Lipid Extracts Research Articles

Extraction of high‐quality Antarctic krill (Euphausia Superba) oil using low‐temperature continuous phase‐transition extraction equipment

AbstractThe aim of this study was to explore a processing method for efficient extraction of high‐quality krill oil (KO) using a low‐temperature continuous phase‐transition extraction equipment (LCPE). The efficiency of lipid extraction and quality of KO and defatted krill meal (DKM) by LCPE were compared with those of supercritical CO2 and n‐hexane extraction. Results showed that compared to other methods, extraction using LCPE had the highest lipid yield (21.72 ± 0.34%), bioactive substances, and dimethyl sulfide (3.12 ± 0.09 mg/kg), the lowest oxidative deterioration. Moreover, compared to other methods, DKM extracted by LCPE had the lowest fat (<2%), the highest protein (>60%), and the best oxidative stability. These benefits would ensure easier transportation and better long‐term storage, allowing for its application on distant‐ocean fishing vessels. Therefore, LCPE is a method that allows for efficient extraction of high‐quality KO.

Preparation of functional supplement powder using nanoliposome‐containing marine bioactive compounds

AbstractThe demand for marine bioactive compounds as therapeutic agents in supplements or functional foods has increased. However, their instability, bitter taste, and potential degradation during digestion have hindered their widespread use. To overcome these problems, a functional supplement powder was produced using the encapsulation technique of nanoliposomes containing shrimp lipid extract, fish oil (FO), and fish protein hydrolysate. Chitosan and whey protein concentrate (WPC) were used to coat the nanoliposomes in mono/bilayer and composite forms, followed by freeze‐drying for 72 h. The physicochemical characteristics, nutritional, in vitro release, and sensory evaluation were investigated. The WPC‐monolayer treatment exhibited the highest solubility (28.83 mg/100 g), encapsulation efficiency (97.67%), and polyunsaturated fatty acids (PUFAs). Although the mono/bilayer treatments of whey protein showed lower docosahexaenoic acid and eicosapentaenoic acid than FO, they presented a favorable amino acid profile. Compared to acidic stomach conditions, the release in the intestine was higher. Incorporating 1.5 g of the supplement powder per 100 g of milk can meet an individual's daily nutritional needs for essential amino acids and PUFAs. Therefore, encapsulating marine bioactive compounds in liposomal carriers could be a beneficial approach to their direct use as a nutritious powder.

Unveiling the Lipid Features and Valorization Potential of Atlantic Salmon (Salmo salar) Heads

The sustainable utilization of co-products derived from the salmon processing industry is crucial for enhancing the viability and decreasing the environmental footprint of both capture and aquaculture operations. Salmon (Salmo salar) is one of the most consumed fish worldwide and a major species produced in aquaculture. As such, significant quantities of salmon co-products are produced in pre-commercialization processing/steaking procedures. The present study characterized a specific co-product derived from the processing of salmon: minced salmon heads. More specifically, this work aimed to reveal the nutritional profile of this co-product, with a special focus on its lipid content, including thoroughly profiling fatty acids and fully appraising the composition in complex lipids (polar lipids and triglycerides) for the first time. The antioxidant potential of lipid extracts from this salmon co-product was also studied in order to bioprospect lipid functional properties and possibly unveil new pathways for added-value applications. Our analysis indicated that these minced salmon heads are exceptionally rich in lipids. Oleic acid is the most prevalent fatty acid in this co-product, followed by palmitic acid, stearic acid, and linoleic acid. Moreover, relevant lipid indexes inferred from the fatty acid composition of this co-product revealed good nutritional traits. Lipidome analysis revealed that triglycerides were clearly the predominant lipid class present in this co-product while phospholipids, as well as ceramides, were also present, although in minimal quantities. The bioprospecting of antioxidant activity in the lipid extracts of the minced salmon heads revealed limited results. Given the high concentration of triglycerides, minced salmon heads can constitute a valuable resource for industrial applications from the production of fish oil to biodiesel (as triglycerides can be easily converted into fatty acid methyl esters), as well as possible ingredients for cosmetics, capitalizing on their alluring emollient properties. Overall, the valorization of minced salmon heads, major co-products derived from the processing of one of the most intensively farmed fish in the world, not only offers economic benefits but also contributes to the sustainability of the salmon processing industry by reducing waste and promoting a more efficient use of marine bioresources.

