Effects of Paramylon Extracted from Euglena gracilis EOD-1 on Parameters Related to Metabolic Syndrome in Diet-Induced Obese Mice

Carboxymethylation of paramylon derived from Euglena gracilis and its hypoglycemic mechanism in diabetic mice

Paramylon is a polysaccharide primarily composed of β-1,3-glucan, characterized by its high crystallinity and insolubility in water. Enhancing its water solubility through structural modifications presents an effective strategy to unlock its biological activity. In this study, carboxymethylation was employed to produce carboxymethylated paramylon (CEP) with varying carboxyl concentrations. The successful introduction of carboxyl groups led to a notable improvement in water solubility. In vivo experiments demonstrated that CEP reduced fasting blood glucose levels by 24.42 %, improved oral glucose tolerance, and enhanced insulin sensitivity in diabetic mice. Additionally, CEP regulated lipid homeostasis and ameliorated liver damage. Through modulation of the adenosine monophosphate-activated protein kinase/phosphoinositide 3-kinase/protein kinase B pathway and the glucose-6-phosphatase/phosphoenolpyruvate carboxykinase pathway, CEP effectively regulated hepatic glucose absorption and production. Furthermore, CEP mitigated diabetes-induced lipid metabolism disorders. These findings suggest that CEP holds significant promise in ameliorating glucose metabolism disorder, indicating its potential as a novel hypoglycemic functional food.

Microbial oil, alone or paired with β-glucans, can control hypercholesterolemia in a zebrafish model

Dyslipidemia is often associated with unhealthy dietary habits, and many mammalian studies have explored the mode of action of certain bioactive compounds such as β-glucans and n-3 PUFAs to understand their potential to normalize the lipid metabolism. There are only a few investigations that adopted omic approaches to unveil their combined effect on hypercholesterolemia. Zebrafish (Danio rerio) was used as a model organism to reveal the efficacy of Schizochytrium oil and β-glucans (from Euglena gracilis and Phaeodactylum tricornutum) against cholesterol-rich diet induced dyslipidemia. One of the folowing four diets was fed to a particular group of fish: a control high-cholesterol diet, a Schizochytrium oil diet or one of the two diets containing the oil and β-glucan. The plasma HDL, expression of hepatic genes linked to, among others, ferric ion binding and plasma phosphatidylcholines were higher and plasma cholesterol esters and triacylglycerols were lower in the microbial oil-fed fish compared to the fish fed high cholesterol diet. While the fish fed a mix of microbial oil and Euglena β-glucan had lower plasma triacylglycerols and expression of hepatic genes linked to PPAR signaling pathway and enriched biosynthesis of plasma unsaturated fatty acids, the fish fed microbial oil-Phaeodactylum β-glucan combination had lower abundance of triacylglycerols rich in saturated and mono-unsaturated fatty acids and cholesterol esters in the plasma.

Metabolomic analysis and pathway profiling of paramylon production in Euglena gracilis grown on different carbon sources

Paramylon (β-1,3-glucan) produced by Euglena gracilis displays antioxidant, antitumor, and hypolipidaemic functions. The biological properties of paramylon production by E. gracilis can be understood by elucidating the metabolic changes within the algae. In this study, the carbon sources in AF-6 medium were replaced with glucose, sodium acetate, glycerol, or ethanol, and the paramylon yield was measured. Adding 0.1260 g/L glucose to the culture medium resulted in the highest paramylon yield of 70.48 %. The changes in metabolic pathways in E. gracilis grown on glucose were assessed via non-targeted metabolomics analysis using ultra-high-performance liquid chromatography coupled to high-resolution quadrupole-Orbitrap mass spectrometry. We found that glucose, as a carbon source, regulated some differentially expressed metabolites, including l-glutamic acid, γ-aminobutyric acid (GABA), and l-aspartic acid. Pathway analysis using the Kyoto Encyclopedia of Genes and Genomes further showed that glucose regulated the carbon and nitrogen balance through the GABA shunt, which enhanced photosynthesis, regulated the flux of carbon and nitrogen into the tricarboxylic acid cycle, promoted glucose uptake, and increased the accumulation of paramylon. This study provides new insights into E. gracilis metabolism during paramylon synthesis.

