Comparative study of DHA-enriched phospholipids and EPA-enriched phospholipids on metabolic disorders in diet-induced-obese C57BL/6J mice

Lipidomics profile and volatile compounds of squids (Illex argentinus, Ommastrephes Bartram and Dosidicus gigas) in the Argentine, North Pacific Ocean, Equator and Peru by UPLC-triple TOF-MS and HS-SPME-GC-O-MS

Comprehensive lipid and volatile compound analyses were performed with squids collected from four varied geographical locations to discriminate the regional characteristics. A total of 1442 lipid molecules and 110 volatiles were detected in the squid muscle samples. There were significant differences in the lipid profiles between Argentine squid (Illex argentinus, AGT), North Pacific Ocean squid (Ommastrephes Bartram, NPO), Equatorial squid (Dosidicus gigas, EQ), and Peruvian squid (Dosidicus gigas, PR) muscle. Phosphatidylcholines (14.64%), triacylglycerols (12.42%), and ceramides (10.97%) were the main lipid components. The contents of polyunsaturated fatty acid in phospholipids and in glycerolipids were 30.35-52.05% and 18.11-25.15%, respectively. The volatiles in squids exhibited significant regional variation; 1-pentanol and 1-octanol, 2-ethyl-1-hexanol and terpinen-4-ol, 2,7-ethyl-1-hexanol, 3-methy-1-butanol and 2-propyl-1-pentanol were identified as characteristic flavor compounds in AGT, NPO, EQ, and PR, respectively. Sphingomyelin, phosphatidylserine, phosphatidylethanolamine, and ceramide were strongly correlated with volatiles in squid muscle. Our study is a reference for the lipid nutritional value and flavor compounds of squids.

Dietary soybean lecithin promoted growth performance and feeding in juvenile Chinese perch (Siniperca chuatsi) could be by optimizing glucolipid metabolism

To explore the potential benefits of dietary phospholipids (PLs) in fish glucose metabolism and to promote feed culture of Chinese perch (Siniperca chuatsi), we set up six diets to feed Chinese perch (initial mean body weight 37.01 ± 0.20 g) for 86 days, including: Control diet (CT), 1% (SL1), 2% (SL2), 3% (SL3), 4% (SL4) soybean lecithin (SL) and 2% (KO2) krill oil (KO) supplemental diets (in triplicate, 20 fish each). Our study found that the SL2 significantly improved the weight gain rate and special growth rate, but the KO2 did not. In addition, the SL2 diet significantly improved feed intake, which is consistent with the mRNA levels of appetite-related genes (npy, agrp, leptin A). Additionally, in the CT and SL-added groups, leptin A expression levels were nearly synchronized with serum glucose levels. Besides, the SL2 significantly upregulated expression levels of glut2, gk, cs, fas and downregulated g6pase in the liver, suggesting that it may enhance glucose uptake, aerobic oxidation, and conversion to fatty acids. The SL2 also maintained the hepatic crude lipid content unchanged compared to the CT, possibly by significantly down-regulating the mRNA level of hepatic lipase gene (hl), and by elevating serum low-density lipoprotein (LDL) level and intraperitoneal fat ratio in significance. Moreover, the serum high-density lipoprotein levels were significantly increased by PL supplementation, and the SL2 further significantly increased serum total cholesterol and LDL levels, suggesting that dietary PLs promote lipid absorption and transport. Furthermore, dietary SL at 1% level could enhance non-specific immune capacity, with serum total protein level being markedly higher than that in the CT group. In conclusion, it is speculated that the promotion of glucose utilization and appetite by 2% dietary SL could be linked. We suggest a 1.91% supplementation of SL in the diet for the best growth performance in juvenile Chinese perch.

Dietary Phospholipids Alleviate Diet-Induced Obesity in Mice: Which Fatty Acids and Which Polar Head

The weight loss effects of dietary phospholipids have been extensively studied. However, little attention has been paid to the influence of phospholipids (PLs) with different fatty acids and polar headgroups on the development of obesity. High-fat-diet-fed mice were administrated with different kinds of PLs (2%, w/w) with specific fatty acids and headgroups, including EPA-enriched phosphatidylcholine/phosphatidylethanolamine/phosphatidylserine (EPA-PC/PE/PS), DHA-PC/PE/PS, Egg-PC/PE/PS, and Soy-PC/PE/PS for eight weeks. Body weight, white adipose tissue weight, and the levels of serum lipid and inflammatory markers were measured. The expression of genes related to lipid metabolism in the liver were determined. The results showed that PLs decreased body weight, fat storage, and circulating lipid levels, and EPA-PLs had the best efficiency. Serum TNF-α, MCP-1 levels were significantly reduced via treatment with DHA-PLs and PS groups. Mechanistic investigation revealed that PLs, especially EPA-PLs and PSs, reduced fat accumulation through enhancing the expression of genes involved in fatty acid β-oxidation (Cpt1a, Cpt2, Cd36, and Acaa1a) and downregulating lipogenesis gene (Srebp1c, Scd1, Fas, and Acc) expression. These data suggest that EPA-PS exhibits the best effects among other PLs in terms of ameliorating obesity, which might be attributed to the fatty acid composition of phospholipids, as well as their headgroup.

