Evaluation of marine algae Undaria pinnatifida and Porphyra purpurea as a food supplement: composition, nutritional value and effect of intake on intestinal, hepatic and renal enzyme activities in rats

Fluorescent imaging and toxicology study of alga-derived carbon dots in zebrafish

With the widespread application of carbon dots (CDs) in fluorescence imaging, their toxicity has become a focal point of concern. The potential toxicity of CDs synthesized from different raw materials remains an unresolved issue. Laver and wakame, which are commonly popular sea vegetable foods rich in nutrients, were utilized to investigate whether synthetic CDs derived from these alga sources retain medicinal value. Herein, two types of fluorescent alga-derived CDs were prepared through hydrothermal synthesis using laver and wakame respectively. Zebrafish were immersed in both types of CDs to observe their fluorescence imaging effects within the zebrafish bodies. It was observed that laver-derived CDs and wakame-derived CDs exhibited similar luminescence properties but differed in terms of fish egg imaging localization. Additionally, intestinal flora sequencing revealed varying degrees of influence on the zebrafish gut microbiota by the two types of CDs, suggesting that both alga-derived CDs could enhance the abundance of intestinal flora in zebrafish.

Elnosary M, L. Ashour M, M. Abd El-Moneam N, A. Shreadah M. Flavonoids Biosynthesis in Plants as a Defense Mechanism: Role and Function Concerning Pharmacodynamics and Pharmacokinetic Properties

Flavonoids are a major class of secondary metabolites that comprises more than 6000 compounds that have been identified. They are biosynthesized via the phenylpropanoid metabolic pathway that involves groups of enzymes such as isomerases, hydroxylases, and reductases that greatly affect the determination of the flavonoid skeleton. For example, transferase enzymes responsible for the modification of sugar result in changes in the physiological activity of the flavonoids and changes in their physical properties, such as solubility, reactivity, and interaction with cellular target molecules, which affect their pharmacodynamics and pharmacokinetic properties. In addition, flavonoids have diverse biological activities such as antioxidants, anticancer, and antiviral in managing Alzheimer’s disease. However, most marine flavonoids are still incompletely discovered because marine flavonoid biosynthesis is produced and possesses unique substitutions that are not commonly found in terrestrial bioactive compounds. The current chapter will illustrate the importance of flavonoids’ role in metabolism and the main difference between marine and terrestrial flavonoids.

Undaria pinnatifida (Wakame) Intake Ameliorates High-Fat Diet-Induced Glucose Intolerance via Promoting GLUT4 Expression and Membrane Translocation in Muscle

Type 2 diabetes mellitus (T2DM), a lifestyle-related disease, is developed due to eating habits and decreased physical activity. Diabetes also increases the risk of cancer and major neurodegenerative diseases; controlling the onset of diabetes helps prevent various illnesses. Eating seaweed, such as Undaria pinnatifida (wakame), is a part of the Asian food culture. Therefore, we analyzed the antidiabetic effect of wakame intake using the high-fat diet-induced diabetes mouse model. Furthermore, we analyzed the effect of wakame extract on the cell membrane translocation of glucose transporter-4 (GLUT4) and activation of insulin signal molecules, such as AKT and AMPK, in insulin-sensitive tissues. Differentiated C2C12 cells were incubated with wakame components. The membrane translocation of GLUT4 and phosphorylation of AKT and AMPK were investigated with immunofluorescence staining and Western blotting, respectively. Also, male C57BL/6J mice were fed the normal diet (ND), high-fat diet (HFD), ND with 1% wakame powder (ND + W), or HFD with 1% wakame powder (HFD + W). We evaluated the effect of wakame intake on high-fat diet-induced glucose intolerance using an oral glucose tolerance test. Moreover, we analyzed insulin signaling molecules, such as GLUT4, AKT, and AMPK, in muscle using Western blotting. GLUT4 membrane translocation was promoted by wakame components. Also, GLUT4 levels and AKT and AMPK phosphorylation were significantly elevated by wakame components in C2C12 cells. In addition, the area under the curve (AUC) of the HFD + W group was significantly smaller than that of the HFD group. Furthermore, the level of GLUT4 in the muscle was increased in the wakame intake group. This study revealed that various wakame components exerted antidiabetic effects on the mice on a high-fat diet by promoting glucose uptake in the skeletal muscle, enhancing GLUT4 levels, and activating AKT and AMPK.

