Lipids最新文献

Furan fatty acids (FuFA) are important antioxidants found in low concentrations in many types of food. In addition to conventional FuFA which normally feature saturated carboxyalkyl and alkyl chains, a few previous studies indicated the FuFA co-occurrence of low shares of unsaturated furan fatty acids (uFuFA). For their detailed analysis, the potential uFuFA were enriched by centrifugal partition chromatography (CPC) or countercurrent chromatography (CCC) followed by silver ion chromatography from a 4,7,10,13,16,19-docosahexaenoic acid ethyl ester oil, a 5,8,11,14,17-eicosapentaenoic acid ethyl ester oil and a latex glove extract. Subsequent gas chromatography with mass spectrometry (GC/MS) analysis enabled the detection of 16 individual uFuFA isomers with a double bond in conjugation with the central furan moiety. In either case, four instead of two uFuFA isomers previously reported in food, respectively, were detected by GC/MS. These isomers showed characteristic elution and abundance patterns in GC/MS chromatograms which indicated the presence of two pairs of cis/trans-isomers (geometrical isomers).

Olive oil has beneficial effects on skin wound healing due to its anti-inflammatory and antioxidant properties; however, the mechanism by which olive oil promotes wound healing is unclear. We evaluated the mechanisms involved in Nrf2 pathway activation by olive oil and its role in cell survival and migration in mouse dermal fibroblasts in a short-term exposition. Our data demonstrated that olive oil and oleic acid promoted reactive oxygen species (ROS) production, while olive oil and hydroxytyrosol stimulated nuclear factor erythroid 2-related factor 2 (Nrf2) activation. Olive oil-mediated ROS production increased nuclear factor kappa B p65 expression, while olive oil-stimulated reactive nitrogen species production augmented the levels of Nrf2. Olive oil augmented cell proliferation, cell migration, and AKT phosphorylation, but decreased apoptotic cell number and cleaved caspase-3 levels. The effect of olive oil on cell migration and protein levels of AKT, BCL-2, and Nrf2 were reversed by an Nrf2 inhibitor. In conclusion, the activation of the Nrf2 pathway by olive oil promotes the survival and migration of dermal fibroblasts that are essential for the resolution of skin wound healing.

Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) are essential for improving the health and performance of athletes. The present study aimed to evaluate the nutritional status of omega-3 PUFAs in Chinese elite athletes by both dietary intake analysis and serum biomarker detection. A cross-sectional analysis of data from 54 elite athletes (24 men and 30 women) from Shanghai professional sports teams was conducted. A food frequency questionnaire (FFQ) was employed to analyze dietary intake, and gas chromatography–mass spectrometry (GC–MS/MS) was conducted to measure serum biomarkers of PUFAs. Correlation analysis was performed to investigate the relationships of PUFA biomarkers with diet, inflammation and oxidative stress. The results showed that the median intake of EPA + DHA among athletes was 132 mg/d, which is lower than the minimum value recommended by dietary guidelines (250 mg/d). The average serum EPA + DHA was 4.0 ± 1.1%, and the ratio of omega-6/omega-3 was 7.7 ± 1.7. Most (96.3%) of the athletes were below the targeted value of serum EPA + DHA, which is associated with a reduction in cardiovascular risk. Correlation analysis showed that the serum EPA + DHA was positively correlated with the long-term dietary intake of EPA + DHA and negatively correlated with inflammatory markers. In conclusion, the serum circulating EPA + DHA and omega-6/omega-3 ratio are effective biomarkers reflecting the nutritional status of PUFAs in athletes. Omega-3 PUFAs have a potential effect on inhibiting inflammatory markers. Hence, it is necessary for Chinese athletes to improve their suboptimal nutritional status of PUFAs through dietary intervention.

Currently, there is a global trend of rapid increase in obesity, especially among adolescents. The antibiotics cocktails (ABX) therapy is commonly used as an adjunctive treatment for gut microbiota related diseases, including obesity. However, the effects of broad-spectrum antibiotics alone on young obese hosts have rarely been reported. In the present study, the 3-week-old C57BL/6J male mice fed a high-fat diet (HFD) were intragastric administration with ampicillin, vancomycin, metronidazole or neomycin for 30 days. The lipid metabolites in plasma were assessed by biochemical assay kits, and genes related to lipid metabolite in the white adipose were assessed by qPCR. To further analyze the underlying mechanisms, the expression of genes related to lipid metabolism, inflammatory reactions and oxidative stress in the liver were determined by qPCR assay. In addition, the expression of oxidative damage-associated proteins in the liver were detected by western blot. The results showed that oral antibiotics exposure could reduce body weight and fat index in HFD-fed mice, concurrent with the increase of white adipose lipolysis genes and the decrease of hepatic lipogenic genes. Furthermore, antibiotics treatment could clearly reverse the HFD-induced elevation of oxidative damage-related proteins in the liver. Together, these findings will provide valuable clues into the effects of antibiotics on obesity.

