Protective effect of diphlorethohydroxycarmalol isolated from Ishige okamurae against high glucose-induced-oxidative stress in human umbilical vein endothelial cells

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.

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.

Anti-Glucotoxicity Effect of Phytoconstituents via Inhibiting MGO-AGEs Formation and Breaking MGO-AGEs

The therapeutic benefits of phytochemicals in the treatment of various illnesses and disorders are well documented. They show significant promise for the discovery and creation of novel medications for treating a variety of human diseases. Numerous phytoconstituents have shown antibiotic, antioxidant, and wound-healing effects in the conventional system. Traditional medicines based on alkaloids, phenolics, tannins, saponins, terpenes, steroids, flavonoids, glycosides, and phytosterols have been in use for a long time and are crucial as alternative treatments. These phytochemical elements are crucial for scavenging free radicals, capturing reactive carbonyl species, changing protein glycation sites, inactivating carbohydrate hydrolases, fighting pathological conditions, and accelerating the healing of wounds. In this review, 221 research papers have been reviewed. This research sought to provide an update on the types and methods of formation of methylglyoxal-advanced glycation end products (MGO-AGEs) and molecular pathways induced by AGEs during the progression of the chronic complications of diabetes and associated diseases as well as to discuss the role of phytoconstituents in MGO scavenging and AGEs breaking. The development and commercialization of functional foods using these natural compounds can provide potential health benefits.

Ishige okamurae Attenuates Neuroinflammation and Cognitive Deficits in Mice Intracerebroventricularly Injected with LPS via Regulating TLR-4/MyD88-Dependent Pathways

Neuroinflammation is one of the critical causes of neuronal loss and cognitive impairment. We aimed to evaluate the anti-neuroinflammatory properties of Ishige okamuae using mice intracerebroventricularly injected with lipopolysaccharides (LPS) and LPS-treated C6 glioma cells. We found that the short- and long-term memory deficits of LPS-injected mice were improved by oral administration of Ishige okamurae extracts (IOE). LPS-induced neuronal loss, increase in amyloid-β plaque, and expression of COX-2 and iNOS were restored by IOE. In addition, LPS-induced activation of Toll-like receptor-4 (TLR-4) and its downstream molecules, such as MyD88, NFκB, and mitogen-activated protein kinases (MAPKs), were significantly attenuated in the brains of mice fed with IOE. We found that pretreatment of IOE to C6 glioma cells ameliorated LPS-induced expression of TLR-4 and its inflammatory cascades, such as MyD88 expression, reactive oxygen species production, MAPKs phosphorylation, and NFκB phosphorylation with consequent downregulation of COX-2, iNOS, proinflammatory cytokines, and nitric oxide expression. Furthermore, IOE (0.2 µg/mL) was found to have equivalent efficacy with 10 μM of MyD88 inhibitor in preventing LPS-induced inflammatory responses in C6 glioma cells. Taken together, these results strongly suggest that IOE could be developed as a promising anti-neuroinflammatory agent which is able to control the TLR-4/MyD88-dependent signaling pathways.

A novel alginate from Sargassum seaweed promotes diabetic wound healing by regulating oxidative stress and angiogenesis

Diabetic skin ulcer is one of the most severe complications in diabetes, however, current therapeutic approaches are not effective enough. Agents modulating oxidative stress, inflammation, and angiogenesis are quite promising for alleviation of diabetic skin ulcers. In this study, a novel Sargassum kjellmanianum-derived polysaccharide (SARP) was prepared. SARP was an alginate with Mw of 45.4 kDa, consisting of 76.56% mannuronic acid, 18.89% guluronic acid, and 4.55% glucuronic acid. SARP could attenuate oxidative stress-induced cell damage via activating nuclear factor erythroid 2-related factor 2 (Nrf2). SARP also promoted the migration and tube formation of HUVECs, which was related to the increased vascular endothelial growth factor (VEGF) expression. In diabetic wound model, SARP (iv, 200 mg/kg) administration increased angiogenesis, alleviated oxidative stress, ameliorated diabetes-related aberrations, and thereby accelerated diabetic wound healing. These findings identified SARP had potential to be developed as a drug candidate for diabetic skin ulcers.

Antidiabetic potential of seaweed and their bioactive compounds: a review of developments in last decade

Diabetes Mellitus is a public health problem worldwide due to high morbidity and mortality rate associated with it. Diabetes can be managed by synthetic hypoglycemic drugs, although their persistent uses have several side effects. Hence, there is a paradigm shift toward the use of natural products having antidiabetic potential. Seaweeds, large marine benthic algae, are an affluent source of various bioactive compounds, including phytochemicals and antioxidants thus exhibiting various health promoting properties. Seaweed extracts and its bioactive compounds have antidiabetic potential as they inhibit carbohydrate hydrolyzing enzymes in vitro and exhibit blood glucose lowering effect in random and post prandial blood glucose tests in vivo. In addition, they have been associated with reduced weight gain in animals probably by decreasing mRNA expression of pro-inflammatory cytokines with concomitant increase in mRNA expression levels of anti-inflammatory cytokines. Their beneficial effect has been seen in serum and hepatic lipid profile and antioxidant enzymes indicating the protective role of seaweeds against free radicals mediated oxidative stress induced hyperglycemia and associated hyperlipidemia. However, the detailed and in-depth studies of seaweeds as whole, their bioactive isolates and their extracts need to be explored further for their health benefits and wide application in food, nutraceutical and pharmaceutical industries.

