Characterization of nutritionally important lipophilic constituents from brown kelp Ecklonia radiata (C. Ag.) J. Agardh

This research study presents information for the first time on the nutritionally relevant lipophilic compounds obtained from Ecklonia radiata, a poorly studied brown kelp. The major lipophilic compounds were analyzed utilizing liquid chromatography (LC)-tandem mass spectrometry (MS/MS) and gas chromatography (GC)-mass spectrometry (MS). The LC-MS/MS results revealed the presence of eight major lipophilic compounds, including sterols, carotenoids, vitamin E, and phylloquinone (vitamin K1). Quantitative analysis showed that fucosterol was the most predominant phytosterol in the fronds and stipes of E. radiata. The carotenoids (all-E)-fucoxanthin and (all-E)-β-carotene were present in higher yield. In terms of vitamin E, α-tocopherol was identified as the main tocol. The coenzyme, phylloquinone, important for protein synthesis, was also identified in E. radiata. GC-MS identified 13 fatty acids with palmitic (C16:0) and oleic acid (C18:1n9c) present in the highest quantities. To our knowledge, this is the first report on E. radiata, and the valuable data presented herein can be used as a baseline for developing novel nutraceuticals.

Lactic acid fermentation in the development of a seaweed sauerkraut-style product: Microbiological, physicochemical, and sensory evaluation

Consumption of nutrient-rich seaweeds and fermented nondairy foods represent fast growing trends among health-minded consumers. Assessment of lacto-fermented seaweed was performed to address these trends, and to offer shelf-life extension and product diversification for fresh kelps. The objectives were to evaluate the effects of kelp species and inclusion level on fermentation kinetics, physicochemical quality, safety, shelf-life, and consumer acceptability of a seaweed sauerkraut-style product. Six formulations with different inclusion levels (25, 50, and 75%) of shredded kelp (sugar kelp, SK or winged kelp, WK) were mixed with cabbage, 2% salt, and inoculated with Lactobacillus plantarum (approximately 106 CFU/g) and Leuconostoc mesenteroides (approximately 101 CFU/g). Products were processed in triplicate, fermented until a target pH of ≤4.6 was achieved, and sampled periodically for 60 days. Kelp species and inclusion level significantly affected most variables tested. The most rapid fermentation (3 days), as evidenced by pH decrease, lactic acid bacteria counts, and lactic acid levels, was noted in WK formulations. Some SK formulations took up to 14 days to achieve the target pH, and coliforms persisted to a greater extent in the SK formulations. Higher levels of kelp decreased the fermentation rate and concentration of fermentable sugars in the brine, but increased the total phenolic content and antioxidant activity of the sauerkrauts. Despite differences in instrumental color (L* a* b* ) and texture (shear force) among formulations, overall liking as rated by a consumer panel was not significantly affected by species or inclusion level. Results support the use of lacto-fermentation in the production of refrigeration-stable seaweed sauerkraut-style product. PRACTICAL APPLICATION: Health-conscious consumers are becoming increasingly interested in plant-based diets and fermented foods, and the development of novel seaweed sauerkraut-style products can help to meet these needs. This study demonstrated the successful production of a sauerkraut-style product formulated with up to 50% farm-raised kelp. Physical, chemical, microbiological, and consumer acceptability testing established lactic acid fermentation as a viable method for shelf life extension and value addition of fresh kelps. These results provide science-based information on an alternative processing method for cultivated seaweeds and can assist the industry in product diversification efforts.

