heat-processing.

24-Hydroxycholesterol Induces Tau Proteasome-Dependent Degradation via the SIRT1/PGC1α/Nrf2 Pathway: A Potential Mechanism to Counteract Alzheimer’s Disease

Considerable evidence indicates that cholesterol oxidation products, named oxysterols, play a key role in several events involved in Alzheimer's disease (AD) pathogenesis. Although the majority of oxysterols causes neuron dysfunction and degeneration, 24-hydroxycholesterol (24-OHC) has recently been thought to be neuroprotective also. The present study aimed at supporting this concept by exploring, in SK-N-BE neuroblastoma cells, whether 24-OHC affected the neuroprotective SIRT1/PGC1α/Nrf2 axis. We demonstrated that 24-OHC, through the up-regulation of the deacetylase SIRT1, was able to increase both PGC1α and Nrf2 expression and protein levels, as well as Nrf2 nuclear translocation. By acting on this neuroprotective pathway, 24-OHC favors tau protein clearance by triggering tau ubiquitination and subsequently its degradation through the ubiquitin-proteasome system. We also observed a modulation of SIRT1, PGC1α, and Nrf2 expression and synthesis in the brain of AD patients with the progression of the disease, suggesting their potential role in neuroprotection. These findings suggest that 24-OHC contributes to tau degradation through the up-regulation of the SIRT1/PGC1α/Nrf2 axis. Overall, the evidence points out the importance of avoiding 24-OHC loss, which can occur in the AD brain, and of limiting SIRT1, PGC1α, and Nrf2 deregulation in order to prevent the neurotoxic accumulation of hyperphosphorylated tau and counteract neurodegeneration.

Site of the Hydroxyl Group Determines the Surface Behavior of Bipolar Chain-Oxidized Cholesterol Derivatives─Langmuir Monolayer Studies Supplemented with Theoretical Calculations.

Cholesterol oxidation products (called oxysterols) are involved in many biological processes, showing both negative (e.g., neurodegenerative) and positive (e.g., antiviral and antimicrobial) effects. The physiological activity of oxysterols is undoubtedly closely related to their structure (i.e., the type and location of the additional polar group in the cholesterol skeleton). In this paper, we focus on determining how a seemingly minor structural change (introduction of a hydroxyl moiety at C(24), C(25), or C(27) in the isooctyl chain of cholesterol) affects the organization of the resulting molecules at the phase boundary. In our research, we supplemented the classic Langmuir monolayer technique, based on the surface pressure and electric surface potential isotherms, with microscopic (BAM) and spectroscopic (PM-IRRAS) techniques, as well as theoretical calculations (DFT and MD). This allowed us to show that 24-OH behaves more like cholesterol and forms stable, rigid monolayers. On the other hand, 27-OH, similar to 25-OH, undergoes the phase transition from monolayer to bilayer structures. Theoretical calculations enabled us to conclude that the formation of bilayers from 27-OH or 25-OH is possible due to the hydrogen bonding between adjacent oxysterol molecules. This observation may help to understand the factors responsible for the unique biological activity (including antiviral and antimicrobial) of 27-OH and 25-OH compared to other oxysterols.

Clinical Evaluation Based on a New Approach to Improve the Accuracy of 4β-Hydroxycholesterol Measurement as a Biomarker of CYP3A4 Activity