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.

Dietary prenylated flavonoid xanthohumol alleviates oxidative damage and accelerates diabetic wound healing via Nrf2 activation

Diabetic skin ulcer is one of the most common complications in patients suffering diabetes mellitus. Xanthohumol (XN), a hop-derived prenylated dietary flavonoid, has multiple health beneficial bioactivities. In the present study, we reported XN alleviates oxidative damage and accelerates diabetic wound healing via Nrf2 activation. In vitro, XN attenuated hydrogen peroxide (H₂O₂)-induced cytotoxicity, ROS production, cell apoptosis, as well as high glucose-induced cell damage. Mechanistic studies further demonstrated that XN could stabilize nuclear factor erythroid 2-related factor 2 (Nrf2) and promote its nuclear translocation, which was associated with AMPKα activation and covalent modification of Keap1 by XN. In vivo, XN increased Nrf2 expression and accelerated diabetic wound healing. Our study revealed a novel function of XN in diabetic wound healing as well as the underlying molecular mechanisms, suggesting XN is a promising lead compound and a potential food and/or drug candidate for the treatment of diabetic skin ulcers.

Extraction and Nano-Sized Delivery Systems for Phlorotannins to Improve Its Bioavailability and Bioactivity

This review aims to provide an informative summary of studies on extraction and nanoencapsulation of phlorotannins to improve their bioavailability and bioactivity. The origin, structure, and different types of phlorotannins were briefly discussed, and the extraction/purification/characterization methods for phlorotannins were reviewed, with a focus on techniques to improve the bioactivities and bioavailability of phlorotannins via nano-sized delivery systems. Phlorotannins are promising natural polyphenol compounds that have displayed high bioactivities in several areas: anticancer, anti-inflammation, anti-HIV, antidiabetic, and antioxidant. This review aims to provide a useful reference for researchers working on developing better utilization strategies for phlorotannins as pharmaceuticals, therapeuticals, and functional food supplements.

Marine Algae-Derived Bioactive Compounds: A New Wave of Nanodrugs?

Marine algae are rich in bioactive nutraceuticals (e.g., carbohydrates, proteins, minerals, fatty acids, antioxidants, and pigments). Biotic (e.g., plants, microorganisms) and abiotic factors (e.g., temperature, pH, salinity, light intensity) contribute to the production of primary and secondary metabolites by algae. Easy, profitable, and sustainable recovery methods include novel solid-liquid and liquid-liquid extraction techniques (e.g., supercritical, high pressure, microwave, ultrasound, enzymatic). The spectacular findings of algal-mediated synthesis of nanotheranostics has attracted further interest because of the availability of microalgae-based natural bioactive therapeutic compounds and the cost-effective commercialization of stable microalgal drugs. Algal extracts can serve as stabilizing/capping and reducing agents for the synthesis of thermodynamically stable nanoparticles (NPs). Different types of nanotherapeutics have been synthesized using physical, chemical, and biological methods. Marine algae are a fascinating source of lead theranostics compounds, and the development of nanotheranostics has been linked to enhanced drug efficacy and safety. Indeed, algae are remarkable nanobiofactories, and their pragmatic properties reside in their (i) ease of handling; (ii) capacity to absorb/accumulate inorganic metallic ions; (iii) cost-effectiveness; and (iv) capacity of eco-friendly, rapid, and healthier synthesis of NPs. Preclinical and clinical trials shall enable to really define effective algal-based nanotherapies. This review aims to provide an overview of the main algal compounds that are nutraceuticals and that can be extracted and purified for nanotheranostic purposes.

Insights into phenolic compounds from microalgae: structural variety and complex beneficial activities from health to nutraceutics

Phenolic compounds (PCs) are a family of secondary metabolites with recognized biological activities making them attractive for the biomedical "red" biotechnology. The development of the eco-sustainable production of natural bioactive metabolites requires using easy cultivable organisms, such as microalgae, which represents one of the most promising sources for biotechnological applications. Microalgae are photosynthetic organisms inhabiting aquatic systems, displaying high levels of biological and functional diversities, and are well-known producers of fatty acids and carotenoids. They are also rich in other families of bioactive molecules e.g. phenolic compounds. Microalgal PCs however are less investigated than other molecular components. This study aims to provide a state-of-art picture of the actual knowledge on microalgal phenolic compounds, reviewing information on the PC content variety and chemodiversity in microalgae, their environmental modulation, and we aim to report discuss data on PC biosynthetic pathways. We report the challenges of promoting microalgae as a relevant source of natural PCs, further enhancing the interests of microalgal "biofactories" for biotechnological applications (i.e. nutraceutical, pharmacological, or cosmeceutical products).

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.

