Sulfated polysaccharides from Enteromorpha prolifera suppress SREBP-2 and HMG-CoA reductase expression and attenuate non-alcoholic fatty liver disease induced by a high-fat diet

Polysaccharide of Atractylodes macrocephala Koidz alleviates NAFLD-induced hepatic inflammation in mice by modulating the TLR4/MyD88/NF-κB pathway

Non-alcoholic fatty liver disease (NAFLD) not only could cause abnormal lipid metabolism in the liver, but also could cause liver inflammation. Previous studies have shown that Polysaccharide of Atractylodes macrocephala Koidz (PAMK) could alleviate animal liver inflammatory damage and alleviate NAFLD in mice caused by high-fat diet(HFD), but regulation of liver inflammation caused by NAFLD has rarely been reported. In this study, an animal model of non-alcoholic fatty liver inflammation in the liver of mice was established to explore the protective effect of PAMK on the liver of mice. The results showed that PAMK could alleviate the abnormal increase of body weight and liver weight of mice caused by HFD, alleviate the abnormal liver structure of mice, reduce the level of oxidative stress and cytokine secretion in the liver of mice, and downregulate the mRNA expression of TLR4, MyD88, NF-κB and protein expression of P-IκB, P-NF-κB-P65, TLR4, MyD88, NF-κB in the liver. These results indicate that PAMK could alleviate hepatocyte fatty degeneration and damage, oxidative stress and inflammatory response of the liver caused by NAFLD in mice.

Exploring the Regulatory Effect of Tegillarca granosa Polysaccharide on High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease in Mice Based on Intestinal Flora

To explore the potential mechanism of action of Tegillarca granosa polysaccharide (TGP) in treating nonalcoholic fatty liver disease (NAFLD), the study conducts in vivo experiments using male C57BL/6 mice fed a high-fat diet while administering TGP for 16 weeks. The study measures body weight, liver weight, serum biochemical markers, pathological histology, liver lipid accumulation, oxidative stress and inflammation-related factors, lipid synthesis and metabolism-related gene and protein expression, and the composition and abundance of intestinal flora. Additionally, short-chain fatty acid (SCFAs) content and the correlation between intestinal flora and environmental factors are measured. The results show that TGP effectively reduces excessive hepatic lipid accumulation, dyslipidemia, abnormal liver function, and steatosis in the mice with NAFLD. Moreover, TGP effectively regulates intestinal flora disorder, increases the diversity of intestinal flora, and affects the relative abundance of specific bacteria while also increasing the content of SCFAs. These findings provide a basis for exploring the regulatory effect of T. granosa polysaccharide on NAFLD based on intestinal flora and highlight its potential as a natural liver nutraceutical.

The therapeutic effects of marine sulfated polysaccharides on diabetic nephropathy

Marine sulfated polysaccharide (MSP) is a natural high molecular polysaccharide containing sulfate groups, which widely exists in various marine organisms. The sources determine structural variabilities of MSPs which have high security and wide biological activities, such as anticoagulation, antitumor, antivirus, immune regulation, regulation of glucose and lipid metabolism, antioxidant, etc. Due to the structural similarities between MSP and endogenous heparan sulfate, a majority of studies have shown that MSP can be used to treat diabetic nephropathy (DN) in vivo and in vitro. In this paper, we reviewed the anti-DN activities, the dominant mechanisms and structure-activity relationship of MSPs in order to provide the overall scene of MSPs as a modality of treating DN.

The anti-hyperlipidemic effects of Poria cocos (Schw.) Wolf extract: Modulating cholesterol homeostasis in hepatocytes via PPARα pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Poria cocos (Schw.) Wolf (Polyporaceae, P.cocos), which is born on the pine root, has a history of more than two thousand years of medicine in China. P.cocos was first recorded in the Shennong's Herbal Classic, studies have proved its lipid-lowering effect.

AIM OF STUDY

The aim of study was to investigate the underlying mechanism of P.cocos extract on hyperlipidemia.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats aged 9-12 weeks were intraperitoneally (IP) injected with Triton-WR 1339 to establish an acute hyperlipidemia model. At 0 h and 20 h after the model was established, low and high doses of P.cocos extract or simvastatin were given twice. After 48 h, the rats were sacrificed, and liver and serum samples were collected for analysis. The cell model was constructed by treating L02 cells with 1% fat emulsion-10% FBS-RPMI 1640 medium for 48 h. At the same time, low and high doses of P.cocos extract and simvastatin were administered. Oil red O staining was used to evaluate the lipid accumulation in the cells, and H&E staining was used to evaluate the liver lesions of rats. Real-time quantitative PCR and western blotting were used to detect the expressions of lipid metabolism-related genes.

RESULTS

P.cocos extract relieved lipid accumulation in vitro and alleviated hyperlipidemia in vivo. Both gene and protein expressions of peroxisome proliferator-activated receptor α (PPARα) were shown to be up-regulated by P.cocos extract. Additionally, P.cocos extract down-regulated the expressions of fatty acid synthesis-related genes sterol regulatory element-binding protein-1 (SREBP-1), Acetyl-CoA Carboxylase 1 (ACC1) and fatty acid synthase (FAS), while up-regulated the expressions of cholesterol metabolism-related genes liver X receptor-α (LXRα), ATP-binding cassette transporter A1 (ABCA1), cholesterol 7alpha-hydroxylase (CYP7A1) and low density lipoprotein receptor (LDLR), which were reversed by the treatment with the PPARα inhibitor GW6471.

CONCLUSION

P.cocos extract ameliorates hyperlipidemia and lipid accumulation by regulating cholesterol homeostasis in hepatocytes through PPARα pathway. This study provides evidence that supplementation with P.cocos extract could be a potential strategy for the treatment of hyperlipidemia.

Algae Food Products as a Healthcare Solution

Diseases such as obesity; cardiovascular diseases such as high blood pressure, myocardial infarction and stroke; digestive diseases such as celiac disease; certain types of cancer and osteoporosis are related to food. On the other hand, as the world's population increases, the ability of the current food production system to produce food consistently is at risk. As a result, intensive agriculture has contributed to climate change and a major environmental impact. Research is, therefore, needed to find new sustainable food sources. One of the most promising sources of sustainable food raw materials is macroalgae. Algae are crucial to solving this nutritional deficiency because they are abundant in bioactive substances that have been shown to combat diseases such as hyperglycemia, diabetes, obesity, metabolic disorders, neurodegenerative diseases and cardiovascular diseases. Examples of these substances include polysaccharides such as alginate, fucoidan, agar and carrageenan; proteins such as phycobiliproteins; carotenoids such as β-carotene and fucoxanthin; phenolic compounds; vitamins and minerals. Seaweed is already considered a nutraceutical food since it has higher protein values than legumes and soy and is, therefore, becoming increasingly common. On the other hand, compounds such as polysaccharides extracted from seaweed are already used in the food industry as thickening agents and stabilizers to improve the quality of the final product and to extend its shelf life; they have also demonstrated antidiabetic effects. Among the other bioactive compounds present in macroalgae, phenolic compounds, pigments, carotenoids and fatty acids stand out due to their different bioactive properties, such as antidiabetics, antimicrobials and antioxidants, which are important in the treatment or control of diseases such as diabetes, cholesterol, hyperglycemia and cardiovascular diseases. That said, there have already been some studies in which macroalgae (red, green and brown) have been incorporated into certain foods, but studies on gluten-free products are still scarce, as only the potential use of macroalgae for this type of product is considered. Considering the aforementioned issues, this review aims to analyze how macroalgae can be incorporated into foods or used as a food supplement, as well as to describe the bioactive compounds they contain, which have beneficial properties for human health. In this way, the potential of macroalgae-based products in eminent diseases, such as celiac disease, or in more common diseases, such as diabetes and cholesterol complications, can be seen.

