Dietary sn-2 palmitic triacylglycerols reduced faecal lipids, calcium contents and altered lipid metabolism in Sprague-Dawley rats

Effects of sn-2 Palmitic Triacylglycerols and the Ratio of OPL to OPO in Human Milk Fat Substitute on Metabolic Regulation in Sprague-Dawley Rats

In this study, the influence of total sn-2 palmitic triacylglycerols (TAGs) and ratio of 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) to 1,3-dioleoyl-2-palmitoylglycerol (OPO) in human milk fat substitute (HMFS) on the metabolic changes were investigated in Sprague-Dawley rats. Metabolomics and lipidomics profiling analysis indicated that increasing the total sn-2 palmitic TAGs and OPL to OPO ratio in HMFS could significantly influence glycine, serine and threonine metabolism, glycerophospholipid metabolism, glycerolipid metabolism, sphingolipid metabolism, bile acid biosynthesis, and taurine and hypotaurine metabolism pathways in rats after 4 weeks of feeding, which were mainly related to lipid, bile acid and energy metabolism. Meanwhile, the up-regulation of taurine, L-tryptophan, and L-cysteine, and down-regulations of lysoPC (18:0) and hypoxanthine would contribute to the reduction in inflammatory response and oxidative stress, and improvement of immunity function in rats. In addition, analysis of targeted biochemical factors also revealed that HMFS-fed rats had significantly increased levels of anti-inflammatory factor (IL-4), immunoglobulin A (IgA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-px), and decreased levels of pro-inflammatory factors (IL-6 and TNF-α) and malondialdehyde (MDA), compared with those of the control fat-fed rats. Collectively, these observations present new in vivo nutritional evidence for the metabolic regulatory effects of the TAG structure and composition of human milk fat substitutes on the host.

Dose-related effects of early-life intake of sn-2 palmitate, a specific positionally distributed human milk fatty acid, on the composition and metabolism of the intestinal microbiota

sn2 Palmitate in human milk plays an important role in the physiological health of infants by reducing mineral loss, improving stool hardness, and relieving constipation. Also, sn-2 palmitate modulates intestinal microbiota. However, it remains unclear whether the effects of sn-2 palmitate on infant gut microbiota are dose-dependent. In this study, we investigated the effects of low, medium, and high doses (600, 1,800, and 5,400 mg/kg body weight, respectively) of sn-2 palmitate on the structure, composition, and metabolic function of intestinal microbes in mice. Our results showed that high doses of sn-2 palmitate significantly modulated α- and β-diversity of the intestinal microbiota. The relative abundance of Lachnospiraceae_NK4A136_group decreased with increasing doses of sn-2 palmitate. In contrast, the abundances of Bacteroidetes phylum, Bacteroides, uncultured_Lachnospiraceae, and uncultured_Muribaculaceae were positively correlated with sn-2 palmitate doses. The number of genes predicted encoding autophagy-yeast, phospholipase D signaling pathway, and pentose and glucuronate interconversion metabolic functions of intestinal microbiota increased with increasing doses of sn-2 palmitate. In addition, low and medium doses of sn-2 palmitate significantly upregulated the arginine and proline metabolic pathways, and high doses of sn-2 palmitate significantly increased purine metabolism. Our results revealed that the effects of sn-2 palmitate intake early in life on the composition and metabolism of the intestinal microbiota of mice showed dose-related differences. The study is expected to provide a scientific basis for the development of infant formulas.

Total Sn-2 Palmitic Triacylglycerols and the Ratio of OPL to OPO in Human Milk Fat Substitute Modulated Bile Acid Metabolism and Intestinal Microbiota Composition in Rats