Thermochemical Characterization of Eight Seaweed Species and Evaluation of Their Potential Use as an Alternative for Biofuel Production and Source of Bioactive Compounds

Algae are underexplored resources in Western countries and novel approaches are needed to boost their industrial exploitation. In this work, eight edible seaweeds were subjected to their valorization in terms of nutritional characterization, thermochemical properties, and bioactive profile. Our results suggest that seaweeds present a rich nutritional profile, in which carbohydrates are present in high proportions, followed by a moderate protein composition and a valuable content of ω-3 polyunsaturated fatty acids. The thermochemical characterization of seaweeds showed that some macroalgae present a low ash content and high volatile matter and carbon fixation rates, being promising sources for alternative biofuel production. The bioactive profile of seaweeds was obtained from their phenolic and carotenoid content, together with the evaluation of their associated bioactivities. Among all the species analyzed, Porphyra purpurea presented a balanced composition in terms of carbohydrates and proteins and the best thermochemical profile. This species also showed moderate anti-inflammatory activity. Additionally, Himanthalia elongata extracts showed the highest contents of total phenolics and a moderate carotenoid content, which led to the highest rates of antioxidant activity. Overall, these results suggest that seaweeds can be used as food or functional ingredient to increase the nutritional quality of food formulations.

Seaweed-Derived Proteins and Peptides: Promising Marine Bioactives

Seaweeds are a typical food of East-Asian cuisine, to which are alleged several beneficial health effects have been attributed. Their availability and their nutritional and chemical composition have favored the increase in its consumption worldwide, as well as a focus of research due to their bioactive properties. In this regard, seaweed proteins are nutritionally valuable and comprise several specific enzymes, glycoproteins, cell wall-attached proteins, red algae phycobiliproteins, lectins, peptides, or mycosporine-like amino acids. This great extent of molecules has been reported to exert significant antioxidant, antimicrobial, anti-inflammatory, antihypertensive, antidiabetic, or antitumoral properties. Hence, knowledge on algae proteins and derived compounds have gained special interest for the potential nutraceutical, cosmetic or pharmaceutical industries based on these bioactivities. Although several molecular mechanisms of action on how these proteins and peptides exert biological activities have been described, many gaps in knowledge still need to be filled. Updating the current knowledge related to seaweed proteins and peptides is of interest to further asses their potential health benefits. This review addresses the characteristics of seaweed protein and protein-derived molecules, their natural occurrence, their studied bioactive properties, and their described potential mechanisms of action.

Seaweeds as Valuable Sources of Essential Fatty Acids for Human Nutrition

The overexploitation of terrestrial habitats, combined with the ever-growing demand for food, has led to the search for alternative food sources. The importance of seaweeds as food sources has been growing, and their potential as sources of fatty acids (FA) make seaweeds an interesting feedstock for the food and nutraceutical industries. The aim of this study is to assess the potential of five red seaweeds (Asparagospis armata, Calliblepharis jubata, Chondracanthus teedei var. lusitanicus, Gracilaria gracilis, and Grateloupia turuturu) and three brown seaweeds (Colpomenia peregrina, Sargassum muticum and Undaria pinnatifida), harvested in central Portugal, as effective sources of essential FA for food or as dietary supplements. FA were extracted from the biomass, transmethylated to methyl esters, and analyzed through gas chromatography-mass spectrometry. G. gracilis presented the highest content of saturated fatty acids (SFA) (41.49 mg·g-1), whereas C. jubata exhibited the highest content of highly unsaturated fatty acids (HUFA) (28.56 mg·g-1); the three G. turuturu life cycle stages presented prominent SFA and HUFA contents. Omega-6/omega-3 ratios were assessed and, in combination with PUFA+HUFA/SFA ratios, it is suggested that C. jubata and U. pinnatifida may be the algae with highest nutraceutical potential, promoting health benefits and contributing to a balanced dietary intake of fatty acids.

