Effect of Undaria pinnatifida (Wakame) on the development of cerebrovascular diseases in stroke-prone spontaneously hypertensive rats

Seaweeds as Source of Bioactive Pigments with Neuroprotective and/or Anti-Neurodegenerative Activities: Astaxanthin and Fucoxanthin

The marine kingdom is an important source of a huge variety of scaffolds inspiring the design of new drugs. The complex molecules found in the oceans present a great challenge to organic and medicinal chemists. However, the wide variety of biological activities they can display is worth the effort. In this article, we present an overview of different seaweeds as potential sources of bioactive pigments with activity against neurodegenerative diseases, especially due to their neuroprotective effects. Along with a broad introduction to seaweed as a source of bioactive pigments, this review is especially focused on astaxanthin and fucoxanthin as potential neuroprotective and/or anti-neurodegenerative agents. PubMed and SciFinder were used as the main sources to search and select the most relevant scientific articles within the field.

Antioxidant and Neuroprotective Effects of Fucoxanthin and Its Metabolite Fucoxanthinol: A Comparative In Vitro Study

Fucoxanthin is the most abundant carotenoid found in marine brown algae that exhibits several healthy properties. Dietary fucoxanthin is metabolized in the intestine, plasma, and other tissues to various metabolites, including fucoxanthinol. In this regard, the contribution of fucoxanthinol to the healthy properties of its precursor, fucoxanthin, against pathogenetic events associated with neurodegenerative diseases remains unexplored. Here, we evaluated and compared the antioxidant and neuroprotective effects of the carotenoids fucoxanthin and fucoxanthinol in in vitro models of Alzheimer's (AD) and Parkinson's (PD) disease. Neuronal SH-SY5Y cells were used to evaluate the antioxidant properties of the carotenoids against ABTS radical in the membrane and cytoplasm and oxidative stress elicited by tert-butyl hydroperoxide using the 2',7'-dichlorodihydrofluorescein diacetate probe. We also assessed the ability of the carotenoids to increase the glutathione (GSH) and activate the Nrf2/Keap1/ARE pathway using the monochlorobimane probe and western blotting method, respectively. The neuroprotective effects of the carotenoids against the neurotoxicity generated by oligomers of Beta-Amyloid (1-42) peptide (OAβ) and 6-hydroxydopamine (6-OHDA), which are neurotoxins of AD and PD, respectively, were finally evaluated in the same neuronal cells using the thiazolyl blue tetrazolium bromide assay. Both carotenoids could reach the cytoplasm, which explains the mainly free radical scavenging activity at this level. Notably, fucoxanthinol had higher and lower antioxidant activity than fucoxanthin at extracellular and cellular levels. Although studied carotenoids exerted the ability to activate the Nrf2/Keap1/ARE pathway, leading to an increase of intracellular GSH, our results suggested that the antioxidant activity of the carotenoids could be mainly attributed to their radical scavenging activity in neuronal membrane and cytoplasm, where they accumulate. Fucoxanthinol also shared similar neuroprotective effects as fucoxanthin against the neurotoxicity generated by OAβ and 6-OHDA, suggesting a potential neuroprotective contribution to the action of fucoxanthin administered as a food supplement in in vivo experimental models. These results encourage further research to evaluate the bioavailability of fucoxanthinol and other metabolites of fucoxanthin at the brain level to elucidate the dietary neuroprotective potential of fucoxanthin.

Dietary Protective Potential of Fucoxanthin as an Active Food Component on Neurological Disorders

The prevalence of neurodegenerative, cerebrovascular, and psychiatric diseases and other neurological disorders has increased dramatically worldwide. Fucoxanthin is an algal pigment with many biological functions, and there is rising evidence that fucoxanthin plays a preventive and therapeutic role in neurological disorders. This review focuses on the metabolism, bioavailability, and blood-brain barrier penetration of fucoxanthin. Furthermore, the neuroprotective potential of fucoxanthin in neurodegenerative diseases, cerebrovascular diseases, and psychiatric diseases as well as other neurological disorders such as epilepsy, neuropathic pain, and brain tumors by acting on multiple targets will be summarized. The multiple targets include regulating apoptosis, reducing oxidative stress, activating the autophagy pathway, inhibiting Aβ aggregation, improving dopamine secretion, reducing α-synuclein aggregation, attenuating neuroinflammation, modulating gut microbiota, and activating brain-derived neurotrophic factor, etc. Additionally, we look forward to brain-targeted oral transport systems due to the low bioavailability and blood-brain barrier permeability of fucoxanthin. We also propose exploring the systemic mechanisms of fucoxanthin metabolism and transport through the gut-brain process and envision new therapeutic targets for fucoxanthin to act on the central nervous system. Finally, we propose dietary fucoxanthin delivery interventions to achieve preventive effects on neurological disorders. This review provides a reference for the application of fucoxanthin in the neural field.

Optimization of fucoxanthin extraction obtained from natural by-products from Undaria pinnatifida stem using supercritical CO2 extraction method

In the recent years, edible brown seaweed, Undaria pinnatifida, has presented beneficial effects, which may be correlated with this species containing major bioactive compounds, such as carotenoids, fatty acids, and phytosterols. Marine carotenoid fucoxanthin is abundantly present in edible Undaria pinnatifida and features strong bioactive activities. The stem of Undaria pinnatifida is very hard to gnaw off and cannot be swallowed; therefore, it is usually discarded as waste, making it an environmental issue. Hence, making full use of the waste stem of Undaria pinnatifida is an urgent motivation. The present study aims to explore the optimal preparation technology of fucoxanthin from Undaria pinnatifida stems using supercritical carbon dioxide methods and provides approaches for the extraction and preparation of bioactive compounds from a waste seaweed part. With the comprehensive optimization conditions applied in this study, the experimental yield of fucoxanthin agreed closely with the predicted value by > 99.3%. The potential of α-amylase and glucoamylase to inhibit bioactive compounds was evaluated. The results demonstrated that the inhibition activity (IC₅₀ value) of α-amylase (0.1857 ± 0.0198 μg/ml) and glucoamylase (0.1577 ± 0.0186 μg/ml) varied with extraction conditions due to the different contents of bioactive components in the extract, especially fucoxanthin (22.09 ± 0.69 mg/g extract). Therefore, this study confirmed supercritical fluid extraction technology to be a useful sample preparation method, which can effectively be used to prepare fucoxanthin from waste marine resources. This method can potentially be applied in functional food and related industries.

Fucoxanthin: A Promising Phytochemical on Diverse Pharmacological Targets

Fucoxanthin (FX) is a special carotenoid having an allenic bond in its structure. FX is extracted from a variety of algae and edible seaweeds. It has been proved to contain numerous health benefits and preventive effects against diseases like diabetes, obesity, liver cirrhosis, malignant cancer, etc. Thus, FX can be used as a potent source of both pharmacological and nutritional ingredient to prevent infectious diseases. In this review, we gathered the information regarding the current findings on antimicrobial, antioxidant, anti-inflammatory, skin protective, anti-obesity, antidiabetic, hepatoprotective, and other properties of FX including its bioavailability and stability characteristics. This review aims to assist further biochemical studies in order to develop further pharmaceutical assets and nutritional products in combination with FX and its various metabolites.