Sustainable production and pharmaceutical applications of β-glucan from microbial sources

β-glucans are a large class of complex polysaccharides found in abundant sources. Our dietary sources of β-glucans are cereals that include oats and barley, and non-cereal sources can consist of mushrooms, microalgae, bacteria, and seaweeds. There is substantial clinical interest in β-glucans; as they can be used for a variety of diseases including cancer and cardiovascular conditions. Suitable sources of β-glucans for biopharmaceutical applications include bacteria, microalgae, mycelium, and yeast. Environmental factors including culture medium can influence the biomass and ultimately β-glucan content. Therefore, cultivation conditions for the above organisms can be controlled for sustainable enhanced production of β-glucans. This review discusses the various sources of β-glucans and their cultivation conditions that may be optimised to exploit sustainable production. Finally, this article discusses the immune-modulatory potential of β-glucans from these sources.

Euglena gracilis-derived β-glucan paramylon entrains the peripheral circadian clocks in mice

Paramylon, a β-1,3-glucan storage polysaccharide derived from Euglena gracilis, has various health benefits, such as anti-obesity effects and modulation of immune function. However, whether paramylon intake affects the circadian clock remains unknown. In this study, we examined the effect of paramylon intake on the circadian clock. The results showed that the paramylon intake regulated peripheral clocks in mice. Furthermore, cecal pH and short-chain fatty acid concentrations after paramylon intake were measured. The correlation between changes in the expression of clock-related genes and alterations in the intestinal environment was confirmed. In addition, peripheral clock entrainment by paramylon intake was not observed in antibiotic-treated mice whose gut microbiota was weakened. These findings suggest that the regulation of the circadian clock by paramylon intake was mediated by changes in gut microbiota. In addition, the entraining effect of paramylon intake was also confirmed in mice bred under conditions mimicking social jetlag, which implies that paramylon intake may contribute to recovery from social jetlag. Thus, the appropriate consumption of paramylon may have a beneficial effect on health from a chrono-nutritional perspective.

Effects of paramylon-rich Euglena gracilisEOD-1 powder on visceral fat obesity in moderately obese Japanese adults: A randomized, double-blind, placebo-controlled, parallel-group trial

To investigate whether supplementation of paramylon (PM)-rich Euglena gracilis EOD-1 powder (EOD-1) reduces visceral fat obesity in moderately obese Japanese subjects. A randomized, double-blind, placebo-controlled intervention study was conducted involving 36 Japanese adults with a body mass index (BMI) ≥25 and <30 kg/m2. Subjects were randomly assigned into two groups to consume EOD-1 capsules (EOD-1 group, 2.6 g PM/day) or cellulose capsules (placebo group) for a 12-week period. Anthropometric measurements including visceral fat area (VFA) and blood samples were measured at baseline and throughout the trial. There was no significant difference in VFA between the two groups, although subgroup analysis by gender showed a significant decrease in VFA in the male EOD-1 group compared with the placebo group. Serum adiponectin levels in all subjects from the EOD-1 group were significantly higher than in the placebo group. By comparison with the placebo group, the subjects in the EOD-1 group showed a significant reduction in serum HbA1c levels. EOD-1 intake led to a significant reduction in VFA in male subjects with moderate obesity (BMI 25-30 kg/m2). PM in EOD-1 may contribute to preventing visceral fat obesity in male Japanese subjects. Moreover, PM may also contribute to improving glucose homeostasis in moderately obese Japanese adults.

Dectin-1 reactivity to paramylon derived from Euglena gracilis EOD-1

Euglena gracilis is a microalga that has recently attracted attention because of its bioactivities. Paramylon (PM), a major β-1,3-glucan, constitutes 70%-80% of the cells of the E. gracilis EOD-1 strain. Dectin-1 is a pattern recognition receptor that recognizes β-glucan. However, it is unclear whether PM binds to dectin-1. In this study, we investigated the reactivity of EOD1PM with dectin-1 by analyzing the binding of soluble murine and human dectin-1-Fc fusion protein (m dectin-1 Fc, h dectin-1 Fc) to EOD1PM using flow cytometry and ELISA.m dectin-1 Fc bound to EOD1PM particles when m dectin-1-Fc is added. Furthermore, the binding specificity was examined in a competitive reaction following addition of a soluble antigen. It was found that the binding of m dectin-1-Fc to EOD1PM was not inhibited by the addition of dextran or ovalbumin but by the addition of solubilized EOD1PM or Candida cell wall- solubilized β-glucan. In addition, the h dectin-1-Fc fusion protein was found to specifically bind to EOD1PM. These results suggest that dectin-1 recognizes and binds to the β-glucan structure of EOD1PM.Dectin-1 is expressed in leukocytes as a β-glucan receptor and is involved in the expression of various biological activities; therefore, the dectin-1 pathway may be involved in the biological activity of EOD1PM.

