In depending on the sulfation method, important effects on the acidity, textural properties as well as on the activity for the esterification of fatty acids with ethanol. Conversions up to 82.2% of the oleic acid and selectivity to ester of 100% were reached after 3 h of reaction at 80 °C in sulfated titania: (▾) titania impregnated with ammonium sulfate; (♦) titania sol–gel sulfated with ammonium sulfate; (▴) titania sol–gel sulfate with sulfuric acid; (●) titania sol–gel; (■) without catalyst. Sulfated titanias were prepared by using ammonium sulfate and sulfuric acid as sulfate precursors. Depending on the sulfation method, important effects on the acidity, textural properties as well as on activity were found. After ammonium sulfate was used, a large amount of S O linked to the titania surface was observed by FTIR spectroscopy. The acidity strength determined with Hammett indicators showed strong acidity in the sulfated samples. The FTIR-pyridine adsorption spectra evidenced the presence of Lewis and Brönsted acid sites in the catalysts sulfated with ammonium sulfate, while in the titania sulfated with sulfuric acid, only Lewis-type sites were observed. The sulfated titanias showed very high activity for the esterification of fatty acids with ethanol in a mixture of oleic acid (79%). Conversions up to 82.2% of the oleic acid and selectivity to ester of 100% were reached after 3 h of reaction at 80 °C. The results showed that sulfated titanias are promising solid acid catalysts to be used in the esterification of free fatty acids with ethanol.
Non-edible oil contains several unsaponifiable and toxic components, which make them unsuitable for human consumption. Karanja ( Pongamia pinnata) is an underutilized plant which is grown in many parts of India. Sometimes the oil is contaminated with high free fatty acids (FFAs) depending upon the moisture content in the seed during collection as well as oil expression. The present study deals with production of biodiesel from high FFA Karanja oil because the conventional alkali-catalyzed route is not the feasible route. This paper discusses the mechanism of a dual process adopted for the production of biodiesel from Karanja oil containing FFA up to 20%. The first step is acid-catalyzed esterification by using 0.5% H 2SO 4, alcohol 6:1 molar ratio with respect to the high FFA Karanja oil to produce methyl ester by lowering the acid value, and the next step is alkali-catalyzed transesterification. The yield of biodiesel from high FFA Karanja oil by dual step process has been observed to be 96.6–97%.
A technique to produce biodiesel from mahua oil ( Madhuca indica) having high free fatty acids (19% FFA) has been developed. The high FFA level of mahua oil was reduced to less than 1% by a two-step pretreatment process. Each step was carried out with 0.30–0.35 v/v methanol-to-oil ratio in the presence of 1% v/v H 2SO 4 as an acid catalyst in 1-hour reaction at 60°C. After the reaction, the mixture was allowed to settle for an hour and methanol–water mixture that separated at the top was removed. The second step product at the bottom was transesterified using 0.25 v/v methanol and 0.7% w/v KOH as alkaline catalyst to produce biodiesel. The fuel properties of mahua biodiesel were found to be comparable to those of diesel and conforming to both the American and European standards.
Impaired mitochondrial function is largely thought to be a core abnormality responsible for disease progression in nonalcoholic fatty liver disease (NAFLD). However, the molecular mechanisms resulting in mitochondrial dysfunction in NAFLD remain poorly understood. This study examined the effects of excessive accumulation of free fatty acids (FFAs) in liver cells on mitochondrial function and the role of the lysosomal‐mitochondrial axis on lipotoxicity. Primary mouse hepatocytes, HepG2 and McNtcp.24 cells, were treated with varied concentrations of FFAs with different degrees of saturation for up to 24 hours. Mitochondrial function was monitored by real‐time imaging, cytochrome c redistribution, and reactive oxygen species (ROS) production. The temporal relationship of lysosomal and mitochondrial permeabilization was established. Activity of the lysosomal protease cathepsin B was suppressed by genetic and pharmacological approaches. Cathepsin B–knockout mice and wild‐type animals were place on a high‐carbohydrate diet for 16 weeks, and mitochondrial function and liver damage were assessed. Exposure of liver cells to saturated FFAs resulted in mitochondrial depolarization, cytochrome c release, and increased ROS production. Lysosomal permeabilization and cathepsin B redistribution into the cytoplasm occurred several hours prior to mitochondrial dysfunction. Either pharmacological or genetic inhibition of cathepsin B preserved mitochondrial function. Finally, cathepsin B inactivation protected mitochondria, decreased oxidative stress, and attenuated hepatic injury in vivo. Conclusion: These data strongly suggest excessive accumulation of saturated FFAs in liver cells directly induce mitochondrial dysfunction and oxidative stress. Our data further suggest this process is dependent on lysosomal disruption and activation of cathepsin B. (HEPATOLOGY 2008.)