Japanese Diet and Mortality, Disability, and Dementia: Evidence from the Ohsaki Cohort Study

The Japanese dietary pattern has long been discussed as one of the factors behind the longevity of Japanese people. However, the health benefits of the Japanese dietary pattern have not been fully elucidated. We published the first report in the world regarding the relation between the Japanese dietary pattern and cardiovascular disease mortality in 2007 using cohort studies including Japanese residents of Ohsaki City, Miyagi Prefecture, Japan. Since then, we have developed the Japanese Diet Index (JDI) that was based on previous findings to assess the degree of the Japanese dietary pattern and to advance the evidence on the health effects of the Japanese dietary pattern. So far, we have explored the associations between the JDI score (in quartiles) and various outcomes. For all-cause mortality, in comparison to Q1 (the lowest), the multivariable hazard ratios (HRs) and 95% confidence intervals (95%CIs) were 0.92 (0.85–1.00) for Q2, 0.91 (0.83–0.99) for Q3, and 0.91 (0.83–0.99) for Q4 (the highest). For functional disability, the multivariable HRs (95%CIs) were 0.94 (0.81–1.09) for Q2, 0.90 (0.77–1.05) for Q3, and 0.79 (0.68–0.92) for Q4. For dementia, the multivariable HRs (95%CIs) were 0.88 (0.74–1.05) for Q2, 0.87 (0.73–1.04) for Q3, 0.79 (0.66–0.95) for Q4. In addition, people with higher adherence to the Japanese dietary pattern also showed decreases in disability and dementia risks. The purpose of this article was to review all six papers, summarize the health effects of the Japanese dietary pattern, and discuss implications for future research.

Algae as an emerging source of bioactive pigments

Algae have been identified as natural producer of bioactive commercial pigments. To perform photosynthesis, algae use pigments to harvest sunlight energy. The pigments found in algae are categorized in chlorophylls, phycobilins, and carotenoids. Popular carotenoids include astaxanthin, lutein,fucoxanthin, canthaxanthin, zeaxanthin, β-cryptoxanthin and finds application as antioxidant, anti-inflammatory, immunoprophylactic, antitumor activities among others. Due to double-bonds in their structure, they exhibit broad health applications while protecting other molecules from oxidative stress induced by active radicals using various mechanisms. These carotenoids are synthesized by certain species as major products however they also present as byproducts in several species based on the pathway and genetic capability. Haematococcus pluvialis and Chlorella zofingiensis are ideal strains for commercial astaxanthin production. This review provides recent updates on microalgal pigment production, extraction, and purification processes to standardize and analyze for commercial production. Also, discussed the factors affecting its production, application, market potential, bottlenecks, and future prospects.

Seaweed Intake and Risk of Cardiovascular Disease: The Circulatory Risk in Communities Study (CIRCS)

AIM

Seaweed contains soluble dietary fibers, potassium, and flavonoids and was recently reported to be inversely associated with the risk of coronary heart disease and mortality from stroke. However, epidemiological evidence on this issue has remained scarce.

METHODS

At the baseline survey of four Japanese communities between 1984 and 2000, we enrolled 6,169 men and women aged 40-79 years who had no history of cardiovascular disease. We assessed their seaweed intake using the data from a 24 h dietary recall survey and categorized the intake into four groups (0, 1-5.5, 5.5-15, and ≥ 15 g/day). We used sex-specific Cox proportional hazards models to examine the association between seaweed intake and risk of cardiovascular disease (stroke, stroke subtypes, and coronary heart disease).

RESULTS

During the 130,248 person-year follow-up, 523 cases of cardiovascular disease occurred: 369 cases of stroke and 154 cases of coronary heart disease. Seaweed intake levels were inversely associated with the risk of total stroke and cerebral infarction among men but not among women. Adjustment for cardiovascular risk factors did not change the associations: the hazard ratios (95% confidence intervals; P for trend) for the highest versus lowest categories of seaweed intake were 0.63 (0.42-0.94; 0.01) for total stroke and 0.59 (0.36-0.97; 0.03) for cerebral infarction. No associations were observed between seaweed intake and risks of intraparenchymal hemorrhage, subarachnoid hemorrhage, or coronary heart disease among men or women.

CONCLUSIONS

We found an inverse association between seaweed intake and risk of total stroke, especially that from cerebral infarction, among Japanese men.

Role of alginate in the mechanism by which brown seaweed Saccharina japonica intake alleviates an increase in blood pressure in 2-kidney, 1-clip renovascular hypertensive rats

BACKGROUND

The intake of Saccharina japonica (SJ), a widely consumed brown seaweed, has been reported to decrease blood pressure (BP) in hypertensive rats. It has been suggested that this effect is related to an increase in fecal sodium excretion (SE) by alginate (Alg) to the gastrointestinal tract; however, the mechanism is still unclear. This study investigated how different seaweeds with different amounts of Alg suppressed BP increase and enhanced fecal SE in 2-kidney, 1-clip renovascular hypertensive (2K1C) rats given SJ diet.

METHODS

Rats with 2K1C or sham operation were fed a normal-/high-salt diet with some kinds of seaweeds (5.0%, w/w) or SJ extract with different Alg contents for 6 weeks. We measured systolic BP every week and mean arterial pressure at the end, and measured the total and molecular weights of Alg in each seaweed. Then, we evaluated the relationship of the Alg amount in each seaweed with the suppression of BP increase in 2K1C rats. Finally, urinary and fecal SE for 24 h was measured.

RESULTS

The intake of SJ, SJ extract, Saccharina ochotensis (SO) blades and SO roots suppressed BP increase in 2K1C rats, but the strength was not proportional to the amounts of Alg contained in the seaweeds. Although SJ intake increased fecal SE in 2K1C rats fed a high-salt diet, the fecal SE was much less than urinary SE.

CONCLUSION

The sodium excretion in feces by Alg in SJ may not be one of the major mechanisms by which SJ intake attenuates hypertension in 2K1C rats.

Suppression of C-C chemokine receptor 1 is a key regulation for colon cancer chemoprevention in AOM/DSS mice by fucoxanthin

Fucoxanthin (Fx) has shown potential cancer chemopreventive functions in a carcinogenic murine azoxymethane/dextran sodium sulfate (AOM/DSS) model. However, the molecular mechanisms based on transcriptome profiles in vivo remain poorly understood. We investigated Fx-dependent alterations of the transcriptome with cancer-associated proteins in colorectal mucosal tissue obtained from AOM/DSS mice with or without Fx treatment. Fx administration (50 mg/kg body weight for 14 weeks) significantly prevented the onset of colorectal adenocarcinoma in AOM/DSS mice. A transcriptome analysis revealed that 11 signals, including adhesion, cell cycle, chemokine receptor, interleukin, MAPK, PI3K/AKT, p53, RAS, STAT, TGF-β, and Wnt were remarkably altered by Fx administration. In particular, chemokine (C-C motif) receptor 1 (Ccr1), which is contained in a gene set related to cytokine-cytokine receptor interactions, was the only significantly down-regulated gene after Fx administration for both 7 and 14 weeks. CCR1, AKT, Cyclin D1, and Smad2 were found to play central roles in the 11 signals shown above. Fx administration significantly down-regulated CCR1 (0.3- and 0.5-fold in mucosal crypts and lamina propria, respectively), pAKT(Ser⁴⁷³) (0.2-fold in mucosal crypts), Cyclin D1 (0.4-fold in mucosal crypts), and pSmad2(Ser^465/467) (0.7-fold in mucosal crypts) compared with proteins in these tissues of control mice after Fx administration for 14 weeks. Our findings suggested that Fx exerts a chemopreventive effect in AOM/DSS mice through attenuation of CCR1 expression along with 11 cancer-associated signals.

