The Furan Fatty Acid 9M5 Acts as a Partial Ligand to Peroxisome Proliferator-Activated Receptor gamma and Enhances Adipogenesis in 3T3-L1 Preadipocytes

The emerging significance of furan fatty acids in food, nutrition, and potential therapeutic use

The emerging significance of furan fatty acids (FuFAs) is explored at the intersection of food, chemistry, nutrition, and therapeutics. FuFAs, with a distinctive furan ring incorporated into fatty acyl chains, are minor yet bioactive constituents of dietary lipids known for their unique chemical properties. This review examines FuFA biosynthesis in various organisms, highlighting their occurrence in food products. We also address the challenges of FuFA instability, which influence their availability and impact on food science. The chemical synthesis of FuFAs is reviewed, paving the way for future animal and human studies. FuFAs exhibit potent antioxidant and anti-inflammatory effects, with growing evidence of their role in metabolic health. Recent research suggests that FuFAs may extend benefits beyond omega-3 fatty acids in promoting cardiovascular and metabolic health. By consolidating current knowledge and identifying gaps, this review sets the stage for future research to harness the therapeutic potential of FuFAs.

Furan fatty acids supplementation in obese mice reverses hepatic steatosis and protects against cartilage degradation

Obesity is a major global health problem associated with numerous metabolic dysfunctions, an increased risk of developing Metabolic Associated Steatotic Liver Disease (MASLD) and osteoarthritis. Recently, we demonstrated that in Diet-induced-Obesity (DIO) mouse model, preventive furan fatty acids (FuFA-F2) supplementation, a natural compounds found in many foods, reduced the onset of metabolic disorders and increased muscle mass. Here, we aimed to determine whether a short FuFA-F2 supplementation is capable of providing beneficial health effects in obese mice, notably by reversing metabolic disorders and limiting cartilage degradation. 6-month-old obese C57Bl/6 J mice were fed for four additional weeks on a high-fat and high-sucrose (HFHS) diet, supplemented or not with FuFA-F2 (40 mg/day/kg of body weight). Liver triglyceride content and histologic analysis revealed that 4 weeks of FuFA-F2 supplementation fully reversed hepatic steatosis in obese mice. Liver RNA-sequencing analysis highlighted that FuFA-F2 partly reversed the gene expression signature induced by the HFHS diet and favorably changed the expression of many genes known to be involved in the development of hepatic steatosis such as Pcsk9, Stard4, Insig1 and Sulf2. We also found that FuFA-F2 supplementation increased skeletal muscle mass and protected against cartilage degradation and synovitis induced by obesity. Our findings demonstrated that FuFA-F2 supplementation for 4 weeks in obese mice was enough to reverse the development of MASLD, promote an increase in skeletal muscle mass and protect against cartilage degradation induced by the HFHS diet. This study highlights that nutritional supplementation with FuFA-F2 could be an effective approach to treat obesity-related disorders.

Omega-3 Fatty Acids, Furan Fatty Acids, and Hydroxy Fatty Acid Esters: Dietary Bioactive Lipids with Potential Benefits for MAFLD and Liver Health

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common form of chronic liver disease, for which only resmetirom has recently received FDA approval. Prevention is crucial, as it can help manage and potentially reverse the progression of MAFLD to more severe stages. Omega-3 fatty acids, which are a type of polyunsaturated fatty acid (PUFA), have numerous beneficial effects in health and disease, including liver disease. Other bioactive lipids, such as furanic fatty acids (FuFA) and hydroxy fatty acid esters (FAHFA), have also demonstrated several benefits on relevant markers of liver dysfunction in animal and cell models. However, the effects of FAHFAs on hepatic steatosis are inconsistent, and studies on the impact of FuFAs in MAFLD are scarce. Further and more extensive research is required to better understand their role in liver health. The aim of this narrative review is to provide a brief overview of the potential effects of omega-3 fatty acids and other bioactive lipids, such as FuFAs and FAHFAs, on liver disease, with a focus on MAFLD.

