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Membrane-associated ring-CH-type finger 6 (MARCH6), also designated as TEB4 or RNF176, is an E3 ligase that is embedded in membranes of the endoplasmic reticulum where it ubiquitinates many substrate proteins to consign them to proteasome-mediated degradation. In recent years, MARCH6 has been identified as a key regulator of several metabolic pathways, including cholesterol and lipid droplet homeostasis, protein quality control, ferroptosis, and tumorigenesis. Despite its importance, there are currently no specific antibodies to detect and monitor MARCH6 levels in cultured cells and animals. Here, we address this deficiency by generating a monoclonal antibody that specifically detects MARCH6 in cultured cells of insect, mouse, hamster, and human origin, as well as in mouse tissues, with minimal cross-reactivity against other proteins. We then used this antibody to assess two properties of MARCH6. First, analysis of mouse tissues with this antibody revealed that the liver contained the highest levels of March6. Second, analysis of five different cell lines with this antibody showed that endogenous levels of MARCH6 are unchanged as the cellular content of cholesterol is varied. This reagent promises to be a useful tool in interrogating additional signaling roles of MARCH6.

Mitochondrial membranes are defined by their diverse functions, complex geometries, and unique lipidomes. In the inner mitochondrial membrane, highly curved membrane folds known as cristae house the electron transport chain and are the primary sites of cellular energy production. The outer mitochondrial membrane is flat by contrast, but is critical for the initiation and mediation of processes key to mitochondrial physiology: mitophagy, interorganelle contacts, fission and fusion dynamics, and metabolite transport. While the lipid composition of both the inner mitochondrial membrane and outer mitochondrial membrane have been characterized across a variety of cell types, a mechanistic understanding for how individual lipid classes contribute to mitochondrial structure and function remains nebulous. In this review, we address the biophysical properties of mitochondrial lipids and their related functional roles. We highlight the intrinsic curvature of the bulk mitochondrial phospholipid pool, with an emphasis on the nuances surrounding the mitochondrially-synthesized cardiolipin. We also outline emerging questions about other lipid classes — ether lipids, and sterols — with potential roles in mitochondrial physiology. We propose that further investigation is warranted to elucidate the specific properties of these lipids and their influence on mitochondrial architecture and function.

The aims of this study are the phytochemical exploration and food valorization of Schinus molle L. (S. molle) and Schinus terebinthifolia Raddi (S. terebinthifolia) from the Rabat, Morocco. Gas chromatography (GC) and high-performance liquid chromatography (HPLC) were used to analyze the chemical composition of the oils extracted from both species by soxhlet and maceration. Moreover, physicochemical characteristics such as lipid quality indexes such as thrombogenic index (TI), atherogenic index (AI), oxidation susceptibility (OS), and calculated oxidability (Cox) were determined. These characteristics included percentage acidity, peroxide, saponification, iodine, specific extinction values, chlorophyll, and carotenoid pigments. As results, the oil yields varied from 7% (S. molle) to 13% (S. terebinthifolia). In addition, unsaturated fatty acids represented the major fraction for S. terebinthifolia (79%) and S. molle (81%). However, S. terebinthifolia contains more saturated fatty acids (20%) than S. molle (16%) with a predominance of linoleic acid (59.53% and 55%, C18,2), oleic acid (19.29% and 21.69%, C18,1), and palmitic acid (12.56% and 15.48%, C16,0) in S. molle and S. terebinthifolia, respectively. Moreover, the main sterols are β-sitosterol followed by campesterol and then Δ-5-avenasterol, while β-sitosterol varies according to the species and the extraction method. Results revealed also that campesterol is influenced by the extraction results in a content of 179.66 mg/kg (soxhlet) and 63.48 mg/kg (maceration) for S. molle, while S. terebinthifolia yeilds concentrations of 170 mg/kg and 138 mg/kg, then Δ-5-avenasterol, which present with (117 mg/kg and 136 mg/kg), (34 mg/kg and 80 mg/kg) of the total amount of sterols for the oils extracted by soxhlet and maceration, respectively. In addition, there are favorable physicochemical properties for all oils, such as chlorophylls (0.4 to 0.8 mg/kg) and carotenoids (0.7 to 2 mg/kg). However, further investigations are needed to determine other chemical compounds of both extracts as well as to evaluate their biological and health benefits.

Nettle (Urtica dioica L.) root is a well-known source of valuable phytosterols, however scientific data regarding their composition are scarce. Therefore, this study aimed to examine the profile of phytosterols and triterpenes in nettle root (12 samples) harvested in three different climate regions and to provide more detailed information on the profile of nettle root lipophilic extract. Nettle root samples were extracted using n-hexane, while detection and quantification of phytosterols and triterpenes was achieved by GC–MS. Average content of total sterols was 0.80–0.86 g kg−1 dry weight and total pentacyclic triterpenes (PT) of 0.0048–0.0070 g kg−1. A total of 10 sterols and 3 PT were detected. The dominant sterol in all samples was β-sitosterol, followed by campesterol and stigmasterol. Lower quantities of Δ7 sterol - citrostadienol were detected. The dominant PT in root samples from warmer regions was β-amyrin acetate, while samples from the colder region showed the predominance of β-amyrin.

Background: Prion diseases involve the conversion of a normal, cell-surface glycoprotein (PrPC) into a misfolded pathogenic form (PrPSc). One possible strategy to inhibit PrPSc formation is to stabilize the native conformation of PrPC and interfere with the conversion of PrPC to PrPSc. Many compounds have been shown to inhibit the conversion process, however, no promising drugs have been identified to cure prion diseases. Objective: This study aims to identify potential anti-prion compounds from plant phytochemicals by integrating traditional ethnobotanical knowledge with modern in silico drug design approaches. Materials and methods: In the current study medicinal phytochemicals were docked with swapped and non-swapped crystal structures of PrPC in silico to identify potential anti-prions to determine their binding modes and interactions. Results: Eleven new phytochemicals were identified based on their binding energies and pharmacokinetic properties. The binding sites and interactions of the known and new anti-prion compounds are similar, and differences in binding modes occur in structures with very subtle differences in side chain conformations. Binding of these compounds poses steric hindrance to neighbouring molecules. Residues shown to be associated with the inhibition of PrPC to PrPSc conversion form interactions with most of the compounds. Conclusion: Identified compounds might act as potent inhibitors of PrPC to PrPSc conversion. These might be attractive candidates for the development of novel anti-prion therapy although further tests in vitro cell cultures and in vivo mouse models are needed to confirm these findings.