Production of Ulvan Oligosaccharides with Antioxidant and Angiotensin-Converting Enzyme-Inhibitory Activities by Microbial Enzymatic Hydrolysis

Seaweed oligosaccharides have attracted attention in food, agricultural, and medical applications recently. Compared to red and brown seaweeds, fewer studies have focused on the biological activity of green seaweed’s oligosaccharides. This study aimed to produce bioactive ulvan oligosaccharides via enzymatic hydrolysis from green seaweed Ulva lactuca. Ulvan, a water-soluble polysaccharide, was obtained by hot water extraction. Two isolated marine bacteria, Pseudomonas vesicularis MA103 and Aeromonas salmonicida MAEF108, were used to produce multiple hydrolases, such as ulvanolytic enzymes, amylase, cellulase, and xylanase, to degrade the ulvan extract. An ultrafiltration system was used to separate the enzymatic hydrolysate to acquire the ulvan oligosaccharides (UOS). The characteristics of the ulvan extract and the UOS were determined by yield, reducing sugar, uronic acid, sulfate group, and total phenols. The FT-IR spectrum indicated that the ulvan extract and the UOS presented the bands associated with O-H, C=O, C-O, and S=O stretching. Angiotensin I converting enzyme (ACE) inhibition and antioxidant activities in vitro were evaluated in the ulvan extract and the UOS. These results provide a practical approach to producing bioactive UOS by microbial enzymatic hydrolysis that can benefit the development of seaweed-based products at the industrial scale.

Fucoxanthin and Colorectal Cancer Prevention

Simple Summary

Colorectal cancer (CRC) is suggested to be preventable by certain food intakes. Fucoxanthin (Fx) is an anticancer agent contained abundantly in edible brown algae. However, epidemiological studies, in vivo and in vitro experiments for CRC, using Fx and Fx-rich foods, have not been fully outlined. To date, it has been reported that Fx, its metabolite of fucoxanthinol (FxOH) and Fx-rich algal extracts exerted anticancer potentials in human CRC cell lines, their cancer stem-cells-like spheroids and CRC animal models through a number of molecular mechanisms. Moreover, many in vivo experiments and interventional human trials have demonstrated that Fx, Fx-rich algal extracts and brown alga itself may improve CRC and/or certain risks, such as obesity, diabetes, metabolic syndrome, inflammation, oxidation, tumor microenvironment and/or gut microbiota. This review is the first report that summarizes the improving effects by Fx, FxOH and its rich brown algae for CRC and the risk factors.

Abstract

Colorectal cancer (CRC), which ranks among the top 10 most prevalent cancers, can obtain a good outcome with appropriate surgery and/or chemotherapy. However, the global numbers of both new cancer cases and death from CRC are expected to increase up to 2030. Diet-induced lifestyle modification is suggested to be effective in reducing the risk of human CRC; therefore, interventional studies using diets or diet-derived compounds have been conducted to explore the prevention of CRC. Fucoxanthin (Fx), a dietary carotenoid, is predominantly contained in edible brown algae, such as Undaria pinnatifida (wakame) and Himanthalia elongata (Sea spaghetti), which are consumed particularly frequently in Asian countries but also in some Western countries. Fx is responsible for a majority of the anticancer effects exerted by the lipophilic bioactive compounds in those algae. Interventional human trials have shown that Fx and brown algae mitigate certain risk factors for CRC; however, the direct mechanisms underlying the anti-CRC properties of Fx remain elusive. Fx and its deacetylated type “fucoxanthinol” (FxOH) have been reported to exert potential anticancer effects in preclinical cancer models through the suppression of many cancer-related signal pathways and the tumor microenvironment or alteration of the gut microbiota. We herein review the most recent studies on Fx as a potential candidate drug for CRC prevention.

Development of a Method for Fucoxanthin Production Using the Haptophyte Marine Microalga Pavlova sp. OPMS 30543

The natural pigment fucoxanthin has attracted global attention because of its superior antioxidant properties. The haptophyte marine microalgae Pavlova spp. are assumed to be promising industrial fucoxanthin producers as their lack of a cell wall could facilitate the commercialization of cultured cells as a whole food. This study screened promising Pavlova strains with high fucoxanthin content to develop an outdoor cultivation method for fucoxanthin production. Initial laboratory investigations of P. pinguis NBRC 102807, P. lutheri NBRC 102808, and Pavlova sp. OPMS 30543 identified OPMS 30543 as having the highest fucoxanthin content. The culture conditions were optimized for OPMS 30543. Compared with f/2 and Walne's media, the use of Daigo's IMK medium led to the highest biomass production and highest fucoxanthin accumulation. The presence of seawater elements in Daigo's IMK medium was necessary for the growth of OPMS 30543. OPMS 30543 was then cultured outdoors using acrylic pipe photobioreactors, a plastic bag, an open tank, and a raceway pond. Acrylic pipe photobioreactors with small diameters enabled the highest biomass production. Using an acrylic pipe photobioreactor with 60-mm diameter, a fucoxanthin productivity of 4.88 mg/L/day was achieved in outdoor cultivation. Thus, this study demonstrated the usefulness of Pavlova sp. OPMS 30543 for fucoxanthin production in outdoor cultivation.

Fucoxanthin Suppresses Osteoclastogenesis via Modulation of MAP Kinase and Nrf2 Signaling

Fucoxanthin (FX), a natural carotenoid present in edible brown seaweed, is known for its therapeutic potential in various diseases, including bone disease. However, its underlying regulatory mechanisms in osteoclastogenesis remain unclear. In this study, we investigated the effect of FX on osteoclast differentiation and its regulatory signaling pathway. In vitro studies were performed using osteoclast-like RAW264.7 cells stimulated with the soluble receptor activator of nuclear factor-κB ligand or tumor necrosis factor-alpha/interleukin-6. FX treatment significantly inhibited osteoclast differentiation and bone resorption ability, and downregulated the expression of osteoclast-specific markers such as nuclear factor of activated T cells 1, dendritic cell-specific seven transmembrane protein, and matrix metallopeptidase 9. Intracellular signaling pathway analysis revealed that FX specifically decreased the activation of the extracellular signal-regulated kinase and p38 kinase, and increased the nuclear translocation of phosphonuclear factor erythroid 2-related factor 2 (Nrf2). Our results suggest that FX regulates the expression of mitogen-activated protein kinases and Nrf2. Therefore, FX is a potential therapeutic agent for osteoclast-related skeletal disorders including osteoporosis and rheumatoid arthritis.