Attenuating effect of Polygala tenuifolia Willd. seed oil on progression of MAFLD

Introduction: Metabolic-associated fatty liver disease (MAFLD) is a common chronic metabolic disease that seriously threatens human health. The pharmacological activity of unsaturated fatty acid-rich vegetable oil interventions in the treatment of MAFLD has been demonstrated. This study evaluated the pharmacological activity of Polygala tenuifolia Willd, which contains high levels of 2-acetyl-1,3-diacyl-sn-glycerols (sn-2-acTAGs). Methods: In this study, a mouse model was established by feeding a high-fat diet (HFD, 31% lard oil diet), and the treatment group was fed a P. tenuifolia seed oil (PWSO) treatment diet (17% lard oil and 14% PWSO diet). The pharmacological activity and mechanism of PWSO were investigated by total cho-lesterol (TC) measurement, triglyceride (TG) measurement and histopathological observation, and the sterol regulatory element-binding protein-1 (SREBP1), SREBP2 and NF-κB signaling pathways were evaluated by immunofluorescence and Western blot analyses. Results: PWSO attenuated the increases in plasma TC and TG levels. Furthermore, PWSO reduced the hepatic levels of TC and TG, ameliorating hepatic lipid accumulation. PWSO treatment effectively improves the level of hepatitic inflammation, such as reducing IL-6 levels and TNF-α level. Discussion: PWSO treatment inactivated SREBP1 and SREBP2, which are involved in lipogenesis, to attenuate hepatic lipid accumulation and mitigate the inflammatory response induced via the NF-κB signaling pathway. This study demonstrated that PWSO can be used as a relatively potent dietary supplement to inhibit the occurrence and development of MAFLD.

Marine algal polysaccharides as future potential constituents against non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is one of the most chronic and incurable liver diseases triggered mainly by an inappropriate diet and hereditary factors which burden liver metabolic stress, and may result in liver fibrosis or even cancer. While the available drugs show adverse side effects. The non-toxic bioactive molecules derived from natural resources, particularly marine algal polysaccharides (MAPs), present significant potential for treating NASH. In this review, we summarized the protective effects of MAPs on NASH from multiple perspectives, including reducing oxidative stress, regulating lipid metabolism, enhancing immune function, preventing fibrosis, and providing cell protection. Furthermore, the mechanisms of MAPs in treating NASH were comprehensively described. Additionally, we highlight the influences of the special structures of MAPs on their bioactive differences. Through this comprehensive review, we aim to further elucidate the molecular mechanisms of MAPs in NASH and inspire insights for deeper research on the functional food and clinical applications of MAPs.

Rehashing Our Insight of Seaweeds as a Potential Source of Foods, Nutraceuticals, and Pharmaceuticals

In a few Southeast Asian nations, seaweeds have been a staple of the cuisine since prehistoric times. Seaweeds are currently becoming more and more popular around the world due to their superior nutritional value and medicinal properties. This is because of rising seaweed production on a global scale and substantial research on their composition and bioactivities over the past 20 years. By reviewing several articles in the literature, this review aimed to provide comprehensive information about the primary and secondary metabolites and various classes of bioactive compounds, such as polysaccharides, polyphenols, proteins, and essential fatty acids, along with their bioactivities, in a single article. This review also highlights the potential of seaweeds in the development of nutraceuticals, with a particular focus on their ability to enhance human health and overall well-being. In addition, we discuss the challenges and potential opportunities associated with the advancement of pharmaceuticals and nutraceuticals derived from seaweeds, as well as their incorporation into different industrial sectors. Furthermore, we find that many bioactive constituents found in seaweeds have demonstrated potential in terms of different therapeutic attributes, including antioxidative, anti-inflammatory, anticancer, and other properties. In conclusion, seaweed-based bioactive compounds have a huge potential to play an important role in the food, nutraceutical, and pharmaceutical sectors. However, future research should pay more attention to developing efficient techniques for the extraction and purification of compounds as well as their toxicity analysis, clinical efficacy, mode of action, and interactions with regular diets.

Tartary buckwheat root polysaccharides ameliorate non-alcoholic fatty liver disease via the IL6-SOCS3-SREBP1c pathway

Our previous study demonstrated that Tartary buckwheat root polysaccharides (TBRP) could reduce insulin resistance in diabetes mellitus by inhibiting SOCS3-stimulated IRS1 protein degradation. However, whether TBRP has the efficiency to treat non-alcoholic fatty liver disease (NAFLD) is still undetermined. This investigation aimed to examine the effects of TBRP on a high-fat diet (HFD)-triggered NAFLD, and elucidate the underlying molecular mechanisms. Briefly, TBRP toxicity in hepatoma (BEL7404) and pancreatic cancer (BxPC3) cells and zebrafish embryos developmental models, were evaluated in-vitro and in-vivo, respectively. TBRP inhibited cellular lipid accumulation by suppressing fat synthesis, furthermore, it improved body weight gain, liver weight, liver-to-body weight ratio, serum lipids triglyceride, total cholesterol, ALT, LDL-C, HDL-C, and AST levels in the NAFLD mice model. Additionally, TBRP treatment also lowered the nitric oxide content. The qPCR assay revealed that mRNA expression of TNF, IL1β, and IL6 was also markedly reduced in TBRP-treated NAFLD mice. The expression of SOCS3, SREBP1c, and STAT3 was elucidated by western blot analysis, which indicated that TBRP markedly decreased the gene expression for de novo fat synthesis by the SOCS3-SREBP1c pathway. These findings reveal that TBRP ameliorates NAFLD via the IL6-SOCS3-SREBP1c signaling pathway and therefore, may represent a promising approach for NAFLD treatment.

