USP19 Stabilizes TAK1 to Regulate High Glucose/Free Fatty Acid-induced Dysfunction in HK-2 Cells

Objective Obesity-induced kidney injury contributes to the development of diabetic nephropathy(DN).Here,we identified the functions of ubiquitin-specific peptidase 19(USP19)in HK-2 cells exposed to a combination of high glucose(HG)and free fatty acid(FFA)and determined its association with TGF-beta-activated kinase 1(TAK1).Methods HK-2 cells were exposed to a combination of HG and FFA.USP19 mRNA expression was detected by quantitative RT-PCR(qRT-PCR),and protein analysis was performed by immunoblotting(IB).Cell growth was assessed by Cell Counting Kit-8(CCK-8)viability and 5-ethynyl-2′-deoxyuridine(EdU)proliferation assays.Cell cycle distribution and apoptosis were detected by flow cytometry.The USP19/TAK1 interaction and ubiquitinated TAK1 levels were assayed by coimmunoprecipitation(Co-IP)assays and IB.Results In HG+FFA-challenged HK-2 cells,USP19 was highly expressed.USP19 knockdown attenuated HG+FFA-triggered growth inhibition and apoptosis promotion in HK-2 cells.Moreover,USP19 knockdown alleviated HG+FFA-mediated PTEN-induced putative kinase 1(PINK1)/Parkin pathway inactivation and increased mitochondrial reactive oxygen species(ROS)generation in HK-2 cells.Mechanistically,USP19 stabilized the TAK1 protein through deubiquitination.Importantly,increased TAK1 expression reversed the USP19 knockdown-mediated phenotypic changes and PINK1/Parkin pathway activation in HG+FFA-challenged HK-2 cells.Conclusion The findings revealed that USP19 plays a crucial role in promoting HK-2 cell dysfunction induced by combined stimulation with HG and FFAs by stabilizing TAK1,providing a potential therapeutic strategy for combating DN.

Berberine reverses free-fatty-acid-induced insulin resistance in 3T3-L1 adipocytes through targeting IKKβ

AIM: To investigate the effects and molecular mechanisms of berberine on improving insulin resistance induced by free fatty acids (FFAs) in 3T3-L1 adipocytes. METHODS: The model of insulin resistance in 3T3-L1 adipocytes was established by adding palmic acid (0.5 mmol/L) to the culture medium. Berberine treatment was performed at the same time. Glucose uptake rate was determined by the 2-deoxy-[3H]-D-glucose method. The levels of IkB kinase beta (IKKβ) Ser181 phosphorylation, insulin receptor substrate-1(IRS-1) Ser307 phosphorylation, expression of IKKβ, IRS-1, nuclear transcription factor kappaB p65 (NF-κB p65), phosphatidylinositol-3-kinase p85 (PI-3K p85) and glucose transporter 4 (GLUT4) proteins were detected by Western blotting. The distribution of NF-κB p65 proteins inside the adipocytes was observed through confocal laser scanning microscopy (CLSM). RESULTS: After the intervention of palmic acid for 24 h, the insulin-stimulated glucose transport in 3T3-L1 adipocytes was inhibited by 67%. Meanwhile, the expression of IRS-1 and PI-3K p85 protein was reduced, while the levels of IKKβ Ser181 and IRS-1 Ser307 phosphorylation, and nuclear translocation of NF-κB p65 protein were increased. However, the above indexes, which indicated the existence of insulin resistance, were reversed by berberine although the expression of GLUT4, IKKβ and total NF-κB p65 protein were not changed during this study. CONCLUSION: Insulin resistance induced by FFAs in 3T3-L1 adipocytes can be improved by berberine. Berberine reversed free-fatty-acid-induced insulin resistance in 3T3-L1 adipocytes through targeting IKKβ.