A Comparative Study about the Neuroprotective Effects of DHA-Enriched Phosphatidylserine and EPA-Enriched Phosphatidylserine against Oxidative Damage in Primary Hippocampal Neurons

Nerve damage caused by accumulated oxidative stress is one of the characteristics and main mechanisms of Alzheimer's disease (AD). Previous studies have shown that phosphatidylserine (PS) rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) plays a significant role in preventing and mitigating the progression of AD. However, whether DHA-PS and EPA-PS can directly protect primary hippocampal neurons against oxidative damage has not been studied. Here, the neuroprotective functions of DHA-PS and EPA-PS against H₂O₂/t-BHP-induced oxidative damage and the possible mechanisms were evaluated in primary hippocampal neurons. It was found that DHA-PS and EPA-PS could significantly improve cell morphology and promote the restoration of neural network structure. Further studies showed that both of them significantly alleviated oxidative stress-mediated mitochondrial dysfunction. EPA-PS significantly inhibited the phosphorylation of ERK, thus playing an anti-apoptotic role, and EPA-PS significantly increased the protein expressions of p-TrkB and p-CREB, thus playing a neuroprotective role. In addition, EPA-PS, rather than DHA-PS could enhance synaptic plasticity by increasing the expression of SYN, and both could significantly reduce the expression levels of p-GSK3β and p-Tau. These results provide a scientific basis for the use of DHA/EPA-enriched phospholipids in the treatment of neurodegenerative diseases, and also provide a reference for the development of related functional foods.

The synergistic effect of sea cucumber saponins and caffeine on preventing obesity in high-fat diet-fed mice by extending the action duration of caffeine

BACKGROUND

Sea cucumber saponins (SCSs) exhibit a unique structure and high bioactivities and might have specialized implications on caffeine metabolic process by altering the activity of N-demethylation enzyme CYP1A2. The present study aimed to clarify the effects of SCS on caffeine metabolism in vivo and in vitro, as well as the synergistic anti-obesity effect of SCS and caffeine on high-fat diet-induced obese mice.

RESULTS

Results found that SCS administration significantly postponed the elimination rate of caffeine and its metabolites in vivo, and further study found CYP1A2-mediated caffeine metabolism was remarkably inhibited in a dose-dependent manner in vitro. The synergistic effect of the SCS and caffeine combination could decrease the total weight of white adipose tissue by 52% compared with high-fat diet-treated group.

CONCLUSION

SCS could prolong caffeine action time, and the combination of the two substances exhibited joint action on high-fat diet-induced obese mice. These findings might provide a basis for the development of functional foods and potential application using the combination of SCS and caffeine. © 2022 Society of Chemical Industry.

Eicosapentaenoic acid-enriched phospholipids alleviate glucose and lipid metabolism in spontaneously hypertensive rats with CD36 mutation: a precise nutrition strategy

Previous studies have found that eicosapentaenoic acid-enriched phospholipids (EPA-PLs) alleviated glucose and lipid metabolism, which was accompanied by an increase of cluster of differentiation 36 (CD36). However, the effects of EPA-PLs on glucose and lipid metabolism in the case of CD36 mutation are unclear. Thus, spontaneously hypertensive rats/NCrl (SHR) were used as a CD36 mutation model to determine the effects of dietary 2% EPA-PLs for 4 weeks on glucose and lipid metabolism. The results showed that the intervention of EPA-PLs significantly alleviated the abnormal increase of serum free fatty acid levels and glycerol levels in SHRs. Moreover, the administration of EPA-PLs decreased the triglyceride levels and cholesterol levels by 31.1% and 37.9%, respectively, in the liver. Dietary EPA-PLs had no effect on epididymal fat weight, but EPA-PLs inhibited adipocyte hypertrophy in SHRs. Further mechanistic research found that EPA-PL pretreatment significantly reduced triacylglycerol catabolism and increased fatty acid β-oxidation. Additionally, the administration of EPA-PLs decreased the area under the curve of the intraperitoneal glucose tolerance test and fasting serum insulin levels by activating the IRS/PI3K/AKT signaling pathway. Furthermore, EPA-PL pretreatment significantly increased the CD36 gene expression in the liver tissues, adipose tissues and muscle tissues even in the case of CD36 mutation. These results indicated that EPA-PLs alleviate glucose and lipid metabolism in the case of CD36 mutation, which provides a precise nutrition strategy for people with CD36 mutation.

