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A water-soluble polysaccharide (EP) was purified from edible algae Enteromorpha prolifera. Gel permeation chromatography (GPC), ion chromatography (IC), and fourier transform infrared (FT-IR) were performed to characterize its structure. EP was defined as a low molecular weight (6625 Da) composed of rhamnose, glucose, glucuronic acid, xylose, galactose, arabinose, and mannose. Moreover, it was a sulfated polysaccharide with a degree of substitution (DS) of 1.48. Then, the high-fat diet/streptozotocin (HFD/STZ) induced diabetic mouse model was established to support evidence for a novel hypoglycemic mechanism. Results showed that blood glucose (47.32%), liver index (7.65%), epididymal fat index (16.86%), serum total cholesterol (26.78%) and triglyceride (37.61%) in the high-dose EP (HEP) group were significantly lower than those in the HFD group. Noticeably, the content of liver glycogen in the HEP group was significantly higher (62.62%) than that in the HFD group, indicating the promotion of glycogen synthesis. These beneficial effects were attributed to significantly increased protein kinase B (AKT) phosphorylation and its downstream signaling response. Further studies showed that diabetic mice exhibited excessive O-GlcNAcylation level and high expression of O-linked β-D-N-acetylglucosamine transferase (OGT), which were decreased by 62.21 and 30.43% in the HEP group. This result suggested that EP had a similar effect to OGT inhibitors, which restored AKT phosphorylation and prevented pathoglycemia. This work reveals a novel hypoglycemic mechanism of EP, providing a theoretical basis for further studies on its pharmacological properties in improvement of T2DM. [ABSTRACT FROM AUTHOR]

The use of seaweed and algal derived products in the food industry has grown rapidly in recent times. Major areas of expansion have been in Western countries where algae derived commodities are being utilised as edible foods or sources of high value ingredients. However, studies focused on potential allergenicity attributed to these food items, prevalence of allergenicity, and public health awareness are limited. Therefore, the current research summarises the existing literature focused on algal induced allergy in humans. Of the available literature, a total of 937 titles were identified, and 33 articles underwent subsequent full-text screening. Most research focused on prevalence and were derived from studies conducted in Europe (58%), North America and Canada (33%), and the remainder Australia and South Korea (9%). No studies addressed the need for public education or labelling of algal products. Our review reports that the available evidence identified points to algal derived products as being potential sources of allergens in the human food chain. Several components have been characterised that are shown to induce allergic responses in humans. Few studies have assessed the prevalence of algal allergenicity in the general population and as such further research is warranted given the increased usage of these products in the food industry. [ABSTRACT FROM AUTHOR]

To clarify the presence of algal-susceptible indigenous bacteria (SIB) in the gut, ICR mice were fed high-sucrose (50% w/w) diets containing either no fibre (NF), 5% brown alga "arame", Eisenia bicyclis; 5% red alga "tsunomata", Chondrus ocellatus; 5% (w/w) green alga "hitoegusa", Monostroma nitidum; or 5% (w/w) cyanobacterium "blue-green alga", Aphanizomenon flos-aquae for 14 days. Faecal frequency and weight were the highest in mice fed M. nitidum. Plasma cholesterol was the lowest in the mice fed C. ocellatus. The caecal microbiome was examined by 16S rDNA (V4) amplicon sequencing. Principal component analysis of operational taxonomical units (OTUs) revealed that the edible algae altered the microbiome. An increase in abundance levels of OTUs by E. bicyclis (Bacteroides acidifaciens-, Bacteroides intestinalis-, Bifidobacterium pseudolongum-like), C. ocellatus (Bacteroides vulgatus- and Escherichia coli-like), M. nitidum (Faecalibaculum rodentium- and Muribaculum sp.-like), and A. flos-aquae (Muribaculum sp.) was detected. Abundance of Lactobacillus johnsonii was the lowest in mice fed the algal diets. Bacteria that increased in numbers were identified as algal SIBs. SIBs might have different effects on host health depending on the food material consumed. From the algal SIBs, B. pseudolongum, B. vulgatus, F. rodentium, and L. johnsonii were isolated using blood-liver agar and identified with the 16S rDNA BLAST search. Future studies should be focused on isolation of other SIBs. [ABSTRACT FROM AUTHOR]

To clarify the anti-oxidant and anti-glycation properties of traditional edible algae, aqueous extract solutions (AESs) from eight dried algal products that were commercially available in the Miura Peninsula of Japan were prepared. AESs of the red alga, Pyropia sp. (nori), demonstrated strong Fe-reducing power with a high total phenolic compound content. On the other hand, the sporophyll of the brown alga Undaria pinnatifida (mekabu) exhibited high superoxide anion radical-scavenging capacity. Anti-glycation activity in bovine serum albumin (BSA)-fructose (Fru) and in BSA-methylglyoxal (MGO) was high for nori and the stem of Sargassum fusiforme (naga-hijiki). The results of the BSA-MGO model agreed with those of the phenolic content and Fe-reducing power. Anti-glycation activities of mekabu, Sargassum horneri (akamoku), naga-hijiki, the frond of U. pinnatifida (wakame), and Gelidium elegans (tengusa) in the BSA-Fru model were clearly increased by fermentation with Lactobacillus plantarum Miura-SU1 isolated from the Miura Peninsula. The results of the present study suggest that, once fermented with lactic acid bacteria (LAB), akamoku and other edible algae will have a potential role in preventing diabetes- and aging-related glycation. [ABSTRACT FROM AUTHOR]

Edible seaweed consumption is a route of exposure to arsenic. However, little attention has been paid to estimate the bioaccessibility and/or bioavailability of arsenosugars in edible seaweed and their possible degradation products during gastrointestinal digestion. This work presents first use of combined inductively coupled plasma mass spectroscopy (ICP-MS) with electrospray ionization tandem mass spectrometry (ESI-MS/MS) with two-dimensional HPLC (size exclusion followed by anion exchange) to compare the qualitative and quantitative arsenosugars speciation of different edible seaweed with that of their bioavailable fraction as obtained using an in vitro gastrointestinal digestion procedure. Optimal extraction conditions for As species from four seaweed namely kombu, wakame, nori and sea lettuce were selected as a compromise between As extraction efficiency and preservation of compound identity. For most investigated samples, the use of ammonium acetate buffer as extractant and 1 h sonication in a water bath followed by HPLC-ICP-MS resulted in 40-61% of the total As to be found in the buffered aqueous extract, of which 86-110% was present as arsenosugars (glycerol sugar, phosphate sugar and sulfonate sugar for wakame and kombu and glycerol sugar and phosphate sugar for nori). The exception was sea lettuce, for which the arsenosugar fraction (glycerol sugar, phosphate sugar) only comprised 44% of the total extracted As. Interestingly, the ratio of arsenobetaine and dimethylarsinic acid to arsenosugars in sea lettuce extracts seemed higher than that for the rest of investigated samples. After in vitro gastrointestinal digestion, approximately 11-16% of the total As in the solid sample was found in the dialyzates with arsenosugars comprising 93-120% and 41% of the dialyzable As fraction for kombu, wakame, nori and sea lettuce, respectively. Moreover, the relative As species distribution in seaweed-buffered extracts and dialyzates was found to be very similar. Collection of specific fractions from the size-exclusion column to be analysed using anion-exchange HPLC-ESI-MS/MS enabled improved chromatographic selectivity, particularly for the less retained arsenosugar (glycerol sugar), facilitating confirmation of the presence of arsenosugars in seaweed extracts and dialyzates. Using this approach, the presence of arsenobetaine in sea lettuce samples was also confirmed. [ABSTRACT FROM AUTHOR]