Effects of dietary fiber on vascular calcification by repetitive diet-induced fluctuations in plasma phosphorus in early-stage chronic kidney disease rats

Vascular calcification progresses under hyperphosphatemia, and represents a risk factor for cardiovascular disease in chronic kidney disease (CKD) patients. We recently indicated that phosphorus (P) fluctuations also exacerbated vascular calcification in early-stage CKD rats. Dietary fiber intake is reportedly associated with cardiovascular risk. This study investigated the effects of dietary fiber on vascular calcification by repeated P fluctuations in early-stage CKD rats. Unilateral nephrectomy rats were used as an early-stage CKD model. For 36 days, a P fluctuation (LH) group was fed low-P (0.02% P) and high-P (1.2% P) diets alternating every 2 days, and a P fluctuation with dietary fiber intake (LH + F) group was fed low-P and high-P diets containing dietary fiber alternating every 2 days. The effect on vascular calcification was measured calcium content. Effects on uremic toxin were measured levels of indoxyl sulfate (IS) and investigated gut microbiota. The LH + F group showed significantly reduced vessel calcium content compared to the LH group. Further, dietary fiber inhibited increases in blood levels of IS after intake of high-P diet, and decreased uremic toxin-producing intestinal bacteria. Dietary fiber may help suppress progression of vascular calcification due to repeated P fluctuations in early-stage CKD rats by decreasing uremic toxin-producing intestinal bacteria.

Impact of seaweed intake on health

Seaweeds contain minerals, vitamins, soluble dietary fibers, and flavonoids, which are regarded as preventive agents against lifestyle-related diseases. Seaweeds are consumed commonly in East Asian countries including Japan. Thus, intake of seaweeds might contribute to Japanese longevity via prevention of lifestyle-related diseases. Recently, two large Japanese cohort studies have reported the association of seaweed intake with reduced risk of cardiovascular diseases. On the other hand, seaweeds also contain iodine and heavy metals such as arsenic species, which are considered to have adverse effects on health. We here reviewed studies of the association between seaweed intake and mortality from or incidence of cancer and cardiovascular diseases, and their risk factors such as blood pressure or serum lipids. We also summarized the adverse effects of iodine and arsenic species in seaweeds. Although seaweeds have not been widely consumed in Western countries, dietary diversification and an increased proportion of immigrants from East Asia may increase seaweed consumption in those countries. Further epidemiological studies including observational and interventional studies are necessary to clarify the effects of seaweeds on disease and health.

Association between adherence to the Japanese diet and all-cause and cause-specific mortality: the Japan Public Health Center-based Prospective Study

Purpose

The present study aimed to examine the association between adherence to the Japanese diet and the subsequent risk of all-cause and cause-specific mortality using a large-scale cohort from settings all over Japan.

Methods

We analyzed data from a cohort study of 92,969 Japanese adults aged 45–74 years, covering 11 public health center areas nationwide. We collected dietary information using a validated 147-item food frequency questionnaire. Adherence to the Japanese diet consisting of eight components (high intake of rice, miso soup, seaweeds, pickles, green and yellow vegetables, fish, and green tea; low intake of beef and pork) was assessed using 8-item Japanese Diet Index (JDI8) score, with scores ranging from 0 to 8. The Cox proportional hazards model was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for all-cause and cause-specific mortality.

Results

During a median follow-up of 18.9 years, we documented 20,596 deaths. A higher JDI8 score was significantly associated with a lower risk for all-cause and cardiovascular disease (CVD) mortality. The multivariable-adjusted HR of all-cause and CVD mortality for the highest JDI8 score group (score of 6–8) versus the lowest JDI8 score group (score of 0–2) were 0.86 (95% CI 0.81–0.90, P trend < 0.001), and 0.89 (95% CI 0.80–0.99, P trend = 0.007), respectively.

Conclusions

Adhering to the Japanese diet, as assessed by the JDI8, was associated with a decreased risk of all-cause and CVD mortality among adults living in multiple areas across Japan.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02330-0) contains supplementary material, which is available to authorized users.

Neuroprotective Potentials of Marine Algae and Their Bioactive Metabolites: Pharmacological Insights and Therapeutic Advances

Beyond their significant contribution to the dietary and industrial supplies, marine algae are considered to be a potential source of some unique metabolites with diverse health benefits. The pharmacological properties, such as antioxidant, anti-inflammatory, cholesterol homeostasis, protein clearance and anti-amyloidogenic potentials of algal metabolites endorse their protective efficacy against oxidative stress, neuroinflammation, mitochondrial dysfunction, and impaired proteostasis which are known to be implicated in the pathophysiology of neurodegenerative disorders and the associated complications after cerebral ischemia and brain injuries. As was evident in various preclinical studies, algal compounds conferred neuroprotection against a wide range of neurotoxic stressors, such as oxygen/glucose deprivation, hydrogen peroxide, glutamate, amyloid β, or 1-methyl-4-phenylpyridinium (MPP+) and, therefore, hold therapeutic promise for brain disorders. While a significant number of algal compounds with promising neuroprotective capacity have been identified over the last decades, a few of them have had access to clinical trials. However, the recent approval of an algal oligosaccharide, sodium oligomannate, for the treatment of Alzheimer's disease enlightened the future of marine algae-based drug discovery. In this review, we briefly outline the pathophysiology of neurodegenerative diseases and brain injuries for identifying the targets of pharmacological intervention, and then review the literature on the neuroprotective potentials of algal compounds along with the underlying pharmacological mechanism, and present an appraisal on the recent therapeutic advances. We also propose a rational strategy to facilitate algal metabolites-based drug development.

Pigments Content (Chlorophylls, Fucoxanthin and Phycobiliproteins) of Different Commercial Dried Algae

Algae are a complex, polyphyletic group of organisms, affordable and naturally rich in nutrients, but also valuable sources of structurally diverse bioactive substances such as natural pigments. The aim of this work was to evaluate the polar and non-polar pigment contents of different commercial dried algae (brown: Himanthalia elongata, Undaria pinnatifida, Laminaria ochroleuca; red: Porphyra spp.; and a blue-green microalga: Spirulina spp.). The pigment extraction was carried out using different solvents (100% methanol, 100% methanol acid free, 100% ethanol, 90% acetone, N,N-dimethylformamide, dimethyl sulfoxide-water (4:1, v/v) and pH 6.8 phosphate buffer), selected according to their affinity for each class of pigments. Acetone proved to be an efficient solvent to extract chlorophylls from brown and red algae, but not from Spirulina spp. Porphyra spp. presented considerably higher levels of all pigments compared to brown algae, although Spirulina spp. presented significantly higher (p < 0.05) levels of chlorophylls, carotenoids and phycobiliproteins, compared to all macroalgae. The content of fucoxanthin extracted from the three brown algae was highly correlated to the carotenoid content. Within this group, Himanthalia elongata presented the highest fucoxanthin/total carotenoids ratio. Although the yield of extraction depended on the solvent used, the algae studied herein are an interesting source of pigments of great value for a wide range of applications.

Seaweeds as a Functional Ingredient for a Healthy Diet

Seaweeds have been used since ancient times as food, mainly by Asian countries, while in Western countries, their main application has been as gelling agents and colloids for the food, pharmaceuticals, and the cosmetic industry. Seaweeds are a good source of nutrients such as proteins, vitamins, minerals, and dietary fiber. Polyphenols, polysaccharides, and sterols, as well as other bioactive molecules, are mainly responsible for the healthy properties associated with seaweed. Antioxidant, anti-inflammatory, anti-cancer, and anti-diabetic properties are attributed to these compounds. If seaweeds are compared to terrestrial plants, they have a higher proportion of essential fatty acids as eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids. In addition, there are several secondary metabolites that are synthesized by algae such as terpenoids, oxylipins, phlorotannins, volatile hydrocarbons, and products of mixed biogenetic origin. Therefore, algae can be considered as a natural source of great interest, since they contain compounds with numerous biological activities and can be used as a functional ingredient in many technological applications to obtain functional foods.