Invasion of human red blood cells by the malaria parasite Plasmodium falciparum is followed by dramatic modifications of erythrocytes properties, including de novo formation of new membrane systems. Lipid transfer proteins from both the parasite and the host cell are most likely an important part of those membrane remodeling processes. Using bioinformatics and in silico structural analysis, we have identified five P. falciparum potential lipid transfer proteins containing cellular retinaldehyde binding - triple functional domain (CRAL-TRIO). Two of these proteins, C6KTD4, encoded by the PF3D7_0629900 gene and Q8II87, encoded by the PF3D7_1127600 gene, were studied in more detail. In vitro lipid transfer assays using recombinant C6KTD4 and Q8II87 confirmed that these proteins are indeed bona fide lipid transfer proteins. C6KTD4 transfers sterols, phosphatidylinositol 4,5 bisphosphate, and, to some degree, also phosphatidylcholine between two membrane compartments. Q8II87 possesses phosphatidylserine transfer activity in vitro. In the yeast model, the expression of P. falciparumQ8II87 protein partially complements the absence of Sec14p and its closest homologue, Sfh1p. C6KTD4 protein can substitute for the collective essential function of oxysterol-binding related proteins. According to published whole genome studies in P. falciparum, absence of C6KTD4 and Q8II87 proteins has severe consequences for parasite viability. Therefore, CRAL-TRIO lipid transfer proteins of P. falciparum are potential targets of novel antimalarials, in search for which the yeast model expressing these proteins could be a valuable tool., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Taraxasterol is one of the bioactive ingredients from traditional Chinese herb Taraxacum, which exhibits multiple pharmacological activities and protective effects. However, the underlying influence and mechanism of its use against kidney damage caused from zearalenone (ZEA) remain unexplored. The ZEA-induced kidney damage model of mice was established by feeding diets containing ZEA (2 mg/kg), and taraxasterol (5 and 10 mg/kg) was administered by gavage for 28 days. Results demonstrated taraxasterol increased average daily gain (ADG) and average daily feed intake (ADFI), reduced feed-to-gain ratio (F/G) and kidney index of mice induced by ZEA. Taraxasterol alleviated histopathological changes of kidney, reduced ZEA residue and the levels of blood urea nitrogen (BUN), uric acid (UA), and creatinine (CRE). Concurrently, taraxasterol reduced the contents of oxidative stress indicator reactive oxygen species (ROS) and malondialdehyde (MDA), and increased the activities of antioxidant enzymes catalase (CAT), total superoxide dismutase (T-SOD), and glutathione peroxidase (GSH-Px). Further, taraxasterol up-regulated the mRNA and protein expression of nuclear factor erythroid-2-related factor 2 (Nrf2), GSH-Px, NAD(P)H quinone oxidoreductase 1 (NQO1), and heme oxygenase-1 (HO-1), and down-regulated the mRNA and protein expression of KELCH like ECH associated protein (Keap1) in Nrf2/Keap1 pathway. Taraxasterol down-regulated the mRNA and protein expression of immunoglobulin binding protein (Bip), C/EBP homologous protein (CHOP), Bcl-2 associated X (Bax), cysteine protease (Caspase)-12, and Caspase-3, and up-regulated B-cell lymphoma 2 (Bcl-2) expression in endoplasmic reticulum stress pathway. This study suggests that taraxasterol attenuates ZEA-induced mouse kidney damage through the modulation of Nrf2/Keapl pathway to play antioxidant role and endoplasmic reticulum stress pathway to enhance anti-apoptotic ability. It will provide a basis for taraxasterol as a potential drug to prevent and treat ZEA-induced kidney damage., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Membrane-associated ring-CH-type finger 6 (MARCH6), also designated as TEB4 or RNF176, is an E3 ligase that is embedded in membranes of the endoplasmic reticulum where it ubiquitinates many substrate proteins to consign them to proteasome-mediated degradation. In recent years, MARCH6 has been identified as a key regulator of several metabolic pathways, including cholesterol and lipid droplet homeostasis, protein quality control, ferroptosis, and tumorigenesis. Despite its importance, there are currently no specific antibodies to detect and monitor MARCH6 levels in cultured cells and animals. Here, we address this deficiency by generating a monoclonal antibody that specifically detects MARCH6 in cultured cells of insect, mouse, hamster, and human origin, as well as in mouse tissues, with minimal cross-reactivity against other proteins. We then used this antibody to assess two properties of MARCH6. First, analysis of mouse tissues with this antibody revealed that the liver contained the highest levels of March6. Second, analysis of five different cell lines with this antibody showed that endogenous levels of MARCH6 are unchanged as the cellular content of cholesterol is varied. This reagent promises to be a useful tool in interrogating additional signaling roles of MARCH6., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The Northern Patagonia coast, characterized by an intricate interaction among terrestrial and marine systems such as Reloncaví Estuarine System (RES), present highly productive marine and aquaculture activities, having a significant socio-economic importance in Chile. Understanding the composition of Organic Matter (OM) in aquatic ecosystems is crucial for elucidating biogeochemical processes, and the use of lipid biomarkers, has proven valuable in identifying OM sources. This study investigates the relationship between phytoplankton biomass indicators, including phytoplankton abundance, chlorophyll-a, and sterol molecules synthesized in high percentages by phytoplankton cells, also known as phytoplankton-derived sterols at the RES. The RES encompasses the Reloncaví Fjord (RF) and the Reloncaví Sound (RS) and exhibits a high influenced by oceanic waters and freshwater discharge from rivers Spatio-temporal sampling was conducted during the austral spring, summer and winter expeditions of 2018 and 2019, at two sites in RS and RF mouth (RFm). Our findings reveal higher sterol concentration at RFm than RS. Notably, high sterol concentrations during austral summer season coinciding with increased phytoplankton abundances. Furthermore, higher concentrations of terrestrial-derived sterols such as β-sitosterol (C 29 Δ 5 ) and stigmasterol (C 29 Δ 5,22 ), at RFm site suggested an input of OM from the inner RF. Phytoplankton-derived sterols such as 24-methylenecholesterol (C 28 Δ 5,24(28) ) provide a reliable estimate of total diatom abundance at both sites (RFm and RS), though they showed a lower relationship with taxonomic subgroups and phytoplankton classes in our study area. Hence, phytoplankton-derived sterols can be considered reliable diatom biomarkers, particularly in the RS, where the primary source of OM is predominantly marine, and even with high sterol degradation values at RES. Our study highlights the importance of interpreting changes in sterol abundances as phytoplankton community shifts. To avoid misinterpretation, it is essential to incorporate direct phytoplankton counts in elucidating the complex biosynthetic sources of sterols within the water column., Competing Interests: Declaration of competing interest The authors declare that they have no known conflicts of interest that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Mitochondrial membranes are defined by their diverse functions, complex geometries, and unique lipidomes. In the inner mitochondrial membrane, highly curved membrane folds known as cristae house the electron transport chain and are the primary sites of cellular energy production. The outer mitochondrial membrane is flat by contrast, but is critical for the initiation and mediation of processes key to mitochondrial physiology: mitophagy, interorganelle contacts, fission and fusion dynamics, and metabolite transport. While the lipid composition of both the inner mitochondrial membrane and outer mitochondrial membrane have been characterized across a variety of cell types, a mechanistic understanding for how individual lipid classes contribute to mitochondrial structure and function remains nebulous. In this review, we address the biophysical properties of mitochondrial lipids and their related functional roles. We highlight the intrinsic curvature of the bulk mitochondrial phospholipid pool, with an emphasis on the nuances surrounding the mitochondrially-synthesized cardiolipin. We also outline emerging questions about other lipid classes - ether lipids, and sterols - with potential roles in mitochondrial physiology. We propose that further investigation is warranted to elucidate the specific properties of these lipids and their influence on mitochondrial architecture and function., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Desulfation of cholesterol sulfate (CholS) to cholesterol (Chol) is an important event in epidermal homeostasis and necessary for stratum corneum (SC) barrier function. The CholS/Chol ratio decreases during SC maturation but remains high in pathological conditions, such as X-linked ichthyosis, characterized by dry and scaly skin. The aim of this study was to characterize the influence of the CholS/Chol molar ratio on the structure, dynamics, and permeability of SC lipid model mixtures. We synthesized deuterated CholS and investigated lipid models with specifically deuterated components using 2H solid-state NMR spectroscopy at temperatures from 25°C to 80°C. Although the rigid acyl chains in ceramides and fatty acids remained essentially rigid upon variation of the CholS/Chol ratio, both sterols were increasingly fluidized in lipid models containing higher CholS concentrations. We also show the X-ray repeat distance of the lipid lamellar phase (105 Å) and the orthorhombic chain packing of the ceramide’s acyl chains and long free fatty acids did not change upon the variation of the CholS content. However, the Chol phase separation visible in models with high Chol concentration disappeared at the 50:50 CholS/Chol ratio. This increased fluidity resulted in higher permeabilities to model markers of these SC models. These results reveal that a high CholS/Chol ratio fluidizes the sterol fraction and increases the permeability of the SC lipid phase while maintaining the lamellar lipid arrangement with an asymmetric sterol distribution.

