Lipid Compounds Research Articles

Lipid changes and volatile compounds formation in different processing stages of dry-cured Spanish mackerel

Abstract This study delves into the alterations in lipids and major flavor compounds occurring throughout various drying stages (raw fish, dry-cured for 4 d, 8 d, and 12 d) of dry-cured Spanish mackerel (DCSM) and elucidates the mechanism behind their formation. The findings exhibit a notable reduction in phospholipid (PL), triacylglycerol (TAG), heptanal, t-2-hexenal, and dimethyl disulfide contents in the samples observed four days before processing. The peroxide value (POV) and thiobarbituric acid reactive substances (TBARS) witnessed a significant surge after 4-8 days, concomitant with the generation of numerous volatile compounds, encompassing alcohols, aldehydes, and ketones. Substantial quantities of 2-methylbutyraldehyde, thiazole, butyl acetate, and trimethylpyrazine emerged during the 8-12 days processing phase. Furthermore, C18:1n-9, C20:5n-3, and C22:6n-3 demonstrated noteworthy correlations with the development of 21 compounds. Principal Component Analysis (PCA), grounded in lipid and volatile compound content, adeptly classified the DCSM drying process into lipolysis and flavor preparation (0-4 d), lipid oxidation and flavor formation (4-8 d), and maturation (8-12 d). The ripening stage played a crucial role in shaping the comprehensive flavor profile. This study offers valuable insights to enhance the traditional DCSM flavor processing and regulation.

Enhancing Tranexamic Acid Penetration through AQP-3 Protein Triggering via ZIF-8 Encapsulation for Melasma and Rosacea Therapy.

The systemic use of tranexamic acid (TA) as an oral drug can bring adverse reactions, while intradermal injection leads to pain and a risk of infection. Moreover, it is difficult for highly hydrophilic TA to penetrate the skin barrier that contains lots of hydrophobic lipid compounds, which poses enormous restrictions on its topical application. Current transdermal TA delivery strategies are suffering from low drug load rates, plus their synthesis complexity, time-consumption, etc. adding to the difficulty of TA topical application in clinical therapeutics. To increase the penetration of TA, a novel approach using TA-loaded ZIF-8 (TA@ZIF-8) is developed. The encapsulation efficiency of TA@ZIF-8 reaches ≈25% through physical adsorption and chemical bonding of TA indicates by theoretical simulation and the improved TA penetration is elevated through activating the aquaporin-3 (AQP-3) protein. Additionally, in vivo and in vitro experiments demonstrate the preponderance of TA@ZIF-8 for penetration ability and the advantages in intracellular uptake, minor cytotoxicity, and inhibition of melanogenesis and inflammatory factors. Moreover, clinical trials demonstrate the safety and efficacy of TA@ZIF-8 in the treatment of melasma and rosacea. This work presents a potential topical application of TA, free from the safety concerns associated with systemic drug administration.

Optical properties and molecular compositions of dissolved organic matter in multiple runoff components during rainfalls on the karst hillslope