The dual effects of riboflavin and kelp polyphenol extracts on the gel properties of myofibrillar protein from Scomberomorus Niphonius under UVA irradiation

In the present study, effects of riboflavin (RF) and kelp polyphenol extracts (KPE) on mackerel (Scomberomorus Niphonius) myofibrillar protein (MP) gel were studied with or without ultraviolet A (UVA) irradiation treatment. The gel strength was increased with the addition of RF and KPE under UVA irradiation. Analysis of the proteins in the gel indicated that the carbonyl content increased, while the contents of total sulfhydryl and amino groups decreased. The proteins appeared to have no α-helix structures, and the endogenous tryptophan content appeared to decrease. The results of SDS-PAGE indicated that the RF and KPE treated samples under UVA irradiation showed massive MP cross-linking by covalent bonds. Electron spin resonance (ESR) results indicated that UVA irradiation generated free radicals in RF and KPE, which ultimately led to an improvement in MP gel properties. It also indicated that KPE could prevent the occurrence of peroxidation to improve the gel properties.

Acid-free preparation and characterization of kelp (Laminaria japonica) nanocelluloses and their application in Pickering emulsions

Cellulose nanofibers (CNFs) from kelp were prepared by cellulase treatment with lengths greater than 3 μm. CNFs were further oxidized by TEMPO-oxidized system, and the lengths of the oxidized CNFs (TEMPO-CNFs) were 0.6-1 μm. AFM and TEM images showed that intertwined CNFs fibers were divided into individual nanofibrils. The crystallinity of TEMPO-CNFs increased to 66.5 %. TGA analysis indicated that TEMPO-CNFs were more sensitive to temperature than cellulose and CNFs. FT-IR spectra revealed no changes in the basic cellulose structures of CNFs and TEMPO-CNFs. In the sunflower oil/water (20/80, v/v) model emulsions, the oil droplet sizes were less than 20 μm in CNFs emulsions, which became smaller in TEMPO-CNFs emulsions. Delamination was found in CNFs emulsions after three days of storage. Addition of NaCl increased the volumes of TEMPO-CNFs emulsions but enlarged the oil droplets sizes. TEMPO-CNFs emulsions had the largest volume with smallest and most homogeneous oil droplets at pH 3. TEMPO-CNFs emulsions showed good stability after storage for 30 days. Further, TEMPO-CNFs could also emulsify 50 % (v/v) of sunflower oil. All these results indicated that TEMPO-CNFs can be used in preparing Pickering emulsions.

Facile Removal of Phytochromes and Efficient Recovery of Pesticides Using Heteropore Covalent Organic Framework-Based Magnetic Nanospheres and Electrospun Films

Nontargeted analysis of food safety requires selective removal of interference matrices and highly efficient recovery of chemical hazards. Porous materials such as covalent organic frameworks (COFs) show great promise in selective adsorption of matrix molecules via size selectivity. Considering the complexity of interference matrices, we prepared crystalline heteropore COFs whose two kinds of pores have comparable sizes to those of several common phytochromes, main interference matrices in vegetable sample analysis. By controlling the growth of COFs on the surface of Fe3O4 nanoparticles or by utilizing a facile co-electrospinning method, heteropore COF-based magnetic nanospheres or electrospun nanofiber films were prepared, respectively. Both the nanospheres and the films maintain the dual-pore structures of COFs and show good stability and excellent reusability. Via simple magnetic separation or immersion operation, respectively, they were successfully used for the complete removal of phytochromes and highly efficient recovery of 15 pesticides from the extracts of four vegetable samples, and the recoveries are in the range of 83.10-114.00 and 60.52-107.35%, respectively. Film-based immersion operation gives better sample pretreatment performance than the film-based filtration one. This work highlights the great application potentials of heteropore COFs in sample pretreatment for nontargeted analysis, thus opening up a new way to achieve high-performance sample preparation in many fields such as food safety analysis, environment monitoring, and so on.

Direct speciation analysis of organic mercury in fish and kelp by on-line complexation and stacking using capillary electrophoresis

To determine organic mercury (Hg) species that could not be detected by ultraviolet (UV), a highly automated on-line complexation method was established, which combined with normal stacking by capillary electrophoresis-diode array detector. The approach was based on the fact that the compounds and complex reagent interacted to form hydrophilic chelates under the effect of the separation voltage, which was effectively separated and detected by UV. Key parameters, such as the type and concentration of complex reagent, separation voltage and so on were systematically investigated. Under the optimized conditions, the precision and repeatability were in the range of 0.16-3.31% and 0.17-1.21%, respectively. Furthermore, PhHg, EtHg and MeHg were effectively separated and determined in fresh fish (Silver carp) muscle and kelp (Kombu) with the recoveries of 84.63-111.39% and 75.68-114.76%, respectively. The proposed method had the advantages of easy-operating, cost-efficient, stable and reliable compared to off-line complexation method.