Anti-Hyperlipidemic Effect of Fucoidan Fractions Prepared from Iceland Brown Algae Ascophyllum nodosum in an Hyperlipidemic Mice Model

Ascophyllum nodosum, a brown algae abundantly found along the North Atlantic coast, is recognized for its high polysaccharide content. In this study, we investigated the anti-hyperlipidemic effect of fucoidans derived from A. nodosum, aiming to provide information for their potential application in anti-hyperlipidemic therapies and to explore comprehensive utilization of this Iceland brown seaweed. The crude fucoidan prepared from A. nodosum was separated using a diethylethanolamine column, resulting in two fucoidan fractions, AFC-1 and AFC-2. Both fractions were predominantly composed of fucose and xylose. AFC-1 exhibited a higher sulfate content of 27.8% compared to AFC-2 with 17.0%. AFC-2 was primarily sulfated at the hydroxy group of C2, whereas AFC-1 was sulfated at both the hydroxy groups of C2 and C4. To evaluate the anti-hyperlipidemic effect, a hyperlipidemia mouse model was established by feeding mice a high-fat diet. The effects of AFC-1, AFC-2, and the crude extract were investigated, with the drug atorvastatin used as a positive comparison. Among the different fucoidan fractions and doses, the high dose of AFC-2 administration demonstrated the most significant anti-hyperlipidemic effect across various aspects, including physiological parameters, blood glucose levels, lipid profile, histological analysis, and the activities of oxidative stress-related enzymes and lipoprotein-metabolism-related enzymes (p < 0.05 for the final body weight and p < 0.01 for the rest indicators, compared with the model group), and its effect is comparable to the atorvastatin administration. Furthermore, fucoidan administration resulted in a lower degree of loss in gut flora diversity compared to atorvastatin administration. These findings highlight the significant biomedical potential of fucoidans derived from A. nodosum as a promising therapeutic solution for hypolipidemia.

Hypolipidemic Activity and Mechanism of Action of Sargassum fusiforme Polysaccharides

Sargassum fusiforme polysaccharide (SFP) is a kind of biologically active macromolecule with biological functions. In this study, oxidative stress and high-fat HepG2 cell models were established to investigate its lipid-lowering activity and mechanism of action. It was found that SFP and its two isolated fractions had antioxidant effects on the cells. It was also found the polysaccharides decreased the content of total cholesterol and total triglyceride in the high-fat cells. RT-qPCR assays revealed that the three polysaccharides down-regulated the mRNA expression level of ACC, PPARγ, and SREBP-2. It could be concluded that the hypolipidemic effect of SFPs is achieved via multiple pathways, including the regulation on the expression level of lipid metabolism-related key enzymes and factors, and binding with bile acids. The hypolipidemic effect of SFPs could be partially due to their antioxidant activity. SFPs developed in the present work have potential as ingredients of functional foods with hypolipidemic effect.

Assessment of Auricularia cornea var. Li. polysaccharides potential to improve hepatic, antioxidation and intestinal microecology in rats with non-alcoholic fatty liver disease

Non-alcoholic fatty acid liver disease (NAFLD) is a reputed global health concern, affecting children and young adults. Accumulating evidence suggests that edible fungi polysaccharides have the potential to relieve NAFLD. Our previous study found that Auricularia cornea var. Li. polysaccharides (ACP) could improve immune by regulating gut microbiota. However, its NAFLD-alleviating potentials have been scarcely reported. This study analyzed the protective effects of Auricularia cornea var. Li. polysaccharides on high-fat diet (HFD)-induced NAFLD and mechanistic actions. We first analyzed the histology and hepatic lipid profile of animals to evaluate this variant's ameliorating effects on NAFLD. Then, antioxidant and anti-inflammatory potentials of ACP were studied. Finally, we explored changes in the gut microbiome diversity for mechanistic insights from the gut-liver region. Results showed that supplementation with ACP substantially reduced homeostasis model assessment-insulin resistance (HOMA-IR), body fat, liver index rates and weight gain (p < 0.05). This variant also improved HDL-C levels while decreasing triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels which were initially triggered by HFD. ACP mediation also decreased the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels considerably with H&E technique indicating that it can reduce liver lipid accumulation, thus lowering liver damages risks (p < 0.05). The antioxidant potentials of ACP were also demonstrated as it decreased the hepatic levels of malondialdehyde (MDA) and increased the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX). Proinflammatory markers like IL-6, IL-1β and TNF-α concentrations were decreased by ACP supplementation, accompanied with increased IL-4 levels. Finally, ACP supplementation regulated the intestinal microbiota to near normal patterns. In all, ACP protects HFD-induced NAFLD by improving liver characteristics and regulating colonic flora composition, our findings assert that ACP can be a promising strategy in NAFLD therapy.

Assessment of Areca Nut Bioactivities in Western Diet-Induced Mice NAFLD Model

The areca nut is often consumed as a chewing food in the Asian region. Our previous study revealed that the areca nut is rich in polyphenols with high antioxidant activity. In this study, we further assessed the effects and molecular mechanisms of the areca nut and its major ingredients on a Western diet-induced mice dyslipidemia model. Male C57BL/6N mice were divided into five groups and fed with a normal diet (ND), Western diet (WD), WD with areca nut extracts (ANE), areca nut polyphenols (ANP), and arecoline (ARE) for 12 weeks. The results revealed that ANP significantly reduced WD-induced body weight, liver weight, epididymal fat, and liver total lipid. Serum biomarkers showed that ANP ameliorated WD-enhanced total cholesterol and non-high-density lipoprotein (non-HDL). Moreover, analysis of cellular signaling pathways revealed that sterol regulatory element-binding protein 2 (SREBP2) and enzyme 3-hydroxy-3-methylglutaryld coenzyme A reductase (HMGCR) were significantly downregulated by ANP. The results of gut microbiota analysis revealed that ANP increased the abundance of beneficial bacterium Akkermansias and decreased the abundance of the pathogenic bacterium Ruminococcus while ARE shown the opposite result to ANP. In summary, our data indicated that areca nut polyphenol ameliorated WD-induced dyslipidemia by increasing the abundance of beneficial bacteria in the gut microbiota and reducing the expressions of SREBP2 and HMGCR while areca nut ARE inhibited this improvement potential.

Effect of Ginkgo biloba extract on pharmacology and pharmacokinetics of atorvastatin in rats with hyperlipidaemia

Ginkgo biloba extract (GBE) is a common dietary supplement used by people with dyslipidaemia worldwide to reduce the risk of cardiovascular disease. Many studies have found that GBE itself has a variety of pharmacological activities. However, the role of GBE as an adjunct to conventional therapy with chemical drugs remains controversial. Therefore, this study explored the additional benefits of GBE in the treatment of hyperlipidaemia with statins in terms of both pharmacodynamics and pharmacokinetics. A hyperlipidaemia model was established by feeding rats a high-fat diet for a long time. The animals were treated with atorvastatin only, GBE only, or a combination of atorvastatin and GBE. The results showed that statins combined with GBE could significantly improve the blood lipid parameters, reduce the liver fat content, and reduce the size of adipocytes in abdominal fat. The effect was superior to statin therapy alone. In addition, the combination has shown additional liver protection against possible pathological liver injury or statin-induced liver injury. A lipidomic study showed that GBE could regulate the abnormal lipid metabolism of the liver in hyperlipemia. When statins are combined with GBE, this callback effect introduced by GBE on endogenous metabolism has important implications for resistance to disease progression and statin resistance. Finally, in the presence of GBE, there was a significant increase in plasma statin exposure. These results all confirmed that GBE has incremental benefits as a dietary supplement of statin therapy for dyslipidaemia.