Understanding the chemical composition, origin, and molecular structure of dissolved organic matter (DOM) in multi-interface runoff is essential for comprehending the fate of laterally transported DOM in complex soil-epikarst systems of karst hillslopes. Limited information, however, is available for the optical properties and molecular compositions of the transported OM in multiple runoff components on the karst hillslope in relation to land-uses and soil thicknesses. In this study, we conducted a study to observe the changes in the quantity and quality of DOM in multiple interface flow (surface, subsurface, and epikarst) during natural rainfall events in 2022 in karst hillslopes that are covered by different land uses (cropland and shrubland) and soil thicknesses (with mean depths of 66.0 cm for deeper soil and 35.4 cm for shallower soil) in the karst region of southwest China. chemcial compositions of runoff DOM were determined by optical analysis and microbial compositions in runoff were inferred with high-throughput sequencing. The results showed that the soil-epikarst structure was controlling the runoff DOM quantity and quality during rainfall events. A decrease in the aromaticity, humification, unsaturation, and oxidation degree and an increase in carbohydrate, aminosugars, protein, and lipid compounds were found from surface to epikarst flow, indicating that plant-and soil-derived carbon decreased, while the microbially-derived carbon increased. The results were further comfirmed by the higher bacterial richness and diversity, along with fungal diversity in the epikarst flow compared to other runoff components. The bio-labile protein materials (C2) were the most important component of runoff DOM output in karst hillslopes. In surface and subsurface flow, rainfall amount, runoff rate, and discharge significantly affected the DOM concentration and quality during rainfalls, indicating that the dynamics of DOM in runoff from karst hillslopes were predominantly influenced by hydrological processes. Furthermore, the runoff DOM quality in cropland was dominated by lower unsaturation and oxidation degrees and higher protein component, compared to those in shrubland. The compositions of DOM in runoff from hillslope plots with thicker soils were primarily characterized by microbially-derived materials. Our findings were conducive to understanding the mechanism governing the migration of DOM quality and quantity in discharge during multi-interface hydrological processes on karst hillslopes.

Synthesis of New Multifunctional Linolenic Acid Vanillyl Ester and Investigation of Antioxidant and Antibacterial Activities.

Vanillyl alcohol (VA) possesses potent antioxidant activity, yet its applicability is hindered by its limited solubility in emulsions or non-polar organic solvents. Conversely, long-chain polyunsaturated fatty acids exhibit antibacterial properties. The combination of these compounds offers the prospect of developing novel phenolic lipid compounds with dual antioxidant and antibacterial activities, alongside enhanced solubility capabilities. In this investigation, linolenic acid vanillyl ester (LAVE) was synthesized from VA and linseed oil (LO) through a transesterification reaction employing immobilized lipase. Optimization of LAVE production was achieved by varying reaction temperature, substrate concentration, and reaction time. LAVE demonstrated efficacy in scavenging both 2,2-diphenyl-1-picryhydrazyl and 2,2'-azino-bis (3-ethylbenthiazoline-6-sulphonic acid) radicals in organic solvents. Antioxidant testing via lipid oxidation analysis revealed that LAVE, when distributed within emulsions, effectively impeded the formation of conjugated dienes and conjugated trienes. Furthermore, LAVE exhibited antibacterial activity against four strains of spoilage bacteria: Bacillus subtilis, Bacillus coagulans, Pseudomonas fluorescens, and Alcaligenes faecalis. Zeta potential analysis substantiated the binding of LAVE to the bacterial cell surface. Propidium iodide uptake assay and fluorescence microscopy further elucidated that LAVE induces cell lysis by augmenting membrane permeability.

An AlphaFold Structure Analysis of COQ2 as Key a Component of the Coenzyme Q Synthesis Complex.

Coenzyme Q (CoQ) is a lipidic compound that is widely distributed in nature, with crucial functions in metabolism, protection against oxidative damage and ferroptosis and other processes. CoQ biosynthesis is a conserved and complex pathway involving several proteins. COQ2 is a member of the UbiA family of transmembrane prenyltransferases that catalyzes the condensation of the head and tail precursors of CoQ, which is a key step in the process, because its product is the first intermediate that will be modified in the head by the next components of the synthesis process. Mutations in this protein have been linked to primary CoQ deficiency in humans, a rare disease predominantly affecting organs with a high energy demand. The reaction catalyzed by COQ2 and its mechanism are still unknown. Here, we aimed at clarifying the COQ2 reaction by exploring possible substrate binding sites using a strategy based on homology, comprising the identification of available ligand-bound homologs with solved structures in the Protein Data Bank (PDB) and their subsequent structural superposition in the AlphaFold predicted model for COQ2. The results highlight some residues located on the central cavity or the matrix loops that may be involved in substrate interaction, some of which are mutated in primary CoQ deficiency patients. Furthermore, we analyze the structural modifications introduced by the pathogenic mutations found in humans. These findings shed new light on the understanding of COQ2's function and, thus, CoQ's biosynthesis and the pathogenicity of primary CoQ deficiency.

