Direct ultrasound-assisted methylation of fatty acids in serum for free fatty acid determinations

The digestion and absorption characteristics of human milk phospholipid analogs: a combination study between in vitro and in vivo

Phospholipids play a crucial role in the growth and neurodevelopment of infants. Currently, soybean phospholipids (SPLs) are the common phospholipid component in most infant formulas (IFs), which, however, shows an obvious difference with the phospholipid (PL) composition of human milk fat. Therefore, in the present study, human milk phospholipid analogs (HMPAs) were prepared by mimicking the composition of PE, PC, PI, PS, and SM in breast milk phospholipids and the composition of the major fatty acids (C16:0, C18:0, C18:1, and C18:2), and their digestion and absorption characteristics were explored using in vitro and mice models. The prepared HMPA contained 26.48% PE, 24.64% PC, 36.19% SM, 6.35% PI, and 6.32% PS, with 40.51% C16:0, 17.02% C18:0, 29.19% C18:1, and 13.26% C18:2, showing different digestive properties relative to SPL. There was little effect on the physical and chemical properties of HMPA under in vitro gastric conditions. The hydrolysis degree, fatty acids release rate, and average particle size decreasing rate of HMPA was significantly higher than that of SPL during digestion in vitro intestine (P < 0.05), showing better digestive process relative to SPL. In terms of the mice model, HMPA had a higher hydrolysis degree in the intestinal tract. Based on the area under curve (AUC) analysis of serum fatty acids, it was found that despite HMPA being absorbed at a slower rate than SPL, it was absorbed more than SPL. In summary, the digestion and absorption of HMPA were preferred to SPL, and these obtained results might provide a theoretical basis for the development and utilization of HMPA in IF.

Knockdown of IL4I1 Improved High Glucose-evoked Insulin Resistance in HepG2 Cells by Alleviating Inflammation and Lipotoxicity Through AHR Activation

Insulin resistance (IR) is one of the leading causes of Type 2 diabetes mellitus (T2DM). Inflammation, as a result of the disordered immune response, plays important roles in IR and T2DM. Interleukin-4-induced gene 1 (IL4I1) has been shown to regulate immune response and be involved in inflammation progress. However, there was little known about its roles in T2DM. Here, high glucose (HG)-treated HepG2 cells were used for T2DM investigation in vitro. Our results indicated that the expression of IL4I1 was up-regulated in peripheral blood samples of T2DM-patients and HG-induced HepG2 cells. The silencing of IL4I1 alleviated the HG-evoked IR through elevating the expressions of p-IRS1, p-AKT and GLUT4, and enhancing glucose consumption. Furthermore, IL4I1 knockdown inhibited inflammatory response by reducing the levels of inflammatory mediators, and suppressed the accumulation of lipid metabolites triglyceride (TG) and palmitate (PA) in HG-induced cells. Notably, IL4I1 expression was positively correlated with aryl hydrocarbon receptor (AHR) in peripheral blood samples of T2DM-patients. The silencing of IL4I1 inhibited the AHR signaling by reducing the HG-induced expressions of AHR and CYP1A1. Subsequent experiments confirmed that 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), an agonist of AHR, reversed the suppressive effects of IL4I1 knockdown on HG-caused inflammation, lipid metabolism and IR in cells. In conclusion, we found that the silencing of IL4I1 attenuated inflammation, lipid metabolism and IR in HG-induced cells via inhibiting AHR signaling, suggesting that IL4I1 might be a potential therapy target for T2DM.

Tetraedron minimum, First Reported Member of Hydrodictyaceae to Accumulate Secondary Carotenoids

We isolated a novel strain of the microalga Tetraedron minimum in Iceland from a terrestrial habitat. During long-term cultivation, a dish culture turned orange, indicating the presence of secondary pigments. Thus, we characterized T. minimum for growth and possible carotenoid production in different inorganic media. In a lab-scale photobioreactor, we confirmed that nitrogen starvation in combination with salt stress triggered a secondary carotenoid accumulation. The development of the pigment composition and the antioxidant capacity of the extracts was analyzed throughout the cultivations. The final secondary carotenoid composition was, on average, 61.1% astaxanthin and 38.9% adonixanthin. Moreover, the cells accumulated approx. 83.1% unsaturated fatty acids. This work presents the first report of the formation of secondary carotenoids within the family Hydrodictyaceae (Sphaeropleales, Chlorophyta).