Oxysterols play a key role in many (patho)physiological processes and they are potential biomarkers for oxidative stress in several diseases. Here we developed a rapid gas chromatographic-mass spectrometry-based method for the separation and quantification of 11 biologically relevant oxysterols bearing hydroxy, epoxy, and dihydroxy groups. Efficient chromatographic separation (resolution ≥ 1.9) was achieved using a medium polarity 35%-diphenyl/65%-dimethyl polysiloxane stationary phase material (30 m × 0.25 mm inner diameter and 0.25 μm film thickness). Based on thorough analysis of the fragmentation during electron ionization we developed a strategy to deduce structural information of the oxysterols. Optimized sample preparation includes (i) extraction with a mixture of n-hexane/iso-propanol, (ii) removal of cholesterol by solid phase extraction with unmodified silica, and (iii) trimethylsilylation. The method was successfully applied on the analysis of brain samples, showing consistent results with previous studies and a good intra- and interday precision of ≤20%. Finally, we used the method for the investigation of oxysterol formation during oxidative stress in HepG2 cells. Incubation with tert-butyl hydroperoxide led to a massive increase in free radical formed oxysterols (7-keto-chol > 7β-OH-chol >> 7α-OH-chol), while 24 h incubation with the glutathione peroxidase 4 inhibitor RSL3 showed no increase in oxidative stress based on the oxysterol pattern. Overall, the new method described here enables the robust analysis of a biologically meaningful pattern of oxysterols with high sensitivity and precision allowing us to gain new insights in the biological formation and role of oxysterols.

It is widely accepted that unesterified polyunsaturated ω-6 and ω-3 fatty acids (PUFA) are converted through various lipoxygenases, cyclooxygenases, and cytochrome P450 enzymes to a range of oxygenated derivatives (oxylipins), among which the polyhydroxides of unesterified PUFA have recently been recognized as cell signaling molecules with anti-inflammatory and pro-resolving properties, known as specialized pro-resolving mediators (SPMs). This study investigates the mono-, di-, and trihydroxy 16:0/PUFA-GPCs, and the corresponding 16:0/SPM-GPC, in plasma lipoproteins. We describe the isolation and identification of mono-, di-, and trihydroxy AA, EPA, and DHA-GPC in plasma LDL, HDL, HDL3, and acute phase HDL using normal phase LC/ESI-MS, as previously reported. The lipoproteins contained variable amounts of the polyhydroxy-PUFA-GPC (0–10 nmol/mg protein), likely the product of lipid peroxidation and the action of various lipoxygenases and cytochrome P450 enzymes on both free fatty acids and the parent GPCs. Polyhydroxy-PUFA-GPC was hydrolyzed to variable extent (20%–80%) by the different secretory phospholipases A₂ (sPLA₂s), with Group IIA sPLA₂ showing the lowest and Group X sPLA₂ the highest activity. Surprisingly, the trihydroxy-16:0/PUFA-GPC of APHDL was largely absent, while large amounts of unidentified material had migrated in the free fatty acid elution area. The free fatty acid mass spectra were consistent with that anticipated for branched chain polyhydroxy fatty acids. There was general agreement between the masses determined by LC/ESI-MS for the polyhydroxy PUFA-GPC and the masses calculated for the GPC equivalents of resolvins, protectins, and maresins using the fatty acid structures reported in the literature.

Current treatment approaches for hyperlipidemia rely mainly on reducing the cholesterol level by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), which is involved in the presqualene pathway of cholesterol biosynthesis. Finding a compound that instead targets the postsqualene pathway could aid in the treatment of hyperlipidemia and synergistically reduce the cholesterol level when used in conjunction with HMGCR inhibitors. Ergosterol is a fungal sterol that is converted to brassicasterol by 7-dehydrocholesterol reductase (DHCR7). DHCR7 is also a cholesterol biosynthesis enzyme, and thus ergosterol may cause the accumulation of 7-dehydrocholesterol, a precursor of cholesterol and vitamin D₃, by a competitive effect. In this study, we examined the effect of ergosterol on the postsqualene pathway by quantifying cholesterol precursors and related sterols using gas chromatography–mass spectrometry and by conducting quantitative RT-PCR and western blot analysis for human HepG2 hepatoma cells. We found that ergosterol is converted into brassicasterol by the action of DHCR7 from HepG2 cells and that it induced the accumulation of cholesterol precursors (lathosterol, 7-dehydrocholesterol, and desmosterol) and decreased the cholesterol level by altering the mRNA and protein levels of cholesterol biosynthesis enzymes (increase of sterol 8,7-isomerase [EBP] and decrease of DHCR7 and 24-dehydrocholesterol reductase [DHCR24]). These results demonstrate that ergosterol inhibits the postsqualene pathway and may be useful for the prevention of hyperlipidemia.