Research progress on the therapeutic effects of polysaccharides on non-alcoholic fatty liver diseases

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease and is a leading cause of cirrhosis and hepatocellular carcinoma. Due to its complex pathophysiology, there is currently no approved therapy. Polysaccharide, a kind of natural product, possesses a wide range of pharmacological activities. Numerous preclinical studies have confirmed that polysaccharides could interfere with the occurrence and development of NAFLD at multiple interrelated levels, such as improvement of glucose and lipid metabolism, antioxidation, anti-inflammation, and regulation of gut-liver axis, thus showing great potential as novel anti-NAFLD drugs. In this paper, we reviewed the polysaccharides with anti-NAFLD effect in recent years, and also systematically analyzed their possible pharmacological mechanisms.

Mulberry Leaf (Morus alba L.) Extracts and Its Chlorogenic Acid Isomer Component Improve Glucolipotoxicity-Induced Hepatic Lipid Accumulation via Downregulating miR-34a and Decreased Inflammation

Mulberry leaf (Morus alba L.) is used as a traditional medicine and potential health food to treat various metabolic diseases, such as hypertension, diabetes, and hyperlipidemia. However, we sought the mechanisms by which functional components of mulberry leaves mediate diabetic steatohepatitis. We applied an in vitro model of HepG2 cells induced by glucolipotoxicity and evaluated the effects of MLE and its major components nCGA, Crp, and CGA. The results showed that MLE and nCGA reduced liver fat accumulation by inhibiting SREBP-1/FASN, SREBP-2/HMG-CoAR, and activating PPARα/CPT-1. Additionally, MLE and nCGA decreased inflammatory responses associated with NF-κB, TNF-α, and IL-6 to alleviate steatohepatitis. Furthermore, we showed that MLE and nCGA exerted anti-glucolipotoxicity effects by downregulating miR-34a, thus activating SIRT1/AMPK signaling, and subsequently suppressing hepatic lipid accumulation.

Regulation of Cholesterol Metabolism by Phytochemicals Derived from Algae and Edible Mushrooms in Non-Alcoholic Fatty Liver Disease

Cholesterol synthesis occurs in almost all cells, but mainly in hepatocytes in the liver. Cholesterol is garnering increasing attention for its central role in various metabolic diseases. In addition, cholesterol is one of the most essential elements for cells as both a structural source and a player participating in various metabolic pathways. Accurate regulation of cholesterol is necessary for the proper metabolism of fats in the body. Disturbances in cholesterol homeostasis have been linked to various metabolic diseases, such as hyperlipidemia and non-alcoholic fatty liver disease (NAFLD). For many years, the use of synthetic chemical drugs has been effective against many health conditions. Furthermore, from ancient to modern times, various plant-based drugs have been considered local medicines, playing important roles in human health. Phytochemicals are bioactive natural compounds that are derived from medicinal plants, fruit, vegetables, roots, leaves, and flowers and are used to treat a variety of diseases. They include flavonoids, carotenoids, polyphenols, polysaccharides, vitamins, and more. Many of these compounds have been proven to have antioxidant, anti-inflammatory, antiobesity and antihypercholesteremic activity. The multifaceted role of phytochemicals may provide health benefits to humans with regard to the treatment and control of cholesterol metabolism and the diseases associated with this disorder, such as NAFLD. In recent years, global environmental climate change, the COVID-19 pandemic, the current war in Europe, and other conflicts have threatened food security and human nutrition worldwide. This further emphasizes the urgent need for sustainable sources of functional phytochemicals to be included in the food industry and dietary habits. This review summarizes the latest findings on selected phytochemicals from sustainable sources-algae and edible mushrooms-that affect the synthesis and metabolism of cholesterol and improve or prevent NAFLD.

Sulfated Polysaccharides from Enteromorpha prolifera Attenuate Lipid Metabolism Disorders in Mice with High-fat Diet-induced Obesity via an AMPK-dependent Pathway

BACKGROUND

Obesity-related metabolic diseases have recently evoked worldwide attention. Studies have demonstrated that Enteromorpha polysaccharide (EP) exerts lipid-lowering effects, but the underlying mechanism remains unclear.

OBJECTIVE

To investigate whether EP regulates lipid metabolism disorders in mice with high-fat diet (HFD)-induced obesity via an AMP-activated protein kinase (AMPK)-dependent pathway.

METHODS

Six-week-old male C57BL/6J mice (18 ± 2 g) were fed a normal diet (ND; 10% energy from fats) or a HFD (60% energy from fats) for 6 weeks to induce obesity and treated intragastrically with EP (200 mg/kg body weight) or distilled water (10 mL/kg body weight) for 8 weeks. Biochemical indicators, AMPK-dependent pathways and lipid metabolism-related genes were evaluated to assess the effects of EP on HFD-induced lipid metabolism disorders. The essential role of AMPK in the EP-mediated regulation of lipid metabolism was confirmed using HFD-fed male Ampka2-knockout mice (aged 6 weeks, 17 ± 2 g) treated or not treated with the above-mentioned dose of EP. The data were analyzed by t tests and two-factor and one-way ANOVAs.

RESULTS

Compared to the ND, the HFD resulted in the greater body weight (24.3%), perirenal fat index (2.2-fold), and serum TC (24.66%) and LDL cholesterol (1.25-fold) concentrations (P < 0.05) and dysregulated the AMPK-dependent pathway and the expression of most lipid metabolism-related genes (P < 0.05). Compared to the HFD, EP treatment resulted in the lower perirenal fat index (31.22%) and the LDL-C concentration (23.98%) and partly reversed the dysregulation of the AMPK-dependent pathway and the altered expression of lipid metabolism-related genes (P < 0.05). Ampka2 knockout abolished the above-mentioned effects of EP in obese mice and the EP-mediated effects on the expression of lipid metabolism-related genes (P > 0.05).

CONCLUSIONS

These findings suggest that EP can ameliorate lipid metabolism disorders in mice with HFD-induced obesity via an AMPK-dependent pathway.

