Ishophloroglucin A, a Novel Phlorotannin for Standardizing the Anti-α-Glucosidase Activity of Ishige okamurae

The Beneficial Roles of Seaweed in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic, inflammatory skin condition characterized by severe pruritus and recurrent flare-ups, significantly impacting patients' quality of life. Current treatments, such as corticosteroids and immunomodulators, often provide symptomatic relief but can lead to adverse effects with prolonged use. Seaweed, a sustainable and nutrient-dense resource, has emerged as a promising alternative due to its rich bioactive compounds-polysaccharides, phlorotannins, polyphenols, and chlorophyll-that offer anti-inflammatory, antioxidant, and immunomodulatory properties. This review explores the therapeutic potential of brown, red, and green algae in alleviating AD symptoms, highlighting the effects of specific species, including Undaria pinnatifida, Laminaria japonica, Chlorella vulgaris, and Sargassum horneri. These seaweeds modulate immune responses, reduce epidermal thickness, and restore skin barrier function, presenting a novel, safe, and effective approach to AD management. Further clinical studies are needed to confirm their efficacy and establish dosing strategies, paving the way for seaweed-derived therapies as natural alternatives in AD treatment.

A review on anti-nutritional factors: unraveling the natural gateways to human health

Humans are constantly facing multiple health challenges from both communicable and non-communicable diseases that significantly affect their health. Additionally, drug resistance or failure has made the situation even worse and poses serious challenges for researchers to develop new drugs. Hence, to address these problems, there is an urgent need to discover and develop timely and long-term-based therapeutic treatments from different sources. One such approach is harnessing the potential of plant secondary metabolites. Plants have been utilized for therapeutic purposes in addition to being used for nutritional benefits. In the last two decades, plant-based drug developments have been one of the effective means of treating human diseases owing to their multiple functions. More recently, anti-nutritional factors (ANFs) have emerged as one of the important targets for novel plant-based drug development due to their multifaceted and potential pharmacological properties. However, their anti-nutritional properties have been the major setback for their limited success in the pharmacological sector. In this review, we provide an overview of ANFs and their beneficial roles in preventing human diseases with multiple case studies. We also highlight the recent developments and applications of ANFs in the food industry, agriculture, and pharmaceutics with future perspectives. Furthermore, we evaluate meta-analyses on ANFs from the last 30 years in relation to their function in human health benefits. This review is an endeavor to reevaluate the merit of these natural compounds and explore their potential for both human and animal health.

Hypoglycaemic Molecules for the Management of Diabetes Mellitus from Marine Sources

Diabetes mellitus (DM) is a chronic metabolic disorder recognized as a major health problem globally. A defective insulin activity contributes to the prevalence and expansion of DM. Treatment of DM is often hampered by limited options of conventional therapies and adverse effects associated with existing procedures. This has led to a spike in the exploration for potential therapeutic agents from various natural resources for clinical applications. The marine environment is a huge store of unexplored diversity of chemicals produced by a multitude of organisms. To date, marine microorganisms, microalgae, macroalgae, corals, sponges, and fishes have been evaluated for their anti-diabetic properties. The structural diversity of bioactive metabolites discovered has shown promising hypoglycaemic potential through in vitro and in vivo screenings via various mechanisms of action, such as PTP1B, α-glucosidase, α-amylase, β-glucosidase, and aldose reductase inhibition as well as PPAR alpha/gamma dual agonists activities. On the other hand, hypoglycaemic effect is also shown to be exerted through the balance of antioxidants and free radicals. This review highlights marine-derived chemicals with hypoglycaemic effects and their respective mechanisms of action in the management of DM in humans.

In Vitro and In Vivo Antidiabetic, α-Glucosidase Inhibition and Antibacterial Activities of Three Brown Algae, Polycladia myrica, Padina antillarum, and Sargassum boveanum, and a Red Alga, Palisada perforata from the Persian Gulf

Background

In recent decades, algae have attracted worldwide attention for their great biological activities, such as antidiabetic and antibacterial properties.