Role of free fatty acids in proliferation of rat hepatic stellate cells(Ⅱ)

AIM To study the role of free fatty acids (arachidonic acid and linoleic acid) in proliferation of rat hepatic stellate cells (HSC). METHODS HSC were isolated and cultured from liver of Wistar rats by in situ perfusion with pronase and collagenase, and density gradient centrifugation with Nycodenz. MTT colorimetric assay was detected for HSC proliferation. RESULTS Arachidonic acid and linoleic acid had an effect on proliferation of HSC. Arachidonic acid of 25mg/L promoted HSC proliferation ( P <0 01), but 50 and 100mg/L had an inhibitory effect on HSC ( P <0 01), and showed cytotoxity on HSC under inverted microscope; 6 25, 12 5 and 25mg/L of linoleic acid had no effect on HSC proliferation ( P >0 05), but with concentration increasing, 50 and 100mg/L of linoleic acid might promote HSC proliferation ( P <0 05 or 0 01). CONCLUSION Arachidonic acid and linoleic acid may promote HSC proliferation, but increased concentration can have cytotoxity on HSC. Arachidonic acid and linoleic acid might be associated with fatty liver and hepatic fibrogenesis by lipid peroxidation.

Effect of sodium salicylate on oxidative stress and insulin resistance induced by free fatty acids

BACKGROUND: It has been reported that high-dose salicylates improve free fatty acids (FFAs)-induced insulin resistance and beta-cell dysfunction in vitro, but the mechanism remains uncertain. In insulin-resistant rats, we found that the supplementation of sodium salicylate is associated with a reduction of plasma malondialdehyde (MDA), a marker of oxidative stress. Few studies have investigated the effects of salicylates on oxidative stress levels in insulin-resistant animal models. This study aimed to assess the effect of sodium salicylate on insulin sensitivity and to explore the potential mechanism by which it improves hepatic and peripheral insulin resistance. METHODS: Intralipid+heparin (IH), saline (SAL), or intralipid+heparin+sodium salicylate (IHS) were separately infused for 7 hours in normal Wistar rats. During the last 2 hours of the infusion, hyperinsulinemic-euglycemic clamping was 3 performed with [6-(3)H] glucose tracer. Plasma glucose was measured using the glucose oxygenase method. Plasma insulin and C-peptide were determined by radioimmunoassay. MDA levels and glutathione peroxidase (GSH-PX) activity in the liver and skeletal muscle were measured with colorimetric kits. RESULTS: Compared with infusion of SAL, IH infusion increased hepatic glucose production (HGP), and decreased glucose utilization (GU) (P<0.05). The elevation of plasma free fatty acids increased the MDA levels and decreased the GSH-PX activity in the liver and muscle (P<0.01). Sodium salicylate treatment decreased HGP, elevated GU (P<0.05), reduced MDA content by 60% (P<0.01), and increased the GSH-PX activity by 35% (P<0.05). CONCLUSIONS: Short-term elevation of fatty acids induces insulin resistance by enhancing oxidative stress levels in the liver and muscle. The administration of the anti-inflammatory drug sodium salicylate reduces the degree of oxidative stress, therefore improving hepatic and peripheral insulin resistance. IKK-beta and NF-kappa B provide potential pathogenic links to oxidative stress.