Combination of curcuma zedoary and kelp inhibits growth and metastasis of liver cancer in vivo and in vitro via reducing endogenous H2S levels

The combination of traditional Chinese medicines can improve the efficacy of cancer treatment. Furthermore, the combination of the traditional Chinese medicine curcuma zedoary and kelp was used to enhance the effect of the dissipation of blood stasis in pediatrics during the Song Dynasty. Curcumenol and laminarin, the main components of curcuma zedoary and kelp, are also reported to have a wide range of biological activities. Therefore, we hypothesize that the combination of curcuma zedoary and kelp may prevent the development of cancer. The aim of this research was to confirm whether a combination of curcuma zedoary and kelp could inhibit the proliferation and metastasis of hepatoma cells and consequently improve prognosis. In this study, we firstly found in H22-bearing mice that the combination of curcuma zedoary and kelp inhibited tumor growth and the expression of metastasis-related proteins (MMPs, VEGF, pAkt, pERK1/2). Meanwhile, the decreased cystathionine beta synthase (CBS, an endogenous hydrogen sulfide (H2S) synthetase) level was also observed in H22-bearing mice admistrated with the combination of curcuma zedoary and kelp. It was also observed that the combination of curcumenol and laminarin inhibited the proliferation, migration and invasion in human hepatoma HepG2 cells. Furthermore, we investigated the potential inhibiting mechanism of the combination of curcumenol and laminarin on HepG2 cell proliferation and metastasis. Our previous research showed that a CBS/H2S system was vital for maintaining the proliferation in hepatoma cells. Here, we found that the levels of pSTAT3 and BCL-2 were decreased in CBS knockdown HepG2 cells and the combination of curcumenol and laminarin significantly decreased the H2S level in a dose-dependent manner and down-regulated the levels of pSTAT3 and BCL-2 in HepG2 cells. Angiogenesis, positively regulated by the vascular endothelial growth factor (VEGF), is essential for human cancer metastasis. In the present study, we found that the combination of curcumenol and laminarin could significantly down-regulate the expression levels of VEGF and its downstream key genes pAkt and pERK1/2. Furthermore, previous research showed that hydrogen sulfide could stimulate angiogenesis. Here, we also observed the reduction of the VEGF, Akt, pAkt, ERK1/2 and pERK1/2 proteins levels and the inhibition of proliferation and metastasis in CBS knockdown HepG2 cells. Moreover, exogenous H2S rescued the cytological results caused by the combination of curcumenol and laminarin. Taken together, the combination of curcuma zedoary and kelp could inhibit the proliferation and metastasis of liver cancer cells in vivo and in vitro by inhibiting endogenous H2S production and down-regulating the pSTAT3/BCL-2 and VEGF pathway, which provides strong evidence for the application of curcuma zedoary and kelp in treatments of liver cancer.

Mycotoxins Contaminant in Kelp: A Neglected Dietary Exposure Pathway

In order to investigated current occurrence of major mycotoxins in dietary kelp in Shandong Province in Northern China, a reliable, sensitive, and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous determination of the 7 most frequent mycotoxins, including 3-acetoxy deoxynivalenol (3AcDON), 15-acetoxy deoxynivalenol (15AcDON), Deoxynivalenol (DON), Fusarenon-X (F-X), Nivalenol (NIV), T-2 toxin (T-2), and Zearalenone (ZEA). Based on optimized pretreatment and chromatographic and mass spectrometry conditions, these target analytes could be monitored with mean recoveries from 72.59~107.34%, with intra⁻day RSD < 9.21%, inter⁻day RSD < 9.09%, LOD < 5.55 μg kg-1, and LOQ < 18.5 μg kg-1. Approximately 43 kelp samples were detected, 3AcDON/15AcDON ranged from 15.3 to 162.5 μg kg-1 with positive rate of 86% in Shandong Province in Northern China. Considering there were no related investigations about mycotoxin contamination in kelp, the high contamination rate of 3AcDON/15AcDON in kelp showed a neglected mycotoxin exposure pathway, which might lead to high dietary exposure risk to consumers.