This study examines 4β-Hydroxycholesterol (4β-HC), which is considered to be a potential marker for the CYP3A4 induction of new chemical entities (NCEs) in drug development. To ensure the use of 4β-HC as a practical biomarker, it is necessary to accurately measure 4β-HC and demonstrate that CYP3A4 induction can be appropriately assessed, even for weak inducers. In clinical trials of NCEs, plasma is often collected with various anticoagulants, in some cases, the plasma is acidified, then stored for an extended period. In this study, we examined the effects of these manipulations on the measurement of 4β-HC, and based on the results, we optimized the plasma collection and storage protocols. We also found that a cholesterol oxidation product is formed when plasma is stored, and by monitoring the compound, we were able to identify when plasma was stored inappropriately. After evaluating the above, clinical drug-drug interaction (DDI) studies were conducted using two NCEs (novel retinoid-related orphan receptor γ antagonists). The weak CYP3A4 induction by the NCEs (which were determined based on a slight decline in the systemic exposure of a probe substrate (midazolam)), was detected by the significant increase in 4β-HC levels (more specifically, 4β-HC/total cholesterol ratios). Our new approach, based on monitoring a cholesterol oxidation product to identify plasma that is stored inappropriately, allowed for the accurate measurement of 4β-HC, and thus, it enabled the evaluation of weak CYP3A4 inducers in clinical studies without using a probe substrate.

Analysis of Non-Amyloidogenic Mutations in APP Supports Loss of Function Hypothesis of Alzheimer's Disease.

Proteolytic processing of amyloid precursor protein (APP) plays a critical role in pathogenesis of Azheimer's disease (AD). Sequential cleavage of APP by β- and γ-secretases leads to generation of Aβ40 (non-amyloidogenic) and Aβ42 (amyloidogenic) peptides. Presenilin-1 (PS1) or presenilin-2 (PS2) act as catalytic subunits of γ-secretase. Multiple familial AD (FAD) mutations in APP, PS1, or PS2 affect APP proteolysis by γ-secretase and influence levels of generated Aβ40 and Aβ42 peptides. The predominant idea in the field is the "amyloid hypothesis" that states that the resulting increase in Aβ42:Aβ40 ratio leads to "toxic gain of function" due to the accumulation of toxic Aβ42 plaques and oligomers. An alternative hypothesis based on analysis of PS1 conditional knockout mice is that "loss of function" of γ-secretase plays an important role in AD pathogenesis. In the present paper, we propose a mechanistic hypothesis that may potentially reconcile these divergent ideas and observations. We propose that the presence of soluble Aβ peptides in endosomal lumen (and secreted to the extracellular space) is essential for synaptic and neuronal function. Based on structural modeling of Aβ peptides, we concluded that Aβ42 peptides and Aβ40 peptides containing non-amyloidogenic FAD mutations in APP have increased the energy of association with the membranes, resulting in reduced levels of soluble Aβ in endosomal compartments. Analysis of PS1-FAD mutations also revealed that all of these mutations lead to significant reduction in both total levels of Aβ produced and in the Aβ40/Aβ42 ratio, suggesting that the concentration of soluble Aβ in the endosomal compartments is reduced as a result of these mutations. We further reasoned that similar changes in Aβ production may also occur as a result of age-related accumulation of cholesterol and lipid oxidation products in postsynaptic spines. Our analysis more easily reconciled with the "loss of γ-secretase function" hypothesis than with the "toxic gain of Aβ42 function" idea. These results may also explain why inhibitors of β- and γ- secretase failed in clinical trials, as these compounds are also expected to significantly reduce soluble Aβ levels in the endosomal compartments.

Effect of thermal processing on the quality parameters of ghee incorporated with curry leaf (Murraya koeneigii) extract

This study examined the effect of adding antioxidants, namely curry leaf extract (CLE) and butylated hydroxyanisole (BHA), on the physicochemical properties of ghee during deep frying. The results showed that the addition of CLE to ghee resulted in significant changes in the L*, a*, and b* values, likely due to the extraction of chlorophyll molecules during CLE preparation. Deep frying caused a decrease in L* values and an increase in a* and b* values of ghee, as well as an increase in the redness and yellowness indices, with control ghee experiencing the most significant changes. The viscosity of ghee increased during frying, and the increase was less in ghee with added antioxidants. Antioxidant-added ghee showed the least increase in total polar compounds (TPC) and thiobarbituric acid reactive substances (TBARS) during frying, which are indicators of oil degradation. CLE and BHA were found to inhibit the production of Cholesterol Oxidation Products (COPs) in ghee during deep frying for up to 45 minutes. Control ghee showed the presence of both COPs (5α, 6α-epoxide and 7β-hydroxy cholesterol) after 45 minutes of frying, whereas ghee with added CLE and BHA had only 5α, 6α-epoxide after 45 minutes of frying.