Nutraceutical characteristics of the brown seaweed carotenoid fucoxanthin

Fucoxanthin (Fx), a major carotenoid found in brown seaweed, is known to show a unique and wide variety of biological activities. Upon absorption, Fx is metabolized to fucoxanthinol and amarouciaxanthin, and these metabolites mainly accumulate in visceral white adipose tissue (WAT). As seen in other carotenoids, Fx can quench singlet oxygen and scavenge a wide range of free radicals. The antioxidant activity is related to the neuroprotective, photoprotective, and hepatoprotective effects of Fx. Fx is also reported to show anti-cancer activity through the regulation of several biomolecules and signaling pathways that are involved in either cell cycle arrest, apoptosis, or metastasis suppression. Among the biological activities of Fx, anti-obesity is the most well-studied and most promising effect. This effect is primarily based on the upregulation of thermogenesis by uncoupling protein 1 expression and the increase in the metabolic rate induced by mitochondrial activation. In addition, Fx shows anti-diabetic effects by improving insulin resistance and promoting glucose utilization in skeletal muscle.

Purification of fucoxanthin from Sargassum wightii Greville and understanding the inhibition of angiotensin 1-converting enzyme: An in vitro and in silico studies

The isolation and purification of active components from the brown algae Sargassum.wightii is highly limited. In the present study, fucoxanthin was purified from S. wightii using simple methods. Ethyl acetate fraction obtained by Soxhlet extraction contained high concentration of fucoxanthin. Fucoxanthin-rich fraction was further subjected to open silica column chromatography and thin layer chromatography to obtain purified fucoxanthin. Purified fucoxanthin showed in vitro antioxidant activity. Fucoxanthin showed inhibition of angiotensin I-converting enzyme (ACE) with half maximal inhibitory value of 822.64 ± 17.69 μM. Kinetic analysis revealed mixed non-competitive inhibition with inhibitory constant of 600 μM for fucoxanthin against ACE. Molecular docking analysis showed the interaction of fucoxanthin with amino acids and zinc ion present in the active site of the human ACE. Molecular dynamics analysis demonstrated the stability of the fucoxanthin and ACE complex in in silico. These results show that S. wightii may be used as food ingredient to overcome hypertension.

Dietary iodine, seaweed consumption, and incidence risk of metabolic syndrome among postmenopausal women: a prospective analysis of the Korean Multi-Rural Communities Cohort Study (MRCohort)

PURPOSE

Despite a beneficial role of iodine and seaweed consumption against metabolic syndrome (MetS), which is high in postmenopausal women, few studies investigated such associations in a prospective study. This study aimed to investigate the association of dietary iodine and seaweed consumption with the incidence of MetS and its components in postmenopausal women.

METHODS

A total of 2588 postmenopausal women aged ≥ 40 years were recruited between 2005 and 2011 in the Multi-Rural Communities Cohort (MRCohort). A validated semiquantitative food frequency questionnaire was used to collect dietary intake data. MetS was defined as three of five components [abdominal obesity, elevated blood pressure, glucose, triglyceride, and low-high density lipoprotein cholesterol (HDL-C)] and the incidence of MetS was checked every 2-4 years. The incidence rate ratio (IRR) was estimated using a modified Poisson regression model with a robust error estimator.

RESULTS

During the mean follow-up period (3.4 ± 2.1 years), MetS occurred in 481 participants. The median cumulative average iodine intake was 108.9 µg/day (interquartile range, 60.8-190.2 µg/day). In multivariable analyses, average iodine and seaweed consumption were inversely associated with MetS (IRR = 0.61, 95% CI 0.47-0.78 in the highest quartile of iodine intake, P for trend = 0.0018; IRR = 0.52, 95% CI 0.39-0.69 in the highest quartile of seaweed consumption, P for trend = 0.0004). Among MetS components, blood glucose (> 100 mg/dL), blood pressure (≥ 130/85 mmHg), and lipid profiles (triglyceride, ≥ 150 mg/dL and HDL-C, < 50 mg/dL) were significantly inversely associated with dietary iodine and seaweed consumption, but there was no clear association for waist circumference (≥ 85 cm).

CONCLUSION

Dietary iodine and seaweed consumption may be inversely associated with MetS incidence and its individual abnormalities in postmenopausal women.

Frequency of Seaweed Intake and Its Association with Cardiovascular Disease Mortality: The JACC Study

AIM

Seaweed is a popular traditional foodstuff in Asian countries. To our knowledge, few studies have examined the association of seaweed intake with mortality from cardiovascular disease. We examined the association of frequency of seaweed intake with total and specific cardiovascular disease mortality.

METHODS

We examined the association of seaweed intake with mortality from cardiovascular disease among 40,234 men and 55,981 women who participated in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk. Sex-specific hazard ratios for mortality from cardiovascular disease (stroke, stroke subtypes, and coronary heart disease) according to the frequency of seaweed intake were calculated stratified by study area and adjusted for potential cardiovascular risk factors and dietary factors.

RESULTS

During the 1,580,996 person-year follow-up, 6,525 cardiovascular deaths occurred, of which 2,820 were due to stroke, and 1,378, to coronary heart disease. Among men, the multivariable analysis showed that participants who ate seaweed almost every day compared with those who never ate seaweed had hazard ratios (95% confidence interval; P for trend) of 0.79 (0.62-1.01; 0.72) for total cardiovascular disease, 0.70 (0.49-0.99; 0.47) for total stroke, 0.69 (0.41-1.16; 0.11) for cerebral infarction. Among women, the multivariable-adjusted hazard ratios were 0.72 (0.55-0.95; 0.001) for total cardiovascular disease, 0.70 (0.46-1.06; 0.01) for total stroke, and 0.49 (0.27-0.90; 0.22) for cerebral infarction. No associations were observed between seaweed intake and risk of intraparenchymal hemorrhage and coronary heart disease among either men or women.

CONCLUSIONS

We found an inverse association between seaweed intake and cardiovascular mortality among Japanese men and women, especially that from cerebral infarction.

Effects of Undaria pinnatifida (Wakame) on Postprandial Glycemia and Insulin Levels in Humans: a Randomized Crossover Trial

Postprandial hyperglycemia is a known risk factor for the development of several health disorders, including type 2 diabetes, obesity and cardiovascular disease. This study aimed to investigate the acute effect of Undaria pinnatifida (Wakame), a discriminative constituent of the Japanese diet, on postprandial blood glucose and insulin levels. The study was conducted using a crossover method among 26 subjects. Blood was sampled for glucose and insulin measurements at 0, 30, 60, 90 and 120 min after a subject consumed either 200 g of rice or 200 g rice with 4 g of dried wakame. Blood glucose and insulin levels were significantly lower at 30 min after consuming rice with wakame than after consuming rice alone. Moreover, the incremental areas under the curves for glucose and insulin were lower when wakame was included. Wakame intake can improve postprandial glucose homeostasis. Wakame intake may offer a simple behavioural strategy that can reduce glycemic excursions in prediabetes. This study was registered with the UMIN Clinical Trial Registry (UMIN000031050).

