Comparative lipid profile of four edible shellfishes by UPLC-Triple TOF-MS/MS

Preparation, identification and application of lipid-Maillard reaction products during the drying process of squid fillets

Squid fillets are susceptible to lipid oxidation and Maillard reaction during the drying process. In this study, a novel additive agent lipid-Maillard reaction products (L-MRPs) was optimized by response surface methodology, then the main antioxidant components of L-MRPs were identified. Finally, L-MRPs was applied to the drying process of squid fillets (LMSF) by comparing with the control group. The results showed that the optimal reaction conditions were pH 10.90, lipid content 1.70 %, reaction temperature 104 °C, reaction time 105 min. The DPPH radical scavenging activity of final L-MRPs was 89.78 %. The main antioxidant components of L-MRPs were Fru-Arg (19.31 μg/g), pyrroles (762.04 μg/g) and other HCCs (293.97 μg/kg). Besides, compared to the control group, LMSF group showed lower thiobarbituric acid reactive substances value (4.58 mg/kg) and formaldehyde content (17.00 mg/kg), but more flavor compounds (455.78 μg/kg) and higher sensory scores. Finally, the potential antioxidant and flavor-enhancing mechanism of L-MRPs was proposed.

Low temperature, high salinity depuration enhances Pacific oyster (Crassostrea gigas) lipid nutrition during anhydrous living-preservation: Lipidomic insights based on RPLC-Q-TOF-MS/MS

Using UHPLC-HRMS-based lipidomics, this study investigated lipid nutrition in Pacific oysters (C. gigas) under two depuration conditions-normal temperature and salinity (N group) and low temperature with high salinity (S group)-during a five-day anhydrous living-preservation period. Quantitative analysis of 927 lipid molecular species across 13 classes revealed that oysters in the S group retained higher levels of glycerolipids, phospholipids, and functional fatty acids (DHA, EPA, and AA) after preservation. Lipid nutritional indices showed the S group had lower risks of atherosclerosis, thrombosis, and favorable cholesterol profiles. Moreover, combined with multivariate and bioinformatics analyses, the results suggested that mild stress during low-temperature, high-salinity depuration enables improved lipid retention in subsequent preservation. These findings provide insights for optimizing pre-transport depuration practices, ensuring consumers receive oysters with superior lipid nutrition, and offer a framework for leveraging stress conditions to enhance shellfish nutritional quality.

Salting-induced lipid hydrolysis and oxidation in dried squid fillets: A mechanistic link to formaldehyde formation, color browning, and flavor alteration

Salt-dried squid fillets (SDSF) is a popular seafood product. In this study, the effect of different NaCl concentrations (0 %, 1 %, 5 % and 10 %) on the color, formaldehyde (FA) and volatile compounds (VOCs) of SDSF was investigated by determining the acid value (AV), thiobarbituric acid reactive substances (TBARS) value, lipid-related enzyme activities and lipidomics. These findings showed that the AV and TBARS value initially increased and subsequently decreased with increasing NaCl concentrations. Lipidomics indicated salting facilitated the hydrolysis of triglycerides and phospholipids by lipase, alongside the oxidation of fatty acids by auto-oxidation and lipoxygenase. Specifically, salting darkened the color via pyrrolization and inhibited the FA content via alleviating lipid oxidation, and contributed to characteristic VOCs (3-methyl-butanal, methionaland nonanal, etc.). Overall, 5 % NaCl SDSF performed less browning and FA content (23.95 mg/kg), but more VOCs (2885.03 μg/kg) and better overall acceptance. This research contributes to improving the quality of salt-dried seafood.

Insight into the mechanism of Maillard reaction and lipids mutually contribute to the flavor release of squid fillets during the drying process

Dried squid fillet is a popular seafood product with a unique flavor. However, its flavor release mechanism is unclear. In this study, volatile compounds (VOCs) were dynamically monitored in thawed squid (TS), salted squid (SS) and dried squid for 6 h (D6) and 24 h (D24). Subsequently, the Maillard reaction (MR) substrate, lipid oxidation index, free fatty acids and lipid profiles were detected. The results showed that the number of VOCs increased from 11 in TS (114.26 μg/kg) to 19 in D24 (1257.89 μg/kg). Besides, MR between glucose/ribose and amino acids (methionine, arginine, etc.) contributed to 3-methyl-butanal, methional and 2,3-butanedione. Meanwhile, lipid oxidation index, lipidomics and correlation analysis indicated that lipids (phosphatidylcholines and triglycerides) containing polyunsaturated fatty acids (C18:2, C20:4, C20:5 and C22:6) were precursors of 3-methyl-butanal, nonanal, heptanal, dodecane and tetradecane. Briefly, lipid hydrolysis, oxidation and MR mutually contributed to the flavor during the drying process of squid fillets.