Objectives

We measured antibacterial and α-glucosidase inhibition potential of methanol and 80% methanol extracts of three brown algae species, Polycladia myrica, Padina antillarum, and Sargassum boveanum, and a red alga, Palisada perforata, from the Persian Gulf coasts.

Methods

Antibacterial activity of the algal extracts was assessed by broth dilution method against three gram-negative and -positive bacteria, including Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa; Staphylococcus epidermidis, Staphylococcus aureus, and Bacillus subtilis, respectively. Furthermore, the yeast's α-glucosidase inhibition of the algal extracts was measured via colorimetric assay. In addition, we investigated the beneficial effect of 80% MeOH extract of S. boveanum on the blood glucose levels in streptozotocin-induced diabetic rats.

Results

The MeOH extract of S. boveanum was the best antibacterial extract with MIC = 2.5 mg/mL against all bacterial strains except for E. coli. The MeOH and 80% MeOH extracts of P. myrica and P. antillarum inhibited α-glucosidase at most with IC50 values of 12.70 ± 1.88 µg/mL and 13.06 ± 4.44 µg/mL, respectively. The oral gavage of S. boveanum extract in streptozotocin- (STZ-) induced diabetic rats resulted in decreasing their postprandial blood glucose levels. The algae and acarbose decreased blood glucose levels after sucrose administration in 60 minutes, compared to the non-drug-treated animals, with p values of 0.03 and 0.007, respectively.

Conclusions

Overall, due to the in vitro and in vivo antidiabetic potential of S. boveanum, we suggest the alga as a new source for the isolation and identification of potential antidiabetic and antibacterial compounds.

Polyphenolic Compounds Isolated from Marine Algae Attenuate the Replication of SARS-CoV-2 in the Host Cell through a Multi-Target Approach of 3CLpro and PLpro

A global health concern has emerged as a response to the recent SARS-CoV-2 pandemic. The identification and inhibition of drug targets of SARS-CoV-2 is a decisive obligation of scientists. In addition to the cell entry mechanism, SARS-CoV-2 expresses a complicated replication mechanism that provides excellent drug targets. Papain-like protease (PLpro) and 3-chymotrypsin-like protease (3CLpro) play a vital role in polyprotein processing, producing functional non-structural proteins essential for viral replication and survival in the host cell. Moreover, PLpro is employed by SARS-CoV-2 for reversing host immune responses. Therefore, if some particular compound has the potential to interfere with the proteolytic activities of 3CLpro and PLpro of SARS-CoV-2, it may be effective as a treatment or prophylaxis for COVID-19, reducing viral load, and reinstating innate immune responses. Thus, the present study aims to inhibit SARS-CoV-2 through 3CLpro and PLpro using marine natural products isolated from marine algae that contain numerous beneficial biological activities. Molecular docking analysis was utilized in the present study for the initial screening of selected natural products depending on their 3CLpro and PLpro structures. Based on this approach, Ishophloroglucin A (IPA), Dieckol, Eckmaxol, and Diphlorethohydroxycarmalol (DPHC) were isolated and used to perform in vitro evaluations. IPA presented remarkable inhibitory activity against interesting drug targets. Moreover, Dieckol, Eckmaxol, and DPHC also expressed significant potential as inhibitors. Finally, the results of the present study confirm the potential of IPA, Dieckol, Eckmaxol, and DPHC as inhibitors of SARS-CoV-2. To the best of our knowledge, this is the first study that assesses the use of marine natural products as a multifactorial approach against 3CLpro and PLpro of SARS-CoV-2.

