Metabolic Conversion of C20 Polymethylene-Interrupted Polyunsaturated Fatty Acids to Essential Fatty Acids

Polymethylene-interrupted (PMI)-polyunsaturated fatty acids (PUFA) are fatty acids present largely in gymnosperm. Sciadonic acid (SciA, 20:3 Δ-5,11,14) and juniperonic acid (JA, 20:4 Δ-5,11,14,17) are typical C20 PMI-PUFA with an isolated double bond at Δ5. Previously, we found that SciA and JA are converted to linoleic acid (LNA) and α-linolenic acid (ΑLA), respectively. The conversion process includes chain-shortening step by peroxisomal β-oxidation for elimination a double bond at Δ5, and subsequent chain-elongation step in microsomes. In this study, we examined the substrate specificity of this metabolism in rodent and human cells. Supplementation of SciA, eicosadienoic acid (EDA, 20:2 Δ-11,14) or JA to CHO-K1 cells (wild type) induced an accumulation of LNA, LNA or ALA, respectively, in cellular lipids. These changes were not observed in the peroxisomes-deficient CHO cells, indicating involvement of peroxisomes in the metabolism. Two types of human cells (MKN74 and HepG2) also converted the C20 PMI-PUFA and EDA to the respective essential fatty acids. In contrast, no chain-shortened metabolite of pinolenic acid (18:3 Δ-5,9,12) was detected in any cell lines tested. From these results, C20 PMI-PUFA and EDA, but not C18 PMI-PUFA, are suggested as being effectively converted to essential fatty acids by the fatty acid remodeling system in rodent and human cells.     

GC-FID/MS Analysis of Fatty Acids in Indian Cultivars of Moringa oleifera: Potential Sources of PUFA

In the present investigation, the fatty acid profile was analysed in vegetative and reproductive parts of eight commercially cultivated Indian cultivars of Moringa oleifera and verified by gas chromatography mass spectra. In leaves, α-linolenic acid (C_18:3, cis-9,12,15) was found in the highest quantity (49–59 %) followed by palmitic acid (C_16:0) (16–18 %), and linoleic acid (C_18:2, cis-9,12) (6–13 %). The total content of saturated fatty acids and unsaturated fatty acids showed a ratio of 0.33 (cv. DHANRAJ) to 0.39 (cv. PKM-2) in leaves, 0.53 in flowers and 0.56 in tender pods. Similarly, polyunsaturated fatty acids and total monounsaturated fatty acids were found in a ratio of 5.68 (cv. DHANRAJ) to 9.71 (cv. CO-1) in leaves, 1.11 in flowers and 2.79 in tender pods. The total lipid content was recorded in the range of 1.92 % (flowers) to 4.82 % (leaves, cv. CO-1). When considering health benefits, M. oleifera leaves contain low amounts of saturated fatty acids, a high mono- and polyunsaturated fatty acid content, which can enhance the health benefits of Moringa-based products.     

Nonalcoholic Fatty Liver: A Possible New Target for Type 2 Diabetes Prevention and Treatment

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder worldwide. Several lines of evidence have indicated a pathogenic role of insulin resistance, and a strong association with type 2 diabetes (T2MD) and metabolic syndrome. Importantly, NAFLD appears to enhance the risk for T2MD, as well as worsen glycemic control and cardiovascular disease in diabetic patients. In turn, T2MD may promote NAFLD progression. The opportunity to take into account NAFLD in T2MD prevention and care has stimulated several clinical studies in which antidiabetic drugs, such as metformin, thiazolidinediones, GLP-1 analogues and DPP-4 inhibitors have been evaluated in NAFLD patients. In this review, we provide an overview of preclinical and clinical evidences on the possible efficacy of antidiabetic drugs in NAFLD treatment. Overall, available data suggest that metformin has beneficial effects on body weight reduction and metabolic parameters, with uncertain effects on liver histology, while pioglitazone may improve liver histology. Few data, mostly preclinical, are available on DPP4 inhibitors and GLP-1 analogues. The heterogeneity of these studies and the small number of patients do not allow for firm conclusions about treatment guidelines, and further randomized, controlled studies are needed.     