Effects of different free fatty acids on insulin resistance in rats

BACKGROUND: Much evidence demonstrates that elevated free fatty acids (FFAs) are associated with insulin resistance. However, it is not clear whether different FFAs can cause different degrees of peripheral insulin resistance. This study aimed to investigate the effects of short-term elevation of FFAs on hepatic and peripheral insulin action, and determine whether FFAs with different degrees of saturation have differential effects on hepatic insulin resistance. METHODS: Intralipid+heparin (IH, polyunsaturated fatty acids), oleate (OLE), lard oil+heparin (LOH), and saline (SAL) were separately infused intravenously for 7 hours in normal Wistar rats. During the last 2 hours of the fat/saline infusion, a hyperinsulinemic-euglycemic clamping was performed with [6-H-3] glucose tracer. Plasma glucose was measured using the glucose oxygenase method. Plasma insulin and C-peptide were determined by radioimmunoassays. Plasma FFAs were measured using a colorimetric method. RESULTS: Compared with infusion of SAL, plasma FFA levels were significantly elevated by infusions of IH, OLE, and LOH (P<0.001). All three fat infusions caused remarkably higher hepatic glucose production (HGP) than SAL (P<0.001). OLE and LOH infusions induced much higher HGP than IH (P<0.01). Glucose utilization (GU) was decreased with all three fat infusions relative to SAL (P<0.001), but GU did not differ among the three types of fat infusions. CONCLUSIONS: Short-term elevation of FFAs can induce hepatic and peripheral insulin resistance. Polyunsaturated fatty acids induced less hepatic insulin resistance than monounsaturated or saturated fatty acids. However, IH, OLE, and LOH infusions induced similar peripheral insulin resistance.

Correlation between serum free fatty acids levels and Gensini score in elderly patients with coronary heart disease

Objectives To investigate the relationship between serum fxee fatty acids （FFAs） levels and the severity of coronary artery lesions in elderly patients with coronary heart disease （CAD）. Methods A total of 172 elderly patients who underwent coronary angiography were divided into CAD group （n = 128） and non-CAD group （n = 44） according to the results of coronary angiography. Serum FFAs and lipid levels were measured and the Gensini score were calculated. Results No matter the differences between age, gender and the usage of stat- ins or not, there was no statistical significance in FFAs levels （P 〉 0.05）. In terms of the Gensini score, it was higher in patients aged 70-79 years than in patients 60-69 years old [15.00 （5.00, 34.00） vs. 10.00 （2.00, 24.00）, P 〈 0.05], higher in men than women [14.00 （4.00, 34.00） vs. 7.00 （2.50, 19.75）, P 〈 0.05], and higher in patients on statins [13.50 （4.25, 33.50）vs. 6.50 （2.00, 18.00）, P 〈 0.05]. The serum FFAs lev- els [449.50 （299.00, 624.75） mEq/L vs. 388.00 （258.50, 495.25） mEq/L, P 〈 0.05J and Gensini score [17.50 （8.00, 41.75） vs. 1.00 （0, 5.00）, P 〈 0.05] were higher in the CAD group than in the non-CAD group. In the CAD group, there was no statistical significance in FFAs levels among patients with different numbers of diseased coronary vessels （P 〉 0.05）. Furthermore, the FFAs levels were positively correlated with the Gensini score （r = 0.394, P = 0.005）. Regression analysis showed that the FFAs levels were related to the Gensini score independently after adjusting for the other risk factors. Conclusions The serum FFAs levels were associated with the Gensini score in elderly patients with CAD. It might indicate FFAs as a biomarker predicting the severity of coronary artery lesions.

The Kinetics of the Esterification of Free Fatty Acids in Waste Cook- ing Oil Using Fe2（SO4）3/C Catalyst

The esterification of free fatty acids(FFA) in waste cooking oil with methanol in the presence of Fe2(SO4)3/C(ferric sulfate/active carbon) catalyst was studied.The effects of different temperature,methanol/FFA mole ratio and amount of catalyst on the conversion of FFA were investigated.The results demonstrated that under optimal esterification conditions the final acid value of the resultant system can be reduced to ～1(mg KOH)·g-1,which met fully the requirements in post-treatment for efficient separation of glycerin and biodiesel.The kinetics of the esterification were also investigated under different temperatures.The results indicated that the rate-control step could be attributed to the surface reaction and the esterification processes can be well-depicted by the as-calculated kinetic formula in the range of the experimental conditions.