Undaria pinnatifida extract feeding increases exercise endurance and skeletal muscle mass by promoting oxidative muscle remodeling in mice

Dietary habits can alter the skeletal muscle performance and mass, and Undaria pinnatifida extracts are considered a potent candidate for improving the muscle mass and function. Therefore, in this study, we aimed to assess the effect of U pinnatifida extracts on exercise endurance and skeletal muscle mass. C57BL/6 mice were fed a 0.25% U pinnatifida extract-containing diet for 8 weeks. U pinnatifida extract-fed mice showed increased running distance, total running time, and extensor digitorum longus and gastrocnemius muscle weights. U pinnatifida extract supplementation upregulated the expression of myocyte enhancer factor 2C, oxidative muscle fiber markers such as myosin heavy chain 1 (MHC1), and oxidative biomarkers in the gastrocnemius muscles. Compared to the controls, U pinnatifida extract-fed mice showed larger mitochondria and increased gene and protein expression of molecules involved in mitochondrial biogenesis and oxidative phosphorylation, including nuclear respiratory factor 2 and mitochondrial transcription factor A. U pinnatifida extract supplementation also increased the mRNA expression of angiogenesis markers, including VEGFa, VEGFb, FGF1, angiopoietin 1, and angiopoietin 2, in the gastrocnemius muscles. Importantly, U pinnatifida extracts upregulated the estrogen-related receptor γ and peroxisome proliferator-activated receptor gamma co-activator 1-alpha (PGC-1α)/AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1) networks, which are partially increased by fucoxanthin, hesperetin, and caffeic acid treatments. Collectively, U pinnatifida extracts enhance mitochondrial biogenesis, increase oxidative muscle fiber, and promote angiogenesis in skeletal muscles, resulting in improved exercise capacity and skeletal muscle mass. These effects are attributable to fucoxanthin, hesperetin, and caffeic acid, bioactive components of U pinnatifida extracts.

Toxicological effects of marine seaweeds: a cautious insight for human consumption

Marine environment is a rich and diverse source for many biologically active substances including functional foods and nutraceuticals. It is well exploited for useful compounds, natural products and aquaculture industry; and seaweeds is one of the major contributors in terms of both food security and healthy nutrition. They are well-known due to their enormous benefits and is consumed globally in many countries. However, there is lack of attention toward their toxicity reports which might be due toxic chemical compounds from seaweed, epiphytic bacteria or harmful algal bloom and absorbed heavy metals from seawater. The excess of these components might lead to harmful interactions with drugs and hormone levels in the human body. Due to their global consumption and to meet increasing demands, it is necessary to address their hazardous and toxic aspects. In this review, we have done extensive literature for healthy seaweeds, their nutritional composition while summarizing the toxic effects of selected seaweeds from red, brown and green group which includes- Gracilaria, Acanthophora, Caulerpa, Cladosiphon, and Laminaria sp. Spirulina, a microalgae (cyanobacteria) biomass is also included in toxicity discussion as it an important food supplement and many times shows adverse reactions and drug interactions. The identified compounds from seaweeds were concluded to be toxic to humans, though they exhibited certain beneficial effects too. They have an easy access in food chain and thus invade the higher trophic level organisms. This review will create an awareness among scientific and nonscientific community, as well as government organization to regulate edible seaweed consumption and keep them under surveillance for their beneficial and safe consumption.

Health Functionality and Quality Control of Laver (Porphyra, Pyropia): Current Issues and Future Perspectives as an Edible Seaweed

The growing interest in laver as a food product and as a source of substances beneficial to health has led to global consumer demand for laver produced in a limited area of northeastern Asia. Here we review research into the benefits of laver consumption and discuss future perspectives on the improvement of laver product quality. Variation in nutritional/functional values among product types (raw and processed (dried, roasted, or seasoned) laver) makes product-specific nutritional analysis a prerequisite for accurate prediction of health benefits. The effects of drying, roasting, and seasoning on the contents of both beneficial and harmful substances highlight the importance of managing laver processing conditions. Most research into health benefits has focused on substances present at high concentrations in laver (porphyran, Vitamin B12, taurine), with assessment of the expected effects of laver consumption. Mitigation of chemical/microbiological risks and the adoption of novel technologies to exploit under-reported biochemical characteristics of lavers are suggested as key strategies for the further improvement of laver product quality. Comprehensive analysis of the literature regarding laver as a food product and as a source of biomedical compounds highlights the possibilities and challenges for application of laver products.