DHA-Enriched Phospholipids and EPA-Enriched Phospholipids Alleviate Lipopolysaccharide-Induced Intestinal Barrier Injury in Mice via a Sirtuin 1-Dependent Mechanism

Intestinal barrier dysfunction has emerged as a potential contributor to the development of several severe diseases. Herein, the effect and underlying mechanism of DHA-enriched phospholipids (DHA-PL) and EPA-enriched phospholipids (EPA-PL) on protecting against lipopolysaccharide (LPS)-induced intestinal barrier injury were elucidated. C57BL/6J male mice were fed an AIN-93G diet containing 1% DHA-PL or EPA-PL for 4 weeks and then were intraperitoneally injected with LPS (10 mg/kg) to cause intestinal barrier injury. The results manifested that DHA-PL and EPA-PL pretreatment balanced apoptosis and autophagy in intestinal epithelial cells and maintained intestinal tight junction integrity. Our findings also demonstrated that cotreatment with EX-527, a sirtuin 1 specific inhibitor, hindered the role of DHA-PL and EPA-PL against LPS-evoked intestinal barrier injury through reversing the inhibitory action of them on NF-κB and MAPKs activation as well as their potentiating actions on Nrf2 nuclear translocation. Overall, DHA-PL and EPA-PL alleviated LPS-mediated intestinal barrier injury via inactivation of the NF-κB and MAPKs pathways as well as activating the Nrf2 antioxidant pathway via up-regulating sirtuin 1.

Omega-3 phospholipids and obesity-associated NAFLD: Potential mechanisms and therapeutic perspectives

Prevalence of non-alcoholic fatty liver disease (NAFLD) increases in line with obesity and type 2 diabetes, and there is no approved drug therapy. Polyunsaturated fatty acids of n-3 series (omega-3) are known for their hypolipidaemic and anti-inflammatory effects. Existing clinical trials suggest varying effectiveness of triacylglycerol- or ethyl ester-bound omega-3 in the treatment of NAFLD, without affecting advanced stages such as non-alcoholic steatohepatitis. Preclinical studies suggest that the lipid class used to supplement omega-3 may determine the extent and nature of their effects on metabolism. Phospholipids of marine origin represent an alternative source of omega-3. The aim of this review is to summarise the available evidence on the use of omega-3 phospholipids, primarily in obesity-related NAFLD, and to outline perspectives of their use in the prevention/treatment of NAFLD. A PubMed literature search was conducted in May 2021. In total, 1088 articles were identified, but based on selection criteria, 38 original papers were included in the review. Selected articles describing the potential mechanisms of action of omega-3 phospholipids have also been included. Preclinical evidence clearly indicates that omega-3 phospholipids have strong antisteatotic effects in the liver, which are stronger compared to omega-3 administered as triacylglycerols. Multiple mechanisms are likely involved in the overall antisteatotic effects, involving not only the liver but also adipose tissue and the gut. Robust preclinical evidence for strong antisteatotic effects of omega-3 phospholipids in the liver should be confirmed in clinical trials. Further research is needed on the possible effects of omega-3 phospholipids on advanced NAFLD.

Supplementation with a Specific Combination of Metabolic Cofactors Ameliorates Non-Alcoholic Fatty Liver Disease, Hepatic Fibrosis, and Insulin Resistance in Mice

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) have emerged as the leading causes of chronic liver disease in the world. Obesity, insulin resistance, and dyslipidemia are multifactorial risk factors strongly associated with NAFLD/NASH. Here, a specific combination of metabolic cofactors (a multi-ingredient; MI) containing precursors of glutathione (GSH) and nicotinamide adenine dinucleotide (NAD+) (betaine, N-acetyl-cysteine, L-carnitine and nicotinamide riboside) was evaluated as effective treatment for the NAFLD/NASH pathophysiology. Six-week-old male mice were randomly divided into control diet animals and animals exposed to a high fat and high fructose/sucrose diet to induce NAFLD. After 16 weeks, diet-induced NAFLD mice were distributed into two groups, treated with the vehicle (HFHFr group) or with a combination of metabolic cofactors (MI group) for 4 additional weeks, and blood and liver were obtained from all animals for biochemical, histological, and molecular analysis. The MI treatment reduced liver steatosis, decreasing liver weight and hepatic lipid content, and liver injury, as evidenced by a pronounced decrease in serum levels of liver transaminases. Moreover, animals supplemented with the MI cocktail showed a reduction in the gene expression of some proinflammatory cytokines when compared with their HFHFr counterparts. In addition, MI supplementation was effective in decreasing hepatic fibrosis and improving insulin sensitivity, as observed by histological analysis, as well as a reduction in fibrotic gene expression (Col1α1) and improved Akt activation, respectively. Taken together, supplementation with this specific combination of metabolic cofactors ameliorates several features of NAFLD, highlighting this treatment as a potential efficient therapy against this disease in humans.