Main bioactive phenolic compounds in marine algae and their mechanisms of action supporting potential health benefits

Given the growing tendency of consumers to choose products with natural ingredients, food industries have directed scientific research in this direction. In this regard, algae are an attractive option for the research, since they can synthesize a group of secondary metabolites, called phenolic compounds, associated with really promising properties and bioactivities. The objective of this work was to classify the major phenolic compounds, compare the effectiveness of the different extractive techniques used for their extraction, from traditional systems (like heat assisted extraction) to the most advance ones (such as ultrasound, microwave or supercritical fluid extraction); the available methods for identification and quantification; the stability of the enriched extract in phenolic compounds and the main bioactivities described for these secondary metabolites, to offer an overview of the situation to consider if it is possible and/or convenient an orientation of phenolic compounds from algae towards an industrial application.

Diphlorethohydroxycarmalol Attenuates Palmitate-Induced Hepatic Lipogenesis and Inflammation

Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease, encompassing a range of conditions caused by lipid deposition within liver cells, and is also associated with obesity and metabolic diseases. Here, we investigated the protective effects of diphlorethohydroxycarmalol (DPHC), which is a polyphenol isolated from an edible seaweed, Ishige okamurae, on palmitate-induced lipotoxicity in the liver. DPHC treatment repressed palmitate-induced cytotoxicity, triglyceride content, and lipid accumulation. DPHC prevented palmitate-induced mRNA and protein expression of SREBP (sterol regulatory element-binding protein) 1, C/EBP (CCAAT-enhancer-binding protein) α, ChREBP (carbohydrate-responsive element-binding protein), and FAS (fatty acid synthase). In addition, palmitate treatment reduced the expression levels of phosphorylated AMP-activated protein kinase (AMPK) and sirtuin (SIRT)1 proteins, and DPHC treatment rescued this reduction. Moreover, DPHC protected palmitate-induced liver toxicity and lipogenesis, as well as inflammation, and enhanced AMPK and SIRT1 signaling in zebrafish. These results suggest that DPHC possesses protective effects against palmitate-induced toxicity in the liver by preventing lipogenesis and inflammation. DPHC could be used as a potential therapeutic or preventive agent for fatty liver diseases.

Activation of Sirtuin1 by lyceum barbarum polysaccharides in protection against diabetic cataract

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum polysaccharide (LBP) extracted from the Lycium barbarum L. has been widely used to improve diabetes and its relative complications. However, the mechanisms have not fully understood. A recent study has demonstrated that LBP upregulates suituin 1 (SIRT1).

OBJECTIVE

This study was to define the role of Sirt1 and its downstream signaling pathways in diabetic cataract using in vitro and in vivo models.

MATERIALS AND METHODS

Human lens epithelial cell line SRA01/04 cells were cultured under high glucose (HG) medium with treatment of LBP or vehicle. Cell viability, apoptosis, protein and/or mRNA levels of Sirt1, BAX, Bcl-2, active-caspase-3, FOXO1, p27 and acetylated p53 were measured. SIRT1 upregulated- and knocked-down cells were generated and tested in high glucose culture. Diabetes mellitus was induced in rats by streptozotocin injection. Body weight, blood glucose levels, lens transparency and retinal function were assessed and SIRT1, as well as the aforementioned biomarkers were measured using Western blotting and qPCR in the animal lens samples.

RESULTS

The results showed that HG decreased cell viability and LBP prevented the decrease. The reduced viability in HG cultured SRA01/04 cells was associated with increased levels of BAX, active caspase 3, FOXO1, p27, and p53 and decreased levels of SIRT1 and Bcl-2. Further experiments using sirt1 gene modulated cells showed that upregulation of Sirt1 improved viability, increase cell division as reflected by an increased proportion of S phase in the cell cycle, reduced the number of apoptotic cell death and suppressed p53 acetylation and caspase 3 activation. Opposite results were observed in SIRT1 knock-down cells. Treating diabetic animals with LBP reduced body weight loss and blood glucose content in diabetic animals. Similarly, LBP hindered the development of cataract in lenses and improved retinal function. The beneficial effect of LBP on diabetic cataract was associated with the supression of p53, caspase 3, FOXO1, BAX, p27 and elevation of SIRT1 and Bcl-2, which were consistent with the in vitro findings.

CONCLUSION

Our findings showed that diabetes caused cataract is associated with suppression of SIRT1 and Bcl-2 and activation of other cell death related genes. LBP prevented diabetic cataract in animals by upregulating Sirt1 and Bcl-2 and suppressing cell death related genes.

Algae Metabolites in Cosmeceutical: An Overview of Current Applications and Challenges

Cosmetics are widely used by people around the world to protect the skin from external stimuli. Consumer preference towards natural cosmetic products has increased as the synthetic cosmetic products caused adverse side effects and resulted in low absorption rate due to the chemicals' larger molecular size. The cosmetic industry uses the term "cosmeceutical", referring to a cosmetic product that is claimed to have medicinal or drug-like benefits. Marine algae have gained tremendous attention in cosmeceuticals. They are one of the richest marine resources considered safe and possessed negligible cytotoxicity effects on humans. Marine algae are rich in bioactive substances that have shown to exhibit strong benefits to the skin, particularly in overcoming rashes, pigmentation, aging, and cancer. The current review provides a detailed survey of the literature on cosmeceutical potentials and applications of algae as skin whitening, anti-aging, anticancer, antioxidant, anti-inflammation, and antimicrobial agents. The biological functions of algae and the underlying mechanisms of all these activities are included in this review. In addition, the challenges of using algae in cosmeceutical applications, such as the effectiveness of different extraction methods and processing, quality assurance, and regulations concerning extracts of algae in this sector were also discussed.