Comparison of lipid profiles of male and female silkworm (Bombyx mori) pupae through high-resolution mass spectrometry-based lipidomics and chemometrics

Silkworm (Bombyx mori) pupae lipid profiles were analyzed using high-resolution mass spectrometry-based lipidomics. A total of 241 lipid molecular species were annotated with high confidence in male and female silkworm pupae. Triacylglycerol (TG), phosphoethanolamine (PE) and phosphocholine (PC) were the main lipid subclasses of silkworm pupae, accounting for 63, 41 and 38 lipid molecular species, respectively. No unique lipid molecular species were identified, but there were differences in the abundance of lipid molecular species between male and female silkworm pupae. Therefore, the differences in the lipid abundance of male and female silkworm pupae were analyzed by chemometrics. As a result, 8 lipid molecular species were screened for differential lipids. Hierarchical clustering analysis (HCA) showed that male and female silkworm pupae samples formed two distinct branches, indicating that these differential lipids could potentially be used as biomarkers to distinguish between male and female silkworm pupae.

Comparative Analysis of the Biochemical Composition, Amino Acid, and Fatty Acid Contents of Diploid, Triploid, and Tetraploid Crassostrea gigas

Tetraploid oysters are artificially produced oysters that do not exist in nature. The successful breeding of 100% triploid oysters resolved the difficulties of traditional drug-induced triploids, such as the presence of drug residues and a low triploid induction rate. However, little is known concerning the biochemical composition and nutrient contents of such tetraploids. Therefore, we investigated compositional differences among diploid, triploid, and tetraploid Crassostrea gigas as well as between males and females of diploids and tetraploids. The findings indicated that glycogen, EPA, ∑PUFA, and omega-3 contents were significantly higher in triploid oysters than in diploids or tetraploids; tetraploid oysters had a significantly higher protein content, C14:0, essential amino acid, and flavor-presenting amino acid contents than diploids or triploids. For both diploid and tetraploids, females had significantly higher levels of glutamate, methionine, and phenylalanine than males but lower levels of glycine and alanine. In addition, female oysters had significantly more EPA, DHA, omega-3, and total fatty acids, a result that may be due to the fact that gonadal development in male oysters requires more energy to sustain growth, consumes greater amounts of nutrients, and accumulates more proteins. With these results, important information is provided on the production of C. gigas, as well as on the basis and backing for the genetic breeding of oysters.

Temperature effects on plasmalogen profile and quality characteristics in Pacific oyster (Crassostrea gigas) during depuration

The quality of Pacific oyster (Crassostrea gigas) can be affected by many factors during depuration, in which temperature is the major element. In this study, we aim to determine the quality and plasmalogen changes in C. gigas depurated at different temperatures. The quality was significantly affected by temperature, represented by varying survival rate, glycogen content, total antioxidant capacity, alkaline phosphatase activity between control and stressed groups. Targeted MS analysis demonstrated that plasmalogen profile was significantly changed during depuration with PUFA-containing plasmalogen species being most affected by temperature. Proteomics analysis and gene expression assay further verified that plasmalogen metabolism is regulated by temperature, specifically, the plasmalogen synthesis enzyme EPT1 was significantly downregulated by high temperature and four plasmalogen-related genes (GPDH, PEDS, Pex11, and PLD1) were transcriptionally regulated. The positive correlations between the plasmalogen level and quality characteristics suggested plasmalogen could be regarded as a quality indicator of oysters during depuration.

Comprehensive untargeted lipidomic analysis of sea buckthorn using UHPLC-HR-AM/MS/MS combined with principal component analysis

Sea buckthorn is an important ecological and economic plant which has multiple bioactivities. The fruits and seeds of sea buckthorn are rich in oil. However, there are few studies on the differences of lipid profiles of sea buckthorn varieties. Herein, the lipidomic fingerprints of sea buckthorn was established. First, a mixture solvent of methanol and chloroform (2:1, v/v) was selected to extract the lipid of the flesh and seed of sea buckthorn. Then, global lipidomic analysis of different varieties of sea buckthorn was conducted. A total of 16 lipid classes and 112 lipid molecular species were determined. Several molecular species, such as PE (phosphatidylethanolamine) 18:1/18:3, PE18:0/18:1, PE18:0/18:2, etc. were selected as the potential biomarkers to classify the samples. Our study provides a scientific basis for quality control of sea buckthorn and promotes the development of sea buckthorn oil.

An overview of food lipids toward food lipidomics

Increasing evidence regarding lipids' beneficial effects on human health has changed the common perception of consumers and dietary officials about the role(s) of food lipids in a healthy diet. However, lipids are a wide group of molecules with specific nutritional and bioactive properties. To understand their true nutritional and functional value, robust methods are needed for accurate identification and quantification. Specific analytical strategies are crucial to target specific classes, especially the ones present in trace amounts. Finding a unique and comprehensive methodology to cover the full lipidome of each foodstuff is still a challenge. This review presents an overview of the lipids nutritionally relevant in foods and new trends in food lipid analysis for each type/class of lipids. Food lipid classes are described following the LipidMaps classification, fatty acids, endocannabinoids, waxes, C8 compounds, glycerophospholipids, glycerolipids (i.e., glycolipids, betaine lipids, and triglycerides), sphingolipids, sterols, sercosterols (vitamin D), isoprenoids (i.e., carotenoids and retinoids (vitamin A)), quinones (i.e., coenzyme Q, vitamin K, and vitamin E), terpenes, oxidized lipids, and oxylipin are highlighted. The uniqueness of each food group: oil-, protein-, and starch-rich, as well as marine foods, fruits, and vegetables (water-rich) regarding its lipid composition, is included. The effect of cooking, food processing, and storage, in addition to the importance of lipidomics in food quality and authenticity, are also discussed. A critical review of challenges and future trends of the analytical approaches and computational methods in global food lipidomics as the basis to increase consumer awareness of the significant role of lipids in food quality and food security worldwide is presented.