Substrate Enantioselective and Product Stereoselective Metabolism of Racemic 2-Hydroxy-3-methylcholanthrene by Rat Liver Microsomes

Racemic 2-hydroxy-3-methylcholanthrene (rac-2-OH-3MC) is a potent carcinogen and 2S-OH-3MC is the most abundant metabolite formed in the metabolism of 3-methylcholanthrene (3MC) by rat liver microsomes. Eighteen identifiable metabolites were formed in the metabolism of rac-2-OH-3MC by liver microsomes prepared from phenobarbital-treated rats. Metabolites were separated by sequential use of reversed-phase and normal-phase high performance liquid chromatography (HPLC) and characterized by ultraviolet-visible absorption, mass, and circular dichroism spectral, and chiral stationary phase (CSP) HPLC analyses. Identified metabolites were: 2-OH-3MC 7,8-dihydrodiol (enriched in 7R,8R enantiomer), 2-OH-3MC 9,10-dihydrodiol (2S,9R,10R:2R,9S,10S ≈ 27:73 and 2R,9R,10R:2S,9S,10S ≈ 81:19), 2-OH-3MC 11,12-dihydrodiol (2R,11R,12R:2S,11S,12S ≈ 5:95 and an essentially optically pure 2S,11R,12R enantiomer), 3MC trans-1,2-diol (1S,2S:1R,2R ≈ 68:32), 3MC cis-1,2-diol (1S,2R:1R,2S ≈ 18:82), 2-OH-3-hydroxymethyl-cholanthrene (2-OH-3-OHMC, 2R:2S ≈ 19:81), 2-OH-3-OHMC 9,10-dihydrodiol (9R,10R:9S,10S ≈ 62:38), 3MC-2-one 9,10-dihydrodiol (9R,10R:9S,10S ≈ 7:3), 3MC cis-1,2-diol:trans-9,10-dihydrodiol, 8-hydroxy-2-OH-3-OHMC, 9-hydroxy-2-OH-3MC, 10-hydroxy-2-OH-3MC, and 3MC-2-one. The enantiomer ratios of some metabolites formed were determined by circular dichroism spectra and/or CSP-HPLC. Six 9,10-dihydrodiols formed in the metabolism of 2-OH-3MC may be further converted to potentially reactive 9,10-diol-7,8-epoxides and may contribute to the overall carcinogenicity exhibited by 3MC.     

Short‐Chain Fatty Acids Enhance the Lipid Accumulation of 3T3‐L1 Cells by Modulating the Expression of Enzymes of Fatty Acid Metabolism

Short‐chain fatty acids (SCFA) such as acetic acid, propionic acid, and butyric acid are produced by fermentation by gut microbiota. In this paper, we investigate the effects of SCFA on 3T3‐L1 cells and the underlying molecular mechanisms. The cells were treated with acetic acid, propionic acid, or butyric acid when cells were induced to differentiate into adipocytes. MTT assay was employed to detect the viability of 3T3‐L1 cells. Oil Red O staining was used to visualize the lipid content in 3T3‐L1 cells. A triglyceride assay kit was used to detect the triacylglycerol content in 3T3‐L1 cells. qRT‐PCR and Western blot were used to evaluate the expression of metabolic enzymes. MTT results showed that safe concentrations of acetic acid, propionic acid, and butyric acid were less than 6.4, 3.2, and 0.8 mM, respectively. Oil Red O staining and triacylglycerols detection results showed that treatment with acetic acid, propionic acid, and butyric acid accelerated the 3T3‐L1 adipocyte differentiation. qRT‐PCR and Western blot results showed that the expressions of lipoprotein lipase (LPL), adipocyte fatty acid binding protein 4 (FABP4), fatty acid transporter protein 4 (FATP4), and fatty acid synthase (FAS) were significantly increased by acetic acid, propionic acid, and butyric acid treatment during adipose differentiation (p < 0.05). In conclusion, SCFA promoted lipid accumulation by modulating the expression of enzymes of fatty acid metabolism.     