Short-term supplementation of DHA-enriched phospholipids attenuates the nephrotoxicity of cisplatin without compromising its antitumor activity in mice

Cisplatin is one of the most effective chemotherapeutic agents used for the treatment of a wide variety of cancers. However, cisplatin has been associated with nephrotoxicity, which limits its application in clinical treatment. Various studies have indicated the protective effect of phospholipids against acute kidney injury. However, no study has focused on the different effects of phospholipids with different fatty acids on cisplatin-induced nephrotoxicity and on the combined effects of phospholipids and cisplatin in tumour-bearing mice. In the present study, the potential renoprotective effects of phospholipids with different fatty acids against cisplatin-induced nephrotoxicity were investigated by determining the serum biochemical index, renal histopathological changes, protein expression level and oxidative stress. The results showed that docosahexaenoic acid-enriched phospholipids (DHA-PL) and eicosapentaenoic acid-enriched phospholipids (EPA-PL) could alleviate cisplatin-induced nephrotoxicity by regulating the caspase signaling pathway, the SIRT1/PGC1α pathway, and the MAPK (mitogen-activated protein kinase) signaling pathway and by inhibiting oxidative stress. In particular, DHA-PL exhibited a better inhibitory effect on oxidative stress and apoptosis compared to EPA-PL. Furthermore, DHA-PL exhibited an additional effect with cisplatin on the survival of ascitic tumor-bearing mice. These findings suggested that DHA-PL are one kind of promising supplement for the alleviation of cisplatin-induced nephrotoxicity without compromising its antitumor activity.

Effect of different phosphatidylcholines on high fat diet-induced insulin resistance in mice

In this study, we systematically investigated the effect of different phosphatidylcholines on high fat diet-induced insulin resistance in mice.

Docosahexaenoic acid-enriched phospholipids and eicosapentaenoic acid-enriched phospholipids inhibit tumor necrosis factor-alpha-induced lipolysis in 3T3-L1 adipocytes by activating sirtuin 1 pathways

Some chronic diseases such as cancer-associated cachexia (CAC) and obesity are associated with the overproduction of tumor necrosis factor-alpha (TNF-α) that stimulates excess lipolysis in adipocytes. Our previous studies have shown that docosahexaenoic acid-enriched phospholipids (DHA-PL) and eicosapentaenoic acid-enriched phospholipids (EPA-PL) ameliorated CAC and obesity-related metabolic disorders. To identify the molecular mechanisms involved, we examined the impact and the associated signaling pathways of DHA-PL and EPA-PL on TNF-α-induced lipolysis in 3T3-L1 adipocytes. The present results revealed that DHA-PL and EPA-PL inhibited the TNF-α-induced increase of glycerol release and protected lipid droplets. In addition, DHA-PL and EPA-PL increased DHA and EPA contents in the phospholipid fraction of adipocytes, respectively. Moreover, DHA-PL and EPA-PL enhanced sirtuin 1 (SIRT1) deacetylase activity and its protein expression. By activating SIRT1, DHA-PL and EPA-PL upregulated the G0/G1 switch gene 2 protein level to inhibit adipose triglyceride lipase activity, activate AMP-activated protein kinase to reverse the downregulation of perilipin expression and phosphorylation of hormone-sensitive lipase (HSL) at Ser565 and prevent the phosphorylation of HSL at Ser660. Furthermore, DHA-PL and EPA-PL improved glucose uptake and glucose transporter type 4 translocation to the plasma membrane in TNF-α-treated adipocytes. Thus, it was concluded that DHA-PL and EPA-PL inhibit TNF-α-induced lipolysis in 3T3-L1 adipocytes by activating the SIRT1 pathways.

Sterol sulfate alleviates atherosclerosis via mediating hepatic cholesterol metabolism in ApoE-/- mice

Compared with terrestrial organisms, the sterols in sea cucumber exhibit a sulfate group at the C-3 position. Our previous study demonstrated that dietary sterol sulfate was superior to phytosterol in alleviating metabolic syndrome by ameliorating inflammation and mediating cholesterol metabolism in high-fat-high-fructose diet mice, which indicated its potential anti-atherosclerosis bioactivity. In the present study, administration with sea cucumber-derived sterol sulfate (SCS) significantly decreased the cholesterol level in oleic acid/palmitic acid-treated HepG2 cells, while no significant changes were observed in the triacylglycerol level. RNA-seq analysis showed that the metabolic changes were mostly attributed to the steroid biosynthesis pathway. ApoE-/- mice were used as an atherosclerosis model to further investigate the regulation of SCS on cholesterol metabolism. The results showed that SCS supplementation dramatically reduced atherosclerotic lesions by 45% and serum low-density lipoprotein cholesterol levels by 59% compared with the model group. Dietary SCS inhibited hepatic cholesterol synthesis via downregulating SREBP-2 and HMGCR. Meanwhile, SCS administration increased cholesterol uptake via enhancing the expression of Vldlr and Ldlr. Noticeably, SCS supplementation altered bile acid profiles in the liver, serum, gallbladder and feces, which might cause the activation of FXR in the liver. These findings provided new evidence about the high bioactivity of sterols with the sulfate group on atherosclerosis.