Mangiferin Improved Palmitate-Induced-Insulin Resistance by Promoting Free Fatty Acid Metabolism in HepG2 and C2C12 Cells via PPARα: Mangiferin Improved Insulin Resistance

Elevated free fatty acid (FFA) is a key risk factor for insulin resistance (IR). Our previous studies found that mangiferin could decrease serum FFA levels in obese rats induced by a high-fat diet. Our research was to determine the effects and mechanism of mangiferin on improving IR by regulating FFA metabolism in HepG2 and C2C12 cells. The model was used to quantify PA-induced lipid accumulation in the two cell lines treated with various concentrations of mangiferin simultaneously for 24 h. We found that mangiferin significantly increased insulin-stimulated glucose uptake, via phosphorylation of protein kinase B (P-AKT), glucose transporter 2 (GLUT2), and glucose transporter 4 (GLUT4) protein expressions, and markedly decreased glucose content, respectively, in HepG2 and C2C12 cells induced by PA. Mangiferin significantly increased FFA uptake and decreased intracellular FFA and triglyceride (TG) accumulations. The activity of the peroxisome proliferator-activated receptor α (PPARα) protein and its downstream proteins involved in fatty acid translocase (CD36) and carnitine palmitoyltransferase 1 (CPT1) and the fatty acid β-oxidation rate corresponding to FFA metabolism were also markedly increased by mangiferin in HepG2 and C2C12 cells. Furthermore, the effects were reversed by siRNA-mediated knockdown of PPARα. Mangiferin ameliorated IR by increasing the consumption of glucose and promoting the FFA oxidation via the PPARα pathway in HepG2 and C2C12 cells.

Fatty acid profiles of typical dietary lipids after gastrointestinal digestion and absorbtion: A combination study between in-vitro and in-vivo

The objective of the present study was to investigate the influences of dietary lipid composition on the gastrointestinal digestion and postprandial serum lipid profiles, and the connections between them. The in-vitro digestion results showed that maximum free fatty acid (FFA) release level of different lipid samples was PO (Palm oil) > RO (Rapeseed oil) > LINO (Linseed oil) > SO (Sunflower oil) > LO (Lard oil), and the first-order kinetics apparent rate constant was PO > SO ≈ RO > LO ≈ LINO, this may probably be ascribed to their specific lipid fatty acid composition and TAG structure. The individual FFA released during 240 min in-vitro digestion time was measured, and it showed that the release rate of short-chain saturated fatty acids (e.g. C16:0 in PO) were higher than the long-chain poly-unsaturated fatty acids (e.g. C18:3n-3 in LINO). Besides, the position of fatty acids within TAG molecules could also impose influences on the lipid hydrolysis process upon pancreas lipase in gastrointestinal tract using in-vitro digestion model. The postprandial serum fatty acid composition of the adult SD male rats were examined within 240 min after oral gavage administration, and the Pearson correlations between lipid fatty acid composition and the serum fatty acid profiles were analyzed. Certain correlations were summarized between lipid compositions (i.e. fatty acid composition and TAG structure), lipid digestion fates and serum fatty acid content in postprandial. The present work may provide some basic understandings of the connections among lipid compositions, lipid gastrointestinal digestion differences and the postprandial serum lipid profiles, and provide useful information about their nutritional and functional evaluation.

Epigallocatechin gallate improves insulin resistance in HepG2 cells through alleviating inflammation and lipotoxicity

AIMS

High levels of circulating free fatty acids (FFAs), inflammation and oxidative stress are important causes for insulin resistance (IR) and type 2 diabetes mellitus. The aim of this study was to investigate the mechanisms of EGCG in alleviating IR in HepG2 cells.

METHODS

HepG2 cells were treated with 25 mM glucose, 0.25 mM palmitic acid (PA), or 50 μM EGCG for 24 h.