Lipids Extracted from Mycobacterial Membrane and Enveloped PLGA Nanoparticles for Encapsulating Antibacterial Drugs Elicit Synergistic Antimicrobial Response against Mycobacteria.

Tuberculosis (TB) is a chronic disease caused byMycobacterium tuberculosis (Mtb), which shows a long treatment cycle often leads to drug resistance, making treatment more difficult. Immunogens present in the pathogen's cell membrane can stimulate endogenous immune responses. Therefore, an effective lipid-based vaccine or drug delivery vehicle formulated from the pathogen's cell membrane can improve treatment outcomes. Herein, we extracted and characterized lipids fromMycobacterium smegmatis, and the extracts contained lipids belonging to numerous lipid classes and compounds typically found associated with mycobacteria. The extracted lipids were used to formulate biomimetic lipid reconstituted nanoparticles (LrNs) and LrNs-coated poly(lactic-co-glycolic acid) nanoparticles (PLGA-LrNs). Physiochemical characterization and results of morphology suggested that PLGA-LrNs exhibited enhanced stability compared with LrNs. And both of these two types of nanoparticles inhibited the growth of M. smegmatis. After loading different drugs, PLGA-LrNs containing berberine or coptisine strongly and synergistically prevented the growth of M. smegmatis. Altogether, the bacterial membrane lipids we extracted with antibacterial activity can be used as nanocarrier coating for synergistic antibacterial treatment of M. smegmatis─an alternative model of Mtb, which is expected as a novel therapeutic system for TB treatment.

Effects of xylo-oligosaccharide on gut microbiota, brain protein expression, and lipid profile induced by high-fat diet

Midlife overweight and obesity are risk factors of cognitive decline and Alzheimer' s disease (AD) in late life. In addition to increasing risk of obesity and cognitive dysfunction, diets rich in fats also contributes to an imbalance of gut microbiota. Xylo-oligosaccharides (XOS) are a kind of prebiotic with several biological advantages, and can selectively promote the growth of beneficial microorganisms in the gut. To explore whether XOS can alleviate cognitive decline induced by high-fat diet (HFD) through improving gut microbiota composition, mice were fed with normal control or 60% HFD for 9 weeks to induce obesity. After that, mice were supplemented with XOS (30 g or 60 g/kg-diet) or without, respectively, for 12 weeks. The results showed that XOS inhibited weight gain, decreased epidydimal fat weight, and improved fasting blood sugar and blood lipids in mice. Additionally, XOS elevated spatial learning and memory function, decreased amyloid plaques accumulation, increased brain-derived neurotrophic factor levels, and improved neuroinflammation status in hippocampus. Changes in glycerolipids metabolism-associated lipid compounds caused by HFD in hippocampus were reversed after XOS intervention. On the other hand, after XOS intervention, increase in immune-mediated bacteria, Faecalibacterium was observed. In conclusion, XOS improved gut dysbiosis and ameliorated spatial learning and memory dysfunction caused by HFD by decreasing cognitive decline-associated biomarkers and changing lipid composition in hippocampus.

A Versatile Thioesterase Involved in Dimerization during Cinnamoyl Lipid Biosynthesis

AbstractThe cinnamoyl lipid compound youssoufene A1 (1), featuring a unique dearomatic carbon‐bridged dimeric skeleton, exhibits increased inhibition against multidrug resistant Enterococcus faecalis as compared to monomeric youssoufenes. However, the formation process of this intriguing dearomatization/dimerization remains unknown. In this study, an unusual “gene‐within‐gene” thioesterase (TE) gene ysfF was functionally characterized. The gene was found to naturally encodes two proteins, an entire YsfF with α/β‐hydrolase and 4‐hydroxybenzoyl‐CoA thioesterase (4‐HBT)‐like enzyme domains, and a nested YsfFHBT (4‐HBT‐like enzyme). Using an intracellular tagged carrier‐protein tracking (ITCT) strategy, in vitro reconstitution and in vivo experiments, we found that: i) both domains of YsfF displayed thioesterase activities; ii) YsfF/YsfFHBT could accomplish the 6π‐electrocyclic ring closure for benzene ring formation; and iii) YsfF and cyclase YsfX together were responsible for the ACP‐tethered dearomatization/dimerization process, possibly through an unprecedented Michael‐type addition reaction. Moreover, site‐directed mutagenesis experiments demonstrated that N301, E483 and H566 of YsfF are critical residues for both the 6π‐electrocyclization and dimerization processes. This study enhances our understanding of the multifunctionality of the TE protein family.