Protective effect of diphlorethohydroxycarmalol against oxidative stress-induced DNA damage and apoptosis in retinal pigment epithelial cells

Purpose: Reactive oxygen species (ROS) contribute to the onset and progression of disease pathogenesis in a variety of organs, including age-related macular degeneration (AMD). Diphlorethohydroxycarmalol (DPHC), a phlorotannin compound, is one of the major components of the brown alga Ishige okamurae Yendo, and has been shown to have strong antioxidant capacity. The purpose of this study was to evaluate the protective effects of DPHC against oxidative stress (hydrogen peroxide, H₂O₂)-induced DNA damage and apoptosis in cultured ARPE19 retinal pigment epithelial (RPE) cells. Materials and methods: Cell viability was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide assay. Intracellular ROS generation was measured by flow cytometer using 2',7'-dichlorofluorescin diacetate. The magnitude of apoptosis was measured by flow cytometry using the annexin V/propidium iodide double staining. DNA damage was evaluated by DNA fragmentation assay, comet assay and 8-hydroxy-2'-deoxyguanosine (8-OHdG) analysis. To observe the mitochondrial membrane potential, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide staining was performed. In order to identify the underling mechanism of DPHC against H₂O₂-induced cellular alteration, we performed immune blotting. Results: The results of this study showed that the decreased survival rate brought about by H₂O₂ could be attributed to the induction of DNA damage and apoptosis accompanied by the increased production of ROS, which was remarkably reversed by DPHC. In addition, the loss of H₂O₂-induced mitochondrial membrane potential was significantly attenuated in the presence of DPHC. The inhibitory effect of DPHC on H₂O₂-induced apoptosis was associated with a reduced Bax/Bcl-2 ratio, the protection of the activation of caspase-9 and -3 and the inhibition of poly (ADP-ribose) polymerase cleavage, which was associated with the blockage of cytochrome c release to the cytoplasm. Conclusions: Our data proved that DPHC protects ARPE19 cells against H₂O₂-induced DNA damage and apoptosis by scavenging ROS and thus suppressing the mitochondrial-dependent apoptosis pathway. Therefore, this study suggests that DPHC has the therapeutic potential to prevent AMD by inhibiting oxidative stress-induced injury in RPE cells.

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.

Protective effect of selenium supplementation following oxidative stress mediated by glucose on retinal pigment epithelium

There are many conditions that affect the retina. However, diabetic retinopathy (RD) as a complication of Diabetes Mellitus continues to be the leading cause of blindness in working people globally. Diabetic retinopathy is an ocular complication of diabetes that is caused by the deterioration of the blood vessels that supply the retina, which has the consequence that the vision deteriorates irreversibly. The retina, and specifically the retinal pigment epithelium (RPE) is the only neural tissue that is exposed directly and frequently to light, which favors the oxidation of lipids that become extremely toxic to the cells of the retina. The RPE is a natural barrier playing an important role in the absorption of light and reduction of light scatter within the eye. In addition, the retina is the tissue that proportionally consumes more oxygen, which generates a high production of reactive oxygen species (ROS). The retina is particularly sensitive to hyperglycemia and oxidative stress. The eye tissues are enriched in certain antioxidants in the form of metabolic enzymes or small molecules. Since selenium is essential for regulating the activity of the enzymes involved in protection against oxidative stress, providing selenium to the ocular tissues could be useful for the treatment of different ocular pathologies. Thus, the aim of this study is to investigate the potential efficacy of selenium in human RPE against glucose-induced oxidative stress and its implications for GPx activity. Chromatographic techniques based on HPLC-ICP-MS will be applied in combination with isotope pattern deconvolution (IPD) to study the effects of selenium supplementation and hyperglycemia in an in vitro model of RPE cells.

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

Nutraceutical use of algae requires understanding of the diversity and significance of their active compositions for intended activities. Ishige okamurae (I. okamurae) extract is well-known to possess α-glucosidase inhibitory activity; however, studies are needed to investigate its active composition in order to standardize its α-glucosidase inhibitory activity. In this study, we observed the intensity of the dominant compounds of each I. okamurae extract harvested between 2016 and 2017, and the different potency of each I. okamurae extract against α-glucosidase. By comparing the anti-α-glucosidase ability of the dominant compounds, a novel Ishophloroglucin A with highest α-glucosidase inhibitory activity was identified and suggested for standardization of anti-α-glucosidase activity in I. okamurae extract. Additionally, a validated analytical method for measurement of Ishophloroglucin A for future standardization of I. okamurae extract was established in this study. We suggest using Ishophloroglucin A to standardize anti-α-glucosidase potency of I. okamurae and propose the significance of standardization based on their composition for effective use of algae as marine-derived nutraceuticals.