The Obscure Effect of Tribulus terrestris Saponins Plus Inulin on Liver Morphology,Liver Fatty Acids,Plasma Glucose,and Lipid Profile in SD Rats with and without Induced Type 2 Diabetes Mellitus

Diabetes is a predictor of nonalcoholic fatty liver disease (NAFLD). There are data suggesting that Tribulus terrestris (TT) saponins act as antidiabetic agents and protect against NAFLD. The effect of saponins may be increased by fermentable fibers such as inulin. The aim of the present study was to investigate the influence of TT saponins and TT saponins plus inulin on the plasma lipid profile and liver fatty acids of rats with induced diabetes mellitus type 2 (T2DM). The study was performed on 36 male Sprague–Dawley rats divided into two main groups: control and diabetic. Animals of the diabetic (DM) group were fed a high-fat diet and injected with streptozotocin (low doses). Animals of the control group (nDM) were on a regular diet and were injected with buffer. After the injections, the animals were split into subgroups: three non-diabetic (nDM): (i) control (c-C); (ii) saponin-treated rats (C-Sap); (iii) rats treated with saponins + inulin (C-Sap + IN), and three diabetic subgroups (DM): (iv) control (c-DM); (v) saponin-treated rats (DM-Sap); (vi) rats treated with saponins + inulin (DM-Sap + IN). Liver fatty acids were extracted and analyzed by gas chromatography, and plasma glucose and lipids were measured. The study showed significant changes in liver morphology, liver fatty acids, plasma lipid profile, and plasma glucose. In summary, supplementation with TT saponins or saponins with inulin for one month decreased the level of steatosis in rats with induced type 2 diabetes. Moreover, there were favorable effects on the plasma lipid profile in the rats. However, additional supplementation with inulin had a negative effect on liver morphology (with a microvesicular type of steatosis) in the non-diabetes group. Moreover, supplementation with inulin had a negative effect on plasma glucose in both diabetic and non-diabetic rats. These data show that a diet enriched with fermentable fibers reveals different effects in different organisms, and not all sources and forms of fiber are beneficial to health.     

Alpha-Lipoic Acid Inhibits Spontaneous Diabetes and Autoimmune Recurrence in Non-Obese Diabetic Mice by Enhancing Differentiation of Regulatory T Cells and Showed Potential for Use in Cell Therapies for the Treatment of Type 1 Diabetes

Type 1 diabetes (T1D) is caused by the destruction of β cells in pancreatic islets by autoimmune T cells. Islet transplantation has been established as an effective treatment for T1D. However, the survival of islet grafts is often disrupted by recurrent autoimmunity. Alpha-lipoic acid (ALA) has been reported to have immunomodulatory effects and, therefore, may have therapeutic potential in the treatment of T1D. In this study, we investigated the therapeutic potential of ALA in autoimmunity inhibition. We treated non-obese diabetic (NOD) mice with spontaneous diabetes and islet-transplantation mice with ALA. The onset of diabetes was decreased and survival of the islet grafts was extended. The populations of Th1 cells decreased, and regulatory T cells (Tregs) increased in ALA-treated mice. The in vitro Treg differentiation was significantly increased by treatment with ALA. The adoptive transfer of ALA-differentiated Tregs into NOD recipients improved the outcome of the islet grafts. Our results showed that in vivo ALA treatment suppressed spontaneous diabetes and autoimmune recurrence in NOD mice by inhibiting the Th1 immune response and inducing the differentiation of Tregs. Our study also demonstrated the therapeutic potential of ALA in Treg-based cell therapies and islet transplantation used in the treatment of T1D.     

l-Carnitine and Long-Chain Acylcarnitines are Positively Correlated with Ambulatory Blood Pressure in Humans: The SABPA Study