Seaweed intake and risk of cardiovascular disease: the Japan Public Health Center-based Prospective (JPHC) Study

BACKGROUND

The minerals, vitamins, soluble dietary fibers, and flavonoids of seaweed are protective for preventing cardiovascular diseases. However, the association between seaweed intake and risk of cardiovascular disease has not been established.

OBJECTIVES

We examined the dietary intake of seaweed and its impact upon stroke and ischemic heart disease risk among a Japanese study population.

METHODS

We surveyed 40,707 men and 45,406 women from 2 large cohorts (age range: 40-69 y). Seaweed intake was determined by FFQ at baseline (1990-1994). Incidences of stroke and ischemic heart disease were ascertained until the end of 2009 (Cohort I) or 2012 (Cohort II). Sex-specific cardiovascular disease HRs (95% CIs) were estimated using Cox proportional hazard models after stratification by area and adjustment for cardiovascular disease risk and dietary factors.

RESULTS

During 1,493,232 person-years of follow-up, 4777 strokes (2863 ischemic stroke, 1361 intraparenchymal hemorrhages, and 531 subarachnoid hemorrhages) and 1204 ischemic heart disease cases were identified. Among men, significant multivariable HRs (95% CIs) for almost daily consumption compared with almost no consumption of seaweed were seen in ischemic heart disease [0.76 (0.58, 0.99); P-trend = 0.04] and total cardiovascular diseases [0.88 (0.78, 1.00); P-trend = 0.08]. Among women, such inverse associations were 0.56 (0.36, 0.85; P-trend = 0.006) for ischemic heart disease and 0.89 (0.76, 1.05; P-trend = 0.10) for total cardiovascular diseases. No significant associations were observed between seaweed intake and risk of total stroke or stroke types among either men or women.

CONCLUSIONS

Seaweed intake was inversely associated with risk of ischemic heart disease.

Association between improved adherence to the Japanese diet and incident functional disability in older people: The Ohsaki Cohort 2006 Study

BACKGROUND & AIMS

Although it has been reported that the Japanese dietary pattern is associated with a lower risk of incident functional disability among older people, the potential benefits of improving adherence to the Japanese diet remain unclear. The aim of the present study was to evaluate the association between 12-year change in adherence to the Japanese diet and the subsequent risk of incident functional disability in older people in Japan.

METHODS

We analyzed 10-year follow-up data from a cohort study of 2923 Japanese older adults (age ≥65 years) in 2006. We collected dietary information using a validated 39-item food frequency questionnaire at two time points (1994 and 2006). Adherence to the Japanese diet (high intake of rice, miso soup, seaweeds, pickles, green and yellow vegetables, fish, green tea; low intake of beef and pork, and coffee) was assessed using the Japanese Diet Index (JDI), which ranges from 0 to 9. Participants were categorized into five groups according to changes in the JDI score at these two time points. Data on incident functional disability from December 2006 to November 2016 were retrieved from the public long-term care insurance database. The Cox proportional hazards model was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for incident functional disability.

RESULTS

During 22,466 person-years of follow-up, 1093 cases of incident functional disability were documented. Compared with participants in the group with the largest decrease in the JDI score (≤-2), the multivariate-adjusted HR (95% CI) of incident functional disability was 0.77 (0.61-0.98) for those in the largest increase group (≥+2).

CONCLUSIONS

Improved adherence to the Japanese diet was associated with a significantly lower risk of incident functional disability in older people in Japan.

Efficient Extraction of Carotenoids from Sargassum muticum Using Aqueous Solutions of Tween 20

The replacement of synthetic compounds by natural products witnesses an increasing demand from the pharmaceutical, cosmetic, food and nutraceutical industries. Included in the set of natural raw materials that are poorly explored are the macroalgae. Despite the detailed characterization and identification of most relevant biomolecules that are present in the main macroalgae species, there remains a lack of efficient and economically viable processes available to meet the needs of the markets. In this work, an efficient and single-step process, based on aqueous solutions of Tween 20, to recover carotenoids from Sargassum muticum, an invasive brown macroalgae species present in the Portuguese coast, is proposed and optimized allowing an extraction yield of 2.78 ± 0.4 mgcarotenoids.gdried mass-1, which is shown to increase the extraction efficiency by 38% when compared with traditional methods.

Japanese diet and survival time: The Ohsaki Cohort 1994 study

BACKGROUND & AIMS

Although it has been suggested that the Japanese diet contributes to the longevity of the Japanese population, no study has examined the association between the Japanese diet and survival time. The present study investigated the association between the Japanese diet and survival time.

METHODS

We analyzed 20-year follow-up data from a cohort study of 14,764 Japanese men and women aged 40-79 years. At the baseline survey in 1994, we collected dietary information using a validated 40-item food frequency questionnaire. Adherence to a Japanese diet consisting of nine components (rice, miso soup, seaweeds, pickles, green and yellow vegetables, fish, green tea, beef and pork, and coffee) was assessed in terms of a Japanese dietary index (JDI) score, the total score ranging from 0 to 9. Cox proportional hazards model and Laplace regression analysis were used to estimate the hazard ratios (HRs) and differences in median age at death (50th percentile differences - PDs in age at death) with 95% confidence intervals (CIs) according to the quartiles of the JDI score.

RESULTS

During the follow-up period, we documented 4,619 deaths. We observed that a higher JDI score was associated with a lower risk of mortality and longer survival time: In comparison to participants in the lowest JDI score quartile (0-4), the multivariate-adjusted HR (95% CI) of all-cause mortality was 0.91 (0.83-0.99) and the multivariate-adjusted 50th PD in age at death (95% CI) was 10.2 (3.2-17.2) months longer for those in the highest quartile (7-9).

CONCLUSIONS

Adherence to a Japanese diet is associated with a longer survival time.

Oral Administration of Edible Seaweed Undaria Pinnatifida (Wakame) Modifies Glucose and Lipid Metabolism in Rats: A DNA Microarray Analysis

SCOPE

Wakame is an edible seaweed that is a common constituent in the Japanese diet. Previous studies showed that wakame consumption is associated with the prevention of metabolic syndrome, but the molecular mechanisms underlying the protective effects are poorly understood.

METHODS AND RESULTS

To determine if the expression of hepatic genes is affected by ingestion of the brown seaweed Undaria pinnatifida (wakame), rats were fed a diet containing 0, 0.1, or 1.0 g per 100 g dried wakame powder for 28 days. Administration of 1% wakame significantly decreased serum total cholesterol levels. Hepatic gene expression was investigated using DNA microarray analysis, and the results showed that wakame suppresses the lipogenic pathway by downregulating SREBF-1. Moreover, bile acid biosynthesis and gluconeogenesis were promoted by upregulation of the PPAR signaling pathway, which leads to a reduction in the accumulation of cholesterol and promotion of β-oxidation.

CONCLUSIONS

These results suggest that wakame ingestion affects glucose and lipid metabolism by altering the expression of SREBF-1 and PPAR signal-related genes.