Undaria pinnatifida a Rich Marine Reservoir of Nutritional and Pharmacological Potential: Insights into Growth Signaling and Apoptosis Mechanisms in Cancer

Seaweeds are an important part of diet consumed in a different part of the world such as New Zealand, Ireland, Wales, and Asian countries including Korea, China, and Japan. In addition, seaweed is nutritious sources possessing health improving effects and therapeutic potential. Recently, one of the widely eaten seaweed species Undaria pinnatifida (U. pinnatifida) has got much attention because of its pharmacological properties for the prevention of various ailments, including cancer, inflammation, and other diseases. It is rich in all essential amino acids, physiologically significant fatty acids, vitamins, minerals, and has a variety of bioactive constituents which include fucoidan, carotenoids, and fucoxanthin. The present study reviews the nutritional aspects, key bioactivities specifically focusing on anticancer potential along with apoptosis and growth signaling mechanisms of U. pinnatifida or its constituents. It exhibited anticancer effects both in vitro and in vivo studies in a variety of experimental models. Due to a variety of pharmacological properties of U. pinnatifida can not only fulfilling nutritional necessities, but it can be used for treating, curing and preventing cancer.

Nutritional and bioactive compounds of commercialized algae powders used as food supplements

The main nutritional/bioactive compounds (protein; aminoacids, AA; fucose; minerals; vitamins B12 and C; and total phenolic content, TPC) of nine commercial algae powders, used as food supplements, were studied. Undaria pinnatifida showed the highest protein/aminoacid contents (51.6/54.4 g 100 g-1). Among brown macroalgae, Himanthalia elongata showed the highest fucose content (26.3 g kg-1) followed by Laminaria ochroleuca (22.5 g kg-1). Mineral contents of 15-24% were observed in the algae, being particularly excellent sources of iodine (69.0-472.0 mg kg-1). Porphyra spp. and Palmaria palmata showed the highest vitamin B12 contents (667-674 µg kg-1). Vitamin C ranged among 490.4-711.8 mg kg-1. H. elongata showed the highest total phenolic content (14.0 g kg-1). In conclusion, the studied algae are excellent sources of protein, AA, minerals, vitamin C and some of them presented particularly high vitamin B12 and fucose contents, which may have a potential use as food supplements.

Protein Determination-Method Matters

The reported protein content of foods depends on the analytical method used for determination, making a direct comparison between studies difficult. The aim of this study was to examine and compare protein analytical methods. Some of these methods require extraction preceding analysis. The efficacy of protein extraction differs depending on food matrices and thus extraction yield was determined. Overall, most analytical methods overestimated the protein contents. The inaccuracies were linked to indirect measurements, i.e. nitrogen determination and subsequent conversion to protein, or interference from other chemical substances. Amino acid analysis is the only protein analysis method where interfering substances do not affect the results. Although there is potential for improvement in regards to the hydrolysis method, we recommend that this method should be the preferred for food protein determination.

Antioxidant properties of the red alga Asparagopsis taxiformis collected on the North West Algerian coast