Diphlorethohydroxycarmalol Attenuates Methylglyoxal-Induced Oxidative Stress and Advanced Glycation End Product Formation in Human Kidney Cells

Diabetic nephropathy is the leading cause of end-stage renal disease in patients with diabetes mellitus. Oxidative stress has been shown to play an important role in pathogeneses of renal damage in diabetic patients. Here, we investigated the protective effect of diphlorethohydroxycarmalol (DPHC), which is a polyphenol isolated from an edible seaweed, Ishige okamurae, on methylglyoxal-induced oxidative stress in HEK cells, a human embryonic kidney cell line. DPHC treatment inhibited methylglyoxal- (MGO-) induced cytotoxicity and ROS production. DPHC activated the Nrf2 transcription factor and increased the mRNA expression of antioxidant and detoxification enzymes, consequently reducing MGO-induced advanced glycation end product formation. In addition, DPHC increased glyoxalase-1 mRNA expression and attenuated MGO-induced advanced glycation end product formation in HEK cells. These results suggest that DPHC possesses a protective activity against MGO-induced cytotoxicity in human kidney cells by preventing oxidative stress and advanced glycation end product formation. Therefore, it could be used as a potential therapeutic agent for the prevention of diabetic nephropathy.

NADPH oxidase 4 and endothelial nitric oxide synthase contribute to endothelial dysfunction mediated by histone methylations in metabolic memory

"Metabolic memory" is identified as a phenomenon that transient hyperglycemia can be remembered by vasculature for quite a long term even after reestablishment of normoglycemia. NADPH oxidases (Noxs) and endothelial nitric oxide synthase (eNOS) are important enzymatic sources of reactive oxygen species (ROS) in diabetic vasculature. The aim of this study is to explore the roles of epigenetics and ROS derived from Noxs and eNOS in the metabolic memory. In this study, we demonstrated that vascular ROS was continuously activated in endothelium induced by transient high glucose, as well as sustained vascular endothelial dysfunction. The Nox4 and uncoupled eNOS are the major sources of ROS, while inhibition of Nox4 and eNOS significantly attenuated oxidative stress and almost recovered the endothelial function in metabolic memory. Furthermore, the aberrant histone methylation (H3K4me1, H3K9me2, and H3K9me3) at promoters of Nox4 and eNOS are the main causes for the persistent up-regulation of these two genes. Modifying the histone methylation could reduce the expression levels of Nox4 and eNOS, thus obviously attenuating endothelial dysfunction. These results indicate that histone methylation of Nox4 and eNOS play a key role in metabolic memory and may be the potential intervention targets for metabolic memory.

Diphlorethohydroxycarmalol from Ishige okamurae Suppresses Osteoclast Differentiation by Downregulating the NF-κB Signaling Pathway

Marine algae possess a variety of beneficial effects on human health. In this study, we investigated whether diphlorethohydroxycarmalol (DPHC), isolated from Ishige okamurae, a brown alga, suppresses receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation. DPHC significantly suppressed RANKL-induced osteoclast differentiation and macrophage-colony stimulating factor (M-CSF) expression in a dose-dependent manner. In addition, it significantly inhibited actin ring formation, the expression of osteoclast marker genes, such as tartrate-resistant acid phosphatase (TRAP), nuclear factor of activated T-cells cytoplasmic 1 (Nfatc1), cathepsin K (Ctsk), and dendritic cell-specific transmembrane protein (Dcstamp), and osteoclast-induced bone resorption. Analysis of the RANKL-mediated signaling pathway showed that the phosphorylation of both IκB and p65 was specifically inhibited by DPHC. These results suggest that DPHC substantially suppresses osteoclastogenesis by downregulating the RANK-NF-κB signaling pathway. Thus, it holds significant potential for the treatment of skeletal diseases associated with an enhanced osteoclast activity.

Phlorotannins: Towards New Pharmacological Interventions for Diabetes Mellitus Type 2

Diabetes mellitus is a group of metabolic disorders characterized by hyperglycaemia, and predicted by the World Health Organization as the expected 7th leading cause of death in 2030. Diabetes mellitus type 2 (DMT2) comprises the majority of diabetic individuals around the world (90%-95%). Pathophysiologically, this disorder results from a deregulation of glucose homeostasis, worsened by overweight and by a sedentary lifestyle, culminating in life-threatening cardiovascular events. The currently available anti-diabetic drugs are not devoid of undesirable side effects, sometimes responsible for poor therapeutic compliance. This represents a challenge for contemporary medicine, and stimulates research focused on the development of safer and more efficient anti-diabetic therapies. Amongst the most promising sources of new bioactive molecules, seaweeds represent valuable, but still underexploited, biofactories for drug discovery and product development. In this review, the role of phlorotannins, a class of polyphenols exclusively produced by brown seaweeds, in the management of DMT2 will be discussed, focusing on various pharmacologically relevant mechanisms and targets, including pancreatic, hepatic and intestinal enzymes, glucose transport and metabolism, glucose-induced toxicity and β-cell cytoprotection, and considering numerous in vitro and in vivo surveys.