Inflammatory bowel diseases are associated with increased risk of developing colitis-associated colorectal cancer (CAC). Epidemiological data show that the consumption of ¿-3 polyunsaturated fatty acids (¿-3 PUFAs) decreases the risk of sporadic colorectal cancer (CRC). Importantly, recent data have shown that eicosapentaenoic acid-free fatty acid (EPA-FFA) reduces polyp formation and growth in models of familial adenomatous polyposis. However, the effects of dietary EPA-FFA are unknown in CAC. We tested the effectiveness of substituting EPA-FFA, for other dietary fats, in preventing inflammation and cancer in the AOM-DSS model of CAC. The AOM-DSS protocols were designed to evaluate the effect of EPA-FFA on both initiation and promotion of carcinogenesis. We found that EPA-FFA diet strongly decreased tumor multiplicity, incidence and maximum tumor size in the promotion and initiation arms. Moreover EPA–FFA, in particular in the initiation arm, led to reduced cell proliferation and nuclear ß-catenin expression, whilst it increased apoptosis. In both arms, EPA-FFA treatment led to increased membrane switch from ¿-6 to ¿-3 PUFAs and a concomitant reduction in PGE2 production. We observed no significant changes in intestinal inflammation between EPA-FFA treated arms and AOM-DSS controls. Importantly, we found that EPA-FFA treatment restored the loss of Notch signaling found in the AOM-DSS control and resulted in the enrichment of Lactobacillus species in the gut microbiota. Taken together, our data suggest that EPA-FFA is an excellent candidate for CRC chemoprevention in CAC.
GPR120, free fatty acid receptor 4, is a recently deorphanized G protein-coupled receptor that seems to play cardinal roles in the regulation of metabolism and in the pathophysiology of inflammatory and metabolic disorders. In the present work a GPR120-Venus fusion protein was expressed in HEK293 Flp-In T-REx cells and its function (increase in intracellular calcium) and phosphorylation were studied. It was observed that the fusion protein migrated in sodium dodecyl sulfate-polyacrylamide gels as a band with a mass of ≈70–75kDa, although other bands of higher apparent weight (>130kDa) were also detected. Cell stimulation with docosahexaenoic acid or α-linolenic acid induced concentration-dependent increases in intracellular calcium and GPR120 phosphorylation. Activation of protein kinase C with phorbol esters also induced a marked receptor phosphorylation but did not alter the ability of 1µM docosahexaenoic acid to increase the intracellular calcium concentration. Phorbol ester-induced GPR120 phosphorylation, but not that induced with docosahexaenoic acid, was blocked by protein kinase C inhibitors (bis-indolyl-maleimide I and Gö 6976) suggesting that conventional kinase isoforms mediate this action. The absence of effect of protein kinase C inhibitors on agonist-induced GPR120 phosphorylation indicates that this kinase does not play a major role in agonist-induced receptor phosphorylation. Docosahexaenoic acid action was associated with marked GPR120 internalization whereas that induced with phorbol esters was smaller at early times.