Studying the effects of sea cucumber ovum powder on nonalcoholic fatty liver disease by proteomics techniques in a rat model

Sea cucumber is a valuable marine food that has antioxidant, anti-diabetic, and anti-obesity functionalities. Sea cucumber ovum (SCO) may contain functional components, however, it is considered to be a waste product during industrial processing. In order to make good use of SCO, this work investigated the effects of freeze-dried SCO powder on NAFLD, using a rat model, through iBT labeling proteomics techniques, tracking changes in the hepatic protein profiles of rats whose diets were supplemented with SCO powder. Male rats were fed with standard food, a high fat diet (HFD), or a HFD supplemented with 150 mg per kg BW or 450 mg per kg BW SCO powder for 6 weeks. Compared with the HFD, low-dose SCO supplementation in the diet could significantly reduce body weight gain and liver weight. Furthermore, in total, 5922 proteins were identified, and 767 proteins were found to be significantly different proteins (p < 0.05) among all four groups. Most of the significantly different proteins were related to apoptosis and lipid metabolism. Fadd, Dci, and Aif1 have been identified as key proteins in the pathways related to apoptosis, lipid metabolism, and inflammation. The results in this study provide an overview of the SCO-induced changes in the liver proteome of NAFLD, which may help us to understand the molecular mechanism behind the effects of SCO on the alleviation of NAFLD.

Advances in exogenous docosahexaenoic acid-containing phospholipids: Sources, positional isomerism, biological activities, and advantages

In recent years, docosahexaenoic acid-containing phospholipids (DHA-PLs) have attracted much attention because of theirs unique health benefits. Compared with other forms of docosahexaenoic acid (DHA), DHA-PLs possess superior biological effects (e.g., anticancer, lipid metabolism regulation, visual development, and brain and nervous system biochemical reactions), more intricate metabolism mechanisms, and a stronger attraction to consumer. The production of DHA-PLs is hampered by several challenges associated with the limited content of DHA-PLs in natural sources, incomplete utilization of by-products, few microorganisms for DHA-PLs production, high cost, and complex process of artificial preparation of DHA-PLs. In this article, the sources, biological activities, and commercial applications of DHA-PLs were summarized, with intensive discussions on advantages of DHA-PLs over DHA, isomerism of DHA in phospholipids (PLs), and brain health. The excellent biological characteristics of DHA-PLs are primarily concerned with DHA and PLs. The metabolic fate of different DHA-PLs varies from the position of DHA in PLs to polar groups in DHA-PLs. Overall, well understanding of DHA-PLs about their sources and characteristics is critical to accelerate the production of DHA-PLs, economically enhance the value of DHA-PLs, and improve the applicability of DHA-PLs and the acceptance of consumers.

Synthesis of DHA/EPA Ethyl Esters via Lipase-Catalyzed Acidolysis Using Novozym® 435: A Kinetic Study

DHA/EPA ethyl ester is mainly used in the treatment of arteriosclerosis and hyperlipidemia. In this study, DHA+EPA ethyl ester was synthesized via lipase-catalyzed acidolysis of ethyl acetate (EA) with DHA+EPA concentrate in n-hexane using Novozym® 435. The DHA+EPA concentrate (in free fatty acid form), contained 54.4% DHA and 16.8% EPA, was used as raw material. A central composite design combined with response surface methodology (RSM) was used to evaluate the relationship between substrate concentrations and initial rate of DHA+EPA ethyl ester production. The results indicated that the reaction followed the ordered mechanism and as such, the ordered mechanism model was used to estimate the maximum reaction rate (Vmax) and kinetic constants. The ordered mechanism model was also combined with the batch reaction equation to simulate and predict the conversion of DHA+EPA ethyl ester in lipase-catalyzed acidolysis. The integral equation showed a good predictive relationship between the simulated and experimental results. 88–94% conversion yields were obtained from 100–400 mM DHA+EPA concentrate at a constant enzyme activity of 200 U, substrate ratio of 1:1 (DHA+EPA: EA), and reaction time of 300 min.

Eicosapentaenoic acid-enriched phospholipids suppressed lipid accumulation by specific inhibition of lipid droplet-associated protein FSP27 in mice

BACKGROUND

Sea cucumber is a rich source of eicosapentaenoic acid in the form of eicosapentaenoic acid-enriched phospholipids (EPA-PL). It is known to be efficacious in preventing obesity. However, few studies have focused on the role of EPA-PL in inhibiting lipid accumulation by lipid droplets (LDs). This study first investigated the effect of EPA-PL from sea cucumber on the formation of LDs and the underlying mechanism in C57BL/6J mice. The mice were randomly divided into two groups and treated for 8 weeks or 3, 7, and 14 days with either (i) a high-sucrose diet (model group), (ii) a high-sucrose diet plus 2% EPA-PL (EPA-PL group).

RESULTS

Eight-week EPA-PL supplementation significantly reduced lipid accumulation and LD size in liver and white adipose tissue (WAT), which was accompanied by the decreased expression of LDs-associated protein FSP27. A 3-day EPA-PL treatment suppressed the mRNA expression of Fsp27. The mRNA level of Fsp27 reached its 'normal level' after withdrawing EPA-PL for 7 days, suggesting that EPA-PL might serve as a rapid regulator of FSP27. Furthermore, EPA-PL increased the expression of lipolysis genes Hsl and Atgl accompanied by the regulation of Pparγ in WAT.