Comparison of Microalgae Nannochloropsis oceanica and Chlorococcum amblystomatis Lipid Extracts Effects on UVA-Induced Changes in Human Skin Fibroblasts Proteome

Lipid extracts from the microalgae Nannochloropsis oceanica and Chlorococcum amblystomatis have great potential to prevent ultraviolet A (UVA)-induced metabolic disorders. Therefore, the aim of this study has been to analyze their cytoprotective effect, focused on maintaining intracellular redox balance and inflammation in UVA-irradiated skin fibroblasts, at the proteome level. The above lipid extracts reversed the suppression of the antioxidant response caused by UVA radiation, which was more visible in the case of C. amblystomatis. Modulations of interactions between heme oxygenase-1 and matrix metalloproteinase 1/Parkinson’s disease protein 7/transcript1-α/β, as well as thioredoxin and migration inhibitory factor/Parkinson’s disease protein 7/calnexin/ATPase p97, created key molecular signaling underlying their cytoprotective actions. Moreover, they reduced pro-inflammatory processes in the control group but they also showed the potential to regulate the cellular inflammatory response by changing inflammasome signaling associated with the changes in the caspase-1 interaction area, including heat shock proteins HSP90, HSPA8, and vimentin. Therefore, lipid extracts from N. oceanica and C. amblystomatis protect skin fibroblast metabolism from UVA-induced damage by restoring the redox balance and regulating inflammatory signaling pathways. Thus, those extracts have proven to have great potential to be used in cosmetic or cosmeceutical products to protect the skin against the effects of solar radiation. However, the possibility of their use requires the evaluation of their effects at the skin level in in vivo and clinical studies.

Tandem Mass Spectrometry in Untargeted Lipidomics: A Case Study of Peripheral Blood Mononuclear Cells

Peripheral blood mononuclear cells (PBMCs), including lymphocytes, are important components of the human immune system. These cells contain a diverse array of lipids, primarily glycerophospholipids (GPs) and sphingolipids (SPs), which play essential roles in cellular structure, signaling, and programmed cell death. This study presents a detailed analysis of GP and SP profiles in human PBMC samples using tandem mass spectrometry (MS/MS). Hydrophilic interaction liquid chromatography (HILIC) and electrospray ionization (ESI) coupled with linear ion-trap MS/MS were employed to investigate the diagnostic fragmentation patterns that aided in determining regiochemistry in complex lipid extracts. Specifically, the study explored the fragmentation patterns of various lipid species, including phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), their plasmalogen and lyso forms, phosphatidylserines (PSs), phosphatidylinositols (PIs), phosphatidylglycerols (PGs), sphingomyelins (SMs), and dihexosylceramides (Hex2Cer). Our comprehensive analysis led to the characterization of over 200 distinct lipid species, significantly expanding our understanding of PBMC lipidome complexity. A freely available spreadsheet tool for simulating MS/MS spectra of GPs is provided, enhancing the accessibility and reproducibility of this research. This study advances our knowledge of PBMC lipidomes and establishes a robust analytical framework for future investigations in lipidomics.

A simultaneous analysis strategy of glycerophospholipids and lipid mediators based on secondary extraction scheme.

Lipid peroxidation plays an important role in physiological and pathophysiological conditions; it occurs mainly in the vicinity of the membrane. Glycerophospholipids are indispensable for normal structure of membranes. Lipid mediators are final products of lipid peroxidation. Glycerophospholipids as a source of lipid mediators are closely related with lipid mediators in lipid peroxidation process. This study developed a strategy for simultaneous analysis of glycerophospholipids and lipid mediators in a sample based on a secondary extraction scheme. Due to differences in physicochemical properties of glycerophospholipids and lipid mediators, we used different solvents and methods to extract glycerophospholipids and lipid mediators based on a sample. In addition, we compared three methods of extracting glycerophospholipids to select the best extraction method. In this study, a UPLC-MRM absolute quantification strategy for three deuterated internal standards of lipid mediator was established. The calibration range of all standards is linear, and the correlation coefficients are greater than 0.999. Quantitative range, precision, and accuracy of all analytes-based analysis method meet requirements of method validation. And the accuracy and precision of this method for glycerophospholipids meet the requirements of method verification. It is satisfactory to apply this method in the analysis of the changes of enzymes in lipid peroxidation during the treatment of asthma with dexamethasone. The quantitative results of phospholipids and lipid mediators in mouse lung tissue were obtained by this method, indicating that dexamethasone may inhibit the activity of phospholipase As enzyme and thus slow down the lipid peroxidation process. This work may be of great significance for exploring the changes of enzymes in lipid peroxidation metabolism.