Circulating oestradiol determines liver lipid deposition in rats fed standard diets partially unbalanced with higher lipid or protein proportions

The ingestion of excess lipids often produces the accumulation of liver fat. The modulation of diet energy partition affects this process and other metabolic responses, and oestrogens and androgens are implied in this process. Ten-week-old male and female rats were fed with either standard rat chow (SD), SD enriched with coconut oil (high-fat diet, HF), SD enriched with protein (high-protein diet, HP) or a ‘cafeteria’ diet (CAF) for 1 month. HF and CAF diets provided the same lipid-derived percentage of energy (40 %), HP diet protein energy derived was twice (40 %) that of the SD. Animals were killed under anaesthesia and samples of blood and liver were obtained. Hepatic lipid content showed sex-related differences: TAG accumulation tended to increase in HF and CAF fed males. Cholesterol content was higher only in the CAF males. Plasma oestradiol in HF and HP males was higher than in CAF. Circulating cholesterol was inversely correlated with plasma oestradiol. These changes agreed with the differences in the expression of some enzymes related to lipid and energy metabolism, such as fatty acid synthetase or phosphoglycolate phosphatase. Oestrogen protective effects extend to males with ‘normal’ diets, that is, not unbalanced by either lipid or protein, but this protection was not enough against the CAF diet. Oestradiol seems to actively modulate the liver core of 2C-3C partition of energy substrates, regulating cholesterol deposition and lactate production.

Marine Sulfated Polysaccharides: Preventive and Therapeutic Effects on Metabolic Syndrome: A Review

Metabolic syndrome is the pathological basis of cardiovascular and cerebrovascular diseases and type 2 diabetes. With the prevalence of modern lifestyles, the incidence of metabolic syndrome has risen rapidly. In recent years, marine sulfate polysaccharides (MSPs) have shown positive effects in the prevention and treatment of metabolic syndrome, and they mainly come from seaweeds and marine animals. MSPs are rich in sulfate and have stronger biological activity compared with terrestrial polysaccharides. MSPs can alleviate metabolic syndrome by regulating glucose metabolism and lipid metabolism. In addition, MSPs prevent and treat metabolic syndrome by interacting with gut microbiota. MSPs can be degraded by gut microbes to produce metabolites such as short chain fatty acids (SCFAs) and free sulfate and affect the composition of gut microbiota. The difference between MSPs and other polysaccharides lies in the sulfation pattern and sulfate content, therefore, which is very important for anti-metabolic syndrome activity of MSPs. This review summarizes the latest findings on effects of MSPs on metabolic syndrome, mechanisms of MSPs in treatment/prevention of metabolic syndrome, interactions between MSPs and gut microbiota, and the role of sulfate group and sulfation pattern in MSPs activity. However, more clinical trials are needed to confirm the potential preventive and therapeutic effects on human body. It may be a better choice to develop new functional foods containing MSPs for dietary intervention in metabolic syndrome.

Extraction Techniques, Biological Activities and Health Benefits of Marine Algae Enteromorpha prolifera Polysaccharide

There is increasing interest in the use of marine algae as functional food additives for improving human health. Enteromorpha (Ulva) prolifera (E. prolifera) is a seaweed green alga (Chlorophyta) that contains many bioactive compounds, of which polysaccharide is the main component. With the advancement of technology in the methods of extraction and analysis, recent studies in in vitro and animals model showed that polysaccharides derived from E. prolifera exert various biological activities, such as gut microbiota modulation, immunomodulation, antioxidant, antidiabetic, antimicrobial, and hypolipidemic. Research evidence has shown that methods of extraction and molecular modification, such as degradation, carboxymethylation, and sulfonation could alter the biological activities of polysaccharides. Therefore, in this review, we discussed the different extraction techniques, structural-activity relationship, and health benefits of sulfated polysaccharides derived from E. prolifera, and suggested future research avenues. This review helps to advance the extraction techniques and promote the application of marine algae polysaccharides as functional food and therapeutic agent.

GC-MS-Based Serum Metabolomic Investigations on the Ameliorative Effects of Polysaccharide from Turpiniae folium in Hyperlipidemia Rats

Hyperlipidemia, a typical metabolic disorder syndrome, can cause various cardiovascular diseases. The polysaccharides were found to have enormous potential in the therapy of hyperlipidemia. This study was aimed at evaluating the ameliorative effects of polysaccharide from Turpiniae folium (TFP) in rats with hyperlipidemia. A serum metabolomic method based on gas chromatography-mass spectrometry (GC-MS) was used to explore the detailed mechanism of TFP in rats with hyperlipidemia. The oxidative stress indicators, biochemical indexes, and inflammatory factors in serum and histopathological changes in the liver were also evaluated after 10-week oral administration of TFP in rats with high-fat diet-induced hyperlipidemia. TFP significantly relieved oxidative stress, inflammation, and liver histopathology and reduced blood lipid levels. Multivariate statistical approaches such as principal component analysis and orthogonal projection to latent structure square-discriminant analysis revealed clear separations of metabolic profiles among the control, HFD, and HFD+TFP groups, indicating a moderating effect of TFP on the metabolic disorders in rats with hyperlipidemia. Seven metabolites in serum, involved in glycine, serine, and threonine metabolism and aminoacyl-tRNA biosynthesis, were selected as potential biomarkers in rats with hyperlipidemia and regulated by TFP administration. It was concluded that TFP had remarkable potential for treating hyperlipidemia. These findings provided evidence for further understanding of the mechanism of action of TFP on hyperlipidemia.

Enteromorpha prolifera polysaccharide prevents high- fat diet-induced obesity in hamsters: A NMR-based metabolomic evaluation

Enteromorpha prolifera polysaccharide (EP) has been shown to exhibit hypolipidemic and hypoglycemic activities in various experimental models. Here, an ¹ H-NMR-based metabolomic study was conducted to explore the regulatory effects of EP on serum metabolic changes in obese hamsters. High-fat diet (HFD)-fed hamsters were orally administrated with EP (300, 450, or 600 mg/kg) once daily for 12 weeks. Compared with HFD-fed hamsters, EP treatment (450 and 600 mg/kg) significantly decreased the body weight (by 8.69 and 8.24%), liver weight (by 7.87 and 8.25%), epididymal white adipose tissue (by 19.54 and 17.26%), perirenal white adipose tissue (by 28.09 and 28.94%), serum total cholesterol (by 24.31 and 18.61%), triglyceride (by 30.64 and 31.38%), and low-density lipoprotein cholesterol (by 38.26 and 36.30%), respectively. In addition, EP intervention also significantly decreased hepatic cholesterol (by 23.20, 38.16, and 34.57%) and triglyceride content (by 17.78, 41.47, and 35.50%) as well as serum levels of alanine aminotransferase (ALT) and ALT/aspartate aminotransferase (AST) ratio. The serum samples of normal diet (ND) group, HFD group and HFD + EP 450 mg/kg (HFD + MEP) group were further analyzed by ¹ H-NMR spectroscopy. Compared with ND group, 17 and 2 metabolites were significantly upregulated and downregulated in HFD group, respectively. Interestingly, EP treatment significantly downregulated nine metabolites and upregulated one metabolite when compared to those in HFD group. Our results indicated that EP intervention partially ameliorated HFD-induced metabolic dysfunction, and the most prominent metabolic pathways included citrate cycle, synthesis and degradation of ketone bodies, pyruvate metabolism, valine, leucine and isoleucine degradation, and arginine biosynthesis. PRACTICAL APPLICATION: Enteromorpha prolifera polysaccharide (EP), the main active component of Enteromorpha prolifera, is reported to have many biological activities. However, the antiobesity effect of EP and its corresponding metabolic mechanism have not been reported so far. The results of this study confirmed the antiobesity effect of EP on HFD-induced obese hamsters and elucidated its possible metabolic mechanism. Our study highlighted that EP might be used in weight-loss functional foods.