RESULTS

EGCG increased glucose uptake and decreased glucose content. EGCG markedly decreased the levels of inflammatory and oxidative stress factors including nuclear factor κB (NF-κB), tumor necrosis factor-α, interleukin-6, reactive oxygen species, malondialdehyde and p53 protein, and markedly increased superoxide dismutases (SOD), glutathione peroxidase and SOD2 protein. EGCG significantly downregulated the levels of FFAs, triacylglycerol and cholesterol in HepG2 cells. The glucose transporter 2 (GLUT2) protein and its downstream proteins peroxisome proliferator-activated receptor γ coactivator (PGC)-1β were significantly increased, and sterol regulatory element-binding-1c (SREBP-1c) protein, and fatty acid synthase (FAS) were significantly decreased by EGCG in HepG2. Moreover, the foregoing effects were reversed by siRNA-mediated knockdown of GLUT2.

CONCLUSION

Our data demonstrated that EGCG improved IR, possibly through ameliorating glucose (25 mM) and PA (0.25 mM)-induced inflammation, oxidative stress, and FFAs via the GLUT2/PGC-1β/SREBP-1c/FAS pathway in HepG2 cells.

Silica sulfuric acid magnetic nanoparticle: an efficient and ecofriendly catalyst for synthesis of spiro[2-amino-4H-pyran-oxindole]s

Silica sulfuric acid magnetic nanoparticles efficiently catalyze the one-pot, three-component reaction of isatins and malononitrile with dimedone, 1,3-dimethylbarbituric acid or 4-hydroxycoumarin in EtOH–H2O to afford the corresponding spiro[2-amino-4H-pyran-oxindole] derivatives in high yields under ultrasound irradiation at 60 °C. The heterogeneous nanocatalyst could be recovered easily from the reaction mixture using an external magnet and reused many times without significant loss of its catalytic activity.

An ultrasonic assisted extraction procedure to free fatty acids from the liver samples of mice

A procedure was evaluated for the extraction of 16 free fatty acids (FFAs) from liver. Ultrasonic energy was used for the extraction and the variables affecting the extraction efficiency were investigated. The best conditions for extraction were: 2 mL isopropanol-n-hexane (3:2, v/v), 20 min and 80 w. Recoveries ranging from 87.00 to 120.00% were obtained under the optimum conditions, and the linearity as correlation coefficient was higher than 0.9914. Analytical results for the 16 FFAs in the same liver sample, analyzed by ultrasound-assisted and conventional extraction, showed acceptable agreement, thus suggesting the possibility of using ultrasound-assisted extraction instead of the conventional procedure. Moreover, the ultrasound-assisted extraction was successfully applied to the determination of FFAs in the liver of mice with hyperlipidemia and normal mice.

Mangiferin decreases plasma free fatty acids through promoting its catabolism in liver by activation of AMPK

Mangiferin has been shown to have the effect of improving dyslipidemia. Plasma free fatty acids (FFA) are closely associated with blood lipid metabolism as well as many diseases including metabolic syndrome. This study is to investigate whether mangiferin has effects on FFA metabolism in hyperlipidemic rats. Wistar rats were fed a high-fat diet and administered mangiferin simultaneously for 6 weeks. Mangiferin (50, 100, 150 mg/kg BW) decreased dose-dependently FFA and triglycerides (TG) levels in plasma, and their accumulations in liver, but increased the β-hydroxybutyrate levels in both plasma and liver of hyperlipidemic rats. HepG2 cells were treated with oleic acid (OA, 0.2 mmol/L) to simulate the condition of high level of plasma FFA in vitro, and were treated with different concentrations of mangiferin simultaneously for 24 h. We found that mangiferin significantly increased FFA uptake, significantly decreased intracellular FFA and TG accumulations in HepG2 cells. Mangiferin significantly increased AMP-activated protein kinase (AMPK) phosphorylation and its downstream proteins involved in fatty acid translocase (CD36) and carnitine palmitoyltransferase 1 (CPT1), but significantly decreased acyl-CoA: diacylgycerol acyltransferase 2 (DGAT2) expression and acetyl-CoA carboxylase (ACC) activity by increasing its phosphorylation level in both in vivo and in vitro studies. Furthermore, these effects were reversed by Compound C, an AMPK inhibitor in HepG2 cells. For upstream of AMPK, mangiferin increased AMP/ATP ratio, but had no effect on LKB1 phosphorylation. In conclusion, mangiferin decreased plasma FFA levels through promoting FFA uptake and oxidation, inhibiting FFA and TG accumulations by regulating the key enzymes expression in liver through AMPK pathway. Therefore, mangiferin is a possible beneficial natural compound for metabolic syndrome by improving FFA metabolism.