A Versatile Thioesterase Involved in Dimerization during Cinnamoyl Lipid Biosynthesis.

The cinnamoyl lipid compound youssoufene A1 (1), featuring a unique dearomatic carbon-bridged dimeric skeleton, exhibits increased inhibition against multidrug resistant Enterococcus faecalis as compared to monomeric youssoufenes. However, the formation process of this intriguing dearomatization/dimerization remains unknown. In this study, an unusual "gene-within-gene" thioesterase (TE) gene ysfF was functionally characterized. The gene was found to naturally encodes two proteins, an entire YsfF with α/β-hydrolase and 4-hydroxybenzoyl-CoA thioesterase (4-HBT)-like enzyme domains, and a nested YsfFHBT (4-HBT-like enzyme). Using an intracellular tagged carrier-protein tracking (ITCT) strategy, in vitro reconstitution and in vivo experiments, we found that: i) both domains of YsfF displayed thioesterase activities; ii) YsfF/YsfFHBT could accomplish the 6π-electrocyclic ring closure for benzene ring formation; and iii) YsfF and cyclase YsfX together were responsible for the ACP-tethered dearomatization/dimerization process, possibly through an unprecedented Michael-type addition reaction. Moreover, site-directed mutagenesis experiments demonstrated that N301, E483 and H566 of YsfF are critical residues for both the 6π-electrocyclization and dimerization processes. This study enhances our understanding of the multifunctionality of the TE protein family.

Variation in the Composition and Quality of Nigella sativa L. Seed Oils-The Underestimated Impact on Possible Health-Promoting Properties.

Nigella sativa L. (black cumin) is one of the most investigated medicinal plants in recent years. Volatile compounds like thymoquinone and unsaponifiable lipid compounds are crucial functional components of this oil. Unfortunately, the composition of oils and their quality indicators are ambiguous both in terms of identified compounds and value ranges. Thirteen oils were extracted with hexane from black cumin seeds grown in India, Syria, Egypt, and Poland and analyzed for their fatty acid composition, unsaponifiable compound content and volatile compounds. Oils were also subjected to quality tests according to standard methods. The fatty acid composition and sterol content/composition were relatively stable among the tested oils. Tocol content varied in the range of 140-631 mg/kg, and among them, β-tocotrienol and γ-tocopherol prevailed. Oils' volatile compounds were dominated by seven terpenes (p-cymene, α-thujene, α-pinene, β-pinene, thymoquinone, γ-terpinene, and sabinene). The highest contents of these volatiles were determined in samples from Poland and in two of six samples from India. High acid and peroxide values were typical features of N. sativa L. oils. To sum up, future research on the medicinal properties of black cumin oil should always be combined with the analysis of its chemical composition.

Western diet-induced ultrastructural changes in mouse pancreatic acinar cells.

Mouse models of diet-induced type 2 diabetes mellitus provide powerful tools for studying the structural and physiological changes that are related to the disease progression. In this study, diabetic-like glucose dysregulation was induced in mice by feeding them a western diet, and light and transmission electron microscopy were used to study the ultrastructural changes in the pancreatic acinar cells. Acinar necrosis and vacuolization of the cytoplasm were the most prominent features. Furthermore, we observed intracellular and extracellular accumulation of lipid compounds in the form of lipid droplets, structural enlargement of the cisternae of the rough endoplasmic reticulum (RER), and altered mitochondrial morphology, with mitochondria lacking the typical organization of the inner membrane. Last, autophagic structures, i.e., autophagosomes, autolysosomes, and residual bodies, were abundant within the acinar cells of western diet-fed mice, and the autolysosomes contained lipids and material of varying electron density. While diets inducing obesity and type 2 diabetes are clearly associated with structural changes and dysfunction of the endocrine pancreas, we here demonstrate the strong effect of dietary intervention on the structure of acinar cells in the exocrine part of the organ before detectable changes in plasma amylase activity, which may help us better understand the development of non-alcoholic fatty pancreas disease and its association with endo- and exocrine dysfunction.