Effects of Danhong injection on dyslipidemia and cholesterol metabolism in high-fat diets fed rats

ETHNOPHARMACOLOGICAL RELEVANCE

Danhong injection (DHI) is a Chinese medical injection applied to the clinical treatment of cardiovascular diseases that has anti-inflammatory, antiplatelet aggregation and antithrombotic effects. This study aimed to explore the effects of DHI on dyslipidemia and cholesterol metabolism in high-fat diet-fed rats.

METHODS

Sprague Dawley (SD) rats were randomly divided into six groups: normal group (Normal); hyperlipidemia model group (Model); DHI-treated groups at doses of 1.0 mL/kg, 2.0 mL/kg, 4.0 mL/kg; and simvastatin positive control group (2.0 mg/kg). The hypolipidemic effects of DHI were evaluated by measuring serum lipid levels, hepatic function and oxidative stress, respectively. And pathological changes in liver tissues were determined using hematoxylin-eosin (H&E) and oil red O staining. Moreover, the mRNA and protein expression levels of cholesterol metabolism related genes were detected by real-time PCR (RT-PCR) and Western blot.

RESULTS

Compared with the Model group, DHI treatment markedly decreased the liver index and improved the pathological morphology of liver tissues. DHI treatment dose-dependently decreased the levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA), and free fatty acids (FFA) in serum or liver tissues (P < 0.01 or P < 0.05), and increased the high-density lipoprotein cholesterol (HDL-C) and tripeptide glutathione (GSH) (P < 0.01 or P < 0.05). The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were increased in the DHI-treated groups (P < 0.01 or P < 0.05), while the alanine transaminase (ALT) and aspartate transaminase (AST) were decreased (P < 0.01 or P < 0.05). Furthermore, the expression levels of LDL receptor (LDLR), cholesterol 7-α-hydroxylase (CYP7A1), liver X receptor α (LXRα), and peroxisome proliferator-activated receptor α (PPARα) were dose-dependently upregulated in the DHI-treated groups, whereas the expression of sterol regulatory element-binding protein-2 (SREBP-2) was downregulated.

CONCLUSIONS

Our study demonstrated that DHI markedly ameliorated hyperlipidemia rats by regulating serum lipid levels, inhibiting hepatic lipid accumulation and steatosis, improving hepatic dysfunction, and reducing oxidative stress. The potential mechanism was also tentatively investigated and may be related to the promotion of bile acid synthesis via activation of the PPARα-LXRα-CYP7A1 pathway. Therefore, DHI could be regarded as a potential hypolipidemic drug for the treatment of hyperlipidemia.

Hepatic cholesterol transport and its role in non-alcoholic fatty liver disease and atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) is a quickly emerging global health problem representing the most common chronic liver disease in the world. Atherosclerotic cardiovascular disease represents the leading cause of mortality in NAFLD patients. Cholesterol metabolism has a crucial role in the pathogenesis of both NAFLD and atherosclerosis. The liver is the major organ for cholesterol metabolism. Abnormal hepatic cholesterol metabolism not only leads to NAFLD but also drives the development of atherosclerotic dyslipidemia. The cholesterol level in hepatocytes reflects the dynamic balance between endogenous synthesis, uptake, esterification, and export, a process in which cholesterol is converted to neutral cholesteryl esters either for storage in cytosolic lipid droplets or for secretion as a major constituent of plasma lipoproteins, including very-low-density lipoproteins, chylomicrons, high-density lipoproteins, and low-density lipoproteins. In this review, we describe decades of research aimed at identifying key molecules and cellular players involved in each main aspect of hepatic cholesterol metabolism. Furthermore, we summarize the recent advances regarding the biological processes of hepatic cholesterol transport and its role in NAFLD and atherosclerosis.

β-patchoulene improves lipid metabolism to alleviate non-alcoholic fatty liver disease via activating AMPK signaling pathway

Non-alcoholic fatty liver disease (NAFLD) has been a leading cause of chronic metabolic disease, seriously posing healthy burdens to the public, whereas interventions available for it are limited to date. Patchouli oil had been reported to attenuate hepatic steatosis in our previous study. β-patchoulene (β-PAE) is a representative component separated from patchouli oil with multiple activities, but its effect against NAFLD is still unknown. To investigate the effect and potential mechanism of β-PAE on NAFLD, we used high fat diet (HFD) in vivo and free fatty acid (FFA) in vitro to induce hepatic steatosis in rats and L02 cells, respectively. Histological examination was evaluated via Hematoxylin-eosin and oil red O staining. The parameters for hepatic steatosis were estimated via biochemical kits, western blotting and quantitative real-time PCR. Compound C, the inhibitor of AMPK, was applied further to examine the precise mechanism of β-PAE on NAFLD. Our results indicated that β-PAE significantly attenuated HFD-induced weight gain, hepatic injury, lipid deposition in serum and hepatic tissue as well as FFA induced-lipid accumulation. Besides, β-PAE markedly improved the expression of AMP-activated protein kinase (AMPK) and its downstream factors which correlate with hepatic lipid synthesis and oxidation in vivo and in vitro. Nevertheless, Compound C abrogated the benefits derived from β-PAE in L02 cells. In conclusion, these results suggest that β-PAE exerts AMPK agonist-like effect to regulate hepatic lipid synthesis and oxidation, eventually prevent NAFLD progression.

Ulva prolifera Extract Alleviates Intestinal Oxidative Stress via Nrf2 Signaling in Weaned Piglets Challenged With Hydrogen Peroxide

Background

Ulva prolifera extract contains a variety of functional active substances. Whether these substances had any beneficial effects on the small intestine of weaned piglets under oxidative stress remained unknown.

Method

We explored the effects of U. prolifera extract on oxidative stress and related mechanisms in weaned piglets and intestinal porcine epithelial cells (IPEC-J2) challenged with hydrogen peroxide.

Results

U. prolifera extract was found to mainly consist of polyphenols and unsaturated fatty acids. U. prolifera extract increased total antioxidant capacity and superoxide dismutase (SOD) activity, while it decreased malondialdehyde content, in the serum of weaned piglets challenged with hydrogen peroxide. Moreover, U. prolifera extract increased mRNA expression of SOD and catalase, as well as the intestinal expression of nuclear NF-E2-related factor 2 (Nrf2), both in vitro and in vivo. Furthermore, U. prolifera extract decreased reactive oxygen species and improved mitochondrial respiration in IPEC-J2 cells treated with hydrogen peroxide. However, AMPK inhibition did not affect nuclear Nrf2 expression and only partially affected the effects of U. prolifera extract on oxidative stress.