Cytochrome P450s (P450s) are heme-containing proteins involved in several cellular functions, including biosynthesis of steroidal hormones, detoxification of xenobiotic compounds, among others. Damage response protein 1 (Dap1) has been described as a positive regulator of P450s through protein-protein interactions in organisms such as Schizosaccharomyces pombe. Three P450s in the carotenogenic yeast Xanthophyllomyces dendrorhous have thus far been characterized: Cyp51 and Cyp61, which are involved in ergosterol biosynthesis, and CrtS (astaxanthin synthase), which is involved in biosynthesis of the carotenoid astaxanthin. In this work, we describe the X. dendrorhous DAP1 gene, deletion of which affected yeast pigmentation by decreasing the astaxanthin fraction and increasing the β-carotene (a substrate of CrtS) fraction, which is consistent with the known role of CrtS. We found that the proportion of ergosterol was also decreased in the Δdap1 mutant. However, even though the fractions of the end products of these two pathways (the synthesis of carotenoids and sterols) were decreased in the Δdap1 mutant, the transcript levels of genes from the P450 systems involved were higher than those in the wild-type strain. We demonstrate that Dap1 coimmunoprecipitates with these three P450s, suggesting that Dap1 interacts with these three proteins. We propose that Dap1 regulates the synthesis of astaxanthin and ergosterol in X. dendrorhous, probably by regulating the P450s involved in both biosynthetic pathways at the protein level. This work suggests a new role for Dap1 in the regulation of carotenoid biosynthesis in X. dendrorhous.

Multi-component lipid emulsions, rather than soy-oil emulsions, prevent cholestasis by an unknown mechanism. Here, we quantified liver function, bile acid pools, and gut microbial and metabolite profiles in premature parenterally fed pigs given a soy-oil lipid emulsion, Intralipid (IL), a multi component lipid emulsion, SMOFlipid (SMOF), a novel emulsion with a modified fatty-acid composition [experimental emulsion (EXP)], or a control enteral diet (ENT) for 22 days. We assayed serum cholestasis markers, measured total bile acid levels in plasma, liver, and gut contents, and analyzed colonic bacterial 16S rRNA gene sequences and metabolomic profiles. Serum cholestasis markers (i.e., bilirubin, bile acids, and γ-glutamyl transferase) were highest in IL-fed pigs and normalized in those given SMOF, EXP, or ENT. Gut bile acid pools were lowest in the IL treatment and were increased in the SMOF and EXP treatments and comparable to ENT. Multiple bile acids, especially their conjugated forms, were higher in the colon contents of SMOF and EXP than in IL pigs. The colonic microbial communities of SMOF and EXP pigs had lower relative abundance of several gram-positive anaerobes, including Clostridrium XIVa, and higher abundance of Enterobacteriaceae than those of IL and ENT pigs. Differences in lipid and microbial-derived compounds were also observed in colon metabolite profiles. These results indicate that multi-component lipid emulsions prevent cholestasis and restore enterohepatic bile flow in association with gut microbial and metabolomic changes. We conclude that sustained bile flow induced by multi-component lipid emulsions likely exerts a dominant effect in reducing bile acid-sensitive gram-positive bacteria.

The ethanol solution extraction of sterols from discarded soybean pod was studied. The effects of factors on sterols yield was investigated by single factor experiment. On this basis, liquid to material ratio, ethanol concentration, extraction time and extraction temperature were selected, response surface method was used to optimize the extraction process of sterols. The model between extraction conditions and yield was established and analyzed for obtaining the optimal technological parameters and improve the sterols yield. The results showed that the sterols yield was significantly affected by the above four selected factors. The model obtained was significant. The optimum technological conditions of the ethanol extraction of soybean pod sterols were the liquid to material ratio of 26.8 mL g-1, ethanol concentration of 72.4%, extracting time of 1.86 h, extraction temperature of 68.4 °C. The theoretical maximum sterols yield was 7.82 mg g-1, the actual sterols yield was 7.74 mg g-1.

In order to make full use of biomass resources and extract sterols from the waste soybean pods, the mass transfer characteristic of the extraction process with ethanol aqueous solution was explored. The relationships between sterols mass concentration in extracting solution and extraction temperature and extraction time were studied under appropriate ethanol concentration and liquid-solid ratio. The kinetics model fitting, the mass transfer characteristic parameters research and thermodynamic analysis of extraction process were carried out. The result showed that the extraction process could be described by a second order kinetic model. Within the research scope, with the increase of extraction temperature, the mass transfer rate constant increased from 0.286 9 mL min−1 mg−1 to 0.848 5 mL min−1 mg−1, the half life was reduced from 20.9 min to 6.5 min, the activation energy of extraction process was 27.73 kJ mol−1. The Gibbs free energies were all less than zero, indicating that the sterols extraction process was spontaneous. The enthalpy change was 33.18 kJ mol−1 and entropy change was 122.2 J mol−1 K−1 in the extraction process, the extraction process was an endothermic and entropy increases process. The research results could provide reference for the large-scale extraction of sterols from soybean pods.