Immunoenhancing Effects of Euglena gracilis on a Cyclophosphamide-Induced Immunosuppressive Mouse Model

In this study, the effects of the immune stimulator Euglena gracilis (Euglena) in cyclophosphamide (CCP)-induced immunocompromised mice were assessed. The key component β-1,3-glucan (paramylon) constitutes 50% of E. gracilis. Mice were orally administered Euglena powder (250 and 500 mg/kg body weight (B.W.)) or β-glucan powder (250 mg/kg B.W.) for 19 days. In a preliminary immunology experiment, ICR mice were intraperitoneally injected with 80 mg of CCP/kg B.W. during the final 3 consecutive days. In the main experiment, BALB/c mice were treated with CCP for the final 5 days. To evaluate the enhancing effects of Euglena on the immune system, mouse B.W., the spleen index, natural killer (NK) cell activity and mRNA expression in splenocytes lungs and livers were determined. To detect cytokine and receptor expression, splenocytes were treated with 5 μg/ml concanavalin A or 1 μg/ml lipopolysaccharide. The B.W. and spleen index were significantly increased and NK cell activity was slightly enhanced in all the experimental groups compared to the CCP group. In splenocytes, the gene expression levels of tumor necrosis factor-α, interferon-γ, interleukin (IL)-10, IL-6, and IL-12 receptor were increased in the E. gracilis and β-glucan groups compared to the CCP group, but there was no significant difference. Treatment with 500mg of Euglena/kg B.W. significantly upregulated dectin-1 mRNA expression in the lung and liver compared to the CCP group. These results suggest that Euglena may enhance the immune system by strengthening innate immunity through immunosuppression.

Paramylon from Euglena gracilis Prevents Lipopolysaccharide-Induced Acute Liver Injury

Acute liver injury (ALI) is a life-threatening syndrome with high mortality and lacks effective therapies. Rodents under LPS (lipopolysaccharide)/D-Gal (D-galactosamine) stress mimic ALI by presenting dramatically increased inflammation and cell death in the liver. Euglena gracilis, functioning like dietary fiber, is commonly used as a paramylon (Pa)-rich nutritional supplement that has various biological effects such as regulating immune system, anti-obesity, and anti-tumor. Here, we found that Pa or sonicated and alkalized paramylon (SA-Pa) alleviated the LPS/D-Gal-induced hepatic histopathological abnormalities in mice. Compared with Pa, SA-Pa had lower molecular weights/sizes and showed better efficacy in alleviating injury-induced hepatic functions, as well as the transcriptional levels of inflammatory cytokines. Moreover, SA-Pa treatment promoted M2 macrophage activation that enhanced the anti-inflammatory function in the liver, and downregulated STAT3 target genes, such as Fos, Jun, and Socs3 upon the injury. Meanwhile, SA-Pa treatment also alleviated apoptosis and necroptosis caused by the injury. Our results demonstrated that SA-Pa efficiently protected the liver from LPS/D-Gal-induced ALI by alleviating inflammation and cell death.

Paramylon extracted from Euglena gracilis EOD-1 augmented the expression of SIRT1

Euglena gracilis, a type of microalgae, contains several nutrients and accumulates paramylon, a β-1,3-glucan. In recent studies, paramylon has shown to exhibit various activities including immunomoduratory and hepatoprotective effects. In the present study, using an in vitro cell culture system, we aimed to determine whether paramylon derived from the E. gracilis EOD-1 strain, which produces large amounts of paramylon, can augment SIRT1 expression in epidermal cells via activating gut–skin interactions. Results showed that paramylon augmented the expression of SIRT1 in Caco-2 cells, a human intestinal cell line. Furthermore, microarray analysis of Caco-2 cells treated with paramylon showed that paramylon activates epidermal cells through inducing the secretion of factors from intestinal cells. Then, we focused on skin cells as target cells of paramylon-activated intestinal cells. Results showed that secretory factors from Caco-2 cells treated with paramylon augmented the expression of SIRT1 in HaCaT cells, a human keratinocyte cell line, and that expression level of genes related to the growth and maintenance of epidermal cells were significantly changed in Caco-2 cells treated with paramylon as evidenced by microarray analysis. All these results suggest that paramylon can activate epidermal cells by inducing the production of secretory factors from intestinal cells.