Genistein Reverses Free Fatty Acid-induced Insulin Resistance in HepG2 Hepatocytes through Targeting JNK

This study investigated the effects and molecular mechanisms of genistein in improving insulin resistance induced by free fatty acids （FFAs） in HepG2 hepatocytes. A model of insulin resistance in HepG2 cells was established by adding palmitic acid （0.5 mmol/L） to the culture medium and the cells were treated by genistein. Glucose consumption of HepG2 cells was determined by glucose oxidase method. The levels of c-jun N-terminal kinase （JNK） phosphorylation, insulin receptor substrate-1 （IRS-1） Ser307 phosphorylation, JNK, IRS-1, phosphatidylinositol-3-kinase p85 （PI-3K p85） and glucose transporter 1 （GLUT1） proteins were detected by Western blotting. The results showed that after the treatment with palmitic acid for 24 h, the insulin-stimulated glucose transport in HepG2 cells was inhibited, and the glucose consumption was substantially reduced. Meanwhile, the expressions of IRS-1, PI-3K p85 protein and GLUT1 were obviously reduced, while the levels of JNK phosphorylation and IRS-1 Ser307 phosphorylation and the expression of JNK protein were significantly increased, as compared with cells of normal control. However, the aforementioned indices, which indicated the existence of insulin resistance, were reversed by genistein at 1-4 μmol/L in a dose-dependent manner. It was concluded that insulin resistance induced by FFAs in HepG2 hepatocytes could be improved by genistein. Genistein might reverse FFAs-induced insulin resistance in HepG2 cells by targeting JNK.

Inhibitory effect of schisandrin B on free fatty acid-induced steatosis in L-02 cells

AIM:To investigate the effects of schisandrin B (Sch B) on free fatty acid (FFA)-induced steatosis in L-02 cells.METHODS:Cellular steatosis was induced by incubating L-02 cells with a FFA mixture (oleate and palmitate at the ratio of 2:1) for 24 h.Cytotoxicity and apoptosis were evaluated by 3-(4,5-dmethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and Annexin V/propidium iodide staining,respectively.Cellular total lipid was determined using a photocolorimetric method after Nile red staining,and triglyceride content was measured using an enzymatic kit.To study the effects of Sch B on steatosis,L-02 cells were treated with Sch B (1-100 μmol/L) in the absence or presence of 1 mmol/L FFA for 24 h,and cellular total lipid and triglyceride levels were measured.To explore the mechanisms of action of Sch B in the steatotic L-02 cells,mRNA levels of several regulators of hepatic lipid metabolism including adipose differentiation related protein (ADRP),sterol regulatory element binding protein 1 (SREBP-1),peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ were measured by quantitative real-time polymerase chain reaction (PCR),and protein levels of ADRP and SREBP-1 were measured by immunoblotting.RESULTS:Treatment with 1 mmol/L FFA for 24 h induced intracellular lipid accumulation in L-02 cells comparable to that in human steatotic livers without causing apparent apoptosis and cytotoxicity.Sch B mitigated cellular total lipid and triglyceride accumulations in the steatotic L-02 cells in a dose-dependent manner.Quantitative real-time PCR and Western blot analyses revealed that treatment of L-02 cells with 100 μmol/L Sch B reverted the FFA-stimulated up-regulation of ADRP and SREBP-1.CONCLUSION:Sch B inhibits FFA-induced steatosis in L-02 cells by,at least in part,reversing the up-regulation of ADRP and SREBP-1.

A kinetic model for a single step biodiesel production from a high free fatty acid (FFA) biodiesel feedstock over a solid heteropolyacid catalyst

Production of biodiesel from yellow grease(waste cooking oil and waste animal fats) is fast emerging as a promising alternative to address the twin challenges before the biodiesel industry today-fluctuation in prices of vegetable oil and the food versus fuel debate. Yellow grease has a high percentage of free fatty acids(FFA) and proves to be an unsuitable feedstock for biodiesel production from commercially viable alkalicatalyzed production systems due to saponification problems.'Green' methodologies based on heterogeneous solid acid catalyzed reactions have the potential to simultaneously promote esterification and transesterification reactions of yellow grease to produce biodiesel without soap formation and offer easy catalyst separation without generation of toxic streams. This paper presents kinetic studies for the conversion of model yellow grease feeds to biodiesel using a heteropolyacid supported on alumina(HSiW/Al2O3) using a batch autoclave. Three model yellow grease feeds were prepared using canola oil with added FFA such as palmitic, oleic and linoleic acid. A pseudo homogeneous kinetic model for the parallel esterification and transesterification was developed. The rate constants and activation parameters for esterification and transesterification reactions for the model yellow grease feeds were determined. The rate constants for esterification are higher than the transesterification rate constants. The kinetic model was validated using the experimental biodiesel data obtained from processing a commercial yellow grease feed. The kinetic model could be used to design novel processes to convert various low-value waste oils, fats and non-food grade oils to sustainable biodiesel.