A novel ulvan lyase family with broad-spectrum activity from the ulvan utilisation loci of Formosa agariphila KMM 3901

Ulvan, which is one of the major structural polysaccharides of the cell walls of green macroalgae, is degraded by ulvan lyases via the β-elimination mechanism with the release of oligosaccharides that have unsaturated 4-deoxy-L-threo-hex-4-enopyranosiduronic acid (∆) at the non-reducing end. These ulvan lyases belong to the PL24 or PL25 or PL28 family in the CAZy database. In this study, we identify and biochemically characterise a periplasmic novel broad-spectrum ulvan lyase from Formosa agariphila KMM 3901. The lyase was overexpressed in Escherichia coli, and the purified recombinant enzyme depolymerised ulvan in an endolytic manner with a Km of 0.77 mg/ml, and displayed optimum activity at 40 °C and pH 8. This lyase also degraded heparan sulphate and chondroitin sulphate. Detailed analyses of the end-products of the enzymatic degradation of ulvan using 1H- and 13C-NMR and LC-MS revealed an unsaturated disaccharide (∆Rha3S) and a tetrasaccharide (∆Rha3S-Xyl-Rha) as the principal end-products. In contrast to the previously described ulvan lyases, this novel lyase is mostly composed of α-helices that form an (α/α)6 incomplete toroid domain and displays a remarkably broad-spectrum activity. This novel lyase is the first member of a new family of ulvan lyases.

Copper nanoclusters as fluorescence-quenching probes for the quantitative analysis of total iodine

Tannic acid-coated copper nanoclusters (CuNCs@TA) were synthesized and used quantitatively to analyze iodine in kelp. Compared with other methods for iodine detection, the proposed method showed excellent performance. The iodine-induced linear decrease in the fluorescence intensity of CuNCs@TA allowed the quantitative detection of iodine in the range 20-100 μM, and the limit of detection for iodine was 18 nM. The probe can be used for the determination of iodine in real samples with reliable and accurate results. Modified Stern-Volmer equation and thermodynamic calculation studies were used to discuss the quenching mechanism.

Properties of Kimchi Fermented with GABA-Producing Lactic Acid Bacteria as a Starter

Kimchi (a traditional Korean fermented vegetable) was prepared with a starter, Lactobacillus zymae GU240 producing γ-aminobutyric acid (GABA), and one precursor of GABA (glutamic acid, glutamic acid monosodium salt (MSG), or kelp extract). L. zymae GU240, an isolate from kimchi, can grow at 7% NaCl and low temperature. Five different kimchi samples were fermented for 20 weeks at -1°C. Kimchi with starter alone could not produce GABA. The GABA content was highest in kimchi with co-inoculation of the starter and MSG (1% (w/w)). Kimchi co-inoculated with the starter and kelp extract powder (3% (w/w)) had the second highest GABA content. Addition of glutamic acid powder (1% (w/w)) caused a reduction in the pH level of kimchi and growth inhibition of lactic acid bacteria and yeasts. Kimchi samples with MSG or kelp extract showed improvement of sensory evaluation scores. The results demonstrate the possibility to produce kimchi with improved functionality and taste by using L. zymae GU240 as a starter along with a suitable precursor such as MSG or kelp extract.