Ishophloroglucin A, a potent PTP1B inhibitor isolated from brown alga Ishige okamurae inhibits adipogenesis in 3T3-L1 adipocytes

Ishophloroglucin A (IPA) is one of the most abundant and active compounds in Ishige okamurae and is known to be a potential therapeutic candidate for the improvement of metabolic diseases. However, IPA on the inhibitory effects of protein tyrosine phosphatase 1B (PTP1B) and adipogenesis have not been determined. In this study, we investigated the effects of IPA on the inhibition of PTP1B, the effects on adipogenesis, and its mechanisms of action in 3 T3-L1 adipocytes. The IC50 value of IPA against PTP1B was 0.43 μM, which evidenced the higher inhibition activity than that of ursolic acid, a known PTP1B inhibitor. For further insight, we predicted the 3D structure of PTP1B and used a docking algorithm to simulate the binding between PTP1B and IPA. Molecular docking studies revealed a high and stable binding affinity between IPA and PTP1B and indicated that the IPA could interacts with the amino acid residues located in a region to the active site of PTP1B. Further studies showed that IPA concentrations between 6.25 μM and 25 μM dose-dependently attenuated adipogenesis, which was accompanied by a reduction in adipogenesis-related factors, including PPARγ, C/EBPα, SREBP-1c, and FABP4. Our findings suggested that IPA may be a promising natural compound for the treatment of obesity and related diseases.

Effect of Ishige okamurae extract on musculoskeletal biomarkers in adults with relative sarcopenia: Study protocol for a randomized double-blind placebo-controlled trial

Introduction

Sarcopenia is a phenomenon in which skeletal muscle mass decreases with age, causing many health problems. Many studies have been conducted to improve sarcopenia nutritionally. Ishige okamura (IO) is a genus of brown algae and plays a role in anti-diabetes, anti-obesity, and myogenesis. However, the effect of IO extract (IOE) on human muscle strength and mass is unclear. Therefore, we will examine the impact and safety of consumption of IOE for 12 weeks on muscle strength and mass in middle-aged and old-aged adults with relatively low skeletal muscle mass.

Materials and methods

A randomized controlled trial is conducted on 80 adults aged 50–80. A total of 80 participants will be enrolled in this study. Participants assign IOE-taking group (n = 40) and placebo taking group (n = 40). At a baseline and 12 weeks after treatment, the following parameters of the participants are checked: knee extension strength, handgrip strength, body composition, laboratory tests, dietary recall, physical activity, and EQ-5D-5L.

Discussion

The present study will be the first randomized, double-blind placebo-controlled trial to examine the efficacy and tolerability of IOE supplementation in adults with relatively low muscle mass. The nutritional intake and physical activity that might influence muscle strength and mass will be considered as covariates for transparency of results. The results of this study will provide clinical evidence for sarcopenia patients with nutrient treatment.

Clinical Trial Registration

www.clinicaltrials.gov/, Identifier: NCT04617951.

Seaweed-Derived Phlorotannins: A Review of Multiple Biological Roles and Action Mechanisms

Phlorotannins are a group of phenolic secondary metabolites isolated from a variety of brown algal species belonging to the Fucaceae, Sargassaceae, and Alariaceae families. The isolation of phlorotannins from various algal species has received a lot of interest owing to the fact that they have a range of biological features and are very biocompatible in their applications. Phlorotannins have a wide range of therapeutic biological actions, including antimicrobial, antidiabetic, antioxidant, anticancer, anti-inflammatory, anti-adipogenesis, and numerous other biomedical applications. The current review has extensively addressed the application of phlorotannins, which have been extensively investigated for the above-mentioned biological action and the underlying mechanism of action. Furthermore, the current review offers many ways to use phlorotannins to avoid certain downsides, such as low stability. This review article will assist the scientific community in investigating the greater biological significance of phlorotannins and developing innovative techniques for treating both infectious and non-infectious diseases in humans.

Ishophloroglucin A, Isolated from Ishige okamurae, Alleviates Dexamethasone-Induced Muscle Atrophy through Muscle Protein Metabolism In Vivo