Development of a Derivatization-free GC-FID Method for Evaluation of Free Fatty Acid Levels in Plasma of Diabetic Nephropathy Patients

Metabolism of free fatty acids（FFAs） is related to several important physiological events and therefore their quantitaion in biological samples arouses extensive interest and efforts.Existing gas chromatography with flame ionization detector（GC-FID） methods for the analysis of FFAs normally require derivatization of them in order to lower boiling points.But this extra procedure tends to induce additional error and it is laborious and time-consuming.A derivatization-free method was therefore established in the present investigation to determine FFAs in human plasma by capillary（GC-FID）.After extraction of FFAs from plasma,a highly polar FFAP（free fatty acid in plasma） column was employed to directly quantitate FFAs concentration,free from derivatization reaction.All sample pretreatments were carried out at room temperature,improving recovery of short-chain FFAs.Heptadecanoic acid（C17：0） was employed as internal standard,and the proposed method was validated for recovery,precision,sensitivity,stabi-lity,and linearity.Validation data show that it is suitable for clinical study that has been applied to the evaluation of FFAs levels in plasma of diabetic nephropathy（DN） patients during the course of treatment.Forty-seven patients diagnosed with DN were admitted to the double-blind experiment.Control group（n=17） underwent solely basic treatment and the patients did not show significant change in FFAs concentration during six months of treatment.Experiment group（n=30） was supplied with traditional Chinese medicine besides basic treatment.After six months of medication,their plasma concentration of palmitic acid（C16：0）,stearic acid（C18：0） and oleic acid（C18：1n-9） decreased while linolenic acid（C18：3n-3） increased significantly（P〈0.05）.These four compounds could be served as biomar-kers in the evaluation of drug efficacy,and their quantitation in plasma may provide additional information for disease progression in DN patients.

Free fatty acids receptors 2 and 3 control cell proliferation by regulating cellular glucose uptake

BACKGROUND Colorectal cancer(CRC)is a worldwide problem,which has been associated with changes in diet and lifestyle pattern.As a result of colonic fermentation of dietary fibres,short chain free fatty acids are generated which activate free fatty acid receptors(FFAR)2 and 3.FFAR2 and FFAR3 genes are abundantly expressed in colonic epithelium and play an important role in the metabolic homeostasis of colonic epithelial cells.Earlier studies point to the involvement of FFAR2 in colorectal carcinogenesis.AIM To understand the role of short chain FFARs in CRC.METHODS Transcriptome analysis console software was used to analyse microarray data from CRC patients and cell lines.We employed short-hairpin RNA mediated down regulation of FFAR2 and FFAR3 genes,which was validated using quantitative real time polymerase chain reaction.Assays for glucose uptake and cyclic adenosine monophosphate(cAMP)generation was done along with immunofluorescence studies to study the effects of FFAR2/FFAR3 knockdown.For measuring cell proliferation,we employed real time electrical impedancebased assay available from xCELLigence.RESULTS Microarray data analysis of CRC patient samples showed a significant down regulation of FFAR2 gene expression.This prompted us to study the FFAR2 in CRC.Since,FFAR3 shares significant structural and functional homology with FFAR2,we knocked down both these receptors in CRC cell line HCT 116.These modified cell lines exhibited higher proliferation rate and were found to have increased glucose uptake as well as increased level of glucose transporter 1.Since,FFAR2 and FFAR3 signal through G protein subunit(Gαi),knockdown of these receptors was associated with increased cAMP.Inhibition of protein kinase A(PKA)did not alter the growth and proliferation of these cells indicating a mechanism independent of cAMP/PKA pathway.CONCLUSION Our results suggest role of FFAR2/FFAR3 genes in increased proliferation of colon cancer cells via enhanced glucose uptake and exclude the role of PKA mediated cAMP signalling.Alternate pathways could be involved that would ultimately result in increased cell proliferation as a result of down regulated FFAR2/FFAR3 genes.This study paves the way to understand the mechanism of action of short chain FFARs in CRC.