Effects of three major amino acids found in Japanese broth on glucose metabolism and gastric emptying

OBJECTIVES

To our knowledge, the effect of the broth of dried kelp and dried bonito, dashi, on glucose metabolism and digestion has rarely been studied. Based on the component analysis of three actual broths served in traditional restaurants, a chemically synthesized broth with three free amino acids (histidine, glutamate, aspartate) and salt was prepared to investigate their effect on glucose metabolism, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide 1 (GLP-1) secretion, and digestion.

METHODS

In study 1, seven healthy individuals were enrolled in a four-period crossover study. Participants drank or ate hot water, synthesized broth, hot water with rice, and synthesized broth with rice. Plasma glucose, serum insulin, plasma glucagon, plasma GIP, and plasma GLP-1 were measured at baseline and after ingestion. In study 2, 6 of the 7 individuals ingested rice steamed with 13C-labeled sodium acetate with hot water or synthesized broth to estimate gastric emptying by the 13C-labeled acetate breath test in a two-period crossover trial.

RESULTS

Ingesting water or synthesized broth alone elicited no change in plasma glucose or serum insulin levels. Ingesting synthesized broth with rice resulted in a rapid rise in plasma glucose and GLP-1 (P = 0.01 and 0.02, respectively) in an early postprandial phase compared with that by ingesting water with rice, but the area under the curve of those showed no significant differences. Ingesting synthesized broth with rice resulted in a significantly higher gastric emptying coefficient than that after rice with water (P = 0.03).

CONCLUSIONS

Three amino acids and sodium chloride corresponding to those found in actual broth promoted gastric emptying and led to a rapid response of plasma glucose. Our findings suggest that ingestion of the broth of dried kelp and dried bonito may improve gastric motility.

Development of a kelp powder (Thallus laminariae) Standard Reference Material

A Standard Reference Material (SRM) of seaweed, SRM 3232 Kelp Powder (Thallus laminariae) has been developed to support food and dietary supplement measurements in compliance with the Food Safety Modernization Act (FSMA) and the Dietary Supplement Health and Education Act of 1994 (DSHEA). The material was characterized for nutritional minerals, arsenic species, isomers of vitamin K1, proximates, and toxic elements. Kelp is a rich source of vitamins and minerals, and it is an excellent source of dietary iodine. Kelp also contains a large amount of arsenic, which is toxic as inorganic species but much less so as organic species. To capture the dietary profile of kelp, certified values were issued for As, Ca, Cd, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Mo, Na, Pb, and Zn. Reference values for proximates were assigned. For the first time, a certified value for iodine, reference values for isomers of vitamin K1, and reference values for arsenic species including arsenosugars were assigned in a seaweed. SRM 3232 fills a gap in Certified Reference Materials (CRMs) needed for quality assurance and method validation in the compositional measurements of kelp and similar seaweeds used as food and as dietary supplements. Graphical Absract Arsenic species and isomers of vitamin K1 were determined in the development of SRM 3232 Kelp Powder (Thallus laminariae).

Development of a Method to Isolate Glutamic Acid from Foodstuffs for a Precise Determination of Their Stable Carbon Isotope Ratio

Recent growing health awareness is leading to increasingly conscious decisions by consumers regarding the production and traceability of food. Stable isotopic compositions provide useful information for tracing the origin of foodstuffs and processes of food production. Plants exhibit different ratios of stable carbon isotopes (δ13C) because they utilized different photosynthetic (carbon fixation) pathways and grow in various environments. The origins of glutamic acid in foodstuffs can be differentiated on the basis of these photosynthetic characteristics. Here, we have developed a method to isolate glutamic acid in foodstuffs for determining the δ13C value by elemental analyzer-isotope-ratio mass spectrometry (EA/IRMS) without unintended isotopic fractionation. Briefly, following acid-hydrolysis, samples were defatted and passed through activated carbon and a cation-exchange column. Then, glutamic acid was isolated using preparative HPLC. This method is applicable to measuring, with a low standard deviation, the δ13C values of glutamic acid from foodstuffs derived from C3 and C4 plants and marine algae.