In this study, the impact of sn-2 palmitic triacyclglycerols (TAGs) in combination with their ratio of two major TAGs (1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) to 1,3-dioleoyl-2-palmitoylglycerol (OPO)) in human milk fat substitute (HMFS) on bile acid (BA) metabolism and intestinal microbiota composition was investigated in newly-weaned Sprague-Dawley rats after four weeks of high-fat feeding. Compared to those of control group rats, HMFS-fed rats had significantly increased contents of six hepatic primary BAs (CDCA, αMCA, βMCA, TCDCA, TαMCA and TβMCA), four ileal primary BAs (UDCA, TCA, TCDCA and TUDCA) and three secondary BAs (DCA, LCA and ωMCA), especially for the HMFS with the highest sn-2 palmitic acid TAGs of 57.9% and OPL to OPO ratio of 1.4. Meanwhile, the inhibition of ileal FXR-FGF15 and activation of TGR5-GLP-1 signaling pathways in HMFS-fed rats were accompanied by the increased levels of enzymes involved in BA synthesis (CYP7A1, CYP27A1 and CYP7B1) in the liver and two key thermogenic proteins (PGC1α and UCP1) in perirenal adipose tissue, respectively. Moreover, increasing sn-2 palmitic TAGs and OPL to OPO ratio in HMFS also altered the microbiota composition both on the phylum and genus level in rats, predominantly microbes associated with bile-salt hydrolase activity, short-chain fatty acid production and reduced obesity risk, which suggested a beneficial effect on host microbial ecosystem. These observations provided important nutritional evidence for developing new HMFS products for infants.

The triacylglycerol structure and composition of a human milk fat substitute affect the absorption of fatty acids and calcium, lipid metabolism and bile acid metabolism in newly-weaned Sprague-Dawley rats

In this study, the effect of sn-2 palmitic triacylglycerols (sn-2 palmitic TAGs) and the ratio between the two major sn-2 palmitic TAGs (OPL to OPO ratio) in a human milk fat substitute (HMFS) on growth, fatty acid and calcium absorptions, and lipid and bile acid metabolic alterations was investigated in Sprague-Dawley rats. After 4 weeks of high-fat feeding, rats fed with the HMFS containing a sn-2 palmitic acid content of 57.87% and an OPL to OPO ratio of 1.4 showed the lowest TAG accumulation in their livers and hypertrophy of perirenal adipocytes, compared to the groups fed with fats containing a lower sn-2 palmitic acid content or a lower OPL to OPO ratio. Meanwhile, synergistically improved absorption of fatty acids and calcium and increased levels of total bile acids (BAs), especially for the tauro-conjugated BAs (TCDCA, TUDCA, TαMCA, TβMCA, TDCA and TωMCA), were observed in rats by both increasing the sn-2 palmitic acid content and the OPL to OPO ratio in HMFS. In addition, the levels of total BAs and tauro-conjugated BAs were negatively correlated with serum TAG, TC, and LDL-c levels and positively correlated with HDL-c levels according to Spearman's correlation analysis (P < 0.05). Collectively, these findings present new nutritional evidence for the potential effects of the TAG structure and composition of a human milk fat substitute on the growth and lipid and bile acid metabolism of the host in infancy.

Computer-Aided Lipase Engineering for Improving Their Stability and Activity in the Food Industry: State of the Art

As some of the most widely used biocatalysts, lipases have exhibited extreme advantages in many processes, such as esterification, amidation, and transesterification reactions, which causes them to be widely used in food industrial production. However, natural lipases have drawbacks in terms of organic solvent resistance, thermostability, selectivity, etc., which limits some of their applications in the field of foods. In this systematic review, the application of lipases in various food processes was summarized. Moreover, the general structure of lipases is discussed in-depth, and the engineering strategies that can be used in lipase engineering are also summarized. The protocols of some classical methods are compared and discussed, which can provide some information about how to choose methods of lipase engineering. Thermostability engineering and solvent tolerance engineering are highlighted in this review, and the basic principles for improving thermostability and solvent tolerance are summarized. In the future, comput er-aided technology should be more emphasized in the investigation of the mechanisms of reactions catalyzed by lipases and guide the engineering of lipases. The engineering of lipase tunnels to improve the diffusion of substrates is also a promising prospect for further enhanced lipase activity and selectivity.