Lipid droplets (LD) are highly dynamic organelles specialized for the regulation of energy storage and cellular homeostasis. LD consist of a neutral lipid core surrounded by a phospholipid monolayer membrane with embedded proteins, most of which are involved in lipid homeostasis. In this study, we focused on one of the major LD proteins, sterol C24-methyltransferase, encoded by ERG6. We found that the absence of Erg6p resulted in an increased accumulation of yeast perilipin Pet10p in LD, while the disruption of PET10 was accompanied by Erg6p LD over-accumulation. An observed reciprocal enrichment of Erg6p and Pet10p in pet10Δ and erg6Δ mutants in LD, respectively, was related to specific functional changes in the LD and was not due to regulation on the expression level. The involvement of Pet10p in neutral lipid homeostasis was observed in experiments that focused on the dynamics of neutral lipid mobilization as time-dependent changes in the triacylglycerols (TAG) and steryl esters (SE) content. We found that the kinetics of SE hydrolysis was reduced in erg6Δ cells and the mobilization of SE was completely lost in mutants that lacked both Erg6p and Pet10p. In addition, we observed that decreased levels of SE in erg6Δpet10Δ was linked to an overexpression of steryl ester hydrolase Yeh1p. Lipid analysis of erg6Δpet10Δ showed that PET10 deletion altered the composition of ergosterol intermediates which had accumulated in erg6Δ. In conclusion, yeast perilipin Pet10p functionally interacts with Erg6p during the metabolism of ergosterol., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Summary: Clathrin-mediated endocytosis (CME) is critical for cellular signal transduction, receptor recycling, and membrane homeostasis in mammalian cells. Acute depletion of cholesterol disrupts CME, motivating analysis of CME dynamics in the context of human disorders of cholesterol metabolism. We report that inhibition of post-squalene cholesterol biosynthesis impairs CME. Imaging of membrane bending dynamics and the CME pit ultrastructure reveals prolonged clathrin pit lifetimes and shallow clathrin-coated structures, suggesting progressive impairment of curvature generation correlates with diminishing sterol abundance. Sterol structural requirements for efficient CME include 3′ polar head group and B-ring conformation, resembling the sterol structural prerequisites for tight lipid packing and polarity. Furthermore, Smith-Lemli-Opitz fibroblasts with low cholesterol abundance exhibit deficits in CME-mediated transferrin internalization. We conclude that sterols lower the energetic costs of membrane bending during pit formation and vesicular scission during CME and suggest that reduced CME activity may contribute to cellular phenotypes observed within disorders of cholesterol metabolism.

Mango is one of the most popular fruit in tropical and subtropical regions of the world. In this study, previously undescribed two sterols (1–2) and one terpenoid (10), as well as ten known phytochemicals (3–9, 11–13), were isolated and identified from mango fruits. In vitro anti-neuroinflammatory activity of the purified compounds was evaluated and most of them exhibited pronounced bioactivity. Among them, compounds 2 and 5 exhibited the most significant anti-neuroinflammatory effects, which were comparable to that of indomethacin (positive control) and suggested that the sterols in the fruits of mango played important roles for the anti-neuroinflammatory activity. Further, Western blotting, quantitative PCR and immunofluorescence staining assays were performed to confirm that compounds 2 and 5 exerted the anti-neuroinflammatory through the NF-κB pathway. The study provided a phytochemical evidence for further development and utilization of the fruits of mango in health products.

Skin aging is a degenerative process with a tremendous impact on appearance and quality of life, which is believed to be an emerging health issue in accordance with the growing aging population. Lipids play a vital role in skin as a barrier and as building blocks for cell membrane and a variety of bioactive molecules. The latest evidence has indicated that the supplementation of certain types of fatty acids and sterols may modulate skin cell function differentially. This review summarizes the recent findings and potential mechanisms of the modulating effect of dietary supplementation and topical application of different classes of fatty acids and sterols on skin aging.

Food adulteration is a serious social problem all over the world. The oil obtained from the niger and sesame is known for its quality and has a high market value in Ethiopia. The cost of the oil obtained from these oilseed crops is high unlike other plant oils, thus prone to be mixed with other cheap oils to increase profits. The study aimed to quantify the sterol profile of niger seed and sesame oils thereby trace adulteration of these oils with palm oil. Gas Chromatography coupled to Mass Spectrometry was used to analyze the sterol fractions of oils. A blend of palm oil, at a level of 10%, with niger seed and sesame oil was prepared. In all the studied oils; sitosterol (467.2–2778.96 mg/kg), campesterol (295.9–869.85 mg/kg) and stigmasterol (125.6–920 mg/kg) were the dominant sterols identified. Lupeol, Lanosterol, and Olean-12-en-3-one were only identified in a significant proportion for niger seed oil. Moreover, cholestroltrimethyl silyl ether (19.9 mg/kg) and 24-Nor-22,23- methylenecholest-5-en-3β-ol trimethylsilyl (TMS) ethers (139.14 mg/kg) were only identified in palm oil and used to trace adulteration. An attempt made to trace these compounds by mixing palm oil at a level of 10% with niger seed and sesame oils was successfully detected its presence. Hence, as the physicochemical properties of oils can be arranged to cover adulteration, marker identification provides a reliable identity of the specific oil.

A variety of biomarkers of sediment core KET-1 were studied to reconstruct both paleoproductivity and phytoplankton community structure variations and to reflect the local climate change of Kuroshio mainstream of east Taiwan over the past millennium. The results showed that sterols in sediments derived from the mixed terrestrial and marine inputs, with the riverine input from eastern Taiwan as the main terrestrial sterol source. The upward increase of terrestrial organic matter over the past millennium suggested the increasing riverine input of eastern Taiwan. The variation of the marine primary productivity was mainly influenced by the nutrient supplements from the riverine input. The changes of brassicasterol to dinosterol ratio indicated a phytoplankton community shift from dinoflagellate-dominated to diatom-dominated since 1500 CE. The increasing terrestrial inputs and the change of phytoplankton community change over time were related to “dry-humid” climate change.

1H-NMR spectroscopy is emerging as powerful robust analytical technique in analyzing bio constituents present in plants. It offers non-invasive method for identification and quantification of several Phyto-constitutes in a single step without much pre-processing of the samples. In the present study, 1H-NMR spectroscopy-based lipid profiling was performed on Gossypium hirsutum seeds, which were collected at different developmental stages. 1H-NMR study reveals the presence of sterols, butyl ester of fatty acids, free fatty acids (FFA), triacyl glycerides (TAG), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) at different percentage at different developmental stages. The 1H-NMR result demonstrates the presence of high concentration of FFA in early developmental stage and increased concentration of TAG at maturation stage. The 1H-NMR results suggest that stage III of seed development can be identified as turning point, as at this stage sterols and butyl ester of fatty acids becomes insignificant followed by high accumulation of TAG.