Potential anti-inflammatory natural products from marine algae

Inflammatory diseases have become one of the leading causes of health issue throughout the world, having a considerable influence on healthcare costs. With the emerging developments in natural product, synthetic and combinatorial chemistry, a notable success has been achieved in discovering natural products and their synthetic structural analogs with anti-inflammatory activity. However, many of these therapeutics have indicated detrimental side effects upon prolonged usage. Marine algae have been identified as an underexplored reservoir of unique anti-inflammatory compounds. These include polyphenols, sulfated polysaccharides, terpenes, fatty acids, proteins and several other bioactives. Consumption of these marine algae could provide defense against the pathophysiology of many chronic inflammatory diseases. With further investigation, algal anti-inflammatory phytochemicals have the potential to be used as therapeutics or in the synthesis of structural analogs with profound anti-inflammatory activity with reduced side effects. The current review summarizes the latest knowledge about the potential anti-inflammatory compounds discovered from marine algae.

Bioactive properties and potentials cosmeceutical applications of phlorotannins isolated from brown seaweeds: A review

Currently, natural ingredients are becoming more attractive for the industries such as functional food, nutraceuticals, cosmeceutical and pharmaceutical industries as people starting to believe naturally occurring compounds are safer to humans than artificial compounds. Seaweeds are one of the most interesting organisms found in oceans around the earth, which are carrying great ecological importance and contribute to increase the biodiversity of ecosystems where they were originated and habitat. Within last few decades, discovery of secondary metabolites with biological activities from seaweeds has been significantly increased. Further, the unique secondary metabolites isolated from seaweeds including polysaccharides, carotenoids and polyphenols possess range of bioactive properties that make them potential ingredient for many industrial applications. Among those groups of compounds phlorotannins isolated from brown seaweeds have shown interesting bioactive properties including anti-cancer, anti-inflammation, anti-oxidant, anti-allergic, anti-wrinkling and hair growth promotion properties. Moreover, these properties associated with phlorotannins make them an ideal compounds to use as a functional ingredient in cosmeceutical products. Up to now no report has been reviewed about discuss properties of phlorotannins related to the cosmeceutical application. In the present review primary attention is given to the collect scientific data published about bioactive properties of brown algal phlorotannins related to the cosmeceutical industry.

Looking Beyond the Terrestrial: The Potential of Seaweed Derived Bioactives to Treat Non-Communicable Diseases

Seaweeds are a large and diverse group of marine organisms that are commonly found in the maritime regions of the world. They are an excellent source of biologically active secondary metabolites and have been shown to exhibit a wide range of therapeutic properties, including anti-cancer, anti-oxidant, anti-inflammatory and anti-diabetic activities. Several Asian cultures have a strong tradition of using different varieties of seaweed extensively in cooking as well as in herbal medicines preparations. As such, seaweeds have been used to treat a wide variety of health conditions such as cancer, digestive problems, and renal disorders. Today, increasing numbers of people are adopting a "westernised lifestyle" characterised by low levels of physical exercise and excessive calorific and saturated fat intake. This has led to an increase in numbers of chronic Non-communicable diseases (NCDs) such as cancer, cardiovascular disease, and diabetes mellitus, being reported. Recently, NCDs have replaced communicable infectious diseases as the number one cause of human mortality. Current medical treatments for NCDs rely mainly on drugs that have been obtained from the terrestrial regions of the world, with the oceans and seas remaining largely an untapped reservoir for exploration. This review focuses on the potential of using seaweed derived bioactives including polysaccharides, antioxidants and fatty acids, amongst others, to treat chronic NCDs such as cancer, cardiovascular disease and diabetes mellitus.

Protective effect of trans-δ-viniferin against high glucose-induced oxidative stress in human umbilical vein endothelial cells through the SIRT1 pathway

Oxidative stress plays a critical role in the pathogenesis of diabetic vascular complications. Trans-δ-viniferin (TVN), a polyphenolic compound, has recently attracted much attention as an antioxidant exhibiting a hypoglycemic potential. In the present study, we aimed at investigating the protective effect of TVN against high glucose-induced oxidative stress in human umbilical vein endothelial cells (HUVECs) and the potential mechanism involved. We found that TVN attenuated reactive oxygen species (ROS) production, increased catalase (CAT) activity and decreased malondialdehyde (MDA) levels to ameliorate cell survival induced by 35 mM glucose. Meanwhile, it inhibited high glucose-induced apoptosis by maintaining Ca(2+) and preserving mitochondrial membrane potential (MMP) levels. The immunoblot analysis indicated that TVN efficiently regulated the cleavage of caspase family, p53, Bax and Bcl-2, all mediated by SIRT1. Furthermore, the increased level of SIRT1 induced by TVN was inhibited by nicotinamide and siRNA-medicated SIRT1 silencing (si-SIRT1), thereby confirming the significant role of SIRT1 in these events. In conclusion, our results indicated that TVN efficiently reduced oxidative stress and maintained mitochondrial function related with activating SIRT1 in high glucose-treated HUVECs. It suggested that TVN is pharmacologically promising for treating diabetic cardiovascular complications.