Although it is well established that glucocorticoids inactivate thermogenesis and promote lipid accumulation in interscapular brown adipose tissue (IBAT), the underlying mechanisms remain unknown. We found that dexamethasone treatment (1 mg/kg) for 7 days in rats decreased the IBAT thermogenic activity, evidenced by its lower responsiveness to noradrenaline injection associated with reduced content of mitochondrial proteins, respiratory chain protein complexes, noradrenaline, and the β₃-adrenergic receptor. In parallel, to understand better how dexamethasone increases IBAT lipid content, we also investigated the activity of the ATP citrate lyase (ACL), a key enzyme of de novo fatty acid synthesis, glucose-6-phosphate dehydrogenase (G6PD), a rate-limiting enzyme of the pentose phosphate pathway, and the three glycerol-3-P generating pathways: (1) glycolysis, estimated by 2-deoxyglucose uptake, (2) glyceroneogenesis, evaluated by phosphoenolpyruvate carboxykinase activity and pyruvate incorporation into triacylglycerol-glycerol, and (3) direct phosphorylation of glycerol, investigated by the content and activity of glycerokinase. Dexamethasone increased the mass and the lipid content of IBAT as well as plasma levels of glucose, insulin, non-esterified fatty acid, and glycerol. Furthermore, dexamethasone increased ACL and G6PD activities (79% and 48%, respectively). Despite promoting a decrease in the incorporation of U-[¹⁴C]-glycerol into triacylglycerol (~54%), dexamethasone increased the content (~55%) and activity (~41%) of glycerokinase without affecting glucose uptake or glyceroneogenesis. Our data suggest that glucocorticoid administration reduces IBAT thermogenesis through sympathetic inactivation and stimulates glycerokinase activity and content, contributing to increased generation of glycerol-3-P, which is mostly used to esterify fatty acid and increase triacylglycerol content promoting IBAT whitening.

Phospholipase C (PLC) β1 hydrolyzes 1-stearoyl-2-arachidonoyl (18:0/20:4)-phosphatidylinositol (PtdIns) 4,5-bisphosphate to produce diacylglycerol, which is converted to phosphatidic acid (PtdOH), in the PtdIns cycle and plays pivotal roles in intracellular signal transduction. The present study identified PLCβ1 as a PtdOH-binding protein using PtdOH-containing liposomes. Moreover, the comparison of the binding of PLCβ1 to various PtdOH species, including 14:0/14:0-PtdOH, 16:0/16:0-PtdOH, 16:0/18:1-PtdOH, 18:0/18:1-PtdOH, 18:0/18:0-PtdOH, 18:1/18:1-PtdOH, 18:0/20:4-PtdOH, and 18:0/22:6-PtdOH, indicated that the interaction of PLCβ1 with 16:0/16:0-PtdOH was the strongest. The PLCβ1-binding activity of 18:0/18:0-PtdOH was almost the same as the binding activity of 16:0/16:0-PtdOH. Furthermore, the binding of PLCβ1 to 16:0/16:0-PtdOH was substantially stronger than 16:0/16:0-phosphatidylserine, 16:0/16:0/16:0/16:0-cardiolipin, 16:0/16:0-PtdIns, and 18:0/20:4-PtdIns. We revealed that a PLCβ1 mutant whose Lys946 and Lys951 residues were replaced with Glu (PLCβ1-KE) did not interact with 16:0/16:0-PtdOH and failed to localize to the plasma membrane in Neuro-2a cells. Retinoic acid-dependent increase in neurite length and numbers was significantly inhibited in PLCβ1-expressing cells; however, this considerable attenuation was not detected in the cells expressing PLCβ1-KE. Overall, these results strongly suggest that PtdOHs containing only saturated fatty acids, including 16:0/16:0-PtdOH, which are not derived from the PtdIns cycle, selectively bind to PLCβ1 and regulate its function.

α-linolenic acid (αLNA) conversion into the functionally important ω-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), has been regarded as inadequate for meeting nutritional requirements for these PUFA. This view is based on findings of small αLNA supplementation trials and stable isotope tracer studies that have been interpreted as indicating human capacity for EPA and, in particular, DHA synthesis is limited. The purpose of this review is to re-evaluate this interpretation. Markedly differing study designs, inconsistent findings and lack of trial replication preclude robust consensus regarding the nutritional adequacy of αLNA as a source of EPC and DHA. The conclusion that αLNA conversion in humans is constrained is inaccurate because it presupposes the existence of an unspecified, higher level of metabolic activity. Since capacity for EPA and DHA synthesis is the product of evolution it may be argued that the levels of EPA and DHA it maintains are nutritionally appropriate. Dietary and supra-dietary EPA plus DHA intakes confer health benefits. Paradoxically, such health benefits are also found amongst vegetarians who do not consume EPA and DHA, and for whom αLNA conversion is the primary source of ω-3 PUFA. Since there are no reported adverse effects on health or cognitive development of diets that exclude EPA and DHA, their synthesis from αLNA appears to be nutritionally adequate. This is consistent with the dietary essentiality of αLNA and has implications for developing sustainable nutritional recommendations for ω-3 PUFA.