Furan fatty acid extracted from Hevea brasiliensis latex increases muscle mass in mice

Skeletal muscle is essential for locomotion and plays a crucial role in energy homeostasis. It is regulated by nutrition, genetic factors, physical activity and hormones. Furan fatty acids (FuFAs) are minor fatty acids present in small quantities in food from plants and animals origin. Recently, we showed that a preventive nutritional supplementation with furan fatty acid in a DIO mouse model reduces metabolic disorders. The present study was designed to determine the influence of FuFA-F2 extracted from Hevea brasiliensis latex on skeletal muscle phenotype. In C2C12 myotubes we found that FuFA-F2 whatever the concentration used increased protein content. We revealed that in C2C12 myotubes FuFA-F2 (10 µM) increases protein synthesis as shown by the stimulation of mTOR phosphorylation. Next, to confirm in vivo our results C57Bl6 mice were supplemented by oral gavage with vehicle or FuFA-F2 (20 mg/kg) for 3 and a half weeks. We found that mice supplemented with FuFA-F2 had a greater lean mass than the control mice. In line with this observation, we revealed that FuFA-F2 increased muscle mass and promoted more oxidative muscle metabolism in mice as attested by cytochrome c oxidase activity. In conclusion, we demonstrated that FuFA-F2 stimulates muscle anabolism in mice in vitro and in vivo, mimicking in part physical activity. This study highlights that in vivo FuFA-F2 may have health benefits by increasing muscle mass and oxidative metabolism.

Preventive nutritional supplementation with furan fatty acid in a DIO mouse model increases muscle mass and reduces metabolic disorders

The increase in obesity has become a major global health problem and is associated with numerous metabolic dysfunctions. Furan fatty acids (FuFAs) are minor lipids present in our diet. Recently we showed that FuFA-F2 extracted from Hevea brasiliensis latex stimulates muscle anabolism in mice in vitro and in vivo, mimicking in part physical activity. While skeletal muscle is essential for energy metabolism and is the predominant site of insulin-mediated glucose uptake in the post prandial state, our results suggested that FuFA-F2 could have favorable effects against obesity. The aim of this work was therefore to study whether a preventive nutritional supplementation with FuFA-F2 (40 mg or 110 mg/day/kg of body weight) in a diet-induced obesity (DIO) mouse model may have beneficial effects against obesity and liver and skeletal muscle metabolic dysfunction. We showed that 12 weeks of FuFA-F2 supplementation in DIO mice decreased fat mass, increased lean mass and restored normal energy expenditure. In addition, we found that FuFA-F2 improved insulin sensitivity. We revealed that FuFA-F2 increased muscle mass but had no effect on mitochondrial function and oxidative stress in skeletal muscle. Furthermore, we observed that FuFA-F2 supplementation reduced liver steatosis without impact on mitochondrial function and oxidative stress in liver. Our findings demonstrated for the first time that a preventive nutritional supplementation with a furan fatty acid in DIO mice reduced metabolic disorders and was able to mimic partly the positive effects of physical activity. This study highlights that nutritional FuFA-F2 supplementation could be an effective approach to treat obesity and metabolic syndrome.

Geometrical and positional isomers of unsaturated furan fatty acids in food

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).

PPARγ Gene as a Possible Link between Acquired and Congenital Lipodystrophy and its Modulation by Dietary Fatty Acids

Lipodystrophy syndromes are rare diseases that could be of genetic or acquired origin. The main complication of lipodystrophy is the dysfunction of adipose tissue, which leads to an ectopic accumulation of triglycerides in tissues such as the liver, pancreas and skeletal muscle. This abnormal fat distribution is associated with hypertriglyceridemia, insulin resistance, liver steatosis, cardiomyopathies and chronic inflammation. Although the origin of acquired lipodystrophies remains unclear, patients show alterations in genes related to genetic lipodystrophy, suggesting that this disease could be improved or aggravated by orchestrating gene activity, for example by diet. Nowadays, the main reason for adipose tissue dysfunction is an imbalance in metabolism, caused in other pathologies associated with adipose tissue dysfunction by high-fat diets. However, not all dietary fats have the same health implications. Therefore, this article aims to summarize the main genes involved in the pathophysiology of lipodystrophy, identify connections between them and provide a systematic review of studies published between January 2017 and January 2022 of the dietary fats that can modulate the development of lipodystrophy through transcriptional regulation or the regulation of protein expression in adipocytes.

Microbial incubations of 8-phenyloctanoic acid and furan fatty acids in rumen fluid

AIMS

The digestive tract of ruminants is specialised in the digestion of various plant components. One of the largest parts of the stomach is the so-called rumen, which contains a large number of microorganisms that may degrade or modify fatty acids e.g. by β-oxidation, chain elongation and/or hydrogenation.

METHODS AND RESULTS

Here we performed incubation experiments with less common fatty acids by in vitro incubations with rumen fluid of fistulated cows for 24 h. Sample extracts were analysed by gas chromatography with mass spectrometry. As substrates, we selected one phenyl fatty acid and four furan fatty acids (FuFAs). All studied fatty acids were degraded by β-oxidation (two or three chain-shortening steps) while chain elongation or saturation of the aromatic part (terminal phenyl or central furan moiety) was not observed in any case.