Diphlorethohydroxycarmalol inhibits interleukin-6 production by regulating NF-κB, STAT5 and SOCS1 in lipopolysaccharide-stimulated RAW264.7 cells

Diphlorethohydroxycarmalol (DPHC) is a phlorotannin compound isolated from Ishige okamuarae, a brown alga. This study was conducted to investigate the anti-inflammatory effect and action mechanism of DPHC in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We found that DPHC strongly reduces the production of interleukin 6 (IL-6), but not that of tumor necrosis factor-alpha (TNF-α) induced by LPS. DPHC (12.5 and 100 μM) suppressed the phosphorylation and the nuclear translocation of NF-kappaB (NF-κB), a central signaling molecule in the inflammation process induced by LPS. The suppressor of cytokine signaling 1 (SOCS1) is a negative feedback regulator of Janus kinase (Jak)-signal transducer and activator of transcription (STAT) signaling. In this study, DPHC inhibited STAT5 expression and upregulated that of SOCS1 at a concentration of 100 μM. Furthermore, N-tosyl-l-phenylalanine chloromethyl ketone (TPCK) (a specific NF-κB inhibitor) and JI (a specific Jak2 inhibitor) reduced the production of IL-6, but not that of tumor necrosis factor-alpha (TNF-α) in LPS-stimulated RAW 264.7 macrophages. These findings demonstrate that DPHC inhibits IL-6 production via the downregulation of NF-κB and Jak2-STAT5 pathway and upregulation of SOCS1.

Gallic acid isolated from Spirogyra sp. improves cardiovascular disease through a vasorelaxant and antihypertensive effect

In this study, we investigated the vasorelaxant and antihypertensive effects of gallic acid (GA), a polyphenol isolated from the green alga Spirogyra sp., to assess its suitability as a therapeutic for cardiovascular diseases (CVDs). We examined the effect of GA on endothelium-dependent vasorelaxation in human umbilical vein endothelial cells (HUVECs). GA increased nitric oxide (NO) levels by increasing phosphorylation of endothelial nitric oxide synthase (eNOS), and its effect on NO production was attenuated by pretreatment with the eNOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). We also investigated its antihypertensive effect by examining GA-mediated inhibition of angiotensin-I converting enzyme (ACE). GA inhibited ACE with a half-maximal inhibitory concentration (IC50) value of 37.38 ± 0.39 μg/ml. In silico simulations revealed that GA binds to the active site of ACE (PDB: 1O86) with a binding energy of -270.487 kcal/mol. Furthermore, GA clearly reduced blood pressure in spontaneously hypertensive rats (SHR) to an extent comparable to captopril. These results suggest that GA isolated from Spirogyra sp. exerts multiple therapeutic effects and has potential as a CVD treatment.

The effects of low and high concentrations of luteolin on cultured human endothelial cells under normal and glucotoxic conditions: involvement of integrin-linked kinase and cyclooxygenase-2

Luteolin protects against high glucose (HG)-induced endothelial dysfunction whereas its cytotoxicity has been reported against normal endothelial cells. This study was undertaken to determine luteolin cytoprotective and cytotoxic dose ranges and to elucidate their respective mechanisms. Luteolin prevented HG-induced human umbilical vein endothelial cell (HUVEC) death with an EC50 value of 2.0 ± 0.07 μM. The protective effect of luteolin was associated with decreased intracellular reactive oxygen species (ROS) and Ca(2+) (Cai(2+)) levels and enhanced nitric oxide (NO) production. At high concentrations, luteolin caused HUVEC death in normal glucose (NG) and HG states (LC50 40 ± 2.23 and 38 ± 1.12 μM, respectively), as represented by increased ROS and Cai(2+) and decreased NO. Western blots illustrated that exposure to HG increased cyclooxygenase-2 (COX-2) and integrin-linked kinase (ILK) expression. Luteolin at low concentrations suppressed HG-mediated up-regulation of COX-2 but maintained HG-induced over-expression of ILK while at high concentrations significantly increased COX-2 and decreased ILK expression in both HG and NG states. Our data indicated that cytoprotective action of luteolin was manifested with much lower concentrations, by a factor of approximately 20, compared with cytotoxic activity under both normal or glucotoxic conditions. It appears that luteolin exerts its action, in part, by modulating ILK expression which is associated with regulation of COX-2 expression and NO production in endothelial cells.

Inhibition of Reactive Oxygen Species (ROS) and Nitric Oxide (NO) by Gelidium elegans Using Alternative Drying and Extraction Conditions in 3T3-L1 and RAW 264.7 Cells

Gelidium (G.) elegans is a red alga inhabiting intertidal areas of North East Asia. We examined anti-oxidative and anti-inflammatory effects of G. elegans, depending on drying and extraction conditions, by determining reactive oxygen species (ROS) and nitric oxide (NO) in 3T3-L1 and RAW 264.7 cells. Extraction yields of samples using hot air drying (HD) and far-infrared ray drying (FID) were significantly higher than those using natural air drying (ND). The 70% ethanol extracts showed the highest total phenol and flavonoid contents compared to other extracts (0, 30, and 50% ethanol) under tested drying conditions. The scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitrite correlated with total phenol or flavonoid content in the extracts. The greatest DPPH scavenging effect was observed in 70% ethanol extract from FID and HD conditions. The production of ROS and NO in 3T3-L1 and macrophage cells greatly decreased with the 70% ethanol extraction derived from FID. This study suggests that 70% ethanol extraction of G. elegans dried by FID is the most optimal condition to obtain efficiently antioxidant compounds of G. elegans.