Triazole fungicides are widely used to treat cereal seeds before sowing. Granivorous birds like the Red-legged Partridge (Alectoris rufa) have high exposure risk because they ingest treated seeds that remain on the field surface. As triazole fungicides can act as endocrine disruptors, affecting sterol synthesis and reproduction in birds several months after exposure, we hypothesized that these effects could also impact subsequent generations of exposed birds. To test this hypothesis, we exposed adult partridges (F0) to seeds treated at commercial doses with four different formulations containing triazoles as active ingredients (flutriafol, prothioconazole, tebuconazole, and a mixture of the latter two), simulating field exposure during late autumn sowing. During the subsequent reproductive season, two to four months after exposure, we examined compound allocation of steroid hormones, cholesterol, vitamins, and carotenoids in eggs laid by exposed birds (F1), as well as the expression of genes encoding enzymes involved in sterol biosynthesis in one-day-old chicks of this F1. One year later, F1 animals were paired again to investigate the expression of the same genes in the F2 chicks. We found changes in the expression of some genes for all treatments and both generations. Additionally, we observed an increase in estrone levels in eggs from partridges treated with flutriafol compared to controls, a decrease in tocopherol levels in partridges exposed to the mixture of tebuconazole and prothioconazole, and an increase in retinol levels in partridges exposed to prothioconazole. Despite sample size limitations, this study provides novel insights into the mechanisms of action of the previously observed effects of triazole fungicide-treated seeds on avian reproduction with evidence that the effects can persist beyond the exposure windows, affecting unexposed offspring of partridges fed with treated seeds. The results highlight the importance of considering long-term chronic effects when assessing pesticide risks to wild birds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background & Aims: Increasing evidence suggests that high cholesterol absorption efficiency enhances the risk of atherosclerotic cardiovascular diseases. It is not known whether inhibiting cholesterol absorption has different metabolic effects in high- vs. low cholesterol absorbers. We evaluated the effects of phytostanol esters on serum lipids and cholesterol metabolism in a post hoc study of three randomized, double-blind, controlled trials. The participants were classified into low (n = 20) and high (n = 21) cholesterol absorbers by median cholesterol absorption efficiency based on the plasma cholesterol absorption marker cholestanol at baseline., Methods: The participants consumed mayonnaise or margarine without or with phytostanol esters for six to nine weeks without other changes in the diet or lifestyle. Serum cholesterol, cholestanol, lathosterol, and faecal neutral sterols and bile acids were analysed by gas-liquid chromatography. According to power calculations, the size of the study population (n = 41) was appropriate., Results: During the control period, cholesterol synthesis, and faecal neutral sterols and bile acids were lower in high- vs. low absorbers (p < 0.05 for all). Phytostanol esters reduced low-density lipoprotein cholesterol by 10-13% in both groups, and directly measured cholesterol absorption efficiency by 41 ± 7% in low- and 47 ± 5% in high absorbers (p < 0.001 for all) without side effects. Cholesterol synthesis and faecal neutral sterols (p < 0.01) increased in both groups, more markedly in the high vs. low absorbers (p < 0.01)., Conclusions: Low cholesterol absorption combined with high faecal neutral sterol excretion are components of reverse cholesterol transport. Thus, high- vs. low absorbers had a more disadvantageous metabolic profile at baseline. In both groups, phytostanol esters induced favourable changes in serum, lipoprotein, and metabolic variables known to help in prevention of the development of atherosclerotic cardiovascular diseases., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In the present study, modified extraction methods using supercritical CO2 were investigated in order to obtain high-added value compounds from rapeseed oil deodorizer distillate and comparisons were done with modified Soxhlet extraction (solvent extraction + silica). For supercritical fluid extraction (SFE), the optimal extraction parameters were temperature of 40 °C, pressure of 350 bar (for phytosterols), 400 bar (for tocopherol), 5 wt% ethanol as co-solvent, and saponification pretreatment. The optimized SFE procedure led to the recovery of three main phytosterols (50 wt % β-sitosterol, 23.91 wt % Brassicasterol, and 36.25 wt % Campesterol) and only α-tocopherol. Moreover, there was no synergistic effect with saponification pretreatment + co-solvent and the efficiency and concentration of target compounds were less than supercritical CO2 + co-solvent. Also, comparative Data showed that the efficiency of phytosterols and tocopherols was approximately three times higher (p < 0.05) in SFE relative to modified Soxhlet extraction. Furthermore, the use of ethanol (5 wt %) as co-solvent, improved phytosterols and tocopherol efficiency and purity. The SFE technique offers various advantages over the modified Soxhlet extraction technique, including increasing the solubility of tocopherols and sterols by using CO2+ co-solvent, minimized usage of toxic organic solvents and increased purity of extracted products.

Regulating blood cholesterol (Chol) levels by pharmacotherapy has successfully improved cardiovascular health. There is growing interest in the role of Chol precursors in the treatment of diseases. One sterol precursor, desmosterol (Des), is a potential pharmacological target for inflammatory and neurodegenerative disorders. However, elevating levels of the precursor 7-dehydrocholesterol (7-DHC) by inhibiting the enzyme 7-dehydrocholesterol reductase is linked to teratogenic outcomes. Thus, altering the sterol profile may either increase risk toward an adverse outcome or confer therapeutic benefit depending on the metabolite affected by the pharmacophore. In order to characterize any unknown activity of drugs on Chol biosynthesis, a chemical library of Food and Drug Administration-approved drugs was screened for the potential to modulate 7-DHC or Des levels in a neural cell line. Over 20% of the collection was shown to impact Chol biosynthesis, including 75 compounds that alter 7-DHC levels and 49 that modulate Des levels. Evidence is provided that three tyrosine kinase inhibitors, imatinib, ponatinib, and masitinib, elevate Des levels as well as other substrates of 24-dehydrocholesterol reductase, the enzyme responsible for converting Des to Chol. Additionally, the mechanism of action for ponatinib and masitinib was explored, demonstrating that protein levels are decreased as a result of treatment with these drugs.

7-Oxocholesterol (7-OC), 5,6-epoxycholesterol (5,6-EC), and its hydrolysis product cholestane-3β,5α,6β-triol (3β,5α,6β-triol) are normally minor oxysterols in human samples; however, in disease, their levels may be greatly elevated. This is the case in plasma from patients suffering from some lysosomal storage disorders, e.g., Niemann-Pick disease type C, or the inborn errors of sterol metabolism, e.g., Smith-Lemli-Opitz syndrome and cerebrotendinous xanthomatosis. A complication in the analysis of 7-OC and 5,6-EC is that they can also be formed ex vivo from cholesterol during sample handling in air, causing confusion with molecules formed in vivo. When formed endogenously, 7-OC, 5,6-EC, and 3β,5α,6β-triol can be converted to bile acids. Here, we describe methodology based on chemical derivatization and LC/MS with multistage fragmentation (MSn) to identify the necessary intermediates in the conversion of 7-OC to 3β-hydroxy-7-oxochol-5-enoic acid and 5,6-EC and 3β,5α,6β-triol to 3β,5α,6β-trihydroxycholanoic acid. Identification of intermediate metabolites is facilitated by their unusual MSn fragmentation patterns. Semiquantitative measurements are possible, but absolute values await the synthesis of isotope-labeled standards.

7S protein is one of four major storage proteins in soybean. The present study compared the relative cholesterol-lowering activity of the 7S protein with that of total soybean protein isolate (SPI). Forty-eight hamsters were divided into six groups fed non-cholesterol diet or one of five high-cholesterol diets containing 24.2% casein, 12.1–24.2% SPI, 12.1–24.2% 7S protein, respectively. Results showed the 7S protein reduced plasma total cholesterol (TC) by 20–41% while SPI reduced it by 9–16%. 7S protein increased the fecal excretion of neutral sterols by 43–116%, while SPI only had 18–68% increase. 7S protein increased the excretion of total bile acids by 208–367%, while SPI only increased it by 41–86%. 7S protein could not only down regulate gene expression of HMG-CoA reductase but also up regulate gene expression of CYP7A1. It was concluded that dietary 7S protein was more hypocholesterolemic than SPI, mediated by increasing the sterol excretion and decreasing the cholesterol synthesis.