Antioxidants ameliorate oxidative stress in alcoholic liver injury by modulating lipid metabolism and phospholipid homeostasis

Alcoholic liver disease (ALD) is a significant risk factor in the global disease burden. The antioxidants vitamin C (Vc) and N-acetyl cysteine (NAC) have shown hepatoprotective effects in preventing and treating ALD. However, the correlation between the improved effect of antioxidants and lipid metabolism is still unclear. In this study, AML12 cells and C57BL/6 mice stimulated with alcohol were used to investigate the protective effects and potential mechanisms of two antioxidants (Vc and NAC) on alcoholic liver injury. Results showed that Vc and NAC attenuated intracellular lipid accumulation and oxidative damage induced by excessive alcohol exposure in hepatic AML12 cells. The in vivo results indicated that antioxidants ameliorated alcohol-induced changes in histopathology, reducing the levels of alcohol metabolizing factors and aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), and total cholesterol (TC) contents, which demonstrated that antioxidants effectively mitigated liver injury in ALD mice. Further studies showed that antioxidants reversed the disruption of fatty acid (FA) synthesis and lipid transport induced by alcohol exposure, and restored phospholipid levels. Especially, Vc and NAC increased the endogenous antioxidant plasmenyl phosphatidylethanolamine (PlsEtn). Additionally, antioxidants ameliorated the alcohol-impaired mitochondrial function and inhibited excessive oxidative stress. In conclusion, antioxidants can regulate lipid metabolism and phospholipid homeostasis, which in turn inhibit oxidative stress and thereby exert protective effects against ALD.

Characterization and discrimination of volatile organic compounds and lipid profiles of truffles under different treatments by UHPLC-QE Orbitrap/MS/MS and P&T-GC-MS

The lipid profiles of the truffles with different treatments were determined by ultra-high-performance liquid chromatography-Quadrupole-Exactive Orbitrap mass spectrometry (UHPLC-QE Orbitrap/MS/MS) and the volatile organic compounds (VOCs) were identified by purge-and-trap-gas chromatography-mass spectrometry (P&T-GC-MS). A total of 37 lipid molecular species and 28 VOCs were tentatively identified. Lysophophatidylcholine (LPC), triacylglycerol (TG) and sphingomyelin (SM) in heat-drying truffles, phosphatidic acid (PA) in freeze-drying and fresh truffles might be the key lipids that bound VOCs. Furthermore, the correlation between lipids and VOCs were analyzed by 19 differential lipids and 7 VOCs. The findings indicated that TG 18:2/18:2/18:2 and Cardiolipin (CL) 16:0/16:0/18:2/18:2 might be the key lipid molecule species for the formation of 2-methoxyphenol. The study helps to understand the effect of different treatments on the lipid profiles and provides the mechanistic insights to the relationship between the lipids and VOCs of truffles.

Comprehensive Lipid Profile of Eight Echinoderm Species by RPLC-Triple TOF-MS/MS

Echinoderms are of broad interest for abundant bioactive lipids. The comprehensive lipid profiles in eight echinoderm species were obtained by UPLC-Triple TOF-MS/MS with characterization and semi-quantitative analysis of 961 lipid molecular species in 14 subclasses of 4 classes. Phospholipids (38.78-76.83%) and glycerolipids (6.85-42.82%) were the main classes in all investigated echinoderm species, with abundant ether phospholipids, whereas the proportion of sphingolipids was higher in sea cucumbers. Two sulfated lipid subclasses were detected in echinoderms for the first time; sterol sulfate was rich in sea cucumbers, whereas sulfoquinovosyldiacylglycerol existed in the sea star and sea urchins. Furthermore, PC(18:1/24:2), PE(16:0/14:0), and TAG(50:1e) could be used as lipid markers to distinguish eight echinoderm species. In this study, the differentiation of eight echinoderms was achieved by lipidomics and revealed the uniqueness of the natural biochemical fingerprints of echinoderms. The findings will help evaluate the nutritional value in the future.

Comparative analysis of lipid components in fresh Crassostrea Hongkongensis (raw) and its dried products by using high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (HPLC/Q-TOF-MS)