Conclusion

We suggest that U. prolifera extract alleviates oxidative stress via Nrf2 signaling, but independent of AMPK pathway in weaned piglets challenged with hydrogen peroxide. These results shed new insight into the potential applications of U. prolifera extract as a therapeutic agent for the prevention and treatment of oxidative stress-induced intestinal diseases.

Current Research Landscape of Marine-Derived Anti-Atherosclerotic Substances

Atherosclerosis is a chronic disease characterized by lipid accumulation and chronic inflammation of the arterial wall, which is the pathological basis for coronary heart disease, cerebrovascular disease and thromboembolic disease. Currently, there is a lack of low-cost therapeutic agents that effectively slow the progression of atherosclerosis. Therefore, the development of new drugs is urgently needed. The research and development of marine-derived drugs have gained increasing interest from researchers across the world. Many marine organisms provide a rich material basis for the development of atherosclerotic drugs. This review focuses on the latest technological advances in the structures and mechanisms of action of marine-derived anti-atherosclerotic substances and the challenges of the application of these substances including marine polysaccharides, proteins and peptides, polyunsaturated fatty acids and small molecule compounds. Here, we describe the theoretical basis of marine biological resources in the treatment of atherosclerosis.

Structural characterization and anti-lung cancer activity of a sulfated glucurono-xylo-rhamnan from Enteromorpha prolifera

A sulfated glucurono-xylo-rhamnan (EP-3-H) was purified from a green alga, Enteromorpha prolifera. EP-3-H and its oligomers were characterized by high performance liquid chromatography, mass spectrometry and one and two-dimensional nuclear magnetic resource spectroscopy. The structural analysis showed EP-3-H has a backbone of glucurono-xylo-rhamnan, branches with glucuronic acid and sulfated at C3 of rhamnose and/or C2 of xylose. The inhibition of EP-3-H on human lung cancer A549 cell proliferation in vitro and its therapeutic effects in BALB/c-nu mice in vivo were determined to evaluate the anti-lung cancer activity of EP-3-H. The tumor inhibition level was 59 %, suggesting that EP-3-H might be a good candidate for the treatment of lung cancer. Surface plasmon resonance (SPR) studies revealed the IC₅₀ on the binding of fibroblast growth factors, (FGF1 and FGF2), to heparin were 0.85 and 1.47 mg/mL, respectively. These results suggest that EP-3-H inhibits cancer proliferation by interacting with these growth factors.

Resource, chemical structure and activity of natural polysaccharides against alcoholic liver damages

Many natural polysaccharides from bio-resources hold advantages of multi-functions, high efficiency, non-toxicity or low side effect, and have strong potentials in protection against alcoholic liver damages. This review summarized the bio-resources, chemical and structural characteristics of natural polysaccharides with potentials in inhibition against alcoholic liver damages, and also emphasized knowledge on correlations between their chemical structure and function. Approximately 95 species were confirmed in generation of hepatoprotective polysaccharides. Products as crude polysaccharides originated from 17 species were sum up despite the indetermination of their accurate structure. Additional four polysaccharides were described for their known chemical structures. Possible roles of hepatoprotective polysaccharides were provided with evidence on antioxidant promotion, lipids regulation, apoptosis inhibition and anti-inflammation, as well as confirmations in immune enhancement, iron removal and anti-fibrosis when currently treated against the alcoholic liver damages. To sum up, this overview could serve to guide development and utilization of natural hepatoprotective polysaccharides.

Beneficial effects of Chinese herbs in the treatment of fatty liver diseases

Eating habits and lifestyle directly impact general health. Consumption of fat- and sugar-rich foods and alcohol increase the risk of developing fatty liver disease. The prevalence of fatty liver disease is markedly critical, and its pathogenesis and progression are complicated. Chinese herbal medicine has been used to treat and prevent human diseases through-out history, and is a rich source of biologically active substances with unique curative properties. More recently, Chinese herbs and their extracts have been identified as a novel source of potential therapeutic agents in the prevention and treatment of fatty liver disease. Beneficial effects of these herbal medicines mean that they can be classified as novel candidates for the treatment and prevention of both alcoholic fatty liver disease (AFLD) and non-alcoholic fatty liver disease (NAFLD), in place of conventional allopathic treatments. In this review, we explore the current literature related to herbal medicines used for the treatment of or protection against fatty liver diseases and describe their mechanisms of action.

Polysaccharides from Enteromorpha prolifera protect against carbon tetrachloride-induced acute liver injury in mice via activation of Nrf2/HO-1 signaling, and suppression of oxidative stress, inflammation and apoptosis

EPP protected against hepatic injury induced by CCl₄-derived reactive intermediates through the suppression of hepatic oxidative stress, inflammation, and apoptosis.

Palmitic Acid Induces MicroRNA-221 Expression to Decrease Glucose Uptake in HepG2 Cells via the PI3K/AKT/GLUT4 Pathway

Obesity-related insulin resistance and high fatty acid concentrations occur during the development of type 2 diabetes mellitus. The role of high concentrations of plasma-free fatty acids is not fully understood. In this study, palmitic acid (PA, 0.8 mM for 24 h) induced the expression of miR-221 that bound to phosphoinositide 3-kinases (PI3K) mRNA to inhibit glucose uptake by HepG2 cells. Compared with controls, PA significantly decreased glucose uptake, increased insulin receptor substrate-2 (IRS-2) and miR-221 expression, and decreased phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), and glucose transporter type 4 (GLUT4) mRNA expression. Luciferase reporter assay revealed that miR-221 binding inhibited PI3K expression. Transfection of HepG2 cells with an miR-221 mimic induced miR-221 expression and inhibited the PI3K/AKT pathway. PA decreased glucose uptake in HepG2 cells by inducing the expression of miR-221, which bound to PI3K mRNA and suppressed PI3K/AKT signaling. miR-221 may be a novel target for preventing and treating obesity-induced insulin resistance.

Lipidomic Analysis of the Protective Effects of Shenling Baizhu San on Non-Alcoholic Fatty Liver Disease in Rats

Shenling Baizhu San (SLBZS), a famous traditional Chinese medicine, has been demonstrated to exert protective effects against non-alcoholic fatty liver disease (NAFLD), but its exact mechanisms have not been well understood. The aim of this study was to investigate the mechanisms underlying the protective effects of SLBZS in a rat model of NAFLD using lipidomics and to evaluate the role of Sirtuin 1 (SIRT1) in the mechanism of SLBZS against NAFLD. The rat model of NAFLD was induced by high-fat feeding. An ultra-performance liquid chromatography-mass spectrometry (UHPLC-MS)-based untargeted lipidomics approach was applied to analyze hepatic lipid alterations, and the SIRT1-selective inhibitor EX 527 was used to inhibit SIRT expression in the liver. The results of body and biochemical parameters, as well as histological changes, indicated that SLBZS administration exerted protective effects against NAFLD. Lipidomic analysis showed that 30 lipid species were effectively regulated by SLBZS administration in rats fed a high-fat diet. Pathway analysis indicated that glycerophospholipid metabolism and glycerolipid metabolism were potential target pathways closely involved in the mechanism of SLBZS against NAFLD. Moreover, the beneficial effects of SLBZS on hepatic steatosis, some biochemical parameters and hepatic lipid species were partly diminished by SIRT1 inhibition. In conclusion, our results suggested that SLBZS administration could effectively alter some hepatic lipid species in rats fed a high-fat diet, which was mainly associated with the regulation of glycerophospholipid and glycerolipid metabolism. Furthermore, the beneficial effects of SLBZS on hepatic lipid metabolism may be at least partly attributed to SIRT1 activation in the liver.