Cholesterol-protein interactions are essential for the architectural organization of cell membranes and for lipid metabolism. While cholesterol-sensing motifs in transmembrane proteins have been identified, little is known about cholesterol recognition by soluble proteins. We reviewed the structural characteristics of binding sites for cholesterol and cholesterol sulfate from crystallographic structures available in the Protein Data Bank. This analysis unveiled key features of cholesterol-binding sites that are present in either all or the majority of sites: i) the cholesterol molecule is generally positioned between protein domains that have an organized secondary structure; ii) the cholesterol hydroxyl/sulfo group is often partnered by Asn, Gln, and/or Tyr, while the hydrophobic part of cholesterol interacts with Leu, Ile, Val, and/or Phe; iii) cholesterol hydrogen-bonding partners are often found on α-helices, while amino acids that interact with cholesterol's hydrophobic core have a slight preference for β-strands and secondary structure-lacking protein areas; iv) the steroid's C21 and C26 constitute the “hot spots” most often seen for steroid-protein hydrophobic interactions; v) common “cold spots” are C8–C10, C13, and C17, at which contacts with the proteins were not detected. Several common features we identified for soluble protein-steroid interaction appear evolutionarily conserved.

This study investigated the biocatalytic performance of immobilized cholesterol oxidase (CHOD) on magnetite-based carbon (MBC) for degrading cholesterol. The results showed that MBC-CHOD exhibited higher activity and good affinity towards substrate compared to free enzyme and other immobilized enzymes. Mass spectra analysis revealed that MBC-CHOD damaged the main structure of cholesterol, benefitting the further biological treatment. The study proposes a Fenton process mechanism by which H 2 O 2 is transferred to free radicals such as ·OH under acidic conditions, promoting further substrate degradation. This suggests that MBC-CHOD has a relay run property leading to high degradation of cholesterol. Molecular docking indicates that cholesterol preferentially binds to TYR-28 residue and LYS-138 residue in CHOD through hydrogen bonds. Overall, MBC-CHOD proved to be a promising candidate for efficient and sustainable cholesterol degradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Herein we report an unprecedented and efficient methodology for accessing 6-alkoxy-Δ 4,6 -diene-3-one derivatives. Such scaffolds were serendipitously obtained in the course of the study of the reaction of Δ 4 -3-keto steroids with catalytic amounts of iodine in refluxing methanol. A series of 6-methoxy and 6-ethoxy- Δ 4,6 -diene-3-ones were prepared from easily-available sterols in a two-step sequence; first, oxidation of sterols furnished the Δ 4 -3-keto steroids, which were then refluxed with ethanol or methanol with I 2 as catalyst to obtain a series of ten derivatives. Furthermore, this protocol was also effective for the introduction of a larger carbon chain at C-6. Druglikeliness properties of synthesized compounds were predicted using the SwissADME tool., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

ABCG5 (G5) and ABCG8 (G8) form a sterol transporter that acts in liver and intestine to prevent accumulation of dietary sterols. Mutations in either G5 or G8 cause sitosterolemia, a recessive disorder characterized by sterol accumulation and premature coronary atherosclerosis. Hepatic G5G8 mediates cholesterol excretion into bile, but the function and relative importance of intestinal G5G8 has not been defined. To determine the role of intestinal G5G8, we developed liver-specific (L-G5G8−/−), intestine-specific (I-G5G8−/−), and total (G5G8−/−) KO mice. Tissue levels of sitosterol, the most abundant plant sterol, were >90-fold higher in G5G8−/− mice than in WT animals. Expression of G5G8 only in intestine or only in liver decreased tissue sterol levels by 90% when compared with G5G8−/− animals. Biliary sterol secretion was reduced in L-G5G8−/− and G5G8−/− mice, but not in I-G5G8−/− mice. Conversely, absorption of plant sterols was increased in I-G5G8−/− and G5G8−/− mice, but not in L-G5G8−/− mice. Reverse cholesterol transport, as assessed from the fraction of intravenously administered 3H-cholesterol that appeared in feces, was reduced in G5G8−/−, I-G5G8−/−, and L-G5G8−/− mice. Thus, G5G8 expression in both the liver and intestine protects animals from sterol accumulation, and intestinal G5G8 contributes to extrahepatic cholesterol efflux in mice.

Evening primrose oil (EPO) is widely used as a dietary supplement from which beneficial effects have been reported in rheumatic and arthritic conditions, atopic dermatitis, psoriasis, premenstrual and menopausal syndrome, and diabetic neuropathy. The aim of this study was to determine whether phytosterols isolated from evening primrose oil (PS-EPO), and its main components β-sitosterol and campesterol, affect proliferation, cell death, and the cell cycle of human colon adenocarcinoma (HT-29) cells. PS-EPO were a potent antiproliferative agents in a dose- and time-dependent manner, with an IC50 of 62.9 µg/mL after 48 h, lower than β-sitosterol and campesterol (79.0 µM and 71.6 µM respectively). Flow cytometry showed that PS-EPO exerted a stimulatory effect on apoptosis and necrosis, increasing the number of cells in G0/G1 phase. PS-EPO produced a significant upregulation in liver X receptor (LXR) gene expression that may be one of the principal mechanisms of the tumor shrinkage by PS-EPO.

Six steroid conjugates of bile acids and sterol derivatives have been synthesized using the click chemistry method. The azide-alkyne Huisgen cycloaddition of the propionyl ester of lithocholic, deoxycholic and cholic acid with azide derivatives of cholesterol and cholestanol gave new bile acid-sterol conjugates linked with a 1,2,3-triazole ring. Previously, sterols were converted to bromoacetate substituted derivatives by reaction with bromoacetic acid bromide in anhydrous dichloromethane. These compounds were then converted to azide derivatives using sodium azide. The propiolic esters of lithocholic, deoxycholic and cholic acids were obtained by reaction with propiolic acid in the presence of p-toluenesulfonic acid. Additionally, two of these steroids: methyl 3α-propynoyloxy-12α-acetoxy-5β-cholane-24-oate and methyl 3α-propynoyloxy-7 α,12α-diacetoxy-5β-cholane-24-oate were also obtained and characterized for the first time. All conjugates were obtained in good yields using an efficient synthesis method. The structures of all conjugates and the four substrates were confirmed by spectral ( 1 H- and 13 C NMR, FT-IR) analysis, mass spectrometry (ESI-MS), and PM5 semiempirical methods. The pharmacotherapeutic potential of the synthesized compounds was estimated based on the in silico Prediction of Activity Spectra for Substances (PASS) method. The cytotoxicity of the compounds was in vitro evaluated in a hemolytic assay using human erythrocytes as a cell model. The in silico and in vitro study results indicate that the selected compound possesses an interesting biological activity and can be considered as potential drug design agent. Additionally, molecular docking was performed for the selected conjugate., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Sterols have several roles in planta, including as membrane components. Sterols are also essential nutrients for insects. Based on this, and the different functions of leaves and pollen, we tested the hypotheses that (a) the sterolome is different in leaves and pollen from the same plant, (b) pollens from wind- and insect pollinated plants comprise different sterols, and (c) sterol provision in pollen-rewarding angiosperms differs from nectar-rewarding species. A novel approach to sterolomics was developed, using LCMS to determine the sterol profile of leaf and pollen from a taxonomically diverse range of 36 plant species. Twenty-one sterols were identified unambiguously, with several more identified in trace amounts. C 29 sterols dominated the sterolome in most plants. The sterol composition was significantly different in leaf and pollen and their main sterols evolved in different ways. The sterolome of pollen from animal- and wind-pollinated was also significantly different, but not between nectar- and pollen-rewarding species. Our results suggest that the sterol composition in different plant tissues is linked to their biological functions. Sterol composition in pollen might be driven by physical role rather than the nutrient needs of pollinating insects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Tibetan chickens (Gallus gallus; TBCs) are a good model for studying hypoxia-related challenges. However, lipid composition in TBC embryonic brains has not been elucidated. In this study, we characterized brain lipid profiles of embryonic day 18 TBCs and dwarf laying chickens (DLCs) during hypoxia (13% O 2 , HTBC18, and HDLC18) and normoxia (21% O 2 , NTBC18, and NDLC18) by using lipidomics. A total of 50 lipid classes, including 3540 lipid molecular species, were identified and grouped into glycerophospholipids, sphingolipids, glycerolipids, sterols, prenols, and fatty acyls. Of these lipids, 67 and 97 were expressed at different levels in the NTBC18 and NDLC18, and HTBC18 and HDLC18 samples, respectively. Several lipid species, including phosphatidylethanolamines (PEs), hexosylceramides, phosphatidylcholines (PCs), and phospha-tidylserines (PSs), were highly expressed in HTBC18. These results suggest that TBCs adapt bet-ter to hypoxia than DLCs and may have distinct cell membrane composition and nervous system development, at least partly owing to differential expression of several lipid species. One tri-glyceride, one PC, one PS, and three PE lipids were identified as potential markers that discrim-inated between lipid profiles of the HTBC18 and HDLC18 samples. The present study provides valuable information about the dynamic composition of lipids in TBCs that may explain the adaptation of this species to hypoxia., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2023. Published by Elsevier Inc.)