The in vitro capacity of Ishige okamurae extract (IO) to improve impaired muscle function has been previously examined. However, the mechanism underlying IO-mediated muscle protein metabolism and the role of its component, Ishophloroglucin A (IPA), in mice with dexamethasone (Dexa)-induced muscle atrophy remains unknown. In the present study, we evaluated the effect of IO and IPA supplementation on Dexa-induced muscle atrophy by assessing muscle protein metabolism in gastrocnemius and soleus muscles of mice. IO and IPA supplementation improved the Dexa-induced decrease in muscle weight and width, leading to enhanced grip strength. In addition, IO and IPA supplementation regulated impaired protein synthesis (PI3K and Akt) or degradation (muscle-specific ubiquitin ligase muscle RING finger and atrogin-1) by modulating mRNA levels in gastrocnemius and soleus muscles. Additionally, IO and IPA upregulated mRNA levels associated with muscle growth activation (transient receptor potential vanilloid type 4 and adenosine A1 receptor) or inhibition (myostatin and sirtuin 1) in gastrocnemius and soleus muscle tissues of Dexa-induced mice. Collectively, these results suggest that IO and IO-derived IPA can regulate muscle growth through muscle protein metabolism in Dexa-induced muscle atrophy.

Marine algal flavonoids and phlorotannins; an intriguing frontier of biofunctional secondary metabolites

Algae are the oldest representatives of the plant world with reserves exceeding hundreds of millions of tons in the world's oceans. Currently, a growing interest is placed toward the use of algae as feedstocks for obtaining numerous natural products. Algae are a rich source of polyphenols that possess intriguing structural diversity. Among the algal polyphenols, phlorotannins, which are unique to brown seaweeds, and have immense value as potent modulators of biochemical processes linked to chronic diseases. In algae, flavonoids remain under-explored compared to other categories of polyphenols. Both phlorotannins and flavonoids are inclusive of compounds indicating a wide structural diversity. The present paper reviews the literature on the ecological significance, biosynthesis, structural diversity, and bioactivity of seaweed phlorotannins and flavonoids. The potential implementation of these chemical entities in functional foods, cosmeceuticals, medicaments, and as templates in drug design are described in detail, and perspectives are provided to tackle what are perceived to be the most momentous challenges related to the utilization of phlorotannins and flavonoids. Moving beyond: industrial biotechnology applications, metabolic engineering, total synthesis, biomimetic synthesis, and chemical derivatization of phlorotannins and flavonoids could broaden the research perspectives contributing to the health and economic up-gradation.

Therapeutic Potential of Seaweed-Derived Bioactive Compounds for Cardiovascular Disease Treatment

Cardiovascular diseases are closely related to hypertension, type 2 diabetes mellitus, obesity, and hyperlipidemia. Many studies have reported that an unhealthy diet and sedentary lifestyle are critical factors that enhance these diseases. Recently, many bioactive compounds isolated from marine seaweeds have been studied for their benefits in improving human health. In particular, several unique bioactive metabolites such as polyphenols, polysaccharides, peptides, carotene, and sterol are the most effective components responsible for these activities. This review summarizes the current in vitro, in vivo, and clinical studies related to the protective effects of bioactive compounds isolated from seaweeds against cardiovascular disorders, including anti-diabetic, anti-hypertensive, anti-hyperlipidemia, and anti-obesity effects. Therefore, this present review summarizes these concepts and provides a basis for further in-depth research.

Ishige okamurae Ameliorates Methylglyoxal-Induced Nephrotoxicity via Reducing Oxidative Stress, RAGE Protein Expression, and Modulating MAPK, Nrf2/ARE Signaling Pathway in Mouse Glomerular Mesangial Cells

Advanced glycation end-products (AGEs) such as methylglyoxal (MGO) play a vital role in the pathogenesis of nephropathy, a diabetic complication. In the present study, we evaluated the anti-glycation and renal protective properties of Ishige okamurae extract (IOE) against AGE-induced oxidative stress. HPLC analysis confirmed that bioactive phlorotannins such as diphlorethohydroxycarmalol and ishophloroglucin A are predominantly present in IOE. IOE showed strong anti-glycation activities via inhibition of AGE formation, inhibition of AGE-protein cross-linking, and breaking of AGE-protein cross-links. In addition, in vitro studies using mesangial cells demonstrated that IOE effectively suppressed intracellular reactive oxygen species production, intracellular MGO accumulation, and apoptotic cell death by MGO-induced oxidative stress, in addition to regulating the expression of proteins involved in the receptor for AGEs and nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response elements (ARE) signaling pathways. Therefore, IOE can serve as a natural therapeutic agent for the management of AGE-related nephropathy.