The aim of the present study was to evaluate the total phenolic and lipid content, fatty acids profiles and in vitro antioxidant activities of aqueous and solvent extracts of the red seaweed Asparagopsis taxiformis, through six different investigations. The present study demonstrated that phenol contents (mg gallic acid/g dry weight) were highest in the aqueous and methanolic extracts, followed by the ethanolic, hydroethanolic and hydromethanolic extracts. The lowest phenol contents were identified in the three remaining extracts: Butanolic, petroleum ether and acetone extracts. Furthermore, the total lipid content of the algae powder amounted to 2.85% of dry weight. The fatty acid methyl ester profiles analysed by gas-liquid chromatography represented indicated that fatty acids comprised 91.0±0.3% of total algae lipids. The saturated to unsaturated fatty acid contents amounted to 23.2±0.1 and 67.9±0.4% respectively. C13:0 (tridecanoate), C15:0 (pentadecanoate) and C17:0 (heptadecanoate) represented 47.4% of the total saturated fatty acids. Notably, the two most abundant unsaturated fatty acids, C15:1 (pentadecenoate) and C18:2 (octadecadienoate) represented 13.4 and 11.4% respectively, of the total unsaturated fatty acid content. Furthermore, the results of the antioxidant screening performed at 1.0 mg/ml, revealed that aqueous and methanolic extracts exhibited higher inhibition against superoxide and nitric oxide radicals and excellent radical scavenging activity [with half maximal inhibitory concentration (IC₅₀) values 5.1 and 15.0 µg/ml, respectively], demonstrating improved antioxidant behavior when compared with standard ascorbic acid (which has an IC₅₀ value of 3.7 µg/ml). Scavenging activity of the aqueous and methanolic extracts exhibited a strong peroxidation inhibition against linoleic acid emulsion system at a concentration of 300 µg/ml in comparison to the butylated hydroxyltoluene. Although all the studied extracts exhibited ferric reducing power, the aqueous and methanolic extracts had greater hydrogen donating ability. By contrast, hydromethanolic, ethanolic, hydroethanolic, butanolic, acetone and petroleum ether extracts exhibited weak antioxidant behavior. The antioxidant activity of potent seaweed species identified in the current study means that as well as being used as a functional food, they may be developed as novel pharmaceutical compounds and may be used as anti-ageing agents.

Changes in total nitrogen and amino acid composition of New Zealand Undaria pinnatifida with growth, location and plant parts

Undaria pinnatifida is known as unwanted organism in New Zealand. However, Wakame is a traditional food made of U. pinnatifida, which is now cultured extensively in East Asia. Therefore, it is important to examine this introduced alga as a potential source of dietary protein for human consumption in New Zealand. This study determined total nitrogen content and amino acid profile of New Zealand U. pinnatifida harvested from the Marlborough Sounds on a monthly basis from June to November 2011. Total average nitrogen content and crude protein content was 21.02 mg/g dry weight and 13.1% of dry weight, respectively. The three most abundant amino acids that contributed to flavour (glutamic acid, aspartic acid and alanine) were present and the most abundant essential amino acids were arginine, leucine, lysine and valine. The results showed that the amino acid content in blades from the exposed farm was significantly higher (P < 0.05) than the others. Sporophyll maturation of U. pinnatifida in New Zealand influenced protein content and amino acid composition. Sporophyll, considered as a waste product by many, was found to be a potentially good source of protein.

Characterization of protein, lipid and mineral contents in common Norwegian seaweeds and evaluation of their potential as food and feed

BACKGROUND

The objectives of this study were to examine protein and amino acid composition, lipid and fatty acid composition, along with a range of essential minerals in common Norwegian seaweed species representing the red (Palmaria palmata and Vertebrata lanosa), green (Cladophora rupestris, Enteromorpha intestinalis and Ulva lactuca) and brown (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Fucus vesiculosus and Pelvetia canaliculata) classes and assess their potential as alternatives to cereals in food and feed. As macroalgae accumulate heavy metals, arsenic, cadmium and mercury were also analyzed.

RESULTS

Proteins ranged from 34 to 123 g kg(-1) dry weight (DW) and the essential amino acid levels may cover both human and salmonid requirements. Lipids were low (6-58 g kg(-1) DW), but the red algae had high relative content of long-chained omega-3 fatty acids (32-34 % of the fatty acids). Iodine contents were particularly high in the Laminaria species. Of the heavy metals only arsenic levels may be of concern.

CONCLUSION

In total, the red alga P. palmata was regarded as the best alternative to cereals in food and feed. For several of the other species, single-component extraction for the ingredients market may be better than using the whole product.