The lipids of the oyster (Crassostrea hongkongensis) have a special physiological activity function, which is essential to maintain human health. However, comprehensive research on their lipids species and metabolism is not so common. In our study, based on the high-performance liquid chromatography/quadrupole time-of-flight mass spectrometer (HPLC/Q-TOF-MS), the non-targeted lipidomics research of Crassostrea hongkongensis fresh and dried products was determined. Meanwhile, we analyzed its lipid outline, screened the differences between the lipid molecules of Crassostrea hongkongensis fresh and dried products, and determined the lipid metabolic pathway. Results showed that 1,523 lipid molecules were detected, in which polyunsaturated fatty acids mostly existed in such lipids as phosphoglyceride. Through the multivariate statistical analysis, according to the conditions of P < 0.05, FC > 2 or FC < 0.05, and VIP > 1.2, 239 different lipid molecules were selected, including 37 fatty acids (FA), 60 glycerol phospholipids (GP), 20 glycerin (GL), 38 sheath lipids (SP), 31 steroid lipids (ST), 36 polyethylene (PK), and 17 progesterone lipids (PR). Combined with the Kyoto Encyclopedia of Genes and Genomes (KEGG), the differential lipid molecules were analyzed to mainly determine the role of the glycerin phospholipid metabolic pathway. As a whole, the results of this study provide the theoretical basis for the high-value utilization of oysters and are helpful to the development of oysters' physiological activity functions and deep utilization.

Characterization of Ginsenosides from the Root of Panax ginseng by Integrating Untargeted Metabolites Using UPLC-Triple TOF-MS

To compare the chemical distinctions of Panax ginseng Meyer in different growth environments and explore the effects of growth-environment factors on P. ginseng growth, an ultra-performance liquid chromatography-tandem triple quadrupole time-of-flight mass spectrometry (UPLC-Triple-TOF-MS/MS) was used to characterize the ginsenosides obtained by ultrasonic extraction from P. ginseng grown in different growing environments. Sixty-three ginsenosides were used as reference standards for accurate qualitative analysis. Cluster analysis was used to analyze the differences in main components and clarified the influence of growth environment factors on P. ginseng compounds. A total of 312 ginsenosides were identified in four types of P. ginseng, among which 75 were potential new ginsenosides. The number of ginsenosides in L15 was the highest, and the number of ginsenosides in the other three groups was similar, but it was a great difference in specie of ginsenosides. The study confirmed that different growing environments had a great influence on the constituents of P. ginseng, and provided a new breakthrough for the further study of the potential compounds in P. ginseng.

Nutritional lipidomics for the characterization of lipids in food

Lipids represent one out of three major macronutrient classes in the human diet. It is estimated to account for about 15-20% of the total dietary intake. Triacylglycerides comprise the majority of them, estimated 90-95%. Other lipid classes include free fatty acids, phospholipids, cholesterol, and plant sterols as minor components. Various methods are used for the characterization of nutritional lipids, however, lipidomics approaches become increasingly attractive for this purpose due to their wide coverage, comprehensiveness and holistic view on composition. In this chapter, analytical methodologies and workflows utilized for lipidomics profiling of food samples are outlined with focus on mass spectrometry-based assays. The chapter describes common lipid extraction protocols, the distinct instrumental mass-spectrometry based analytical platforms for data acquisition, chromatographic and ion-mobility spectrometry methods for lipid separation, briefly mentions alternative methods such as gas chromatography for fatty acid profiling and mass spectrometry imaging. Critical issues of important steps of lipidomics workflows such as structural annotation and identification, quantification and quality assurance are discussed as well. Applications reported over the period of the last 5years are summarized covering the discovery of new lipids in foodstuff, differential profiling approaches for comparing samples from different origin, species, varieties, cultivars and breeds, and for food processing quality control. Lipidomics as a powerful tool for personalized nutrition and nutritional intervention studies is briefly discussed as well. It is expected that this field is significantly growing in the near future and this chapter gives a short insight into the power of nutritional lipidomics approaches.

The nutritional functions of dietary sphingomyelin and its applications in food

Sphingolipids are common structural components of cell membranes and are crucial for cell functions in physiological and pathophysiological conditions. Sphingomyelin and its metabolites, such as sphingoid bases, ceramide, ceramide-1-phosphate, and sphingosine-1-phosphate, play signaling roles in the regulation of human health. The diverse structures of sphingolipids elicit various functions in cellular membranes and signal transduction, which may affect cell growth, differentiation, apoptosis, and maintain biological activities. As nutrients, dietary sphingomyelin and its metabolites have wide applications in the food and pharmaceutical industry. In this review, we summarized the distribution, classifications, structures, digestion, absorption and metabolic pathways of sphingolipids, and discussed the nutritional functioning of sphingomyelin in chronic metabolic diseases. The possible implications of dietary sphingomyelin in the modern food preparations including dairy products and infant formula, skin improvement, delivery system and oil organogels are also evaluated. The production of endogenous sphingomyelin is linked to pathological changes in obesity, diabetes, and atherosclerosis. However, dietary supplementations of sphingomyelin and its metabolites have been shown to maintain cholesterol homeostasis and lipid metabolism, and to prevent or treat these diseases. This seemly paradoxical phenomenon shows that dietary sphingomyelin and its metabolites are candidates for food additives and functional food development for the prevention and treatment of chronic metabolic diseases in humans.