Marine natural products

This review covers the literature published between January and December in 2018 for marine natural products (MNPs), with 717 citations (706 for the period January to December 2018) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1554 in 469 papers for 2018), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. The proportion of MNPs assigned absolute configuration over the last decade is also surveyed.

Diphlorethohydroxycarmalol (DPHC) Isolated from the Brown Alga Ishige okamurae Acts on Inflammatory Myopathy as an Inhibitory Agent of TNF-α

Inflammation affects various organs of the human body, including skeletal muscle. Phlorotannins are natural biologically active substances found in marine brown algae and exhibit anti-inflammatory activities. In this study, we focused on the effects of phlorotannins on anti-inflammatory activity and skeletal muscle cell proliferation activity to identify the protective effects on the inflammatory myopathy. First, the five species of marine brown algal extracts dramatically inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells without toxicity at all the concentrations tested. Moreover, the extracts collected from Ishige okamurae (I. okamurae) significantly increased cell proliferation of C2C12 myoblasts compared to the non-treated cells with non-toxicity. In addition, as a result of finding a potential tumor necrosis factor (TNF)-α inhibitor that regulates the signaling pathway of muscle degradation in I. okamurae-derived natural bioactive compounds, Diphlorethohydroxycarmalol (DPHC) is favorably docked to the TNF-α with the lowest binding energy and docking interaction energy value. Moreover, DPHC down-regulated the mRNA expression level of pro-inflammatory cytokines and suppressed the muscle RING-finger protein (MuRF)-1 and Muscle Atrophy F-box (MAFbx)/Atrgoin-1, which are the key protein muscle atrophy via nuclear factor-κB (NF-κB), and mitogen-activated protein kinase (MAPKs) signaling pathways in TNF-α-stimulated C2C12 myotubes. Therefore, it is expected that DPHC isolated from IO would be developed as a TNF-α inhibitor against inflammatory myopathy.

Ishophloroglucin A Isolated from Ishige okamurae Suppresses Melanogenesis Induced by α-MSH: In Vitro and In Vivo

Diphlorethohydroxycarmalol (DPHC) isolated from Ishige okamurae (IO) showed potential whitening effects against UV-B radiation. However, the components of IO as well as their molecular mechanism against α-melanocyte-stimulating hormone (α-MSH) have not yet been investigated. Thus, this study aimed to investigate the inhibitory effects of Ishophloroglucin A (IPA), a phlorotannin isolated from brown algae IO, and its crude extract (IOE), in melanogenesis in vivo in an α-MSH-induced zebrafish model and in B16F10 melanoma cells in vitro. Molecular docking studies of the phlorotannins were carried out to determine their inhibitory effects and to elucidate their mode of interaction with tyrosinase, a glycoprotein related to melanogenesis. In addition, morphological changes and melanin content decreased in the α-MSH-induced zebrafish model after IPA and IOE treatment. Furthermore, Western blotting results revealed that IPA upregulated the extracellular related protein expression in α-MSH-stimulated B16F10 cells. Hence, these results suggest that IPA isolated from IOE has a potential for use in the pharmaceutical and cosmetic industries.

Protective Effect of Diphlorethohydroxycarmalol Isolated from Ishige okamurae Against Particulate Matter-Induced Skin Damage by Regulation of NF-κB, AP-1, and MAPKs Signaling Pathways In Vitro in Human Dermal Fibroblasts

Particulate matters (PM), the main contributor to air pollution, have become a serious issue that threatens human's health. Skin is the largest organ in humans, as well as the primary organ exposed to PM. Overexposure of PM induces skin damage. Diphlorethohydroxycarmalol (DPHC), an algal polyphenol with the potential of skin protection, has been isolated from the edible brown seaweed Ishige okamurae. The purpose of the present study is to investigate the protective effect of DPHC against PM (ERM-CZ100)-induced skin damage in human dermal fibroblasts (HDF) cells. The results indicated that DPHC significantly and dose-dependently reduced intracellular reactive oxygen species generation in HDF cells. In addition, DPHC significantly induced collagen synthesis and inhibited collagenase activity in ERM-CZ100-stimulated HDF cells. Further study demonstrated that DPHC remarkably reduced the expression of human matrix metalloproteinases through regulation of nuclear factor kappa B, activator protein 1, and mitogen-activated protein kinases signaling pathways in ERM-CZ100-stimulated HDF cells. This study suggested that DPHC is a potential candidate to protect skins against PM-induced damage, and it could be used as an ingredient in pharmaceutical and cosmeceutical industries.