Influence of Long Chain Free Fatty Acids on the Thermal Resistance Reduction of Bacterial Spores

Aims: The objective of this study was to investigate the effect of free fatty acid length chain and unsaturated bond number on the heat resistance and recovery media of bacterial spores. Methods and results: For 6 species, bacterial spore heat resistances were estimated at different free fatty acid concentrations added to heating media or in recovery media. The addition of free fatty acids to heating media has a slight influence on the heat resistance of bacterial spores whatever the species or type of acid studied. On the contrary, the addition of free fatty acids to the recovery medium after the heat treatment greatly reduces the ability to bacterial spores to recover and form colonies. This effect varies depending on chain length, unsaturated bond number of fatty acid and on the bacterial strain studied. Conclusion: The presence of free acids in the recovery media is an additive stress which decreases the capability of injured spores to germinate and grow thereafter. Significance and impact of this study: The impact of free fatty acids presented in this study can be taken into account to reduce the thermal intensity of food sterilization in relation to their availability in food matrix.

Characteristics of physico-chemical properties, volatile compounds and free fatty acid profiles of commercial set-type Turkish yoghurts

Ten most popular brands of commercial Turkish set-type yoghurts were collected from local retail outlets in Hatay, Turkey for two separate periods, and analyzed for basic nutrients, physico-chemical properties, volatile aroma compounds and free fatty acid profiles to compare their differences among the yoghurt products. The results showed that there were significant differences (P<0.05, 0.01, or 0.001) and variations in physico-chemical indices, volatile aroma compounds and volatile free fatty acid profiles among the yoghurt brands, which ultimately influence the flavor quality of the product. Acetaldehyde was predominant volatile compound in yoghurts, which followed by acetone, acetoin, diacetyl and ethanol. The level of diacetly was inversely related to titratable acidity, acetaldehyde and ethanoic acid. From ketones with high carbones 2-undecanone and 2-pentadecanone were higher than 2-butanone, 2-nanonane and 2-tridecanone. These ketones are related to fat content of yoghurt. Among short chain free fatty acids, ethanoic (acetic) acid was the most abundant in yoghurts, followed by hexanoic, octanoic and butanoic acids. These differences in detected chemical compositions of volatile compounds and free fatty acids would be applicable to predict flavor, nutritional value, quality control or shelf-life of the commmercial set-type Turkish yoghurts.

Role of Free Fatty Acids in Physiological Conditions and Mitochondrial Dysfunction

The role of free fatty acids (FFAs) as a source of energy and their functions in energy transport within the body are well established. Equally important is a role that FFAs play in oxidative stress following cell membrane depolarization. FFAs are physiologically active, not only as nutritional components, but also as molecules involved in cell signaling and stabilization of membranes via palmitoylation and myristoylation. Protein palmitoylation is involved in numerous cellular processes, including apoptosis, and neuronal transmission. Besides nuclear peroxisome proliferator-activated receptors that mediate the biological effects of FFAs, G protein-coupled receptors (GPCRs) that are activated by FFA, have been recently identified. Those multiple FFA receptors (FFARs), which function on the cell surface as activated FFAs, play significant roles in the regulation of energy metabolism and mediate a wide range of important metabolic processes. FFARs have been targeted in drug development for the treatment of type 2 diabetes and metabolic syndrome. FFAs upregulate transcription of uncoupling proteins, increasing their expression in brain, cardiac, and skeletal muscle that may be protective or cytotoxic, depending on the cellular energy state. Recently, FFA effects on the endothelial function and dysfunction are being recognized. FFAs play a key role in endothelium-dependent nitric oxide production. A disturbance of endothelial function, due to an imbalance in production and release of relaxing and constricting factors, has implications in the development of cardiovascular problems, such as hypertension, as well as neurotoxicity following loss of blood-brain barrier integrity. This review presents information on broad range of FFAs actions of prime importance for physiological processes. Understanding of FFA functions in the body is crucial for developing new therapeutic strategies against several metabolic disorders.