CONCLUSIONS

The percentage of β-oxidation products was low, especially in the case of the FuFAs. This could be due to the rather long carbon number of FuFAs (19-22 carbon atoms). In addition, compound-specific differences in the degradation rates were observed in our experiments.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results produce evidence that FuFAs, which are valuable antioxidants that are known to be present in various feed items of the cow, can be effectively passed on the rumen into the milk.

Furan fatty acids in enriched ω-3 fish oil: Oxidation kinetics with and without added monomethyl furan fatty acid as potential natural antioxidant

This study investigated the lipid oxidation reactions of furan fatty acids, long-chain ω-3 polyunsaturated fatty acids, and tocopherols in an enriched ω-3 fish oil to better understand their degradation kinetics. Furthermore, the influence of an added monomethyl furan fatty acid 9-(3-methyl-5-pentylfuran-2-yl) nonanoic acid (9M5) at 50-250 µM on the oxidation reactions was evaluated. The results showed that the fish oil was rich in monomethyl and dimethyl furan fatty acids (c = 1.3 g/100 g lipids). Upon oxidation of the fish oil, the dimethyl furan fatty acids degraded faster than the monomethyl ones, but also faster than tocopherols. The addition of 9M5 revealed antioxidant activity: It inhibited the degradation of the ω-3 polyunsaturated fatty acids and the formation of primary and secondary lipid oxidation products, and slowed down the degradation of the furan fatty acids and tocopherols. This research offers new insights into the importance of furan fatty acids in lipid oxidation reactions.

Metabolic Differences between Subcutaneous and Visceral Adipocytes Differentiated with an Excess of Saturated and Monounsaturated Fatty Acids

Obesity is a major health problem in highly industrialized countries. High-fat diet (HFD) is one of the most common causes of obesity and obesity-related disorders. There are considerable differences between fat depots and the corresponding risks of metabolic disorders. We investigated the various effects of an excess of fatty acids (palmitic 16:0, stearic 18:0, and oleic acids 18:1n-9) on adipogenesis of subcutaneous- and visceral-derived mesenchymal stem cells (MSCs) and phenotypes of mature adipocytes. MSCs of white adipose tissue were acquired from adipose tissue biopsies obtained from subcutaneous and visceral fat depots from patients undergoing abdominal surgery. The MSCs were extracted and differentiated in vitro with the addition of fatty acids. Oleic acid stimulated adipogenesis, resulting in higher lipid content and larger adipocytes. Furthermore, oleic acid stimulated adipogenesis by increasing the expression of CCAAT enhancer binding protein β (CEBPB) and peroxisome proliferator activated receptor γ (PPARG). All of the examined fatty acids attenuated the insulin-signaling pathway and radically reduced glucose uptake following insulin stimulation. Visceral adipose tissue was shown to be more prone to generate inflammatory stages. The subcutaneous adipose tissue secreted a greater quantity of adipokines. To summarize, oleic acid showed the strongest effect on adipogenesis. Furthermore, all of the examined fatty acids attenuated insulin signaling and secretion of cytokines and adipokines.

Virtual screening of potentially endocrine-disrupting chemicals against nuclear receptors and its application to identify PPARγ-bound fatty acids

Nuclear receptors (NRs) are key regulators of energy homeostasis, body development, and sexual reproduction. Xenobiotics binding to NRs may disrupt natural hormonal systems and induce undesired adverse effects in the body. However, many chemicals of concerns have limited or no experimental data on their potential or lack-of-potential endocrine-disrupting effects. Here, we propose a virtual screening method based on molecular docking for predicting potential endocrine-disrupting chemicals (EDCs) that bind to NRs. For 12 NRs, we systematically analyzed how multiple crystal structures can be used to distinguish actives and inactives found in previous high-throughput experiments. Our method is based on (i) consensus docking scores from multiple structures at a single functional state (agonist-bound or antagonist-bound), (ii) multiple functional states (agonist-bound and antagonist-bound), and (iii) multiple pockets (orthosteric site and alternative sites) of these NRs. We found that the consensus enrichment from multiple structures is better than or comparable to the best enrichment from a single structure. The discriminating power of this consensus strategy was further enhanced by a chemical similarity-weighted scoring scheme, yielding better or comparable enrichment for all studied NRs. Applying this optimized method, we screened 252 fatty acids against peroxisome proliferator-activated receptor gamma (PPARγ) and successfully identified 3 previously unknown fatty acids with Kd = 100-250 μM including two furan fatty acids: furannonanoic acid (FNA) and furanundecanoic acid (FUA), and one cyclopropane fatty acid: phytomonic acid (PTA). These results suggested that the proposed method can be used to rapidly screen and prioritize potential EDCs for further experimental evaluations.