An association analysis of lipidome and transcriptome highlights the involvement of MmGDPD1 in regulating low phosphorus tolerance in Malus mandshurica

Phosphorus (Pi) plays a crucial role in the growth and development of plants. Membrane lipid regulation is one of the main mechanisms underlying plant adaptation to Pi deficiency. Previously, the high tolerance to low-Pi stress was justified in an elite line, MSDZ 109, which was obtained from Malus mandshurica. To better understand the mechanism underlying high adaptation to low-Pi stress, currently, lipidomic and transcriptomic analysis, as well as CRISPR/Cas9 and MmGDPD1-overexpressing methodologies were comprehensively integrated into a strategy for elucidating the high tolerance to low-Pi stress. Totally, 770 differential metabolites were identified from the roots between the low-Pi and stress-free, belonging to 21 sub-classes of lipid compounds. Fatty acids (FA) constituted the predominant lipid component, accounting for approximately 50%–60% of the total lipids, and triglycerides (TAG) ranked the second, comprising around 12% of the total, consecutively followed by phosphatidylcholine (PC) and diacylglycerol (DAG) with approximately 10% and 8% of the total, respectively. The synchronous transcriptomic analysis revealed a significant up-regulation of genes related to glycerophospholipid and glycerolipid metabolism, specifically those (e.g., MmGDPD1, MmDGDG1, MmMGDG1, MmSQDG, etc.) involved in phospholipid and galactosyl synthesis in response to low-Pi stress. GUS fusing reporter assay showed that MmGDPD1 promoter induced GUS gene expression and demonstrated initiation activity. Based on expression analysis, a dual-luciferase reporter assay, as well as yeast one-hybrid (Y1H) identification, MmPHR1 was justified to bind with the MmGDPD1 promoter and positively regulate plant tolerance to low-Pi stress. To further elucidate the role of MmGDPD1, CRISPR/Cas9 and MmGDPD1-overexpressing vectors were successfully introduced into apple (‘Royal Gala’) calli. Interestingly, the MmGDPD1-KO line calli exhibited the remarkable decreases in the contents of phosphodiesterase (PDE), activity, as well as the contents of total Pi, and Pi in comparison with those of the wild type. Conversely, MmGDPD1-OE ones demonstrated the significant elevation in Pi accumulations, further justifying its potential role in Pi remobilization in apple. Therefore, MmGDPD1 substantially involves elevating low-Pi tolerance via promoting Pi release in M. mandshurica.

Mechanism of Peppermint Extract-Induced Delay of 'Packham's Triumph' Pear (Pyrus communis L.) Postharvest Ripening.

Postharvest ripening is correlated to the quality and shelf life of European pear fruit. In this study, the effects of peppermint extract on fruit phenotype, related physiological activities, and aroma components during postharvest ripening of the European pear variety 'Packham's Triumph' were examined. Fruit treated with 2.0 g L-1 peppermint extract for 12 h showed delayed softening by 4 d compared with that of the untreated control group. The peak values of ethylene and respiratory rate in fruit were reduced to a certain extent after peppermint extract treatment; however, the peppermint extract did not delay the occurrence of the respiratory climacteric peak. Peppermint extract treatment also did not significantly increase the content of the characteristic peppermint aroma in pear fruit. Further, widely targeted metabolome analysis revealed 298 significantly different metabolites, with flavonoids (40%) and lipid compounds (15%) accounting for the highest proportion on the first day after treatment. The Kyoto Encyclopedia of Genes and Genomes pathway result showed significant enrichment in the metabolic pathways of biosynthesis of flavonoid, isoflavonoid, flavone and flavonol, linoleic acid, and alpha-linolenic acid metabolism following peppermint extract treatment. The combined analysis of transcriptome and metabolome data showed significant enrichment in linoleic acid metabolism and alpha-linolenic acid metabolism on the first, third, and fifth days after peppermint extract treatment. This study indicates that peppermint extract mainly affects the pear fruit softening process in the early stage after treatment.