Protective effect of diphlorethohydroxycarmalol isolated from Ishige okamurae against UVB-induced damage in vitro in human dermal fibroblasts and in vivo in zebrafish

Excessive exposure to ultraviolet (UV) irradiation from the sun is the primary environmental factor that causes aging of the skin. Most skin diseases caused by UV are attributed to UVB (280-320 nm). The purpose of this study is to investigate the protective effect of diphlorethohydroxycarmalol (DPHC), isolated from the marine brown alga, Ishige okamurae, against UVB-induced photodamage using both in vitro and in vivo models. Results indicate that DPHC remarkably inhibited commercial collagenase and elastase activities. It also reduced intracellular levels of ROS, improved cell viability and collagen content in UVB-irradiated human dermal fibroblasts (HDF cells). In addition, DPHC significantly inhibited activities of intracellular collagenase and elastase and reduced the expression of matrix metalloproteinases (MMPs) and pro-inflammatory cytokines. These events occurred through regulation of nuclear factor kappa B (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPKs) signaling pathways in UVB-irradiated HDF cells. Furthermore, DPHC also protected against in vivo photodamage by decreasing cell death through reducing lipid peroxidation and inflammatory response via decreasing ROS levels in UVB-irradiated zebrafish. In conclusion, DPHC has strong in vitro and in vivo photoprotective effects and has the potential to be used as an ingredient in pharmaceutical and cosmeceutical industries.

Ishige okamurae Extract and Its Constituent Ishophloroglucin A Attenuated In Vitro and In Vivo High Glucose-Induced Angiogenesis

Diabetes is associated with vascular complications, such as impaired wound healing and accelerated vascular growth. The different clinical manifestations, such as retinopathy and nephropathy, reveal the severity of enhanced vascular growth known as angiogenesis. This study was performed to evaluate the effects of an extract of Ishige okamurae (IO) and its constituent, Ishophloroglucin A (IPA) on high glucose-induced angiogenesis. A transgenic zebrafish (flk:EGFP) embryo model was used to evaluate vessel growth. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), gap closure, transwell, and Matrigel® assays were used to analyze the proliferation, migration, and capillary formation of EA.hy926 cells. Moreover, protein expression were determined using western blotting. IO extract and IPA suppressed vessel formation in the transgenic zebrafish (flk:EGFP) embryo. IPA attenuated cell proliferation, cell migration, and capillary-like structure formation in high glucose-treated human vascular endothelial cells. Further, IPA down regulated the expression of high glucose-induced vascular endothelial growth factor receptor 2 (VEGFR-2) and downstream signaling molecule cascade. Overall, the IO extract and IPA exhibited anti-angiogenic effects against high glucose-induced angiogenesis, suggesting their potential for use as therapeutic agents in diabetes-related angiogenesis.

Effect of Ishophloroglucin A, A Component of Ishige okamurae, on Glucose Homeostasis in the Pancreas and Muscle of High Fat Diet-Fed Mice

Ishophloroglucin A (IPA), a component of Ishige okamurae (IO), was previously evaluated to standardize the antidiabetic potency of IO. However, the potential of IPA as a functional food for diabetes prevention has not yet been evaluated. Here, we investigated if 1.35 mg/kg IPA, which is the equivalent content of IPA in 75 mg/kg IO, improved glucose homeostasis in high-fat diet (HFD)-induced diabetes after 12 weeks of treatment. IPA significantly ameliorated glucose intolerance, reducing fasting glucose levels as well as 2 h glucose levels in HFD mice. In addition, IPA exerted a protective effect on the pancreatic function in HFD mice via pancreatic β-cells and C-peptide. The level of glucose transporter 4 (GLUT4) in the muscles of HFD mice was stimulated by IPA intake. Our results suggested that IPA, which is a component of IO, can improve glucose homeostasis via GLUT4 in the muscles of HFD mice. IO may be used as a functional food for the prevention of diabetes.