Sphingolipids as Functional Food Components: Benefits in Skin Improvement and Disease Prevention

Sphingolipids are ubiquitous components in eukaryotic organisms and have attracted attention as physiologically functional lipids. Sphingolipids with diverse structures are present in foodstuffs as these structures depend on the biological species they are derived from, such as mammals, plants, and fungi. The physiological functions of dietary sphingolipids, especially those that improve skin barrier function, have recently been noted. In addition, the roles of dietary sphingolipids in the prevention of diseases, including cancer and metabolic syndrome, have been studied. However, the mechanisms underlying the health-improving effects of dietary sphingolipids, especially their metabolic fates, have not been elucidated. Here, we review dietary sphingolipids, including their chemical structures and contents in foodstuff; digestion, intestinal absorption, and metabolism; and nutraceutical functions, based on the available evidence and hypotheses. Further research is warranted to clearly define how dietary sphingolipids can influence human health.

Lipidomics analysis unravels changes from flavor precursors in different processing treatments of purple-leaf tea

BACKGROUND

Lipids are one of the most important bioactive compounds, affecting the character and quality of tea. However, the contribution of lipids to tea productions is still elusive. Here, we systematically identified the lipid profiles of green, oolong, and black teas in purple-leaf tea (Jinmingzao, JMZ) and green-leaf tea (Huangdan, HD), respectively.

RESULTS

The lipids analysis showed regular accumulation in tea products with different manufacturing processes, among which the fatty acids, glycerolipids, glycerophospholipids, and sphingolipids contribute to the quality characteristics of tea products, including typical fatty acyl (FA), monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerols (DGDG), and phosphatidylcholine (PC). Compared tea materials with products, levels of fatty acids were up-regulated, while glycerolipids and glycerophospholipids were down-regulated in tea products. FA 18:3, FA 16:0, MGDG 36:6, DGDG 36:6, PC 34:3, and PC 36:6 were the negative contributors to green tea flavor formation of purple-leaf tea. The pathway analysis of significant lipids in materials and products of purple-leaf tea were enriched linolenic acid metabolism pathway and glycerolipid metabolism.

CONCLUSION

This study provides insights into the lipid metabolism profiles of different tea leaf colors, and found that fatty acids are essential precursors of black tea flavor formation. © 2021 Society of Chemical Industry.

Identification of novel biomarkers for acute radiation injury using multi-omics approach and nonhuman primate model

PURPOSE

The availability of validated biomarkers to assess radiation exposure and to assist in developing medical countermeasures remains an unmet need.

METHODS AND MATERIALS

We used a cobalt-60 gamma-irradiated nonhuman primate (NHP) model to delineate a multi-omics-based serum probability index of radiation exposure. Both male and female NHPs were irradiated with different doses ranging from 6.0 to 8.5 Gy, with 0.5 Gy increments between doses. We leveraged high-resolution mass spectrometry for analysis of metabolites, lipids, and proteins at 1, 2, and 6 days post-irradiation in NHP serum.

RESULTS

A logistic regression model was implemented to develop a 4-analyte panel to stratify irradiated NHPs from unirradiated with high accuracy that was agnostic for all doses of gamma-rays tested in the study, up to six days after exposure. This panel was comprised of Serpin Family A9, acetylcarnitine, PC (16:0/22:6), and suberylglycine, which showed 2 - 4-fold elevation in serum abundance upon irradiation in NHPs and can potentially be translated as a molecular diagnostic for human use following larger validation studies.

CONCLUSIONS

Taken together, this study, for the first time, demonstrates the utility of a combinatorial molecular characterization approach using an NHP model for developing minimally invasive assays from small volumes of blood that can be effectively used for radiation exposure assessments.

Advances in analysis, metabolism and mimicking of human milk lipids

Human milk lipids differ from the milk lipids of other mammals in composition and positional distribution of fatty acids. Analysis and detection technology of lipids is key to understanding milk lipids, and thus the concentrations, compositions and distribution characteristics of milk lipids are discussed. Differences between human milk lipids and their substitutes in form, composition and structure affect their digestion, absorption and function in infants. Characteristics and mimicking of human milk lipids have been intensively studied with the objective of narrowing the gap between human milk and infant formulae. Based on the existing achievements, further progress may be made by improving detection techniques, deepening knowledge of metabolic pathways and perfecting fat substitutes. This review detailed the characteristics of human milk lipids and related detection technologies with a view towards providing a clear direction for research on mimicking human milk lipids in formulae to further improve infant nutrition.

Comparative lipidomics profiling of the sea urchin, Strongylocentrotus intermedius

Strongylocentrotus intermedius is an edible sea urchin and well-known for its nutritional value, such as a high content of polyunsaturated fatty acids (PUFAs). We carried out an untargeted lipidomics via high-resolution ultra-high-performance liquid chromatography - mass spectrometry (UPLC-MS) to highlight the features of the lipids profile of sea urchin gonad, which allowed for a more detailed interpretation of the accumulation of PUFAs with different abundances among sea urchins. For the first time, lipidomics profiling of lipid abundances in S. intermedius was demonstrated. We detected 11 PUFAs in sea urchin gonads, which represented >54.13% of the total fatty acid content. A total of 1552 lipid molecular species belonging to 36 lipid classes were identified. Lipidomics profiles data were analyzed using orthogonal partial least squares discriminant analysis (OPLS-DA) model and distinguished the PUFA abundances in both sexes of sea urchins. The significant differences in lipid molecules were highlighted and the major lipid classes identified were phosphatidylcholine (PC [19 species]) among females and triglycerides (TG [11 species]) among males. PC (42: 11) may be used as a potential marker for distinguishing high levels of PUFAs in sea urchin individuals, which as the result of the high level of PC (42:11). These data enrich the lipid profile library of aquatic products and provide a more reliable and refined biomarkers for the further research on fatty acid synthesis and metabolism in aquatic animals.