The prevalence of hypertension in sub-Saharan Africa is increasing rapidly, and treatment remains challenging. Although the use of l-carnitine in treatment has received much attention, studies reporting on physiological l-carnitine levels in hypertensives are limited. Our aim was to determine physiological levels of l-carnitine and acylcarnitines in African and Caucasian men, and to investigate associations between ambulatory blood pressure (BP) and carnitine levels. Participants included 101 African and 101 Caucasian teachers. Ambulatory BP measurements were conducted, and l-carnitine and acylcarnitine levels determined. African men showed significantly higher systolic BP (p < 0.001), diastolic BP (p < 0.001) and l-carnitine levels (p = 0.01). In both ethnic groups, partial regression analyses revealed a positive association between BP and l-carnitine, although in Caucasians it was with systolic (r = 0.20, p = 0.045), and in Africans with diastolic BP (r = 0.23, p = 0.023). After adjusting for confounders, an independent positive association between systolic (R ² = 0.37, β = 0.12, p = 0.041) and diastolic BP (R ² = 0.39, β = 0.14, p = 0.018) and l-carnitine and long-chain acylcarnitines (R ² = 0.38, β = 0.17, p = 0.005 and R ² = 0.39, β = 0.15, p = 0.011) were found, independent of ethnicity. Physiological l-carnitine levels were not only higher in Africans than in Caucasians but also above the expected reference range. Despite promising results on l-carnitine (and its short-chain derivatives) in hypertension treatment regimens, our findings paradoxically show that elevated BP is significantly associated with higher physiological l-carnitine and long-chain acylcarnitine levels.     

Profile of Bioactive Compounds in Avocado Pulp Oil: Influence of the Drying Processes and Extraction Methods

The influence of different procedures of pulp drying and oil extraction methods on the concentrations of α-tocopherol, squalene and several phytosterols in avocado oil was evaluated. Pulp portions of Fortune variety avocados were dried either by lyophilization or under circulating air at 40 or 70 °C. For lyophilization and for each air drying temperature, the oil was obtained either by cold pressing or with Soxhlet extraction using petroleum ether. The dehydrated pulp (73 % of the pulp weight) yielded 25–33 % oil by cold pressing, and 45–57 % oil by Soxhlet extraction. Infrared spectroscopy and gas chromatography with FID and mass spectrometry detection were used to analyze the oils. α-Tocopherol, squalene, cycloartenol acetate, β-sitosterol, campesterol and stigmasterol were present in all the oil samples. In comparison to lyophilization, hot air drying resulted in smaller concentrations of α-tocopherol, squalene and β-sitosterol, and larger relative concentrations of campesterol and cycloartenol acetate. On the other hand, extraction by cold pressing produced a smaller amount of oil, with greater concentrations of α-tocopherol and squalene, and lower contents of campesterol and cycloartenol acetate, than Soxhlet extraction. Thus, the oil yield was maximal with lyophilization and Soxhlet extraction, but lyophilization and cold pressing produced oils which had greater concentrations of antioxidants and other bioactive compounds.     

Long-Term Adverse Effect of Liver Stiffness on Glycaemic Control in Type 2 Diabetic Patients with Nonalcoholic Fatty Liver Disease: A Pilot Study

Currently, there are limited data regarding the long-term effect of liver stiffness on glycaemic control in patients with type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD). We prospectively followed an outpatient sample of 61 consecutive postmenopausal women with T2DM and NAFLD who had baseline data on liver ultrasonography and Fibroscan^®-assessed liver stiffness measurement (LSM) in 2017 and who underwent follow-up in 2022. Haemoglobin A1c (HbA1c) was measured both at baseline and follow-up. At baseline, 52 patients had NAFLD (hepatic steatosis) alone, and 9 had NAFLD with coexisting clinically significant fibrosis (defined as LSM ≥ 7 kPa on Fibroscan^®). At follow-up, 16 patients had a worsening of glycaemic control (arbitrarily defined as HbA1c increase ≥ 0.5% from baseline). The prevalence of NAFLD and coexisting clinically significant fibrosis at baseline was at least three times greater among patients who developed worse glycaemic control at follow-up, compared with those who did not (31.3% vs. 8.9%; p = 0.030). In logistic regression analysis, the presence of NAFLD and clinically significant fibrosis was associated with an approximately 4.5-fold increased likelihood of developing worse glycaemic control at follow-up (odds ratio 4.66, 95% confidence interval 1.07–20.3; p = 0.041), even after adjustment for baseline confounding factors, such as age, body mass index, haemoglobin A1c (or HOMA-estimated insulin resistance) and use of some glucose-lowering agents that may positively affect NAFLD and liver fibrosis. In conclusion, our results suggest that the presence of Fibroscan^®-assessed significant fibrosis was associated with a higher risk of developing worse glycaemic control in postmenopausal women with T2DM and NAFLD.     