Shuangyu Tiaozhi Granule Attenuates Hypercholesterolemia through the Reduction of Cholesterol Synthesis in Rat Fed a High Cholesterol Diet

Shuangyu Tiaozhi Granule (STG) is composed of two kinds of Chinese medicinal herbs in dioscorea, which are used for managing cholesterol levels in patients with hypercholesterolemia in traditional Chinese medicine (TCM). However, the potential molecular mechanisms of administration of STG in hypercholesterolemia remain unknown. In this study, we investigated the effects of STG on hepatic cholesterol metabolism in high cholesterol (HC) diet-induced hypercholesterolemic rat models and simvastatin was used as a positive control. Male Sprague Dawley (SD) rats were fed general or HC diet, respectively. After 4 weeks of feeding, HC diet-induced hypercholesterolemic rats were fed HC diet, STG at 5% (w/w) or 10% (w/w) mixed in the HC diet, or HC diet combined with simvastatin gavages (4 mg·kg⁻¹·d⁻¹) for 4 or 8 weeks. STG treatment decreased body weight gain, liver weight ratio, serum lipids levels and hepatic lipids accumulation in rats fed a HC diet. Moreover, the effects of STG on decreasing body weight and lowering liver cholesterol levels were in dose- and time-dependent. Furthermore, STG or simvastatin treatment decreased the mRNA and protein levels of HMGCR and SREBP-2 in liver. The ACAT-2 and CYP7A1 mRNA expression were significantly decreased in HC diet supplemented with STG, while the mRNA levels of LDLR were markedly increased. STG attenuates hypercholesterolemia via inhibiting SREBP-2 signaling pathway activation and increasing hepatic uptake genes expression, providing a novel idea of TCM keeping cholesterol levels down for the clinical application.

Polysaccharides derived from natural sources regulate triglyceride and cholesterol metabolism: a review of the mechanisms

This paper presents a comprehensive review of hypolipidemic mechanism of polysaccharides from natural sources.

Enteromorpha prolifera oligomers relieve pancreatic injury in streptozotocin (STZ)-induced diabetic mice

The polysaccharides of Enteromorpha prolifera (PEP) displayed various bioactivities such as anti-viral, anti-inflammatory and immune-regulative effects. However, no studies were performed on the biological effect of Enteromorpha prolifera oligomers (EPO). In this study, we prepared EPO and evaluated their anti-diabetic effect. By enzymatic degradation, EPO were produced from PEP, and the average molecular weight was identified to be 44.1 kDa by Gel Permeation Chromatography (GPC) analysis. The major monosaccharide units of EPO were measured to be rhamnose, glucuronic acid, glucose, xylose and galactose by capillary electrophoresis assay. Based on the in vitro studies, EPO presented potent reducing power and antioxidant effect such as the scavenging of 1, 1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and NO radicals. The in vivo studies show that EPO relieved the symptoms of polydipsia, polyphagia, emaciation and hyperglycemia in streptozotocin (STZ)-induced diabetic mice to a certain extent. Further, by using the quantitative real-time PCR (qPCR) assay and immunofluorescence staining, EPO was proved to promote the insulin secretion by reducing pancreatic inflammation and apoptosis in diabetic mice. In summary, our results indicate that the mitigation of EPO on pancreatic damage might be an effective way to ameliorate the diabetes mellitus.

Anti-Obesity Effect of Chitosan Oligosaccharide Capsules (COSCs) in Obese Rats by Ameliorating Leptin Resistance and Adipogenesis

Obesity is a global disease that causes many metabolic disorders. However, effective agents for the prevention or treatment of obesity remain limited. This study investigated the anti-obesity effect and mechanism of chitosan oligosaccharide capsules (COSCs) on rats suffering from obesity induced by a high-fat diet (HFD). After the eight-week administration of COSCs on obese rats, the body weight gain, fat/body ratio, and related biochemical indices were measured. The hepatic expressions of the leptin signal pathway (JAK2-STAT3) and gene expressions of adipogenesis-related targets were also determined. Our data showed that COSCs can regulate body weight gain, lipids, serum alanine aminotransferase, and aspartate aminotransferase, as well as upregulate the hepatic leptin receptor-b (LepRb) and the phosphorylation of JAK2 and STAT3. Meanwhile, marked increased expressions of liver sterol regulatory element-binding protein-1c, fatty acid synthase, acetyl-CoA carboxylase, 3-hydroxy-3-methylglutaryl-CoA reductase, adiponectin, adipose peroxisome proliferator-activated receptor γ, CCAAT-enhancer binding protein α, adipose differentiation-related protein, and SREBP-1c were observed. The results suggested that COSCs activate the JAK2-STAT3 signaling pathway to alleviate leptin resistance and suppress adipogenesis to reduce lipid accumulation. Thus, they can potentially be used for obesity treatment.

Marine polysaccharides attenuate metabolic syndrome by fermentation products and altering gut microbiota: An overview

Marine polysaccharides (MPs), including plant, animal, and microbial-derived polysaccharides, can alleviate metabolic syndrome (MetS) by different regulation mechanisms. MPs and their derivatives can attenuate MetS by vary cellular signal pathways, such as peroxisome proliferator-activated receptor, 5' adenosine monophosphate-activated protein kinase, and CCAAT/enhancer binding protein-α. Also, most of MPs cannot be degraded by human innate enzymes, but they can be degraded and fermented by human gut microbiota. The final metabolic products of these polysaccharides are usually short-chain fatty acids (SCFAs), which can change the gut microbiota ecology by altering the existing percentage of special microorganisms. In addition, the SCFAs and changed gut microbiota can regulate enteroendocrine hormone secretion, blood glucose, lipid metabolism levels, and other MetS symptoms. Here, we summarize the up-to-date findings on the effects of MPs, particularly marine microbial-derived polysaccharides, and their metabolites on attenuating MetS.

Sulfated polysaccharide from Enteromorpha prolifera increases hydrogen sulfide production and attenuates non-alcoholic fatty liver disease in high-fat diet rats

EP upregulates hepatic CBS expression, thus increasing serum H₂S level, which reduces serum TG level and ameliorates NAFLD induced by a high-fat diet.