Antioxidant addition improves cholesterol and astaxanthin stability in dry salted shrimp.

Traditional production of dry salted shrimp enhances cholesterol oxidation and astaxanthin degradation in the product. The aim of this study was to evaluate the effect of addition of the antioxidants butylhydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) to cooked shrimp on the formation of cholesterol oxidation products (COPs) and astaxanthin degradation during solar drying of shrimp. The added antioxidants significantly inhibited COPs formation after the product was boiled in brine. Smaller amounts of COPs were formed in antioxidant-treated shrimps (~-23%) as compared to untreated samples. The antioxidants continued to significantly inhibit COPs formation (~-39%) during sun drying. Similarly, TBHQ and BHT reduced by 51.3% and 37.2%, respectively, the degradation rate of astaxanthin, favoring a higher retention of this carotenoid in the final product. The use of the antioxidants BHT and TBHQ in the preparation of dry salted shrimp significantly inhibited the formation of COPs after cooking raw shrimp and during direct solar drying. They also protected astaxanthin contained in the cooked shrimp from photodegradation. These results are technologically relevant because it is possible to prepare a product with a higher content of astaxanthin and lower the presence of hazardous COPs. © 2022 Society of Chemical Industry.

Macrophage-Derived 25-Hydroxycholesterol Promotes Vascular Inflammation, Atherogenesis, and Lesion Remodeling.

Cross-talk between sterol metabolism and inflammatory pathways has been demonstrated to significantly affect the development of atherosclerosis. Cholesterol biosynthetic intermediates and derivatives are increasingly recognized as key immune regulators of macrophages in response to innate immune activation and lipid overloading. 25-Hydroxycholesterol (25-HC) is produced as an oxidation product of cholesterol by the enzyme cholesterol 25-hydroxylase (CH25H) and belongs to a family of bioactive cholesterol derivatives produced by cells in response to fluctuating cholesterol levels and immune activation. Despite the major role of 25-HC as a mediator of innate and adaptive immune responses, its contribution during the progression of atherosclerosis remains unclear. The levels of 25-HC were analyzed by liquid chromatography-mass spectrometry, and the expression of CH25H in different macrophage populations of human or mouse atherosclerotic plaques, respectively. The effect of CH25H on atherosclerosis progression was analyzed by bone marrow adoptive transfer of cells from wild-type or Ch25h-/- mice to lethally irradiated Ldlr-/- mice, followed by a Western diet feeding for 12 weeks. Lipidomic, transcriptomic analysis and effects on macrophage function and signaling were analyzed in vitro from lipid-loaded macrophage isolated from Ldlr-/- or Ch25h-/-;Ldlr-/- mice. The contribution of secreted 25-HC to fibrous cap formation was analyzed using a smooth muscle cell lineage-tracing mouse model, Myh11ERT2CREmT/mG;Ldlr-/-, adoptively transferred with wild-type or Ch25h-/- mice bone marrow followed by 12 weeks of Western diet feeding. We found that 25-HC accumulated in human coronary atherosclerotic lesions and that macrophage-derived 25-HC accelerated atherosclerosis progression, promoting plaque instability through autocrine and paracrine actions. 25-HC amplified the inflammatory response of lipid-loaded macrophages and inhibited the migration of smooth muscle cells within the plaque. 25-HC intensified inflammatory responses of lipid-laden macrophages by modifying the pool of accessible cholesterol in the plasma membrane, which altered Toll-like receptor 4 signaling, promoted nuclear factor-κB-mediated proinflammatory gene expression, and increased apoptosis susceptibility. These effects were independent of 25-HC-mediated modulation of liver X receptor or SREBP (sterol regulatory element-binding protein) transcriptional activity. Production of 25-HC by activated macrophages amplifies their inflammatory phenotype, thus promoting atherogenesis.