Antioxidant marine products in cancer chemoprevention

SIGNIFICANCE

Oxidative stress resulting from excessive reactive oxygen/nitrogen/electrophilic species (ROS/RNS/RES) can lead to diseases such as cancer. The health benefits of dietary fruits and vegetables with antioxidant potential have received a great deal of attention. On the other hand, marine botanicals have been less well characterized and still remain as terra incognita.

RECENT ADVANCES

In some parts of the world, appreciable quantities of seaweeds are consumed on a daily basis. Along with current globalization, cuisines using seaweeds are now being used throughout the world, sometimes considered as healthy delicacies. Thus, it is relevant to explore the medicinal and pharmacological properties of seaweeds, as well as the health ramifications of this dietary practice.

CRITICAL ISSUES

We currently review the antioxidant potential of seaweed components such as sulfated polysaccharides, phenolic compounds (phlorotannins and bromophenols), and fucoxanthins. In addition to seaweeds, the chemistry and antioxidant activities of some marine fungi and bacteria are described. Since antioxidants are considered promising cancer chemopreventive agents, the in vitro, in vivo, and clinical aspects of antioxidant marine products are presented, and potential implications are discussed.

FUTURE DIRECTIONS

Although some data suggest that health benefits are derived from the consumption of marine natural products, further epidemiological or clinical studies are needed to strengthen these observations. In addition, many studies have demonstrated the antioxidant effects of seaweeds with in vitro models, but further characterization of bioavailability is necessary to suggest the significance of these responses. It is also important to define the safety of some seaweeds containing inorganic arsenics.

Anti-diabetic effects of brown algae derived phlorotannins, marine polyphenols through diverse mechanisms

Marine algae are popular and abundant food ingredients mainly in Asian countries, and also well known for their health beneficial effects due to the presence of biologically active components. The marine algae have been studied for biologically active components and phlorotannins, marine polyphenols are among them. Among marine algae, brown algae have extensively studied for their potential anti-diabetic activities. Majority of the investigations on phlorotannins derived from brown algae have exhibited their various anti-diabetic mechanisms such as α-glucosidase and α-amylase inhibitory effect, glucose uptake effect in skeletal muscle, protein tyrosine phosphatase 1B (PTP 1B) enzyme inhibition, improvement of insulin sensitivity in type 2 diabetic db/db mice, and protective effect against diabetes complication. In this review, we have made an attempt to discuss the various anti-diabetic mechanisms associated with phlorotannins from brown algae that are confined to in vitro and in vivo.

Effect of methionine sulfoxide reductase B1 silencing on high-glucose-induced apoptosis of human lens epithelial cells

AIMS

To determine roles of methionine sulfoxide reductase B1 (MsrB1) in protecting lens mitochondria against oxidative damage, the influences of MsrB1 gene silencing on high-glucose-induced apoptosis in human lens epithelial (HLE) cells were studied.

MAIN METHODS

Our study used four groups of cells: normal control, MsrB1 gene silenced, high glucose (30mM) exposed and MsrB1 gene silenced cells followed with high glucose exposure. In all cases we detected cell viability, cell apoptosis rate, intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) levels, alteration of mitochondrial membrane potential, release of mitochondrial cytochrome c as well as an increase in activity of caspase-3.

KEY FINDINGS

The results showed that MsrB1 gene silencing by short interfering RNA (siRNA) in HLE cells clearly resulted in oxidative stress, decrease in mitochondrial membrane potential and release of mitochondrial cytochrome c as well as an increase in activity of caspase-3 and the percentage of apoptotic cells. When MsrB1-silenced HLE cells were exposed to high glucose, characteristic of high-glucose-induced mitochondrial dysfunctions were further exacerbated.

SIGNIFICANCE

MsrB1 plays important roles in protecting HLE cell mitochondria against oxidative damage and inhibits oxidative stress-induced apoptosis in diabetic cataracts by scavenging ROS.

Neuroprotective effect of phlorotannin isolated from Ishige okamurae against H₂O₂ -induced oxidative stress in murine hippocampal neuronal cells, HT22

The present study is designed to investigate the neuroprotective effect of a kind of phlorotannins, diphlorethohydroxycarmalol (DPHC) isolated from Ishige okamurae against hydrogen peroxide (H(2)O(2))-induced oxidative stress in murine hippocampal neuronal cells, HT22. H(2)O(2) treatment induced neurotoxicity, whereas DPHC prevented cells from H(2)O(2)-induced damage then restoring cell viability was significantly increased. DPHC slightly reduced the expression of Bax induced by H(2)O(2) but recovered the expression of Bcl-xL as well as caspase-9 and -3 mediated PARP cleavage by H(2)O(2). Intracellular reactive oxygen species (ROS) and lipid peroxidation was overproduced as the result of the addition of H(2)O(2); however, these ROS generations and lipid peroxidation were effectively inhibited by addition of DPHC in a dose-dependent manner. Moreover, DPHC suppressed the elevation of H(2)O(2)-induced Ca(2+) release. These findings indicate that DPHC has neuroprotective effects against H(2)O(2)-induced damage in neuronal cells, and that an inhibitory effect on ROS production may contribute to the underlying mechanisms.