K/Ni/β-Mo2C: A highly active and selective catalyst for higher alcohols synthesis from CO hydrogenation

Nickel and potassium promoted β-Mo₂C catalysts were prepared for CO hydrogenation to higher alcohols synthesis. The results revealed that β-Mo₂C produced mainly hydrocarbons, but the addition of potassium resulted in a remarkable selectivity shift from hydrocarbons to alcohols over β-Mo₂C. Moreover, it was found that potassium enhanced the ability of chain propagation of β-Mo₂C catalyst and led to a higher selectivity to C₂⁺OH. The addition of nickel further enhanced higher alcohols synthesis, which showed the optimum at 1/8–1/6 of Ni/Mo molar ratios. The characterization suggested that there might be a synergistic effect of potassium and nickel on β-Mo₂C, which favored the alcohols synthesis. The production of alcohols appeared to be relevant to the presence of Mo⁴⁺ species, whereas the formation of hydrocarbons was closely associated with Mo²⁺ and/or Mo⁰ species on the surface of β-Mo₂C-based catalysts.     

Total Synthesis and Structural Elucidation of Two Unusual Non-Methylene-Interrupted Fatty Acids in Ovaries of the Limpet <Emphasis Type="Italic">Cellana toreuma</Emphasis>

In our previous study, unusual odd‐numbered dienoic acids with a terminal olefin were found as minor components in ovaries of the Japanese limpet Cellana toreuma, and the synthetic interests have been focused onto their structural confirmation and the inspection into their potential biological activity. Here, we describe an efficient and stereoselective total synthesis of two new unusual dienoic acids, 19:2?7,18 and 21:2?7,20, through a common pathway involving the strategic combination of alkyne‐zipper reaction and Lindlar hydrogenation for the construction of their unique carbon chains. In our synthetic study, 2‐propyn‐1‐ol was at first subjected to alkylation and alkyne‐zipper reaction to form the two fragments, and the subsequent carbon chain elongation was achieved by the usual coupling reaction to obtain the C‐19 and C‐21 products bearing an internal acetylenic group. Then, the internal acetylenic group of these products was subjected to Lindlar hydrogenation to form a Z‐alkenyl moiety, and the subsequent deprotection of the products was carried out under an acidic condition without isomerization of the internal Z‐alkenyl group. Total synthesis of target fatty acids, 19:2?7,18 and 21:2?7,20, was finally accomplished by two‐step oxidation of the resulting alcohols into carboxylic acids in a highly chemoselective manner, and the structures of these unusual natural fatty acids were finally elucidated by identifying the GC–MS spectra of the methyl esters of authentic and synthetic fatty acids.     

Lost-in-Translation of Metabolic Effects of Inorganic Nitrate in Type 2 Diabetes: Is Ascorbic Acid the Answer?

Beneficial metabolic effects of inorganic nitrate (NO₃⁻) and nitrite (NO₂⁻) in type 2 diabetes mellitus (T2DM) have been documented in animal experiments; however, this is not the case for humans. Although it has remained an open question, the redox environment affecting the conversion of NO₃⁻ to NO₂⁻ and then to NO is suggested as a potential reason for this lost-in-translation. Ascorbic acid (AA) has a critical role in the gastric conversion of NO₂⁻ to NO following ingestion of NO₃⁻. In contrast to AA-synthesizing species like rats, the lack of ability to synthesize AA and a lower AA body pool and plasma concentrations may partly explain why humans with T2DM do not benefit from NO₃⁻/NO₂⁻ supplementation. Rats also have higher AA concentrations in their stomach tissue and gastric juice that can significantly potentiate gastric NO₂⁻-to-NO conversion. Here, we hypothesized that the lack of beneficial metabolic effects of inorganic NO₃⁻ in patients with T2DM may be at least in part attributed to species differences in AA metabolism and also abnormal metabolism of AA in patients with T2DM. If this hypothesis is proved to be correct, then patients with T2DM may need supplementation of AA to attain the beneficial metabolic effects of inorganic NO₃⁻ therapy.     