Oxysterols in catfish skin secretions (Arius bilineatus, Val.) exhibit anti-cancer properties

The edible catfish Arius bilineatus, (Valenciennes) elaborates a proteinaceous gel-like material through its epidermis when threatened or injured. Our on-going studies on this gel have shown it to be a complex mixture of several biologically active molecules. Anti-cancer studies on lipid fractions isolated from the gel-like materials showed them to be active against several cancer cell lines. This prompted us to investigate further the lipid composition of the catfish epidermal gel secretions (EGS). Analysis of the lipid fraction of EGS resulted in identification of 12 oxysterols including cholesterol and 2 deoxygenated steroids i.e., 7α-hydroxy cholesterol, 7β-hydroxycholesterol, 5,6 epoxycholesterol, 3β-hydroxycholest-5-ene-7-one and cholesta-3,5-dien-7-one. Progesterone, cholest-3,5-diene, cholesta-2,4-diene, cholest-3,5,6-triol and 4-cholesten-3-one were found as minor components, and were identified through their MS, 1HNMR and FTIR spectral data and were compared with those of the standards. Cholest-3,6-dione, cholesta-4,6-diene-3-one, cholesta-2,4-diene, and cholesta-5,20(22)-dien-3-ol were found only in trace amounts and were identified by GC/MS/MS spectral data. Since cholesterol is the major component of EGS, the identified oxysterols (OS) are presumably cholesterol oxidation products. Many of the identified OS are known important biological molecules that play vital physiological role in the producer and recipient organisms. We report herein the effects of these sterols on three human cancer cell lines in vitro, i.e., K-562 (CML cell line), MDA MB-231 (estrogen positive breast cancer cell line) and MCF-7 (estrogen negative breast cancer cell line). Interestingly significant (p < 0.05) dose differences were observed between tested OS on cell types used. The presence of these sterols in EGS may help explain some aspects of the physiological activities of fraction B (FB) prepared from EGS, such as enhanced wound and diabetic ulcer healing, anti-inflammatory action and cytotoxic activities reported in our previous studies. The anti-proliferative actions of some of these oxysterols especially the cholesterol 3,5,6-triol (#5) as established on selected cancer cell lines in this study support our previous studies and make them candidates for research for human application.

Assessment of a Diterpene-Rich Rosemary (Rosmarinus officinalis L.) Extract as a Natural Antioxidant for Salmon Pâté Formulated with Linseed.

The use of natural plant extracts with standardised antioxidant properties is a growing strategy to stabilise food products. The use of a rosemary lipophilic extract (RLE), obtained from the by-product of high-yield selected plants and rich in polyphenols (334 mg/g, with diterpenes such as carnosic acid and carnosol as main compounds), is here proposed. Four RLE doses (0, 0.21, 0.42 and 0.63 g/kg) were tested in a salmon pâté formulated with sunflower oil and linseed, which was pasteurised (70 °C for 30 min) and subjected to storage at 4 °C and 600 lux for 42 days. Rosemary diterpenes resisted pasteurisation without degrading and showed antioxidant activities during the shelf-life of pasteurised pâté. RLE addition led to increased peroxide value (from 3.9 to 5.4 meq O2/kg), but inhibited formation of secondary oxidised lipids such as malondialdehyde (from 1.55 to 0.89 mg/g) and cholesterol oxidation products (from 286 to 102 µg/100 g) and avoided discolouration (slight brownness) in the refrigerated pâté. However, this did not entail relevant changes in fatty acid content or in the abundance of volatile organic compounds from oxidised lipids. Increasing the RLE dose only improved its antioxidant efficacy for some oxidation indexes. Thus, the oxidative deterioration of these types of fish emulsion can be naturally controlled with rosemary extracts rich in diterpenes.