Appearance of Intact Molecules of Dietary Ceramides Prepared from Soy Sauce Lees and Rice Glucosylceramides in Mouse Plasma

Although the beneficial effects of dietary sphingolipids have recently been reported, the mechanism of their intestinal absorption has yet to be fully elucidated. In this study, the absorption and metabolism of dietary ceramides and glucosylceramides were evaluated by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis in the plasma of mice after a single oral administration. Ceramide molecules prepared from soy sauce lees (mainly composed of phytosphingosine and its derivatives) were undetectable or minor compounds in the plasma of control mice but appeared 1-6 h after administration. Rice glucosylceramide (mainly composed of sphingadienine) was endogenously detected in mouse plasma and showed a tendency to increase 1-6 h after administration by LC-MS/MS analysis. In addition, the ceramide molecules, which are hydrolysates of dietary glucosylceramide, were significantly increased in the plasma after administration. These findings strongly suggest that dietary ceramides and glucosylceramides are partly absorbed as intact molecules or hydrolysates.

Sphingolipids in foodstuff: Compositions, distribution, digestion, metabolism and health effects - A comprehensive review

Sphingolipids (SLs) are common in all eukaryotes, prokaryotes, and viruses, and played a vital role in human health. They are involved in physiological processes, including intracellular transport, cell division, and signal transduction. However, there are limited reviews on dietary effects on endogenous SLs metabolism and further on human health. Various dietary conditions, including the SLs-enriched diet, high-fat diet, and vitamins, can change the level of endogenous SLs metabolites and even affect human health. This review systematically summarizes the main known SLs in foods concerning their variety and contents, as well as their isolation and identification approaches. Moreover, the present review discusses the role of dietary (particularly SLs-enriched diet, high-fat diet, and vitamins) in endogenous SLs metabolism, highlighting how exogenous SLs are digested and absorbed. The role of SLs family in the pathogenesis of diseases, including cancers, neurological disorders, infectious and inflammatory diseases, and cardiovascular diseases, and in recently coronavirus disease-19 outbreak was also discussed. In the post-epidemic era, we believe that the concern for health and the need for plant-based products will increase. Therefore, a need for research on the absorption and metabolism pathway of SLs (especially plant-derived SLs) and their bioavailability is necessary. Moreover, the effects of storage treatment and processing on the content and composition of SLs in food are worth exploring. Further studies should also be conducted on the dose-response of SLs on human health to support the development of SLs supplements. More importantly, new approaches, such as, making SLs based hydrogels can effectively achieve sustained release and targeted therapies.

Fast and Specific Screening of EPA/DHA-Enriched Phospholipids in Fish Oil Extracted from Different Species by HILIC-MS

Eicosapentaenoic acid- and docosahexaenoic acid-enriched phospholipids (PL_EPA/DHA) have versatile health-beneficial functions and can be well absorbed in the intestine. Herein, a precursor ion scan-driven hydrophilic interaction chromatography mass spectrometry (PreIS-HILIC-MS) method with the fatty acyl moieties of m/z 301.6 and 327.6 locked was established to specifically and selectively screen PL_EPA/DHA in different fish oil samples, including saury, grass carp, hairtail, and yellow croaker. Taking saury oil as an example, a total of 24 PL_EPA/DHA were successfully identified and quantified, including 20 PC_EPA/DHA and 4 PE_EPA/DHA. Finally, this method was validated in terms of sensitivity (limit of detection ≤ 4.15 μg·mL^-1), linearity (≥0.9979), precision (RSD_intraday ≤ 4.65%), and recovery (≥78.6%). The performance of the PreIS-HILIC-MS method was also compared with that of the traditional full-scan mode, and the former demonstrated its unique superiority in targeted screening of PL_EPA/DHA in fish oils.

Characterization and bioactivities of phospholipids from squid viscera and gonads using ultra-performance liquid chromatography-Q-exactive orbitrap/mass spectrometry-based lipidomics and zebrafish models

There has been great interest in phospholipids (PLs) from marine by-products due to their long-chain polyunsaturated fatty acids with unique health and functional properties. Here, marine PLs from squid viscera and gonads were comprehensively characterized and compared by UPLC-Q-Exactive Orbitrap/MS-based lipidomics analysis. A total of thirteen phospholipid classes including 1223 molecular species were identified and quantified in both resources. PC, PE and SM were further isolated from the total PLs of squid viscera and gonads, respectively. All isolated squid PL components were first evaluated for anti-inflammatory, antioxidant and cardiovascular effects using in vivo zebrafish models. Our results showed the diversity, content and physiological functions of PLs from squid by-products, which provided a basis for their future application in the nutritional and pharmaceutical industry.