Chemical Profile, Antioxidant Activity and α-Glucosidase Inhibition of Sea Grape Caulerpa lentillifera Collected from Different Sites in Thailand

Caulerpa lentillifera (sea grapes) stands out for its nutritional profile and associated health advantages. Seaweeds, including sea grapes, exhibit diverse chemical compositions that are influenced by environmental conditions. This study aimed to compare the chemical composition, metabolite content, antioxidant activity and α-glucosidase inhibition of sea grapes collected at different sites (Phetchaburi and Trang) and at different times during the month of January, April, and July 2022. Both collection times and sites have influenced all assessed parameters. The sea grapes collected from Trang had a significantly higher amount of metabolite, antioxidant activity and α-glucosidase inhibitory activity than those from Phetchaburi at p < 0.001. The highest amount of phenolic compound (93.76 ± 2.39 mg GAE/g extract) and reducing power (EC50 = 25.86 ± 0.20 mg/mL) occurred in sea grapes in April month, while those collected in January and April had high DPPH and ABTS radical scavenging (EC50 < 7.50 mg/mL). The highest inhibitory activity against α-glucosidase (EC50 = 19.27 ± 0.40 mg/mL) was found in the sea grapes collected in January. The LC-QTOF MS/MS result of sea grape extract indicated similar compounds in amino acids, fatty acids, lipids, nucleic acids, carboxylic acids, cyanogenic glucosides, steroids, terpenoids and vitamins. The disparity in phenolic profiles between Phetchaburi (9) and Trang (14) sea grapes was related to higher phenolic compound and flavonoid contents, coupled with antioxidant properties in Trang. These findings supported the possible use of sea grapes from Trang as a reservoir of bioactive compounds. HIGHLIGHTS Chemical profile and content, antioxidant and α-glucosidase inhibition of sea grapes was analyzed Collection times and sites affected all measured parameters of sea grapes extract Sea grapes from Trang exhibited higher all measured parameters than Phetchaburi A novel chemical profiling of sea grapes was displayed via LC-QTOF MS/MS analysis GRAPHICAL ABSTRACT

Polyphenolics extracts from Ascophyllum nodosum protect against ultraviolet B-induced oxidative damage in mouse retinal Müller cells

Long-term exposure to sunlight, especially ultraviolet (UV), induces eye injury in people. We investigated the protective potential of Polyphenolic extract from Ascophyllum nodosum (PEAn) against UV-B-induced oxidative damage in retinal Müller cells (RMCs). In the UV-B-induced damage model of RMCs, PEAn demonstrated a potent photoprotective effect that reduced oxidative damage and apoptosis. PEAn significantly regulated the concentrations of ROS, Caspase-3, and Calcium ions (Ca2+) in RMCs generated by UV-B. The mitochondrial membrane potential (ΔΨm) and activities of various antioxidant enzymes (SOD, CAT, and GSH-Px) were significantly increased, whereas the MDA was reduced. Lipidomic research in RMCs also revealed that UV-B irradiation significantly altered the lipid compounds in the cells, while PEAn therapy gradually restored normal cells. Both the accumulation of triacylglycerides and the toxicity of the lipids in RMCs were simultaneously reduced by PEAn. The findings indicated that PEAn could be a potential natural photochemical protectant against UV-B-induced oxidative damage.