Free fatty acids, glucose, and insulin in type 2 diabetes mellitus

Xu et al used the HOMA2 model to estimate theβ-cell function and insulin resistance levels in an individual from simultaneously measured fasting plasma glucose and fasting plasma insulin levels.This method is based on the assumption that the glucose-insulin axis is central for the metabolic activities,which led to type 2 diabetes.However,significant downregulation of both the NKX2-1 gene and the TPD52L3 gene force an increase in the release of free fatty acids(FFAs)into the blood circulation,which leads to a marked reduction in membrane flexibility.These data favor a FFA-glucose-insulin axis.The authors are invited to extend their study with the introduction of the saturation index(number of carbon-carbon double bonds per 100 fatty-acyl chains),as observed in erythrocytes.

Free fatty acids profiling in cold-pressed rapeseed oil pretreated by microwave

This study proposed a strategy based on simple chemical derivatization coupled with neutral loss scan tandem to electrospray ionization source of mass spectrometer (NLS-ESI-MS/MS) for rapid and sensitive detection of free fatty acids (FFAs) in coldpressed rapeseed oils without sample purification and enrichment. The method was applied to investigate contents of FFAs and their changes in cold-pressed rapeseed oil pretreated by microwave. Results showed that main FFAs in rapeseed oil control samples were myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). The highest content of C18:1 was 7163.69 nmol/g and C18:2 was 5221.18 nmol/g among 8 oil samples. FFAs generally increased after microwave pretreatment except C14:0 in oil sample of ‘Xinyou 17’ and ‘Suyou 6’. C18:1 and C18:2 significantly changed (P<0.05) after microwave pretreatment. With this established simple,practical and reliable analysis approach, changes of FFAs would be monitored to ensure safety and quality of edible oils. A powerful tool is provided for thermal degradation mechanism research of edible oils.

Regulatory Role of Free Fatty Acids (FFAs)—Palmitoylation and Myristoylation

Multicellular organisms use chemical messengers to transmit signals among organelles and to other cells. Relatively small hydrophobic molecules such as lipids are excellent candidates for this signaling purpose. In most proteins, palmitic acid and other saturated and some unsaturated fatty acids are esterified to the free thiol of cysteines and to the N-amide terminal. This palmitoylation process enhances the surface hydrophobicity and membrane affinity of protein substrates and plays important roles in modulating proteins’ trafficking, stability, and sorting etc. Protein palmitoylation has been involved in numerous cellular processes, including signaling, apoptosis, and neuronal transmission. The palmitoylation process is involved in multiple diseases such as Huntington’s disease, various cardiovascular and T-cell mediated immune disorders, as well as cancer. Protein palmitoylation through the thioester (S-acylation) is unique in that it is the only reversible lipid modification. Our study on lipopolysaccharide (LPS) and deoxynivalenol (DON) treatment to rats provides some insights to the complex role of protein palmitoylation in chemical and microbial toxicity. In contrast, myrisoylated proteins contain the 14-carbon fatty acid myristate attached via amide linkage to the N-terminal glycine residue of protein, and occur cotranslationally. The bacterial outer membrane enzyme lipid A palmitoyltransferase (PagP) confers resistance to host immune defenses by transferring a palmitate chain from a phospholipid to the lipid A component of LPS. PagP is sensitive to cationic antimicrobial peptides (CAMP) which are included among the products of the Toll-like receptor 4 (TLR4) signal transduction pathway. This modification of lipid A with a palmitate appears to both and protects the pathogenic bacteria from host immune defenses and attenuates the activation of those same defenses through the TLR4 signal transduction pathway.