CONCLUSIONS

Dietary EPA-PL from sea cucumber (Cucumaria frondosa) protected against lipid accumulation by regulating LDs-associated protein FSP27, which might provide novel evidence for the anti-obesity action of EPA-PL. © 2020 Society of Chemical Industry.

Synergistic effect of sea cucumber saponins and EPA-enriched phospholipids on insulin resistance in high-fat diet-induced obese mice

Sea cucumber saponins (SCS) exhibit a significant effect on ameliorating glucose and lipid disorders by inhibiting fatty acid biosynthesis; however, high cytotoxicity and hemolytic activity limit their application. Eicosapentaenoic acid-enriched phospholipids (EPA-PL) significantly ameliorate insulin resistance and elevate the level of hepatic lipolysis, which may have a synergistic effect with SCS in alleviating obesity-related insulin resistance via multiple mechanisms. In the present study, high-fat diet-induced male C57BL/6J mice with obesity-related insulin resistance were used to evaluate the synergistic effect of SCS and EPA-PL on alleviating the insulin resistance. Results show that the combination of SCS and EPA-PL at a half dose exhibited a significant improvement on glucose intolerance and systematic insulin sensitivity than SCS or EPA-PL alone. Moreover, the half dose-combination remarkably inhibited the macrophage infiltration (F4/80) to white adipose tissue (WAT) and significantly down-regulated the level of MCP1, TNF-α and IL-6 compared with SCS and EPA-PL alone. Consequently, the combined administration not only decreased hepatic gluconeogenesis and increased hepatic glycogen synthesis (P < 0.05), but also stimulated the glucose uptake in WAT and muscle (P < 0.05). Nevertheless, neither SCS or EPA-PL alone exhibited any effect on the glucose uptake. The combination of SCS and EPA-PL contributed to a synergistic effect on alleviating the obesity-related insulin resistance due to the amelioration of an inflammation-centric peripheral insulin response.

A pilot study on the effects of DHA/EPA-enriched phospholipids on aerobic and anaerobic exercises in mice

DHA/EPA-PL andl-carnitine had significant effects on aerobic exercise, while astaxanthin improved anaerobic exercise. The possible mechanism involved carbohydrate and lipid metabolism, mitochondrial respiratory chain and tricarboxylic acid cycle.

DHA-PC protects kidneys against cisplatin-induced toxicity and its underlying mechanisms in mice

DHA-PC protected the kidney against cisplatin-induced toxicity through sirtuin 1 activation, the inhibition of oxidative stress and apoptosis.

DHA-phospholipids (DHA-PL) and EPA-phospholipids (EPA-PL) prevent intestinal dysfunction induced by chronic stress

DHA-PL and EPA-PL may effectively protect mice against intestinal dysfunction under chronic stress exposure.

Synergistic effect of eicosapentaenoic acid-enriched phospholipids and sea cucumber saponin on orotic acid-induced non-alcoholic fatty liver disease in rats

Non-alcoholic fatty liver disease (NAFLD) is becoming an increasingly prevalent chronic liver disease all over the world. The present study was undertaken to explore the synergistic effects of sea cucumber saponins (SCS) and eicosapentaenoic acid-enriched phospholipids (EPA-PL) at ratios of 0.5 : 0.5 and 1 : 1 on NAFLD and demonstrate possible protective mechanisms. It was found that the combination of EPA-PL and SCS at half dose exhibited better effects than EPA-PL or SCS alone and the combination of EPA-PL and SCS at full dose in alleviating orotic acid (OA)-induced symptoms including growth parameters, serum parameters and liver function. Further evaluation of the mechanism illustrated that EPA-PL and SCS combination at the ratio of 0.5 : 0.5 could markedly reduce the mRNA expressions of fatty acid synthase, acetyl-CoA carboxylase, glucose-6-phosphate dehydrogenase and malic enzyme genes and significantly increase expression of genes relevant to fatty acid β-oxidation including peroxisome proliferator-activated receptor and its target genes (CPT1, CPT2 and ACOX1), suggesting that the protection of the EPA-PL and SCS combination at the ratio of 0.5 : 0.5 against OA-induced NAFLD might be mainly via lipogenesis inhibition and β-oxidation enhancement in the liver. The synergistic effects of EPA-PL and SCS make it possible to reduce the doses of EPA-PL or SCS to avoid side effects, which is of value for the development of dietary supplements or functional foods for preventing or treating NAFLD.