Cytochromes P450 (CYP), enzymes involved in the metabolism of endogenous and xenobiotic substrates, provide an excellent model system to study how membrane proteins with unique functions have catalytically adapted through evolution. Molecular adaptation of deep-sea proteins to high hydrostatic pressure remains poorly understood. Herein, we have characterized recombinant cytochrome P450 sterol 14α-demethylase (CYP51), an essential enzyme of cholesterol biosynthesis, from an abyssal fish species, Coryphaenoides armatus. C. armatus CYP51 was heterologously expressed in Escherichia coli following N-terminal truncation and purified to homogeneity. Recombinant C. armatus CYP51 bound its sterol substrate lanosterol giving a Type I binding spectra (K D 15 μM) and catalyzed lanosterol 14α-demethylation turnover at 5.8 nmol/min/nmol P450. C. armatus CYP51 also bound the azole antifungals ketoconazole (K D 0.12 μM) and propiconazole (K D 0.54 μM) as determined by Type II absorbance spectra. Comparison of C. armatus CYP51 primary sequence and modeled structures with other CYP51s identified amino acid substitutions that may confer an ability to function under pressures of the deep sea and revealed heretofore undescribed internal cavities in human and other non-deep sea CYP51s. The functional significance of these cavities is not known. PROLOGUE: This paper is dedicated in memory of Michael Waterman and Tsuneo Omura, who as good friends and colleagues enriched our lives. They continue to inspire us., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Prion diseases involve the conversion of a normal, cell-surface glycoprotein (PrP C ) into a misfolded pathogenic form (PrP Sc ). One possible strategy to inhibit PrP Sc formation is to stabilize the native conformation of PrP C and interfere with the conversion of PrP C to PrP Sc . Many compounds have been shown to inhibit the conversion process, however, no promising drugs have been identified to cure prion diseases., Objective: This study aims to identify potential anti-prion compounds from plant phytochemicals by integrating traditional ethnobotanical knowledge with modern in silico drug design approaches., Materials and Methods: In the current study medicinal phytochemicals were docked with swapped and non-swapped crystal structures of PrP C in silico to identify potential anti-prions to determine their binding modes and interactions., Results: Eleven new phytochemicals were identified based on their binding energies and pharmacokinetic properties. The binding sites and interactions of the known and new anti-prion compounds are similar, and differences in binding modes occur in structures with very subtle differences in side chain conformations. Binding of these compounds poses steric hindrance to neighbouring molecules. Residues shown to be associated with the inhibition of PrP C to PrP Sc conversion form interactions with most of the compounds., Conclusion: Identified compounds might act as potent inhibitors of PrP C to PrP Sc conversion. These might be attractive candidates for the development of novel anti-prion therapy although further tests in vitro cell cultures and in vivo mouse models are needed to confirm these findings., Competing Interests: Declaration of competing interest None., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Nigrograna sp. LY66, an endophytic fungus associated with the herbal medicinal plant Clematis shensiensis, produced four undescribed steroids, nigergostanes A-D (1-4), including an unusual ketal-containing nigergostane (1), and four undescribed sesquiterpenoids decorated with cyclohexanone motifs, nigbisabolanes A-D (7-10), along with three known compounds, 23R-hydroxy-(20Z,24R)-ergosta-4,6,8(14),20(22)-tetraen-3-one (5), ergosta-5,7,22-trien-3β-ol (6), and curculonone A (11). The structures and absolute configurations of these undescribed compounds were confirmed using spectroscopic data (NMR and HRESIMS), modified Mosher's method, and ECD experiments. Additionally, compounds 5 and 8 displayed significant inhibition of nitric oxide generation in lipopolysaccharide-induced BV-2 microglial cells with IC 50 values of 2.8 and 2.7 μM, respectively, and is thus more potent than that of the positive control, quercetin (IC 50  = 8.77 μM). A molecular docking study revealed that 23-OH of 5 binds to the Y347 residue of inducible nitric oxide synthase (iNOS), whereas the 2-OH and 9,10-diol moieties of 8 bind to R381 and W463 and haeme residues of iNOS, respectively, which has rarely been reported in previous studies. These findings provide a set of undescribed lead compounds that can be developed into anti-neuroinflammatory agents., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Phytosterols are essential structural components of plant cell membranes and possess health-related benefits, including lowering blood cholesterol levels in humans. Numerous analytical methods are being used to profile plant and animal sterols. Chromatography hyphenated to tandem mass spectrometry, is a better option due to its specificity, selectivity, and sensitivity. An ultra-performance supercritical fluid chromatography hyphenated with atmospheric pressure chemical ionization (APCI) tandem mass spectrometric method was developed and evaluated for fingerprint analysis of seven phytosterols. Mass spectrometry fragmentation behavior was used for phytosterol identification, and multiple reaction monitoring scanning was utilized for phytosterol confirmation, where APCI outperformed superiority in terms of ion intensity, particularly in the production of [M + H-H 2 O] + ions rather than [M + H] + ions. The chromatographic conditions were thoroughly evaluated, and the ionization parameters were optimized as well. In a 3 min. run, the seven phytosterols were separated concurrently. The calibration and repeatability tests were conducted to check the instrument's performance, and the results indicated that all of the phytosterols tested had correlation coefficients (r 2 ) greater than 0.9911 over the concentration range of 5-5000 ng/mL. The limit of quantification was below 20 ng/mL for all the tested analytes except for stigmasterol and campesterol. The partially validated method was applied for the evaluation of phytosterols in pure coconut oil and palm oil in order to demonstrate its applicability. Total sterols in coconut and palm oils were 126.77 ng/mL and 101.73 ng/mL, respectively. In comparison to earlier methods of phytosterol analysis, the novel method offers a far faster, more sensitive, and more selective analytical process., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: S. J. Kumari A. Ubhayasekera reports a relationship with Uppsala University that includes: employment. No other activities., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