1-Oleate-2-palmitate-3-linoleate glycerol improves lipid metabolism and gut microbiota and decreases the level of pro-inflammatory cytokines

Numerous studies have shown that 1-oleate-2-palmitate-3-linoleate (OPL) is the most abundant TAG in Chinese human milk, which is significantly different from human milk in other countries, where 1,3-oleate-2-palmitate (OPO) is the most abundant TAG. However, there have been few studies revealing the nutritional outcomes of OPL. Hence, the present study investigated the effects of an OPL supplementation diet on mice's nutritional outcomes, including liver lipid parameters, inflammation, lipidomes in the liver and serum, and the gut bacterial community. A high OPL (HOPL) diet decreased body weight, weight gain, liver TG, TC and LDL-C, and TNF-α, IL-1β, and IL-6 in mice relative to low OPL (LOPL) diet. Lipidomics results showed that HOPL feeding elevated the level of anti-inflammatory lipids, such as very long-chain Cer, LPC, PC and ether TG in the liver, and serum PC, and reduced the level of oxidized lipids (liver OxTG, HexCer 18:1;2O/22:0) and serum TG. In the gut, intestinal probiotics, including Parabacteroides, Alistipes, Bacteroides, Alloprevotella and Parasutterrlla, were enriched in the HOPL-fed group. Meanwhile, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis results showed that the HOPL diet up-regulated energy metabolism and the immune system. Correlation analysis further showed that there was a relationship among the gut bacteria, lipidome profile, and nutritional outcomes. Altogether, these results indicated that an OPL-supplemented diet improved lipid metabolism and gut bacteria, reducing the level of pro-inflammatory cytokines.

Preparation of Human Milk Fat Substitutes: A Review

Human milk is generally regarded as the best choice for infant feeding. Human milk fat (HMF) is one of the most complex natural lipids, with a unique fatty acid composition and distribution and complex lipid composition. Lipid intake in infants not only affects their energy intake but also affects their metabolic mode and overall development. Infant formula is the best substitute for human milk when breastfeeding is not possible. As the main energy source in infant formula, human milk fat substitutes (HMFSs) should have a composition similar to that of HMF in order to meet the nutritional needs of infant growth and development. At present, HMFS preparation mainly focuses on the simulation of fatty acid composition, the application of structured lipids and the addition of milk fat globule membrane (MFGM) supplements. This paper first reviews the composition and structure of HMF, and then the preparation development of structured lipids and MFGM supplements are summarized. Additionally, the evaluation and regulation of HMFSs in infant formula are also presented.

Triacylglycerol and Fatty Acid Compositions of Blackberry, Red Raspberry, Black Raspberry, Blueberry and Cranberry Seed Oils by Ultra-Performance Convergence Chromatography-Quadrupole Time-of-Flight Mass Spectrometry

The triacylglycerol (TAG) compositions of blackberry, red raspberry, black raspberry, blueberry and cranberry seed oils were examined using ultra-performance convergence chromatography-quadrupole time-of-flight mass spectrometry (UPC²-QTOF MS). A total of 52, 53, 52, 59 and 58 TAGs were detected and tentatively identified from the blackberry, red raspberry, black raspberry, blueberry and cranberry seed oils, respectively, according to their accurate molecular weight in MS1 and fragment ion profiles in MS2. OLL was the most abundant TAG in the blackberry, red raspberry and black raspberry seed oils. Furthermore, the fatty acid compositions of the five berry seed oils were directly determined by gas chromatography coupled with mass spectrometry (GC-MS). In addition, the seed oils had total phenolic contents ranging 13.68–177.06 µmol GAE (gallic acid equivalent)/L oil, and significant scavenging capacities against DPPH, peroxyl, and ABTS⁺ radicals. These results indicated that the combination of UPC² and QTOF MS could effectively identify and semi-quantify the TAGs compositions of the berry seed oils with sn-position information for the fatty acids. Understanding the TAGs compositions of these berry seed oils could improve the utilization of these potentially high nutritional value oils for human health.