Advances in utilizing reverse micelles to investigate membrane proteins.

Reverse micelles (RMs) have emerged as useful tools for the study of membrane associated proteins. With a nanoscale water core surrounded by surfactant and solubilized in a non-polar solvent, RMs stand apart as a unique membrane model. While RMs have been utilized as tools to investigate the physical properties of membranes and their associated water, RMs also effectively house membrane associated proteins for a variety of studies. High-resolution protein NMR revealed a need for development of improved RM formulations, which greatly enhanced the use of RMs for aqueous proteins. Protein-optimized RM formulations enabled encapsulation of challenging membrane associated protein types, including lipidated proteins, transmembrane proteins, and peripheral membrane proteins. Improvements in biological accuracy of RMs using phospholipid-based surfactants has advanced their utility as a membrane mimetic even further, better matching the chemistry of the most common cellular membrane lipids. Natural lipid extracts may also be used to construct RMs and house proteins, resulting in a membrane model that better represents the complexity of biological membranes. Recent applications in high-resolution investigations of protein-membrane interactions and inhibitor design of membrane associated proteins have demonstrated the usefulness of these systems in addressing this difficult category of protein. Further developments of RMs as membrane models will enhance the breadth of investigations facilitated by these systems and will enhance their use in biophysical, structural, and drug discovery pursuits of membrane associated proteins. In this review, we present the development of RMs as membrane models and their application to structural and biophysical study of membrane proteins.

Assessing the Effect of Minimally Invasive Lipid Extraction on Parchment Integrity by Artificial Ageing and Integrated Analytical Techniques.

To assess the short and long-term effect of a newly developed minimally invasive lipid extraction method on parchment, sacrificial pieces of parchments were subjected to artificial ageing and investigated using various analytical methods. Lipids were extracted using our novel vacuum-aided extraction method and characterised by high-temperature gas chromatography (HTGC-FID). Lipids were identified as arising from degraded animal fats. The physical, molecular, and mechanical properties of the parchment samples before/after lipid extraction, and before/after ageing were assessed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and pure shear single notch fracture testing. SEM imaging allowed for an assessment of potential structural changes of the collagen fibres while FTIR was used to investigate the possible molecular changes indicated by changes in amide I and II bands. Mechanical tests were used to record the changes in brittleness and stiffness occurring in the materials through lipid extraction and ageing. The multimodal investigation did not highlight measurable changes in the structural, molecular, and mechanical properties of the lipid-extracted parchment, thus indicating the suitability for the minimally invasive lipid extraction method to be applied to historical parchments.

Enhanced Lipidomics Analysis of Breast Cancer Cells Using Three-phase Liquid Extraction and Ultra High-performance Liquid Chromatography Coupled With Quadrupole Time-of-Flight Tandem Mass Spectrometry.

Lipid extraction of complex biological samples is essential for high-quality data in liquid chromatography-mass spectrometry (LC-MS)-based lipidomics. This study introduces a three-phase liquid extraction (3PLE)-ultra-high-performance LC coupled with quadrupole time-of-flight tandem MS method. This method was successfully applied to lipidomics analysis of breast cancer cells, including highly metastatic MDA-MB-231 and slightly metastatic MCF7 cells. The 3PLE method employed an n-hexane/methyl tert-butyl ether/acetonitrile/water solvent system that formed one aqueous and two organic phases. Neutral and polar lipids were enriched in the upper and middle organic phases, respectively, and combined for detection, thereby reducing analysis time. Compared with the Bligh and Dyer method, 3PLE achieved higher sensitivity and detected more features, with over a 50% increase in the relative abundance of nearly 50% of the differential lipids. In total, 21 differential lipids were identified in the MDA-MB-231 group and 22 in the MCF7 group compared to normal breast epithelial cells (MCF10A). Pathway analysis suggested that lipid changes in breast cancer cells were associated with glycerophospholipid metabolism, arachidonic acid metabolism, sphingolipid metabolism, and linoleic acid metabolism. The study presents a highly efficient lipidomics method, providing a scientific foundation for understanding breast cancer pathogenesis and aiding in diagnosis.