This review considers the hypothesis that a small portion of plasma membrane cholesterol regulates reverse cholesterol transport in coordination with overall cellular homeostasis. It appears that almost all of the plasma membrane cholesterol is held in stoichiometric complexes with bilayer phospholipids. The minor fraction of cholesterol that exceeds the complexation capacity of the phospholipids is called active cholesterol. It has an elevated chemical activity and circulates among the organelles. It also moves down its chemical activity gradient to plasma HDL, facilitated by the activity of ABCA1, ABCG1, and SR-BI. ABCA1 initiates this process by perturbing the organization of the plasma membrane bilayer, thereby priming its phospholipids for translocation to apoA-I to form nascent HDL. The active excess sterol and that activated by ABCA1 itself follow the phospholipids to the nascent HDL. ABCG1 similarly rearranges the bilayer and sends additional active cholesterol to nascent HDL, while SR-BI simply facilitates the equilibration of the active sterol between plasma membranes and plasma proteins. Active cholesterol also flows downhill to cytoplasmic membranes where it serves both as a feedback signal to homeostatic ER proteins and as the substrate for the synthesis of mitochondrial 27-hydroxycholesterol (27HC). 27HC binds the LXR and promotes the expression of the aforementioned transport proteins. 27HC-LXR also activates ABCA1 by competitively displacing its inhibitor, unliganded LXR. § Considerable indirect evidence suggests that active cholesterol serves as both a substrate and a feedback signal for reverse cholesterol transport. Direct tests of this novel hypothesis are proposed., Competing Interests: Conflict of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Skin surface lipids (SSLs) arising from both sebaceous glands and skin removal form a complex lipid mixture composed of free fatty acids and neutral lipids. High-temperature gas chromatography coupled with electron impact or chemical ionization mass spectrometry was used to achieve a simple analytical protocol, without prior separation in classes and without prior cleavage of lipid molecules, in order to obtain simultaneously i) a qualitative characterization of the individual SSLs and ii) a quantitative evaluation of lipid classes. The method was first optimized with SSLs collected from the forehead of a volunteer. More than 200 compounds were identified in the same run. These compounds have been classified in five lipid classes: free fatty acids, hydrocarbons, waxes, sterols, and glycerides. The advantage to this method was it provided structural information on intact compounds, which is new for cholesteryl esters and glycerides, and to obtain detailed fingerprints of the major SSLs. These fingerprints were used to compare the SSL compositions from different body areas. The squalene/cholesterol ratio was used to determine the balance between sebaceous secretion and skin removal. This method could be of general interest in fields where complex lipid mixtures are involved.

Grain sorghum is a rich source of phytochemicals. In this study, male hamsters were fed AIN-93M diets supplemented with a hexane-extractable lipid fraction from sorghum distillers dried grains with solubles (DDGS). Diets contained 0.0%, 0.5%, 1.0%, and 5.0% (w/w) DDGS lipid extract. After 4 wk, the 5.0% DDGS lipids group had significantly lower plasma non-HDL cholesterol and liver esterified cholesterol concentration. Faecal neutral sterol (i.e., cholesterol) excretion was significantly higher in the 5.0% DDGS lipids group compared to the other treatments (66% higher compared to controls). Bile acid excretion was not affected by DDGS lipid intake. Faecal cholesterol excretion was negatively correlated with liver cholesterol concentration (r = −0.97, P = 0.026), and liver cholesterol concentration was directly correlated with plasma total cholesterol concentration (r = 0.96, P = 0.041). Thus, lipid extract of sorghum DDGS exhibited cholesterol-lowering properties due, at least in part, to increased cholesterol excretion from the body and could provide health benefits when incorporated into human diets.

Chemotaxonomic biomarkers are needed to monitor and evaluate the nutritional quality of phytoplankton communities. The biomolecules produced by different phytoplankton species do not always follow genetic phylogeny. Therefore, we analyzed fatty acids, sterols, and carotenoids from 57 freshwater phytoplankton strains to evaluate the usability of these biomolecules as chemotaxonomic biomarkers. We found 29 fatty acids, 34 sterols, and 26 carotenoids in our samples. The strains were grouped into cryptomonads, cyanobacteria, diatoms, dinoflagellates, golden algae, green algae, and raphidophytes, and the phytoplankton group explained 61%, 54%, and 89% of the variability of fatty acids, sterols, and carotenoids, respectively. Fatty acid and carotenoid profiles distinguished most phytoplankton groups, but not flawlessly. For example, fatty acids could not distinguish golden algae and cryptomonads, whereas carotenoids did not separate diatoms and golden algae. The sterol composition was heterogeneous but seemed to be useful for distinguishing different genera within a phytoplankton group. The chemotaxonomy biomarkers yielded optimal genetic phylogeny when the fatty acids, sterols, and carotenoids were used together in multivariate statistical analysis. Our results suggest that the accuracy of phytoplankton composition modeling could be enhanced by combining these three biomolecule groups., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Smith-Lemli-Opitz syndrome (SLOS) is an inherited autosomal recessive cholesterol deficiency disorder. Our studies have shown that in SLOS children, urinary mevalonate excretion is normal and reflects hepatic HMG-CoA reductase activity but not ultimate sterol synthesis. Hence, we hypothesized that in SLOS there may be increased diversion of mevalonate to nonsterol isoprenoid synthesis. To test our hypothesis, we measured urinary dolichol and ubiquinone, two nonsterol isoprenoids, in 16 children with SLOS and 15 controls, all fed a low-cholesterol diet. The urinary excretion of both dolichol (P < 0.002) and ubiquinone (P < 0.02) in SLOS children was 7-fold higher than in control children, whereas mevalonate excretion was comparable. In a subset of 12 SLOS children, a high-cholesterol diet decreased urinary mevalonate excretion by 61% (P < 0.001), dolichol by 70% (P < 0.001), and ubiquinone by 67% (P < 0.03). Our hypothesis that in SLOS children, normal urinary mevalonate excretion results from increased diversion of mevalonate into the production of nonsterol isoprenoids is supported. Dietary cholesterol supplementation reduced urinary mevalonate and nonsterol isoprenoid excretion but did not change the relative ratios of their excretion. Therefore, in SLOS, a secondary peripheral regulation of isoprenoid synthesis may be stimulated.

Cholesterol is a major lipid component of the plasma membrane in animal cells. In addition to its structural requirement, cholesterol is essential in cell proliferation and other cell processes. The aim of the present study was to elucidate the stringency of the requirement for cholesterol as a regulator of proliferation and cell cycle progression, compared with other sterols of the cholesterol biosynthesis pathway. Human promyelocytic HL-60 cells were cultured in cholesterol-free medium and treated with different distal inhibitors of cholesterol biosynthesis (zaragozic acid, SKF 104976, SR 31747, BM 15766, and AY 9944), which allow the synthesis of isoprenoid derivatives and different sets of sterol intermediates, but not cholesterol.The results showed that only the inhibition of sterol Δ7-reductase was compatible with cell proliferation. Blocking cholesterol biosynthesis upstream of this enzyme resulted in the inhibition of cell proliferation and cell cycle arrest selectively in G2/M phase.