Changes in the chemical properties and metabolite profiling of fish sauce prepared from underutilized large yellow croaker roes during fermentation at different temperatures

Fish sauce is a popular aquatic condiment with unique flavor. In this study, the changes in the chemical properties and metabolite profiling of fish sauce from large yellow croaker roes during fermentation at different temperatures were revealed. The results found that the contents of total acid, amino acid nitrogen, total soluble nitrogen and soluble salt-free solids of fish sauce fermented at 40 °C were higher than those in other temperatures groups (25 °C and 32 °C), while the contents of total volatile basic nitrogen were lower than other temperatures. Therefore, 40 °C was the ideal fermentation temperature for fish sauce. The metabolomics analysis showed that organic acids, amino acids, nucleotide, and lipid compounds were found to participate in the biosynthesis pathway. Compared to 25 °C and 32 °C, fermented at 40 °C could increase the abundance of metabolic substances in the fish sauce, such as sugar alcohols, L-Citrulline, L-Aspartic acid, L-Cysteine, Glutathione, and L-Arginine. These results provide a theoretical basis for the production of high-quality fish sauce and the high-value utilization of fish roes.

Nitro Indole Derivatives as Novel Dual-Polarity Matrices for MALDI Mass Spectrometry and Imaging with Broad Applications.

A new matrix framework is presented in this study for the improved ionization efficiency of complex mixtures by matrix-assisted laser desorption ionization (MALDI) mass spectrometry/imaging. Five nitro indole (NI) derivatives [3-methyl-4-nitro-1H-indole (3,4-MNI), 3-methyl-6-nitro-1H-indole (3,6-MNI), 2,3-dimethyl-4-nitro-1H-indole (2,3,4-DMNI), 2,3-dimethyl-6-nitro-1H-indole (2,3,6-DMNI), and 4-nitro-1H-indole (4-NI)] were synthesized and shown to produce both positive and negative ions with a broad class of analytes as MALDI matrices. NI matrices were compared to several common matrices, such as 2,5-dihydroxybenzoic acid (DHB), alpha-cyano-4-hydroxylcinnamic acid (CHCA), sinapinic acid (SA), 1,5-diaminonaphthelene (1,5-DAN), and 9-aminoacridine (9-AA), for the analysis of lipid, peptide, protein, glycan, and perfluorooctanesulfonic acid (PFOS) compounds. 3,4-MNI demonstrated the best performance among the NI matrices. This matrix resulted in reduced ion suppression and better detection sensitivity for complex mixtures, for example, egg lipids/milk proteins/PFOS in tap water, while 2,3,6-DMNI was the best matrix for blueberry tissue imaging. Several important aspects of this work are reported: (1) dual-polarity ion production with NI matrices and complex mixtures; (2) quantitative analysis of PFOS with a LOQ of 0.5 ppb in tap water and 0.05 ppb in MQ water (without solid phase extraction enrichment), with accuracy and precision within 5%; (3) MALDI imaging with 2,3,6-DMNI as a matrix for plant metabolite/lipid identification with ionization enhancement in the negative ion mode m/z 600-900 region; and (4) development of a thin film deposition under/above tissue method for MALDI imaging with a vacuum sublimation matrix on a high-vacuum MALDI instrument.

Human lipocalins bind and export fatty acids through the secretory pathway of yeast cells.