Fucoxanthin Inhibits β-Amyloid Assembly and Attenuates β-Amyloid Oligomer-Induced Cognitive Impairments

β-Amyloid (Aβ) can form aggregates through self-assembly and produce neurotoxicity in the early stage of Alzheimer's disease (AD). Therefore, the inhibition of Aβ assembly is considered as the primary target for AD therapy. In this study, we reported that fucoxanthin, a marine carotenoid, potently reduced the formation of Aβ fibrils and oligomers. Moreover, the fucoxanthin-triggered modification significantly reduced the neurotoxicity of Aβ oligomers in vitro. Molecular dynamics simulation analysis further revealed a hydrophobic interaction between fucoxanthin and Aβ peptide, which might prevent the conformational transition and self-assembly of Aβ. Most importantly, fucoxanthin could attenuate cognitive impairments in Aβ oligomer-injected mice. In addition, fucoxanthin significantly inhibited oxidative stress, enhanced the expression of brain-derived neurotrophic factor, and increased ChAT-positive regions in the hippocampus of mice. On the basis of these novel findings, we anticipated that fucoxanthin might ameliorate AD via inhibiting Aβ assembly and attenuating Aβ neurotoxicity.

A comprehensive approach to formulation of seaweed-enriched meat products: From technological development to assessment of healthy properties

Meat consumption is influenced by various kinds of factors, among them health implications. Different strategies can be effective in developing meat-based functional foods. These basically entail reducing the presence of compounds with negative health implications and enhancing the presence of beneficial compounds. This article reviews a comprehensive model for the development of meat-based functional foods based on a presentation of the research achieved in terms of the design and development of qualitatively and quantitatively modified meat products (frankfurters, patties and restructured steaks). These were reformulated to incorporate nutrients associated with three different seaweeds (wakame-Undaria pinnatifida; nori-Porphyra umbilicalis; and sea spaghetti-Himanthalia elongata) as sources of bioactive substances, while simultaneously reducing sodium and fat and improving fatty acid profiles. Those seaweeds were chosen, because in terms of composition and health implications, abundance on Spanish coasts, relatively widespread consumption, and suitability in terms of flavour and colour they are better suited than others for use as ingredients in new products. It also discusses the consequences of the use of this type of meat-based functional foods (combination of pork meat and 5% of each seaweed with or without hypercholesterolaemic agent included in the diets) on growing animals (Wistar male rats), and their effects on different aspects of lipoprotein metabolism, oxidative stress and liver structure. This article, then, reports a comprehensive approach to the production of seaweed-enriched meat products, considering aspects of technological development aimed at achieving the functional effect.

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.

Algae Undaria pinnatifida Protects Hypothalamic Neurons against Endoplasmic Reticulum Stress through Akt/mTOR Signaling

Increased endoplasmic reticulum (ER) stress is known to be one of the causes of hypothalamic neuronal damage, as well as a cause of metabolic disorders such as obesity and diabetes. Recent evidence has suggested that Undaria pinnatifida (UP), an edible brown algae, has antioxidant activity. However, the neuroprotective effect of UP has yet to be examined. In this study, to investigate the neuroprotective effect of UP on ER stress-induced neuronal damage in mouse hypothalamic neurons, mice immortal hypothalamic neurons (GT1-7) were incubated with extract of UP. ER stress was induced by treating with tunicamycin. Tunicamycin induced apoptotic cell death was compared with the vehicle treatment through excessive ER stress. However UP protected GT1-7 cells from cell death, occurring after treatment with tunicamycin by reducing ER stress. Treatment with UP resulted in reduced increment of ATF6 and CHOP, and recovered the decrease of phosphorylation of Akt/mTOR by tunicamycin and the increment of autophagy. These results show that UP protects GT1-7 cells from ER stress induced cell death through the Akt/mTOR pathway. The current study suggests that UP may have a beneficial effect on cerebral neuronal degeneration in metabolic diseases with elevated ER stress.

Marine Carotenoids against Oxidative Stress: Effects on Human Health

Carotenoids are lipid-soluble pigments that are produced in some plants, algae, fungi, and bacterial species, which accounts for their orange and yellow hues. Carotenoids are powerful antioxidants thanks to their ability to quench singlet oxygen, to be oxidized, to be isomerized, and to scavenge free radicals, which plays a crucial role in the etiology of several diseases. Unusual marine environments are associated with a great chemical diversity, resulting in novel bioactive molecules. Thus, marine organisms may represent an important source of novel biologically active substances for the development of therapeutics. In this respect, various novel marine carotenoids have recently been isolated from marine organisms and displayed several utilizations as nutraceuticals and pharmaceuticals. Marine carotenoids (astaxanthin, fucoxanthin, β-carotene, lutein but also the rare siphonaxanthin, sioxanthin, and myxol) have recently shown antioxidant properties in reducing oxidative stress markers. This review aims to describe the role of marine carotenoids against oxidative stress and their potential applications in preventing and treating inflammatory diseases.

Biological Properties of Fucoxanthin in Oil Recovered from Two Brown Seaweeds Using Supercritical CO2 Extraction

The bioactive materials in brown seaweeds hold great interest for developing new drugs and healthy foods. The oil content in brown seaweeds (Saccharina japonica and Sargassum horneri) was extracted by using environmentally friendly supercritical CO2 (SC-CO2) with ethanol as a co-solvent in a semi-batch flow extraction process and compared the results with a conventional extraction process using hexane, ethanol, and acetone mixed with methanol (1:1, v/v). The SC-CO2 method was used at a temperature of 45 °C and pressure of 250 bar. The flow rate of CO2 (27 g/min) was constant for the entire extraction period of 2 h. The obtained oil from the brown seaweeds was analyzed to determine their valuable compounds such as fatty acids, phenolic compounds, fucoxanthin and biological properties including antioxidant, antimicrobial, and antihypertension effects. The amounts of fucoxanthin extracted from the SC-CO2 oils of S. japonica and S. horneri were 0.41 ± 0.05 and 0.77 ± 0.07 mg/g, respectively. High antihypertensive activity was detected when using mixed acetone and methanol, whereas the phenolic content and antioxidant property were higher in the oil extracted by SC-CO2. The acetone-methanol mix extracts exhibited better antimicrobial activities than those obtained by other means. Thus, the SC-CO2 extraction process appears to be a good method for obtaining valuable compounds from both brown seaweeds, and showed stronger biological activity than that obtained by the conventional extraction process.

Fucoxanthin: A Promising Medicinal and Nutritional Ingredient

Fucoxanthin, an allenic carotenoid, can be isolated from edible brown seaweeds. Recent studies have reported that fucoxanthin has many physiological functions and biological properties, such as antiobesity, antitumor, antidiabetes, antioxidant, anti-inflammatory, and hepatoprotective activities, as well as cardiovascular and cerebrovascular protective effects. Therefore, fucoxanthin can be used as both medicinal and nutritional ingredient to prevent and treat chronic diseases. Although fucoxanthin possesses many medicinal ingredient and nutritional qualities, studies indicated that its structure was unstable. In this paper, we consulted the current documents and reviewed structural properties and factors affecting the stability of fucoxanthin. We also reported the metabolism, safety, pharmacological activities, and the methods of improving the bioavailability of fucoxanthin. Based on these studies providing essential background knowledge, fucoxanthin can be developed into marine drugs and nutritional products.

Carotenoids: potential allies of cardiovascular health?