Comparison of free fatty acid composition between low-fat and full-fat goat milk cheeses stored for 3 months under refrigeration

Differences in free fatty acid (FFA) compositions between low-fat (LF) and full-fat (FF: whole milk) goat cheeses were evaluated during 3 months at 4oC refrigeration. The two types of cheeses were manufactured using a bulk milk from the mixed herd of Saanen, Alpine, and Nubian goat breeds. LF cheeses were made using LF milk after cream separation. FFAs of all cheeses were extracted in diisoprophyl ether using polypropylene chromatography column, and FFA concentrations were quantified using a gas chromatograph equipped with a fused silica capillary column. Moisture, fat, protein contents (%) and pH of fresh LF and FF cheeses were: 55.1, 52.3;1.30, 25.6;35.7, 22.5;5.40, 5.42, respectively. The FFA contents (mg/g cheese) of fresh FF and LF cheeses prior to storage treatments for C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C16:0, C18:0, C18:1, and C18:2 were: 0.020, 0.072;0.070, 0.035;0.061, 0.055;0.181, 0.167;0.073, 0.047;0.174, 0.112;0.579, 0.152;0.308, 0.202;0.521, 0.174;and 0.057, 0.026, respectively. The respective FFA to total fatty acid ratios for 0, 1 and 3 months aged FF and LF cheeses were 8.44, 12.4;6.31, 16.91;12.03, 14.19. The LF cheeses generated more FFA than FF cheeses, while actual FFA content in FF cheese was significantly higher than in LF cheese. The FFA contents of LF cheese at 0, 1 and 3 months storage were 48.0, 96.8 and 36.4% of those of FF cheese, respectively. It was concluded LF cheese generated higher amount of FFA than FF cheese, although total FFA content was significantly (P<0.05) lower in LF cheese than in FF cheese.

Synthesis of spinel ferrite and its role in the removal of free fatty acids from deteriorated vegetable oil

Deterioration and loss of quality of vegetable oil is a big challenge in the food industry.This study investigated the synthesis of nickel ferrite(Ni Fe_(2)_(O4))via co-precipitation method and its use for the removal of free fatty acids(FFAs)in deteriorated vegetable oil.Ni Fe2 O4 was characterized using Fourier transformed infrared spectroscopy(FTIR),X-ray diffraction(XRD),thermogravimetric(TG)analysis,Brunauer–Emm ett–Teller(BET)surface area,transmission electron microscopy(TEM),scanning electron microscopy(SEM)and energy-dispersive X-ray spectroscopy(EDX).Synthesis of Ni Fe_(2)_(O4)was confirmed by characterization,which revealed a BET surface area of 16.30 m^(2)·g^(-1)and crystallite size of 29 nm.Ni Fe_(2)_(O4)exhibited an adsorption capacity of 145.20 L·kg^(-1)towards FFAs with an 80.69%removal in a process,which obeys Langmuir isotherm and can be described by the pseudo-second-order kinetic model.The process has enthalpy(DH)of 11.251 k Jámolà1 and entropy(DS)of 0.038 k J·mol^(-1)K^(-1)with negative free energy change(DG),which suggests the process to be spontaneous and endothermic.The quantum chemical computation analysis via density functional theory further revealed the sorption mechanism of FFAs by Ni Fe_(2)_(O4)occurred via donor–acceptor interaction,which may be described by the lowest unoccupied molecular orbital(LUMO)and the highest occupied molecular orbital(HOMO).The study showed Ni Fe_(2)_(O4)to be a potential means that can remove FFAs from deteriorated vegetable oil.