Oxysterols profiles in zebrafish (Danio rerio) embryos exposed to bisphenol A

IntroductionOxysterols are cholesterol oxidation products and bioactive lipids involved in developmental signalling pathways, embryonic and postembryonic tissue patterning and homeostasis. The embryonic period is a very sensitive window of exposure to bisphenol A (BPA), hence the role of BPA on the levels of oxysterols in the very early stages of zebrafish embryogenesis is a relevant novel field of investigation. ObjectivesTo compare the role of BPA on oxysterols levels in zebrafish embryos at 8 and 24 h post fertilization (hpf) with cytochromes P450 (CYPs)-modulating chemicals (carbamazepine, ketoconazole, and hydrogen peroxide). MethodsUpon a dose range finding, zebrafish embryos were exposed to environmentally relevant (0.04 μM) and toxicological (17.5 μM) BPA concentrations. Seven oxysterols were profiled by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). ResultsSimilarly to the CYPs-modulating chemicals, BPA caused: i) no significant changes at 8 hpf and ii) a dose-dependent increase of total oxysterols at 24 hpf, with 27-hydroxycholesterol as the most regulated oxysterol. DiscussionIn the first day post-fertilization of the zebrafish embryos, the role of BPA alike a CYPs-modulating chemical was confirmed by the similar oxysterol changes observed with the already known CYPs-modulating chemicals.

Effects of Oxysterols on Immune Cells and Related Diseases.

Oxysterols are the products of cholesterol oxidation. They have a wide range of effects on several cells, organs, and systems in the body. Oxysterols also have an influence on the physiology of the immune system, from immune cell maturation and migration to innate and humoral immune responses. In this regard, oxysterols have been involved in several diseases that have an immune component, from autoimmune and neurodegenerative diseases to inflammatory diseases, atherosclerosis, and cancer. Here, we review data on the participation of oxysterols, mainly 25-hydroxycholesterol and 7α,25-dihydroxycholesterol, in the immune system and related diseases. The effects of these oxysterols and main oxysterol receptors, LXR and EBI2, in cells of the immune system (B cells, T cells, macrophages, dendritic cells, oligodendrocytes, and astrocytes), and in immune-related diseases, such as neurodegenerative diseases, intestinal diseases, cancer, respiratory diseases, and atherosclerosis, are discussed.

Parsley (Petroselinum crispum Mill.): A source of bioactive compounds as a domestic strategy to minimize cholesterol oxidation during the thermal preparation of omelets

This study evaluated the protective effect of parsley (Petroselinum crispum Mill.) against lipid and cholesterol oxidation in omelets prepared by air frying, pan frying, and microwaving. The bioactive composition and in vitro antioxidant capacity of parsley extract was characterized. Compounds such as phenolic acids and their derivatives (p-coumaric acid, p-coumaric acid 4-O-hexoside) and flavonoids (apigenin 7-glucoside, quercetin-O-pentosyl-hexoside) were identified in parsley by UHPLC-ESI-MS. Moreover, the presence of these bioactive constituents was investigated in omelets. Cooking induced lipid oxidation and increased the level of cholesterol oxidation products (COPs) in control omelets, which was more pronounced after air frying and microwaving. The total content of COPs increased from 40.69 ± 2.26 μg/g (raw) to 821.05 ± 13.77 μg/g (air frying), 805.21 ± 14.50 μg/g (microwaving), and 311.07 ± 13.84 μg/g (pan frying). The addition of parsley proved to be effective reducing COPs formation, mainly in air-fried samples with 0.75% parsley (81.73% of protection). Chromatographic analyses revealed the thermo-degradation of parsley compounds, since only two flavonoids detected in parsley were found in omelets containing the herb after cooking. Nonetheless, these findings indicate the potential application of parsley as a natural inhibitor of cholesterol and lipid oxidation in food systems such as omelets.