The activation of fatty acids to their acyl-CoA derivatives is a crucial step for their integration into more complex lipids or their degradation via beta-oxidation. Yeast cells employ five distinct acyl-CoA synthases to facilitate this ATP-dependent activation of acyl chains. Notably, mutant cells that are deficient in two of these fatty acid-activating (FAA) enzymes, namely, Faa1 and Faa4, do not take up free fatty acids but rather export them out of the cell. This unique fatty acid export pathway depends on small, secreted pathogenesis-related yeast proteins (Pry). In this study, we investigate whether the expression of human fatty acid-binding proteins, including Albumin, fatty acid-binding protein 4 (Fabp4), and three distinct lipocalins (ApoD, Lcn1, and Obp2a), could promote fatty acid secretion in yeast. To optimize the expression and secretion of these proteins, we systematically examined various signal sequences in both low-copy and high-copy number plasmids. Our findings reveal that directing these fatty-acid binding proteins into the secretory pathway effectively promotes fatty acid secretion from a sensitized quadruple mutant model strain (faa1∆ faa4∆ pry1∆ pry3∆). Furthermore, the level of fatty acid secretion exhibited a positive correlation with the efficiency of protein secretion. Importantly, the expression of all human lipid-binding proteins rescued Pry-dependent fatty acid secretion, resulting in the secretion of both long-chain saturated and unsaturated fatty acids. These results not only affirm the in vitro binding capabilities of lipocalins to fatty acids but also present a novel avenue for enhancing the secretion of valuable lipidic compounds. Given the growing interest in utilizing yeast as a cellular factory for producing poorly soluble compounds and the potential of lipocalins as platforms for engineering substrate-binding specificity, our model is considered as a powerful tool for promoting the secretion of high-value lipid-based molecules.

Enhancement of weak signals by applying a suppression method to high-intense methyl and methylene signals of lipids in NMR spectroscopy.

Lipids play crucial roles in human biology, serving as energy stores, cell membranes, hormone production, and signaling molecules. Accordingly, their study under lipidomics has advanced the study of living organisms. 1-Dimensional (D) and 2D NMR methods, particularly 1D 1H and 2D 1H-1H Total Correlation Spectroscopy (TOCSY), are commonly used in lipidomics for quantification and structural identification. However, these NMR methods suffer from low sensitivity, especially in cases of low concentrated molecules such as protons attached to hydroxy, esters, aliphatic, or aromatic unsaturated carbons. Such molecules are common in complex mixtures such as dairy products and plant oils. On the other hand, lipids have highly populated fractions of methyl and methylene groups that result in intense peaks that overwhelm lower peaks and cause inhomogeneities in 2D TOCSY spectra. In this study, we applied a method of suppression to suppress these intense peaks of methyl and methylene groups to detect weaker peaks. The suppression method was investigated on samples of cheese, butter, a mixture of lipids, coconut oil, and olive oil. A significant improvement in peak sensitivity and visibility of cross-peaks was observed, leading to enhanced comparative quantification and structural identification of a greater number of lipids. Additionally, the enhanced sensitivity reduced the time required for the qualitative and comparative quantification of other lipid compounds and components. This, in turn, enables faster and more reliable structural identification and comparative quantification of a greater number of lipids. Additionally, it reduces the time required for the qualitative, and comparative quantification due to the enhancement of sensitivity.

CircFOXO3 upregulation mediates the radioresistance of glioblastoma by affecting cellular metabolome.

Radioresistance remains a significant challenge in the treatment of glioblastoma multiforme (GBM), the most prevalent and lethal brain cancer in adults. Metabolic alterations are known to contribute to radioresistance by activating antioxidant responses and promoting DNA repair. However, the role of circular RNAs in this process, particularly circFOXO3, is not well understood. In this study, we investigated the expression of circFOXO3 in glioma cells exposed to radiation and in recurrent GBM tissues. We performed knockdown and overexpression experiments in vitro and in vivo to assess the effects of circFOXO3 on radiosensitivity. Metabolomic profiling was conducted to explore the metabolic changes associated with circFOXO3 overexpression following irradiation. Our results showed significant upregulation of circFOXO3 in glioma cells upon radiation exposure and in recurrent GBM tissues. Knockdown of circFOXO3 increased radiosensitivity both in vitro and in vivo, whereas overexpression of circFOXO3 attenuated radiosensitivity. Metabolomic analysis revealed substantial alterations in lipid and organic compound profiles between circFOXO3-overexpressing and control groups. Additionally, circFOXO3 suppression increased proapoptotic protein levels (Caspase 7 and Bax) and decreased anti-apoptotic protein Bcl-2 levels following radiotherapy. These findings demonstrate the pivotal role of circFOXO3 in promoting tumor radioresistance through metabolic modulation, suggesting that circFOXO3 could serve as a potential diagnostic and therapeutic target for GBM.