Optimization of the marine microalgae Nannochloropsis oculata harvesting by flocculation: Effects on biomass quality and residual medium reuse for a new cycle

ABSTRACT Flocculation using natural plant-based biopolymers from Moringa oleifera seeds and Acacia mearnsii flocculant as Tanfloc® (TSG) has emerged as an efficient strategy for microalgae biomass harvesting. This study optimized the recovery process of Nannochloropsis oculata by varying flocculant concentration, sedimentation time, and culture pH. Results revealed that 1.2 mg.L−1 of TSG at pH 8.9 achieved optimal conditions, although TSG proved effective across different pH ranges. Alkaline flocculation (ALK) also enhanced microalgae harvesting, yielding a high harvesting efficiency (>96%) within 30 minutes of sedimentation. Both methods achieved a concentration factor exceeding 20. However, the use of ALK resulted in reduced lipid and carbohydrate content compared to the control condition. Carotenoid levels showed no significant difference. TSG influenced lipid extraction but not fatty acid quality or carbohydrate extraction. Importantly, the residual medium from TSG flocculation could sustain subsequent cultivation cycles without nutrient supplementation, presenting a cost-effective solution for microalgae cultivation and harvesting.

Evaluation of the pharmacological efficiency of the lipid extract from the tunic of the marine hydrobiont Halocynthia aurantium (Pallas, 1774)

It was studied effect of the lipid extract isolated from the tunic of the marine hydrobiont Halocynthia aurantium. It was evaluated its administration during hypothermia, hyperthermia, muscle load and the introduction of hexenal as well as its embryotoxic and teratogenic effects The impact of stress (vertical fixation of rats by the dorsal neck fold) was accompanied by an increase in plasma levels of total lipids, total cholesterol, cholesterol/phospholipid ratios and a decrease in total phospholipids, as well as by a change in the quantitative characteristics of classes of neutral and phospholipid. It was carried out a correction of the developed changes by a lipid extract of ascidia and a commercial reference preparation “Omega-3”. The lipid extract of H. aurantium showed a higher efficiency in restoring the lipid composition of the blood plasma under stress impact compared to the preparation “Omega-3” due to a wider range of neutral and phospholipid classes, polyunsaturated fatty acids of the n-3 and n-6 families. The tunica of ascidian can be used as a raw material for obtaining preparations with stress-protector and lipid-correcting properties.

Characterization of Extracellular Vesicles by Sulfophosphovanillin Colorimetric Assay and Raman Spectroscopy.

Detailed characterization of extracellular vesicles (EVs) is crucial for their application in medical diagnostics. However, the complexity of their chemical composition and the heterogeneity of EV populations make their characterization challenging. Here we describe two analytical procedures that can help overcome this challenge. Small EVs were isolated from conditioned cell culture media using ultracentrifugation and characterized using nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). Raman spectroscopy was used to assess the overall composition of the isolated samples and lipids extracted from them. Sulfophosphovanillin (SPV) colorimetric assay was used to quantify the contents of lipid. Six samples of EVs were characterized. The lipid contents measured using SPV assay was in reasonable agreement with the quantitative estimates based on the particle size and concentration measured using NTA. The most peaks observed in the Raman spectra could be attributed to either proteins or lipids, and their origins was confirmed by lipid extraction. The protein-to-lipid ratio was estimated based on the Raman spectra. The experiential procedures described in this study will help to overcome the challenge of quick and highly informative characterization of the EVs.