Carotenoids are a class of natural, fat-soluble pigments found principally in plants. They have potential antioxidant biological properties because of their chemical structure and interaction with biological membranes. Epidemiologic studies supported the hypothesis that antioxidants could be used as an inexpensive means of both primary and secondary cardiovascular disease (CVD) prevention. In fact, the oxidation of low-density lipoproteins (LDL) in the vessels plays a key role in the development of atherosclerotic lesions. The resistance of LDL to oxidation is increased by high dietary antioxidant intake, so that carotenoids, as part of food patterns such as the Mediterranean diet, may have beneficial effects on cardiovascular health too. Further properties of carotenoids leading to a potential reduction of cardiovascular risk are represented by lowering of blood pressure, reduction of pro-inflammatory cytokines and markers of inflammation (such as C-reactive protein), and improvement of insulin sensitivity in muscle, liver, and adipose tissues. In addition, recent nutrigenomics studies have focused on the exceptional ability of carotenoids in modulating the expression of specific genes involved in cell metabolism. The aim of this review is to focus attention to this effect of some carotenoids to prevent CVD.

Wakame (Undaria pinnatifida ) modulates hyperphosphatemia in a rat model of chronic renal failure

In chronic renal failure, inorganic phosphate (Pi) retention speeds up the progression to end-stage renal disease. The current therapy for hyperphosphatemia in patients with chronic renal failure consists of dietary Pi restriction combined with administration of Pi binders, but each therapy has practical problems. Thus, the discovery of foods or nutrients that inhibit Pi absorption may be useful for the treatment of hyperphosphatemia. In the present study, we investigated whether wakame (Undaria pinnatifida) is a useful food for the prevention of hyperphosphatemia in a rat model of renal failure. Feeding a diet containing 5% wakame significantly decreased plasma and urinary Pi levels and increased the amount of fecal Pi. In addition, wakame significantly reduced plasma blood urea nitrogen and plasma Pi levels in 5/6 nephrectomized rats fed a high-Pi diet. Biochemical analyses showed that the reduction of intestinal Pi absorption is the main reason for the decrease in plasma Pi levels in rats fed a diet containing wakame. In addition, feeding alginic acid and fucoidan, major components of wakame fiber, was effective in reducing plasma Pi levels in normal rats. Finally, we concluded that wakame may be a useful food for the prevention of hyperphosphatemia in rodents.

Bioactive compounds from macroalgae in the new millennium: implications for neurodegenerative diseases

Marine environment has proven to be a rich source of structurally diverse and complex compounds exhibiting numerous interesting biological effects. Macroalgae are currently being explored as novel and sustainable sources of bioactive compounds for both pharmaceutical and nutraceutical applications. Given the increasing prevalence of different forms of dementia, researchers have been focusing their attention on the discovery and development of new compounds from macroalgae for potential application in neuroprotection. Neuroprotection involves multiple and complex mechanisms, which are deeply related. Therefore, compounds exerting neuroprotective effects through different pathways could present viable approaches in the management of neurodegenerative diseases, such as Alzheimer's and Parkinson's. In fact, several studies had already provided promising insights into the neuroprotective effects of a series of compounds isolated from different macroalgae species. This review will focus on compounds from macroalgae that exhibit neuroprotective effects and their potential application to treat and/or prevent neurodegenerative diseases.

Undariase, a direct-acting fibrin(ogen)olytic enzyme from Undaria pinnatifida, inhibits thrombosis in vivo and exhibits in vitro thrombolytic properties

A direct-acting fibrinolytic serine protease named undariase possessing anticoagulant and antiplatelet properties was purified from Undaria pinnatifida. Undariase showed a molecular weight of 50 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry. It displayed a strong fibrin zymogram lysis band corresponding to the same molecular mass. The N-terminal sequence of undariase, LTATTCEELAAAPTD, does not match with any known fibrinolytic enzyme. The enzyme was stable and active at high temperatures (35-70 °C). The fibrinolytic activity of undariase was strongly inhibited by phenylmethylsulfonyl fluoride (PMSF) and 4-(amidinophenyl) methanesulfonyl fluoride (APMSF). The K m and V max values for substrate S-2251 were determined as 6.15 mM and 90.91 mM/min/ml, respectively. Undariase resulted in clot lysis by directly cleaving α and β chains of fibrin. Similarly, it preferentially acted on the Aα chain of fibrinogen followed by cleavage of the Bβ chain. It significantly prolonged the PFA-100 closure times of citrated whole human blood. In addition, undariase delayed the coagulation time and increased activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). Undariase exerted a significant protective effect against collagen plus epinephrine-induced pulmonary thromboembolism in mice. It prevented carrageenan-induced thrombus formation in the tail of mice. It also resulted in prolongation of APTT ex vivo. In conclusion, these results suggested a therapeutic potential of undariase for thrombosis.

Protective effect of telmisartan against progressive oxidative brain damage and synuclein phosphorylation in stroke-resistant spontaneously hypertensive rats

Previously, we reported that reactive oxygen species and signaling molecules of angiotensin II produced lipid peroxides, degenerated proteins, and injured DNA after cerebral ischemia in normotensive Wistar rats. Here, we investigated the long-term effect of the angiotensin II type I receptor blocker telmisartan on oxidative stress and hyperphosphorylated α-synuclein accumulation in stroke-resistant spontaneously hypertensive rats (SHR-SR). At the age of 3 months, SHR-SR were divided into 3 treatment groups: SHR-SR vehicle (SHR/Ve), SHR-SR low-dose telmisartan (.3 mg/kg/day) (SHR/low), and SHR-SR high-dose telmisartan (3 mg/kg/day) (SHR/high). Immunohistologic analyses were conducted in these groups and Wistar rats at the age of 6, 12, and 18 months. The SHR/Ve group demonstrated more progressive increase in advanced glycation end product (AGE)-, 4-hydroxy-2-nonenal (4-HNE)-, and phosphorylated α-synuclein (pSyn)-positive cells in the cerebral cortex and hippocampus compared with the Wistar group at 18 months. These expressions were reduced in the SHR/low group even without lowering blood pressure (BP), and expressions were dramatically suppressed in the SHR/high group with lowering of BP. These data suggest that persistent hypertension in SHR-SR strongly potentiate the markers of oxidative damage (AGEs and 4-HNE) and abnormal accumulation of pSyn, which were greatly suppressed by telmisartan in a dose-dependent manner without and with lowering of BP.

Differential neuritogenic activities of two edible brown macroalgae, Undaria pinnatifida and Saccharina japonica

Undaria pinnatifida (Harvey) Suringar and Saccharina japonica Areschoug are two common seaweeds, and both are known to have numerous pharmacological properties that include neuroprotective effects. In a previous study, we found that the ethanol extracts of U. pinnatifida (UPE) and S. japonica (SJE) had neurite promoting activities on developing hippocampal neurons. In the present study, we studied and compared the effects of UPE and SJE on neuronal maturation. Both UPE and SJE promoted neurite outgrowth in a dose-dependent manner with optimal concentrations of 5 and 15 μg/mL, respectively. Initial neuronal differentiation was significantly promoted by UPE and SJE. Subsequently, treatment with both increased indices of axonal and dendritic cytoarchitecture, such as, the numbers and lengths of primary processes, although only UPE had a significant effect on branching frequencies. In addition, UPE and SJE showed no evidence of cytotoxicity, rather they protected neurons from naturally occurring death in vitro. These results indicate that UPE and SJE promote axodendritic maturation and neuronal survival and suggest that these algal extracts, especially UPE, have beneficial effects on the nervous system.