Characterization of Gangliosides in Three Sea Urchin Species by HILIC-ESI-MS/MS

Sea urchin gangliosides (SU-GLSs) are well acknowledged for their nerve regeneration activity and neuroprotective property. The present study sought to characterize and semi-quantitate different SU-GLS subclasses in three sea urchin species, including Strongylocentrotus nudus, Hemicentrotus pulcherrimus, and Glyptocidaris crenularis. A total of 14 SU-GLS subclasses were identified by a hydrophilic interaction liquid chromatography-Q-Exactive tandem mass spectrometry method. Three sialic acid (Sia) structures, including Neu5Ac, Neu5Gc, and KDN, were identified in SU-GLSs, of which Neu5Ac and Neu5Gc had their corresponding sulfated forms. The linkage among Sias was determined to be 2-8. Additionally, KDN2-6Glc1-1Cer, KDN2-8Neu5Gc2-6Glc1-1Cer, and KDN2-8Neu5Gc2-8Neu5Gc2-6Glc-1Cer were speculated to be novel SU-GLS structures. Furthermore, the total SU-GLS content was 2.0-7.3 mg/g in the three sea urchin species. These results will provide useful data for developing a SU-GLS database of aquatic products. Besides, this study will provide a theoretical basis to explore the nutritional values of seafood products further.

UHPLC-Q-Orbitrap HRMS-based quantitative lipidomics reveals the chemical changes of phospholipids during thermal processing methods of Tan sheep meat

Thermal processing affects the lipid compositions of meat products. The study determined the effects of boiled, steamed and roasted processing methods on the lipidomics profiles of Tan sheep meat with a validated UPLC-Q-Orbitrap HRMS combined lipid screening strategy method. Combined with sphingolipid metabolism, the boiled approach was the suitable choice for atherosclerosis patients for more losses of sphingomyelin than ceramide in meat. The similarly less losses of phosphatidylcholine and lysophosphatidylcholine showed in glycerophospholipid metabolism implied that steamed Tan sheep meat was more suitable for the populations of elderly and infants. Furthermore, a total of 90 lipids with significant difference (VIP > 1) in 6 lipid subclasses (sphingomyelin, ceramide, lysophosphatidylcholine, phosphatidylcholine, phosphatidylethanolamines, triacylglycerol,) were quantified among raw and three types of thermal processed Tan sheep meat, further providing useful information for identification of meat products with different thermal processing methods (LOD with 0.14-0.31 μg kg^-1, LOQ with 0.39-0.90 μg kg^-1).

Application of Comparative Lipidomics to Elucidate Postprandial Metabolic Excursions Following Dairy Milk Ingestion in Individuals with Prediabetes

Nutrient-dense dairy foods are an important component of a healthy diet. Recommendations, however, advise non- and low-fat dairy foods despite controversy concerning whether full-fat dairy foods adversely impact cardiometabolic health. Therefore, in this study, our objective is to examine the differential plasma lipidomic responses to non-fat or full-fat milk ingestion during postprandial hyperglycemia. Seven adults with prediabetes completed a randomized cross-over study in which glucose was consumed alone or with non-fat or full-fat dairy milk. Plasma samples collected at 90 min and 180 min post milk ingestion were used to perform untargeted lipidomics analysis. A total of 332 lipids from 20 classes and five lipid categories were detected at different time points during the postprandial period. Dairy milk, especially non-fat milk, protected against lipid changes otherwise induced by glucose ingestion. Co-ingestion of dairy milk with glucose, regardless of fat content, significantly altered lipid profiles although full-fat milk more substantially modulated lipid profiles. For the identified lipid biomarkers, 68.0% and 66.7% of the lipids significantly increased at 90 and 180 min, respectively, while phosphatidylcholines (GPs) contributed most for the significant increase. Comparative lipidomics analysis indicated that both types of dairy milk induced significant changes in several lipid pathways, including glycerophospholipid metabolism and α-linolenic acid metabolism, to protect against postprandial hyperglycemia. In summary, our comparative lipidomics results suggested that dairy milk-mediated lipid modulation may be an effective dietary approach to reduce the risk of metabolic diseases among those with prediabetes.

Seasonal variations in biochemical composition and nutritional quality of Crassostrea hongkongensis, in relation to the gametogenic cycle

Variations in the biochemical composition and nutritional quality with annual changes in gonad development were investigated to identify the optimal harvesting time of C. hongkongensis. The glycogen levels in the mantle, muscle, and gonad-visceral mass were significantly lower in June than in December, associated with changes in the expressions of ChGS and ChGP. Protein content consistently exceeded 52% of dry weight. The only significant change in protein levels was an increase between April and June in the gonad-visceral mass, which was associated with the gonadal transition from proliferation to maturation. Moreover, C. hongkongensis consistently had a well-balanced essential amino acid profile, meeting the essential amino acid requirements of preschool children. The lipid content and fatty acid composition of C. hongkongensis varied with the reproductive cycle, but the omega-3:omega-6 ratio was consistently higher than those of C. gigas and C. virginica. In summary, the optimal harvest time of C. hongkongensis was during the inactive stage of most gonads (from August to February at Beihai).