Environmental impact assessment in microalgal lipid production: carbon footprint and net emissions

This study focuses on analyzing the role of microalgae in mitigating climate change through CO2 capture and lipid production, which can be used in the development of energy products and commercially relevant products. The objective was to evaluate the net CO2 emissions in three lipid production scenarios from microalgae, in addition to analyzing the impact of various biomass pretreatment technologies before lipid extraction. For this purpose, only the emissions directly generated by energy consumption in the process and the amount of CO2 that can be captured by microalgae cultivation were considered. In all three scenarios, CO2 capture during biomass cultivation and emissions associated with maintaining the process in operation were evaluated. The results show that the emissions generated by energy consumption were 3.56 kg-CO2/kg-oil, 2.19 kg-CO2/kg-oil, and 2.36 kg-CO2/kg-oil in scenarios 1, 2, and 3, respectively, while the CO2 emissions captured in microalgae cultivation were three to four times higher, ultimately resulting in negative emissions in all scenarios. The efficiency of CO2 capture per kilogram of oil produced varies between scenarios, suggesting that the choice of technology and process conditions significantly influence the overall environmental impact. This analysis identifies areas of opportunity to improve microalgal biomass utilization processes, highlighting the stages of the process with the greatest impact on the carbon footprint and enabling the comparison of different technologies on the same basis.

Ultrasound-assisted extraction vs. microwave-assisted extraction for sustainable development goals: Selecting the ideal lipid extraction and fatty acid profile

The objective of this study was to compare the efficiency of ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) methods for extracting lipids from the green microalga Chlorococcum novae-angliae. This study specifically focused on the fatty acid profiles of the extracted lipids, using ethanol as the solvent and wet biomass as the starting material. Ultrasound-assisted extraction yielded a maximum of 0.026 ± 0.001 g lipid/g wet biomass at a biomass ratio of 1:25 for 2 min with a 1-second cycle at 180 W and 20 kHz, which was 21% higher than that of microwave-assisted extraction conducted at a ratio of 1:30 for 2 min at 300 W and 35 °C. Ultrasound-assisted extraction enhanced saturated fatty acids (SFAs), which were 1.5 times higher than to microwave-assisted extraction, while microwave-assisted extraction significantly increased polyunsaturated fatty acids (PUFAs) by 4.4 times. The findings suggest that ultrasound-assisted extraction is more suitable for applications requiring high SFA content, such as in the fuel industry, whereas microwave-assisted extraction is preferable for sectors focused on fatty acid quality, such as food and health. This comparative analysis contributes to the literature by highlighting the impact of extraction methods on fatty acid profiles and supports sustainable development goals (SDGs), particularly SDG 12, by promoting environmentally friendly extraction techniques.

Mechanistic insights into lipid extraction from wet microalgae using hydrophobic deep eutectic solvents under hydrothermal conditions

Hydrophobic deep eutectic solvents (HDESs) were first employed under hydrothermal conditions to form a two-phase system for instantaneous and efficient lipid extraction from wet microalgae, preventing lipid degradation and avoiding the use of toxic solvents. Ten HDESs were assessed for their efficiency and selectivity in lipid extraction. Among them, OCT-DEC, composed of octanoic acid and decanoic acid, achieved the highest extraction efficiency at 95.42 %, while also preventing the co-extraction of proteins and reducing sugars. Molecular dynamics simulations revealed that lipid extraction efficiency is primarily influenced by lipid-HDES interactions, which drive lipid diffusion, and the interfacial properties of the two-phase hydrothermal system, which resist lipid diffusion. The superior performance of OCT-DEC is attributed to its high hydrogen bond density and short bond lifetimes, which, combined with its structural stability, synergistically reduce resistance to lipid diffusion at the interface. Additionally, OCT-DEC significantly enhances the thermal stability of unsaturated fatty acids, such as C20:5, effectively preventing the degradation of high-value lipids and highlighting its potential for hydrothermal extraction of these valuable compounds.

Bioactive Lipids in Dunaliella salina: Implications for Functional Foods and Health.