Microarray Analysis of Paramylon, Isolated from Euglena Gracilis EOD-1, and Its Effects on Lipid Metabolism in the Ileum and Liver in Diet-Induced Obese Mice

We previously showed that supplementation of a high fat diet with paramylon (PM) reduces the postprandial glucose rise, serum total and LDL cholesterol levels, and abdominal fat accumulation in mice. The purpose of this study was to explore the underlying mechanism of PM using microarray analysis. Male mice (C57BL/BL strain) were fed an experimental diet (50% fat energy) containing 5% PM isolated from Euglena gracilis EOD-1 for 12 weeks. After confirming that PM had an improving effect on lipid metabolism, we assessed ileal and hepatic mRNA expression using DNA microarray and subsequent analysis by gene ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The results suggested that dietary supplementation with PM resulted in decreased abdominal fat accumulation and serum LDL cholesterol concentrations via suppression of the digestion and absorption pathway in the ileum and activation of the hepatic PPAR signaling pathway. Postprandial glucose rise was reduced in mice fed PM, whereas changes in the glucose metabolism pathway were not detected in GO classification and KEGG pathway analysis. PM intake might enhance serum secretory immunoglobulin A concentrations via promotion of the immunoglobulin production pathway in the ileum.

Isolation and Characterization of Euglena gracilis-Associated Bacteria, Enterobacter sp. CA3 and Emticicia sp. CN5, Capable of Promoting the Growth and Paramylon Production of E. gracilis under Mixotrophic Cultivation

Euglena gracilis produces paramylon, which is a feedstock for high-value functional foods and nutritional supplements. The enhancement of paramylon productivity is a critical challenge. Microalgae growth-promoting bacteria (MGPB) can improve microalgal productivity; however, the MGPB for E. gracilis remain unclear. This study isolated bacteria capable of enhancing E. gracilis growth and paramylon production under mixotrophic conditions. Enterobacter sp. CA3 and Emticicia sp. CN5 were isolated from E. gracilis grown with sewage-effluent bacteria under mixotrophic conditions at pH 4.5 or 7.5, respectively. In a 7-day E. gracilis mixotrophic culture with glucose, CA3 increased E. gracilis biomass and paramylon production 1.8-fold and 3.5-fold, respectively (at pH 4.5), or 1.9-fold and 3.5-fold, respectively (at pH 7.5). CN5 increased E. gracilis biomass and paramylon production 2.0-fold and 4.1-fold, respectively (at pH 7.5). However, the strains did not show such effects on E. gracilis under autotrophic conditions without glucose. The results suggest that CA3 and CN5 promoted both E. gracilis growth and paramylon production under mixotrophic conditions with glucose at pH 4.5 and 7.5 (CA3) or pH 7.5 (CN5). This study also provides an isolation method for E. gracilis MGPB that enables the construction of an effective E. gracilis–MGPB-association system for increasing the paramylon yield of E. gracilis.

Effects of Euglena gracilis Intake on Mood and Autonomic Activity under Mental Workload, and Subjective Sleep Quality: A Randomized, Double-Blind, Placebo-Controlled Trial

While the human body maintains homeostasis by altering the balance in the autonomic nervous, endocrine, and immune systems, a prolonged imbalance in these systems can result in physical and mental symptoms, including a decline in sleep quality and work efficiency. Euglena gracilis (Euglena) is a single-celled microalga with the properties of both plants and animals and contains abundant nutrients, such as vitamins, minerals, amino acids, and fatty acids, which have various beneficial health effects. This study evaluated the effects of Euglena intake on the mood states and stress coping under mental workload tasks, and subjective sleep quality. We assigned men and women aged 20 to 64 years to Euglena and placebo intake groups, and measured indices related to the autonomic nervous system, psychological states, and sleep quality together with the application of workload stress before food intake, and 4, 8, and 12 weeks after commencing intake. Euglena intake regulated the autonomic nervous system under a workload and improved psychological parameters and sleep conditions. These results indicate that the consumption of Euglena may regulate the balance of the autonomic nervous system during stress and may have a favorable effect on psychological status and sleep quality.

Effect of Food Containing Paramylon Derived from Euglena gracilis EOD-1 on Fatigue in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Trial

Euglena gracilis EOD-1, a kind of microalgae, is known to contain a high proportion of paramylon, a type of β-1,3-glucan. Paramylon derived from E. gracilis EOD-1 is presumed to suppress cellular oxidative injury and expected to reduce fatigue and fatigue sensation. Therefore, we aimed to examine whether food containing paramylon derived from E. gracilis EOD-1 (EOD-1PM) ingestion reduced fatigue and fatigue sensation in healthy adults. We conducted a randomized, double-blind, placebo-controlled, parallel-group comparison study in 66 healthy men and women who ingested a placebo or EOD-1PM daily for 4 weeks (daily life fatigue). Furthermore, at the examination days of 0 and 4 weeks, tolerance to fatigue load was evaluated using mental tasks (task-induced fatigue). We evaluated fatigue sensation using the Visual Analogue Scale, the work efficiency of the advanced trail making test and measured serum antioxidant markers. The EOD-1PM group showed significantly lower levels of physical and mental fatigue sensations and higher levels of work efficiency as well as serum biological antioxidant potential levels than the placebo group. These results indicate that EOD-1PM ingestion reduced fatigue and fatigue sensation, which may be due to an increase in antioxidant potential and maintenance of selective attention during work.