Lipidomics phenotyping of clam (Corbicula fluminea) through graphene/fibrous silica nanohybrids based solid-phase extraction and HILIC-MS analysis

Polyunsaturated phospholipids are abundant in clam (Corbicula fluminea) but difficult to be fully extracted. Herein, graphene/fibrous silica (G/KCC-1) nanohybrids were synthesized, characterized, and applied for solid-phase extraction (SPE) of phospholipids in clam. The effectiveness of G/KCC-1 SPE was verified by hydrophilic interaction chromatography mass spectrometry (HILIC-MS) based lipidomics and statistical analysis. The ions of PE 16:0/18:1 (m/z 716.4), PC 16:0/20:5 (m/z 824.6) and etc. were regarded as the main difference among the crude lipids, acetone washed extract, and eluate of G/KCC-1 SPE. Finally, this method was validated in terms of linearity (R² 0.9965 to 0.9981), sensitivity (LOD 0.19-0.51 μg·mL^-1 and LOQ 0.48 - 1.47 μg·mL^-1), and precision (RSD_intra-day ≤ 7.16% and RSD_inter-day ≤ 7.30%). In conclusion, the G/KCC-1 SPE and HILIC-MS method was shown to be accurate and efficient in selective extracting and phenotyping phospholipids in C. fluminea.

Characterizing gangliosides in six sea cucumber species by HILIC-ESI-MS/MS

An HILIC-ESI-MS/MS method was established to analyze ganglioside (GLS) in sea cucumbers. In total, 17 GLS subclasses were detected in six sea cucumber species. The basic sea cucumber GLSs (SC-GLSs) were elucidated as NeuGc2-6Glc1-1Cer (SC-GM₄). The polymerization degree of the sialic acid (Sia) of SC-GLSs can be up to 4, and the linkage among Sias was mostly determined to be 2-8 or 2-11. Neu5Gc, sulfated and fucosylated NeuGc prevalently existed in SC-GLSs. Moreover, a new SC-GLSs structure with phosphoinositidyled Sia was first observed in Bohadschia marmorata. For the first time, we demonstrated that the content of SC-GD₄, which is the dominant GLS in sea cucumbers, was 27-67%. Minor GLSs characterized as SC-GT₂(Neu5GcMe) and SC-GQ₂(Neu5GcMe) were also discovered. Additionally, SC-GD₄ and SC-GD₄(1S) could significantly promote the differentiation of PC12 cells with structure-selectivity (p < 0.05). Our results provide insights into SC-GLSs to elucidate their Sia substituent and core saccharide chain linkage.

Immunological Responses of Marine Bivalves to Contaminant Exposure: Contribution of the -Omics Approach

The increasing number of data studies on the biological impact of anthropogenic chemicals in the marine environment, together with the great development of invertebrate immunology, has identified marine bivalves as a key invertebrate group for studies on immunological responses to pollutant exposure. Available data on the effects of contaminants on bivalve immunity, evaluated with different functional and molecular endpoints, underline that individual functional parameters (cellular or humoral) and the expression of selected immune-related genes can distinctly react to different chemicals depending on the conditions of exposure. Therefore, the measurement of a suite of immune biomarkers in hemocytes and hemolymph is needed for the correct evaluation of the overall impact of contaminant exposure on the organism's immunocompetence. Recent advances in -omics technologies are revealing the complexity of the molecular players in the immune response of different bivalve species. Although different -omics represent extremely powerful tools in understanding the impact of pollutants on a key physiological function such as immune defense, the -omics approach has only been utilized in this area of investigation in the last few years. In this work, available information obtained from the application of -omics to evaluate the effects of pollutants on bivalve immunity is summarized. The data shows that the overall knowledge on this subject is still quite limited and that to understand the environmental relevance of any change in immune homeostasis induced by exposure to contaminants, a combination of both functional assays and cutting-edge technology (transcriptomics, proteomics, and metabolomics) is required. In addition, the utilization of metagenomics may explain how the complex interplay between the immune system of bivalves and its associated bacterial communities can be modulated by pollutants, and how this may in turn affect homeostatic processes of the host, host–pathogen interactions, and the increased susceptibility to disease. Integrating different approaches will contribute to knowledge on the mechanism responsible for immune dysfunction induced by pollutants in ecologically and economically relevant bivalve species and further explain their sensitivity to multiple stressors, thus resulting in health or disease.

Sphingolipids in food and their critical roles in human health

Sphingolipids (SLs) are ubiquitous structural components of cell membranes and are essential for cell functions under physiological conditions or during disease progression. Abundant evidence supports that SLs and their metabolites, including ceramide (Cer), ceramide-1-phosphate (C1P), sphingosine (So), sphingosine-1-phosphate (S1P), are signaling molecules that regulate a diverse range of cellular processes and human health. However, there are limited reviews on the emerging roles of exogenous dietary SLs in human health. In this review, we discuss the ubiquitous presence of dietary SLs, highlighting their structures and contents in foodstuffs, particularly in sea foods. The digestion and metabolism of dietary SLs is also discussed. Focus is given to the roles of SLs in both the etiology and prevention of diseases, including bacterial infection, cancers, neurogenesis and neurodegenerative diseases, skin integrity, and metabolic syndrome (MetS). We propose that dietary SLs represent a "functional" constituent as emerging strategies for improving human health. Gaps in research that could be of future interest are also discussed.