Dunaliella salina is a green microalga extensively explored for β-carotene production, while knowledge of its lipid composition is still limited and poorly investigated. Among lipids, polar lipids have been highlighted as bioactive phytochemicals with health-promoting properties. This research aimed to provide an in-depth lipidome profiling of D. salina using liquid and gas chromatography coupled with mass spectrometry. The lipid content was 6.8%, including phospholipids, glycolipids, betaine lipids, sphingolipids, triglycerides, diglycerides, and pigments. Among the total esterified fatty acids, 13.6% were 18:3 omega-3 and 14.7% were 18:1 omega-9. The lipid extract of D. salina showed anti-inflammatory activity by inhibiting cyclooxygenase-2 activity at 100 µg/mL, dose-dependent antioxidant scavenging activity, and antidiabetic activity by inhibiting α-glucosidase activity at 25 and 125 µg/mL. In conclusion, the lipid extract of D. salina has the potential to be used as a functional food ingredient or in the nutraceutical and cosmeceutical industries.

Radical-directed dissociation mass spectrometry for differentiation and relative quantitation of isomeric ether-linked phosphatidylcholines

BackgroundEther-linked phosphatidylcholines (PCs) include both plasmanyl and plasmenyl PCs, which contain an ether or a vinyl ether bond at the sn-1 linkage position, respectively. Profiling and quantifying ether PCs with accurate structural information is challenging because of the common presence of isomeric and isobaric species in a lipidome. ResultsIn the present study, radical directed dissociation (RDD) from collision-induced dissociation (CID) of the bicarbonate anion adduct of ether PCs has been investigated to differentiate and relatively quantify ether PCs. Alkyl- and alkenyl- PCs give diagnostic characteristic fragment patterns that enable their confident identification and isomer differentiation. Additionally, the sn-position specific product ions have proven effective for relative quantitation among isomers in ether PCs and their isobaric PC species. Using this methodology, we successfully identified a total of 30 PC-O species, 21 PC-P species at the chain composition level, and 22 species of isobaric PC at the sn-position level in the human plasma lipid extract. The quantitative analysis revealed that ether PCs with a 20:4 fatty acyl chain are relatively more abundant in human plasma. Finally, the profile of ether PCs in type 2 diabetic (T2D) groups compared to normal control groups revealed a significant decrease in PC-O 18:1/20:5. We also found it is the PC species containing a 17-carbon fatty acyl chain, rather than their isobaric ether PCs, that shows a decreasing trend in the T2D groups. Significanceether-linked PCs are firstly investigated by RDD mass spectrometry.

Allosteric coupling of substrate binding and proton translocation in MmpL3 transporter from Mycobacterium tuberculosis.

Infections caused by Mycobacterium spp. are very challenging to treat, and multidrug-resistant strains rapidly spread in human populations. Major contributing factors include the unique physiological features of these bacteria, drug efflux, and the low permeability barrier of their outer membrane. Here, we focus on MmpL3 from Mycobacterium tuberculosis, an essential inner membrane transporter of the resistance-nodulation-division superfamily required for the translocation of mycolic acids in the form of trehalose monomycolates (TMM) from the cytoplasm or plasma membrane to the periplasm or outer membrane. The MmpL3-dependent transport of TMM is essential for the growth of M. tuberculosis in vitro, inside macrophages, and in M. tuberculosis-infected mice. MmpL3 is also a validated target for several recently identified anti-mycobacterial agents. In this study, we reconstituted the lipid transport activity of the purified MmpL3 using a two-lipid vesicle system and established the ability of MmpL3 to actively extract phospholipids from the outer leaflet of a lipid bilayer. In contrast, we found that MmpL3 lacks the ability to translocate the same phospholipid substrate across the plasma membrane indicating that it is not an energy-dependent flippase. The lipid extraction activity was modulated by substitutions in critical charged and polar residues of the periplasmic substrate-binding pocket of MmpL3, coupled to the proton transfer activity of MmpL3 and inhibited by a small molecule inhibitor SQ109. Based on the results, we propose a mechanism of allosteric coupling wherein substrate translocation by MmpL3 is coupled to the energy provided by the downhill transfer of protons. The reconstituted activities will facilitate understanding the mechanism of MmpL3-dependent transport of lipids and the discovery of new therapeutic options for Mycobacterium spp. infections.IMPORTANCEMmpL3 from Mycobacterium tuberculosis is an essential transporter involved in the assembly of the mycobacterial outer membrane. It is also an important target in undergoing efforts to discover new anti-tuberculosis drugs effective against multidrug-resistant strains spreading in human populations. The recent breakthrough structural studies uncovered features of MmpL3 that suggested a possible lipid transport mechanism. In this study, we reconstituted and characterized the lipid transport activity of MmpL3 and demonstrated that this activity is blocked by MmpL3 inhibitors and substrate mimics. We further uncovered the mechanism of how the binding of a substrate in the periplasmic domain is communicated to the transmembrane proton relay of MmpL3. The uncovered mechanism and the developed assays provide new opportunities for mechanistic analyses of MmpL3 function and its inhibition.