Mechanisms of DHA-enriched phospholipids in improving cognitive deficits in aged SAMP8 mice with high-fat diet

Recent studies have shown that a high-fat diet (HFD) is involved in both metabolic dysfunction and cognitive deficiency and that docosahexaenoic-acid-enriched phospholipids (DHA-PLs) have beneficial effects on obesity and cognitive impairment. However, there are only a few studies comparing differences between DHA-PC and DHA-PS in HFD-induced Alzheimer's disease (AD) models. After 8 weeks feeding with HFD, 10-month-old SAMP8 mice were fed with 1% (w/w) DHA-PC or 1% DHA-PS (biosynthesized from DHA-PC) for 8 weeks; we then tested the behavioral performances in the Barnes maze test and Morris maze test. The changes of the generation and accumulation of Aβ, oxidative stress, apoptosis, neuroinflammation and neurotrophic factors were also measured. The results indicated that both DHA-PC and DHA-PS significantly improved the metabolic disorders and cognitive deficits. Both DHA-PC and DHA-PS could ameliorate oxidative stress, and DHA-PS presented more notable benefits than DHA-PC on Aβ pathology, mitochondrial damage, neuroinflammation and neurotrophic factors; DHA-PS was for the first time found to increase the production of insoluble Aβ (less pathogenic) in this AD model. These data suggest that DHA-PLs can significantly improve cognitive deficiency, and the molecular mechanisms for this closely relate to the phospholipid polar groups.

Effects of Frozen Storage on Phospholipid Content in Atlantic Cod Fillets and the Influence on Diet-Induced Obesity in Mice

A large fraction of the n-3 polyunsaturated fatty acids (PUFAs) in cod fillet is present in the form of phospholipids (PLs). Freezing initiates hydrolysis of the PLs present in the fillet. Here, we compared the effects of Western diets based on frozen cod, fresh cod or pork with a diet based on casein in male C57BL/6J mice fed for 12 weeks at thermoneutrality. Diets based on fresh cod contained more PL-bound n-3 PUFAs (3.12 mg/g diet) than diets based on frozen cod (1.9 mg/g diet). Mice fed diets containing pork and fresh cod, but not frozen cod, gained more body and fat mass than casein-fed mice. Additionally, the bioavailability of n-3 PUFAs present in the cod fillets was not influenced by storage conditions. In a second experiment, diets with pork as the protein source were supplemented with n-3 PUFAs in the form of PL or triacylglycerol (TAG) to match the levels of the diet containing fresh cod. Adding PL-bound, but not TAG-bound, n-3 PUFAs, to the pork-based diet increased body and fat mass gain. Thus, supplementation with PL-bound n-3 PUFAs did not protect against, but rather promoted, obesity development in mice fed a pork-based diet.

Activation of Macrophages in vitro by Phospholipids from Brain of Katsuwonus pelamis (Skipjack Tuna)

The biological activities of phospholipids (PLs) have attracted people's attention, especially marine phospholipids with omega-3 polyunsaturated fatty acids DHA and EPA. In this study, we investigated the immunity activation of macrophages in vitro by phospholipids from skipjack brain. The phospholipids were extracted with hexane and ethanol ultrasonication instead of the traditional method of methanol and chloroform. The content of phospholipids from Skipjack brain was 19.59 g/kg by the method (the ratio of hexane and ethanol 2:1, 40 min, 35°C, 1:9 of the ratio of material to solvent, ultrasonic power 300W, ultrasonic extraction 2 times). The RAW264.7 macrophages were stimulated by the phospholipids from the Skipjack, by which the volume, viability and phagocytosis of macrophages were increased. The concentration of NO and the activity of SOD of the cells were also enhanced. The gene expressions of IL-1β, IL-6, iNOS and TNF-α mRNA assayed by RT-PCR were up-regulated. Phospholipids from brain of Skipjack Tuna could activate macrophages immunity which displayed to induce pro-inflammatroy cytokines mRNA expression.

Comparative Analysis of EPA/DHA-PL Forage and Liposomes in Orotic Acid-Induced Nonalcoholic Fatty Liver Rats and Their Related Mechanisms

Nonalcoholic fatty liver disease (NAFLD) has become one predictive factor of death from various illnesses. The present study was to comparatively investigate the effects of eicosapentaenoic acid-enriched and docosahexaenoic acid-enriched phospholipids forage (EPA-PL and DHA-PL) and liposomes (lipo-EPA and lipo-DHA) on NAFLD and demonstrate the possible protective mechanisms involved. The additive doses of EPA-PL and DHA-PL in all treatment groups were 1% of total diets, respectively. The results showed that Lipo-EPA could significantly improve hepatic function by down-regulating orotic acid-induced serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels by 55.6% and 34.2%, respectively (p < 0.01). Moreover, lipo-EPA exhibited excellent inhibition on the mRNA expression of SREBP-1c and FAS at the values of 0.454 ± 0.09 (p < 0.01) and 0.523 ± 0.08 (p < 0.01), respectively, thus ameliorating OA-induced NAFLD. Meanwhile, lipo-EPA could significantly suppress the SREBP-2 and HMGR levels (31.4% and 66.7%, p < 0.05, respectively). In addition, EPA-PL and lipo-DHA could also significantly suppress hepatic lipid accumulation mainly by enhancement of hepatic lipolysis and cholesterol efflux. Furthermore, DHA-PL played a certain role in inhibiting hepatic lipogenesis and accelerating cholesterol efflux. The results obtained in this work might contribute to the understanding of the biological activities of EPA/DHA-PL and liposomes and further investigation on its potential application values for food supplements.