Arginase 2 and Polyamines in Human Pancreatic Beta Cells: Possible Role in the Pathogenesis of Type 2 Diabetes

Arginase 2 (ARG2) is a manganese metalloenzyme involved in several tissue specific processes, from physiology to pathophysiology. It is variably expressed in extra-hepatic tissues and is located in the mitochondria. In human pancreatic beta cells, ARG2 is downregulated in type 2 diabetes. The enzyme regulates the synthesis of polyamines, that are involved in pancreas development and regulation of beta cell function. Here, we discuss several features of ARG2 and polyamines, which can be relevant to the pathophysiology of type 2 diabetes.     

Plasma Levels of 14:0, 16:0, 16:1n-7, and 20:3n-6 are Positively Associated,but 18:0 and 18:2n-6 are Inversely Associated with Markers of Inflammation in Young Healthy Adults

Inflammation is a recognized risk factor for the development of chronic diseases, such as type 2 diabetes and atherosclerosis. Evidence suggests that individual fatty acids (FA) may have distinct influences on inflammatory processes. The goal of this study was to conduct a cross-sectional analysis to examine the associations between circulating FA and markers of inflammation in a population of young healthy Canadian adults. FA, high-sensitivity C-reactive protein (hsCRP), and cytokines were measured in fasted plasma samples from 965 young adults (22.6 ± 0.1 years). Gas chromatography was used to measure FA. The following cytokines were analyzed with a multiplex assay: regulated upon activation normal T cell expressed and secreted (RANTES/CCL5), interleukin 1-receptor antagonist (IL-1Ra), interferon-γ (IFN-γ), interferon-γ inducible protein 10 (IP-10), and platelet-derived growth factor β (PDGF-ββ). Numerous statistically significant associations (p < 0.05, corrected for multiple testing) were identified between individual FA and markers of inflammation using linear regression. Myristic (14:0), palmitic (16:0), palmitoleic (16:1n-7), and dihomo-γ-linolenic (20:3n-6) acids were positively associated with all markers of inflammation. In contrast, stearic acid (18:0) was inversely associated with hsCRP and RANTES, and linoleic acid (18:2n-6) was inversely associated with hsCRP, RANTES and PDGF-ββ. In conclusion, our results indicate that specific FA are distinctly correlated with various markers of inflammation. Moreover, the findings of this study suggest that FA profiles in young adults may serve as an early indicator for the development of future complications comprising an inflammatory component.     

Daily Treatment of Mice with Type 2 Diabetes with Adropin for Four Weeks Improves Glucolipid Profile,Reduces Hepatic Lipid Content and Restores Elevated Hepatic Enzymes in Serum

Adropin is a peptide hormone encoded by Energy Homeostasis Associated gene. Adropin modulates energy homeostasis and metabolism of lipids and carbohydrates. There is growing evidence demonstrating that adropin enhances insulin sensitivity and lowers hyperlipidemia in obese mice. The aim of this study was to investigate the effects of daily administration of adropin for four weeks in mice with experimentally induced type 2 diabetes (T2D). Adropin improved glucose control without modulating insulin sensitivity. Adropin reduced body weight, size of adipocytes, blood levels of triacylglycerol and cholesterol in T2D mice. T2D mice treated with adropin had lower liver mass, reduced hepatic content of triacylglycerol and cholesterol. Furthermore, adropin attenuated elevated blood levels of hepatic enzymes (ALT, AST, GGT and ALP) in T2D mice. In T2D mice, adropin increased the circulating adiponectin level. Adropin had no effects on circulating insulin and glucagon levels and did not alter pancreatic islets morphology. These results suggest that adropin improves glucose control, lipid metabolism and liver functions in T2D. In conjunction with reduced lipid content in hepatocytes, these results render adropin as an interesting candidate in therapy of T2D.