Elevated Porcupine Disrupts Lipid Metabolism and Promotes Inflammatory Response in MASLD.

Metabolic dysfunction-associated steatotic liver disease (MASLD) presents a high incidence globally and is a major cause of cirrhosis and hepatocellular carcinoma, lacking of efficient interventions. Patients with MASLD exhibit exceeded serum levels of palmitic acid (PA). However, the association between PA and MASLD remains obscure. Gene expression omnibus dataset analysis, western blotting, mRNA-sequencing, RT-qPCR, a click chemistry-immunoprecipitation-immunofluorescence system, ELISA, lipid extraction and UHPLC-MS/MS analysis, CyTOF mass cytometry, gene knockdown via lentivirus-mediated shRNA, and high-fat methionine and choline-deficient diet-fed WT and db/db mice models were used to reveal the expression and functions of Porcupine in MASLD development both invitro and invivo. Our findings show that PA, as a crucial substrate for protein palmitoylation, induced the expression of palmitoyltransferase Porcupine in a time-dependent manner. This induction was closely associated with dysregulated lipid metabolism and stimulated inflammatory response observed invitro. Porcupine protein levels were significantly increased in liver tissues from both MASLD mice models, which was predominantly localised in lipid droplet-rich hepatocytes. Pharmacological inhibition of Porcupine by Wnt974 markedly ameliorated the aberrant lipid accumulation and inflammatory response in mouse livers. Furthermore, increased Porcupine positively correlated with CD36 at protein levels, and its inhibition or knockdown decreased CD36 protein levels via mechanisms irrelevant to transcriptional regulation, but primarily dependent on protein palmitoylation. The current study reveals that PA-induced Porcupine disrupts lipid metabolism and promotes inflammatory response during MASLD development, which can be ameliorated by the Porcupine inhibitor Wnt974. Therefore, Porcupine may be a potential pharmacological target for the treatment of MASLD.

A lipidomic approach towards identifying the effects of fragrance hydroperoxides on keratinocytes.

Limonene and linalool are used in cosmetic products for their floral scents, but their oxidation products are strong contact allergens whose mechanisms of action are still not fully understood. The effects of limonene hydroperoxide (Lim-2-OOH) and linalool hydroperoxides (Lin-6/7-OOH) on the lipid profile of a human keratinocyte cell line (HaCaT) were evaluated. 2,4-Dinitrofluorobenzene (DNFB) was also included. Lim-2-OOH and Lin-6/7-OOH were synthesised according to previous methods. HaCaT cells were treated with allergens (10 μM) for 24 h and the cellular lipid extracts were analysed by C18 liquid chromatography with tandem mass spectrometry (LC-MS/MS). Data analysis was performed using Lipostar software. Statistical analysis was carried out using Metaboanalyst and R software. All three sensitisers used caused significant changes in the lipidome of HaCaT cells in a similar trend. There was an upregulation in several plasmanyl/plasmenyl phospholipids (O-/P-phosphatidylcholines [PC] and O-/P-phosphatidylethanolamines [PE]), sphingolipids (HexCer) and triacylglycerol lipid species, and a decrease in some polyunsaturated fatty acids-containing phospholipid (PE and PC) species suggesting oxidative stress and inflammation. This study is the first to evaluate the plasticity of the HaCaT cell lipidome in response to allylic hydroperoxide allergens Lim-2-OOH and Lin-6/7-OOH, together with the experimental contact allergen DNFB. These allergens are able to upregulate and downregulate certain lipid classes to a varying degree.