Protective Effects of DHA-PC against Vancomycin-Induced Nephrotoxicity through the Inhibition of Oxidative Stress and Apoptosis in BALB/c Mice

The clinical use of glycopeptide antibiotic vancomycin is usually accompanied by nephrotoxicity, limiting its application and therapeutic efficiency. The aim of this study was to investigate the protection of DHA-enriched phosphatidylcholine (DHA-PC) against nephrotoxicity using a model of vancomycin-induced male BALB/c mice with renal injury by measuring death curves, histological changes, and renal function indexes. The addition of DHA in DHA and DHA-PC groups were 300 mg/kg per day on the basis of human intake level in our study. Results indicated that DHA-PC could dramatically extend the survival time of mice, while traditional DHA and PC had no significant effects. Moreover, oral administration of DHA-PC exhibited better effects on reducing vancomycin-induced increases of blood urea nitrogen, creatinine, cystatin C, and kidney injury molecule-1 levels than traditional DHA and PC. DHA-PC significantly delayed the development of vancomycin-induced renal injury, including tubular necrosis, hyaline casts, and tubular degeneration. A further mechanistic study revealed that the protective effect of DHA-PC on vancomycin-mediated toxicity might be attributed to its ability to inhibit oxidative stress and inactivate mitogen-activated protein kinase (MAPK) signaling pathways, which was associated with upregulation of Bcl-2 and downregulation of caspase-9, caspase-3, cytochrome-c, p38, and JNK. These findings suggest that DHA-PC may be acted as the dietary supplements or functional foods against vancomycin-induced nephrotoxicity.

Lipid profiling in serum from apolipoprotein E-knock out mice fed with different diets and its application to the study of the regulatory effect on lipid metabolism

A lipidome profiling platform was established that could evaluate the cardiovascular health products from lipid changes, their metabolism regulation and intervention mechanism in chronic disease, such as atherosclerosis.

Proteomic Analysis of the Effect of DHA-Phospholipids from Large Yellow Croaker Roe on Hyperlipidemic Mice

Previously, we found that phospholipids derived from large yellow croaker (Pseudosciaena crocea) roe had a higher level of docosahexaenoic acid (DHA-PL), which had beneficial effects on lipid metabolism. However, the mechanism by which DHA-PL from P. crocea roe exerts these effects has not yet been illuminated. Herein, we investigated the underlying molecular action of DHA-PL by examining changes in liver protein expression in control, hyperlipidemic, and DHA-PL-treated mice. A total of 16 proteins, 9 up-regulated and 7 down-regulated, were identified and classified into several metabolic pathways, such as fat digestion and absorption, peroxisome proliferator activated receptor (PPAR) signaling, and antigen processing and presentation; the largest functional class found was that of fat digestion and absorption. We revealed Apoa1 to be a biomarker of DHA-PL effects on hyperlipidemic mice by DHA-PL diet. These results not only improve our current understanding of hyperlipidemic regulation by DHA-PL, but also suggest that DHA-PL should be applied as a beneficial food additive.

A high fat diet enriched with sea cucumber gut powder provides cardio-protective and anti-obesity effects in C57BL/6 mice

We have previously reported that sea cucumber (SC) inhibits fat accumulation and insulin resistance in 3T3-L1 cells. The present study investigated the anti-obesity and cardio-protective effects of SC freeze-dried gut powder using C57BL/6 as an animal model. Male mice were fed a normal chow diet, a high fat diet (HFD) or a HFD enriched with 2.5, 5 or 7.5% SC gut powder for 4, 8 and 12weeks. Diets enriched with SC caused a significant reduction in body weight gain and fat weight, compared to the HFD, without affecting food intake. Both 2.5% and 5% SC treatment showed a significant reduction in plasma glucose, triacylglycerol (TG), total cholesterol (TC) and non-esterified fatty acids, compared to the HFD. However, animals fed the 7.5% SC diet showed an increase in liver weight, liver TG and TC, compared to the HFD diet. Diets enriched with 2.5% SC caused an increase in adiponectin mRNA expression in adipose tissue and reduced plasma interleukin-6, compared to the HFD diet. Fecal cholesterol excretion increased after 2.5% SC treatment, coinciding with an increase in ATP-binding cassette-5 and -8 mRNA expression in the small intestine. Although both 2.5 and 5% SC treatment caused weight and fat reduction to a similar extent, 2.5% SC was more effective at improving the metabolic profile. None of the tested SC doses caused any toxic effects. Our findings demonstrate for the first time that SC freeze-dried gut powder has the potential as a nutraceutical to target obesity and related disorders.