Euglena Gracilis and β-Glucan Paramylon Induce Ca2+ Signaling in Intestinal Tract Epithelial, Immune, and Neural Cells

The intestinal tract contains over half of all immune cells and peripheral nerves and manages the beneficial interactions between food compounds and the host. Paramylon is a β-1,3-glucan storage polysaccharide from Euglena gracilis (Euglena) that exerts immunostimulatory activities by affecting cytokine production. This study investigated the signaling mechanisms that regulate the beneficial interactions between food compounds and the intestinal tract using cell type-specific calcium (Ca²⁺) imaging in vivo and in vitro. We successfully visualized Euglena- and paramylon-mediated Ca²⁺ signaling in vivo in intestinal epithelial cells from mice ubiquitously expressing the Yellow Cameleon 3.60 (YC3.60) Ca²⁺ biosensor. Moreover, in vivo Ca²⁺ imaging demonstrated that the intraperitoneal injection of both Euglena and paramylon stimulated dendritic cells (DCs) in Peyer’s patches, indicating that paramylon is an active component of Euglena that affects the immune system. In addition, in vitro Ca²⁺ imaging in dorsal root ganglia indicated that Euglena, but not paramylon, triggers Ca²⁺ signaling in the sensory nervous system innervating the intestine. Thus, this study is the first to successfully visualize the direct effect of β-1,3-glucan on DCs in vivo and will help elucidate the mechanisms via which Euglena and paramylon exert various effects in the intestinal tract.

Hypolipidemic Effects of β-Glucans, Mannans, and Fucoidans: Mechanism of Action and Their Prospects for Clinical Application

The search for lipid-lowering drugs is important for clinical medicine. This review summarizes our research findings regarding the hypolipidemic activity of polysaccharides. There are several validated agents altering lipid levels which reduce the risk of atherosclerotic cardiovascular events. Nonetheless, for many people, the risk of such an event remains unacceptably high despite treatment with these agents. This situation has prompted the search for new therapies to reduce the residual cardiovascular risk. The lipid-lowering effect of β-glucans consumed with food was demonstrated in patients with atherosclerosis. The mechanism of the protective effect of β-glucans is poorly studied. The effects of β-glucans are mediated by Toll-like receptors, by dectin-1, and possibly by other receptors. Nevertheless, the mechanism of the protective action of β-glucan in lipemic mice has been studied insufficiently. This review will present up-to-date information regarding experimental hypolipidemic polysaccharide compounds that hold promise for medicine. Phagocyte-specific chitotriosidase in humans contributes to innate immune responses against chitin-containing fungi. This enzyme has been first described in patients with Gaucher disease and serves as an important diagnostic biomarker. It has been reported that, in mice, chitin particles of certain size are recognized by macrophages through Toll-like receptors, dectin-1, and to a lesser extent through mannose receptor.

Morphometric Analysis of Paramylon Particles Produced by Euglena gracilis EOD-1 Using FIB/SEM Tomography

Euglena gracilis EOD-1, a microalgal strain, produces large quantities of paramylon, a class of polymers known as β-1,3-glucans and has been reported to function as a dietary fiber and to improve the metabolic syndrome including obesity. However, despite its importance, the morphometric analysis of paramylon has not been conducted so far. In this study, we attempted to observe the detailed three-dimensional structure of paramylon by focused ion beam/scanning electron microscopy (FIB/SEM). Paramylon samples were fixed and three-dimensional image reconstruction and segmentation of the image stack were created using computer software (Amira v6.0.1, FEI). The results indicated that the inside of paramylon particles (diameter: 5 µm, thickness: 3 µm) was comprised of a dense structure with no evidence of the presence of large pores and gaps, although a small 100 nm crack was observed. The specific surface area of paramylon particles measured by the Brunauer-Emmet-Teller (BET) method, was not as large as activated charcoal, but similar to those of plant starches, indicating that the cholesterol-lowering effect of paramylon cannot be simply attributed to its adsorption ability. The FIB/SEM method was found to be useful for elucidating the internal structure of small solid particles.