OBJECTIVE-Obesity is associated with monocyte-macrophage accumulation in adipose tissue. Previously, we showed that glucose-stimulated production by adipocytes of serum amyloid A (SAA), monocyte chemoattractant protein (MCP)-1, and hyaluronan (HA) facilitated monocyte accumulation. The current objective was to determine how the other major nutrient, free fatty acids (FFAs), affects these molecules and monocyte recruitment by adipocytes. RESEARCH DESIGN AND METHODS-Differentiated 3T3-L1, Simpson-Golabi-Behmel syndrome adipocytes, and mouse embryonic fibroblasts were exposed to various FFAs (250 mu mol/1) in either 5 or 25 mmol/l (high) glucose for evaluation of SAA, MCP-1, and HA regulation in vitro. RESULTS-Saturated fatty acids (SFAs) such as laurate, myristate, and palmitate increased cellular triglyceride accumulation, SAA, and MCP-1 expression; generated reactive oxygen species (ROS); and increased nuclear factor (NF) kappa B translocation in both 5 and 25 mmol/l glucose. Conversely, polyunsaturated fatty acids (PUFAs) such as arachidonate, eicosapentaenate, and docosahexaenate (DHA) decreased these events. Gene expression could be dissociated from triglyceride accumulation. Although excess glucose increased HA content, SFAs, oleate, and linoleate did not. Antioxidant treatment repressed glucose- and palmitate-stimulated ROS generation and NF kappa B translocation and decreased SAA and MCP-1 expression and monocyte chemotaxis. Silencing toll-like receptor-4 (TLR4) markedly reduced SAA and MCP-1 expression in response to palmitate but not glucose. DHA suppressed NF kappa B translocation stimulated by both excess glucose and palmitate via a peroxisome prolifterator-activated receptor (PPAR) gamma-dependent pathway. CONCLUSIONS-Excess glucose and SFAs regulate chemotactic factor expression by a mechanism that involves ROS generation, NF kappa B, and PPAR gamma, and which is repressed by PUFAs. Certain SFAs, but not excess glucose, trigger chemotactic factor expression via a TLR4-dependent pathway. Diabetes 59:386-396,2010
Nonalcoholic fatty liver disease (NAFLD) is a serious health problem. Although NAFLD represents a form of lipotoxicity, its pathogenesis remains poorly understood. The aim of this study was to examine the cellular mechanisms involved in free fatty acid (FFA)‐mediated hepatic lipotoxicity. FFA treatment of liver cells resulted in Bax translocation to lysosomes and lysosomal destabilization with release of cathepsin B (ctsb), a lysosomal cysteine protease, into the cytosol. This process was also partially dependent on ctsb. Lysosomal destabilization resulted in nuclear factor κB–dependent tumor necrosis factor α expression. Release of ctsb into the cytoplasm was also observed in humans with NAFLD and correlated with disease severity. In a dietary murine model of NAFLD, either genetic or pharmacological inactivation of ctsb protected against development of hepatic steatosis, liver injury, and insulin resistance with its associated “dysmetabolic syndrome.” In conclusion, these data support a lipotoxic model of FFA‐mediated lysosomal destabilization. Supplemental material for this article can be found on the HEPATOLOGY website (http://www.interscience.wiley.com/jpages/0270‐9139/suppmat/index.html). (HEPATOLOGY 2004;40:185–194.)
It is widely appreciated that G protein‐coupled receptors have been the most successfully exploited class of targets for the development of small molecule medicines. Despite this, to date, less than 15% of the non‐olfactory G protein‐coupled receptors in the human genome are the targets of a clinically used medicine. In many cases, this is likely to reflect a lack of understanding of the basic underpinning biology of many G protein‐coupled receptors that are not currently in the spotlight, as well as a paucity of pharmacological tool compounds and appropriate animal models to test in vivo function of such G protein‐coupled receptors in both normal physiology and in the context of disease. ‘Open Innovation’ arrangements, in which pharmaceutical companies and public–private partnerships provide wider access to tool compounds identified from ligand screening programmes, alongside enhanced medicinal chemistry support to convert such screening ‘hits’ into useful ‘tool’ compounds will provide important routes to improved understanding. However, in parallel, novel approaches to define and fully appreciate the selectivity and mode of action of such tool compounds, as well as better understanding of potential species orthologue variability in the pharmacology and/or signalling profile of a wide range of currently poorly understood and understudied G protein‐coupled receptors, will be vital to fully exploit the therapeutic potential of this large target class. I consider these themes using as exemplars two G protein‐coupled receptors, free fatty acid receptor 2 and GPR35.