Proteomic Analyses of 3-Monochloropropanediol 1-Monooleate and 1-Monostearate Induced Testicular Toxicity in a 90 Day Sprague-Dawley Rats' Study

3-Monochloropropane 1,2-diol (3-MCPD) esters are toxicants formed during food thermal processing, and their testicular toxicities were widely reported. In this 90 day in vivo study, Sprague-Dawley rats were treated with 3-MCPD 1-monooleate at 10 and 100 mg/kg body weight (bw)/day or 1-monostearate at 15 and 150 mg/kg bw/day. Histological results indicated that testicular impairment was observed, and the level of serum testosterone was decreased dose dependently, while the levels of serum transforming growth factor beta and interferon-γ in rats' serum were increased dose dependently. To address the molecular mechanisms leading to testicular toxicities of 3-MCPD esters, testes samples were investigated with a mass spectrometry proteomic approach. The deregulated proteins affected by 3-MCPD esters include many enzymes related with the inflammatory necrosis pathways. While verifying the results in cellular level, 3-MCPD 1-monooleate and 3-MCPD 1-monostearate showed almost similar testicular cytotoxicity, and they could activate RIPK1 and MLKL pathways at the cellular level. All of these results showed the possible mechanisms about the toxicity of 3-MCPD esters in rats' testes and play a vital role in understanding the toxic effects of 3-MCPD esters both in vivo and in vitro.

Triacylglycerols and Fatty Acid Compositions of Cucumber, Tomato, Pumpkin, and Carrot Seed Oils by Ultra-Performance Convergence Chromatography Combined with Quadrupole Time-of-Flight Mass Spectrometry

The triacylglycerol (TAG) compositions of cucumber, tomato, pumpkin, and carrot seed oils were analyzed using ultra-performance convergence chromatography (UPC2) combined with quadrupole time-of-flight mass spectrometry (Q-TOF MS). A total of 36, 42, 39, and 27 different TAGs were characterized based on their Q-TOF MS accurate molecular weight and MS2 fragment ion profiles in the cucumber, tomato, pumpkin, and carrot seed oils, respectively. Generally, different vegetable seed oils had different TAGs compositions. Among the identified fatty acids, linoleic acid was the most abundant fatty acid in cucumber, tomato, and pumpkin seed oils and the second most abundant in carrot seed oil with relative concentrations of 54.48, 48.69, 45.10, and 15.92 g/100 g total fatty acids, respectively. Oleic acid has the highest concentration in carrot seed oil and the second highest in cucumber, tomato, and pumpkin seed oils, with relative concentrations of 78.97, 18.57, 27.16, and 33.39 g/100 g total fatty acids, respectively. The chemical compositions of TAGs and fatty acids could promote understanding about the chemical profiles of certain vegetable seed oils, thus improving the potential ability to select appropriate oils with specific functions and a high nutritional value and then develop functional foods in the future.

Chemical composition of tetraploid Gynostemma pentaphyllum gypenosides and their suppression on inflammatory response by NF-κB/MAPKs/AP-1 signaling pathways

The chemical composition and anti-inflammatory activity of gypenosides isolated from tetraploid Gynostemma pentaphyllum (GP) leaves were investigated. The gypenosides accounted for 7.43 mg/g of the tested GP sample, which were composed of four major saponins including isomers of gypenoside 1 and 2 (C47H76O18), 3 (C47H76O17), and 4 (C46H74O17). Pretreatment of gypenosides reduced mRNA expressions of the proinflammatory mediators in LPS-stimulated RAW264.7 macrophage cells, such as IL-6, IL-1β, COX-2, and TNF-α in a dose-dependent manner. The secreted protein levels of IL-6 and TNF-α, and NO production were also decreased by gypenosides within the concentration range of 50-200 μg/ml. Moreover, the mechanism studies demonstrated that gypenosides (200 μg/ml) treatment significantly inhibited the nuclear translocation of nuclear factor-κB and activator protein 1 (c-Fos and c-Jun) through down-regulating the phosphorylation of their upstream IκB kinase and mitogen-activated protein kinases (MAPKs), especially that of c-Jun N-terminal kinase and extracellular regulated protein kinase(JNK and ERK), but not that of the p38 MAPK. These results suggested that the gypenosides might have potential anti-inflammatory effect and use for improving human health.