Ishige okamurae Extract Ameliorates the Hyperglycemia and Body Weight Gain of db/db Mice through Regulation of the PI3K/Akt Pathway and Thermogenic Factors by FGF21

Type 2 diabetes mellitus and related metabolic disorders, such as dyslipidemia, present increasing challenges to health worldwide, as a result of urbanization, the increasing prevalence of obesity, poor lifestyle, and other stress-related factors. Ishige okamurae extract (IOE) is known to be effective at lowering blood glucose and ameliorating metabolic disease. However, detailed mechanisms for these effects have yet to be elucidated. Here, we show that IOE ameliorates substrate (IRS)/ phosphatidylinositol 3-kinase (PI3K)/Akt pathway and increasing glucose transporter 4 (GLUT4) expression in skeletal muscle and white adipose tissue (WAT). We also demonstrate that IOE increases the expression of fibroblast growth factor (FGF)21, a regulator of glucose and energy metabolism in muscle and WAT. In addition, IOE administration increased peroxisome proliferator-activated receptor γ coactivator 1α expression, which regulates expression of the key thermogenic molecule uncoupling protein 1 in WAT. Thus, the effects of IOE to ameliorate hyperglycemia and adiposity may be mediated through FGF21 activating insulin signaling and increasing the expression of GLUT4 and pro-thermogenic factors.

Anti-Obesity and Anti-Diabetic Effects of Ishige okamurae

Obesity is associated with several health complications and can lead to the development of metabolic syndrome. Some of its deleterious consequences are related to insulin resistance, which adversely affects blood glucose regulation. At present, there is a growing concern regarding healthy food consumption, owing to awareness about obesity. Seaweeds are well-known for their nutritional benefits. The brown alga Ishige okamurae (IO) has been studied as a dietary supplement and exhibits various biological activities in vitro and in vivo. The bioactive compounds isolated from IO extract are known to possess anti-obesity and anti-diabetic properties, elicited via the regulation of lipid metabolism and glucose homeostasis. This review focuses on IO extract and its bioactive compounds that exhibit therapeutic effects through several cellular mechanisms in obesity and diabetes. The information discussed in the present review may provide evidence to develop nutraceuticals from IO.

Ishige okamurae Extract Suppresses Obesity and Hepatic Steatosis in High Fat Diet-Induced Obese Mice

Obesity is caused by the expansion of white adipose tissue (WAT), which stores excess triacylglycerol (TG), this can lead to disorders including type 2 diabetes, atherosclerosis, metabolic diseases. Ishige okamurae extract (IOE) is prepared from a brown alga and has anti-oxidative properties. We investigated the detailed mechanisms of the anti-obesity activity of IOE. Treatment with IOE blocked lipid accumulation by reducing expression of key adipogenic transcription factors, such as CCAAT/enhancer-binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ), in 3T3-L1 cells. Administration of IOE to high fat diet (HFD)-fed mice inhibited body and WAT mass gain, attenuated fasting hyperglycemia and dyslipidemia. The obesity suppression was associated with reductions in expression of adipogenic proteins, such as C/EBPα and PPARγ, increases in expression of lipolytic enzymes, such as adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), in WAT of HFD-fed mice. In addition, IOE-treated mice had lower hepatic TG content, associated with lower protein expression of lipogenic genes, such as diglyceride acyltransferase 1 (DGAT1), sterol regulatory element-binding protein 1 (SREBP1), fatty acid synthase (FAS). IOE treatment also reduced serum free fatty acid concentration, probably through the upregulation of β-oxidation genes, suggested by increases in AMPKα and CPT1 expression in WAT and liver. In summary, IOE ameliorates HFD-induced obesity and its related metabolic disease, hepatic steatosis, by regulating multiple pathways.