Extraction, isolation and characterization of nanocrystalline cellulose from industrial kelp (Laminaria japonica) waste

Kelp (Laminaria japonica) is an economically important type of algae cultured in East Asia. Kelp waste is a by-product from the extraction of commercial alginate from kelp. This work reports the isolation of nanocrystalline cellulose (NCC) from the cellulose extracted from the kelp waste. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) show that the crystallinity index of the isolated kelp NCC was 69.4%, which was slightly higher than that of kelp cellulose as well as maintained the cellulose I crystalline form and typical cellulose chemical structure. In thermogravimetric analysis (TGA), kelp NCC showed decreased thermostability and a higher residual mass. Transmission electronic microscopy (TEM) confirmed the ordinary rod-like shape of the produced NCC with various dimensions. The kelp NCC aqueous dispersions displayed the expected characteristic optical and gel effects. Studies on the variables and the orthogonal experiment of NCC preparation contributed a maximum yield of 52.3%. The exploration on the preparation of kelp NCC in this study lays foundations for future applications.

The potential role of kelp forests on iodine speciation in coastal seawater

Kelps have a major role in marine and atmospheric iodine cycling in the coastal zone of temperate regions, with potential wide-ranging impacts on ozone destruction in the coastal marine boundary layer. However, little is known about the impact of kelp forests on iodine speciation in coastal sea water. To address this, we examined iodide and iodate concentrations in seawater in and around a giant kelp forest near San Diego, CA, USA, and a nearby site that was not influenced by kelp biology. Our data shows that while both iodide and iodate concentrations remained unchanged during the year at the nearby site, these concentrations changed significantly in and around the kelp forest, and were strongly related to changes in kelp canopy biomass. In particular, iodide reached its highest concentration and iodate reached its lowest concentration during the summer when the kelp canopies were near their maximum, while the opposite pattern was observed during the winter and spring when the kelp canopies were near their minimum. Further, comparisons of these changes with corresponding changes in seawater temperature and wind speed indicated that these relationships were relatively small compared to those with changes in kelp biomass. Together, our data show a strong relationship between kelp biomass and iodine metabolism.

Ultra-trace determination of methylmercuy in seafood by atomic fluorescence spectrometry coupled with electrochemical cold vapor generation

A homemade electrochemical flow cell was adopted for the determination of methylmercury. The cold vapor of mercury atoms was generated from the surface of glassycarbon cathode through the method of electrolytic reduction and detected by atomic fluorescence spectroscopy subsequently. The operating conditions were optimized with 2 ng mL(-1) methylmercury standard solution. The caliberation curve was favorably linear when the concentrations of standard HgCH3(+) solutions were in the range of 0.2-5 ng mL(-1)(as Hg). Under the optimized conditions, the limit of detection (LOD) for methylmercury was 1.88×10(-3)ng mL(-1) and the precision evaluated by relative standard deviation was 2.0% for six times 2 ng mL(-1) standard solution replicates. The terminal analytical results of seafood samples, available from local market, showed that the methylmercury content ranged within 3.7-45.8 ng g(-1). The recoveries for methylmercury spiked samples were found to be in the range of 87.6-103.6% and the relative standard deviations below 5% (n=6) were acquired, which showed this method was feasible for real sample analysis.

Effect of kelp waste extracts on the growth and lipid accumulation of microalgae

Kelp waste extracts (KWE) contained massive soluble sugars, amino acids and various mineral elements. To probe the effects of KWE on microalgal physiological and biochemical responses, the cultures were carried out under the different dilutions. The results showed that 8.0% KWE increased the biomass productivities and total lipid contents of Chlorella strains dramatically, which were 1.83-31.86 times and 20.78-25.91% higher than that of the control. Phaeodactylum tricornutum and Spirulina maxima presented a better growth performance in 1.0% and 4.0% treatment respectively, while their lipid accumulation were not enhanced. In Chlorella-Arc, Chlorella sorokiniana and P. tricornutum, the contents of saturated and monounsaturated fatty acids could be increased, and polyunsaturated fatty acids could be decreased under the conditions of high concentration of KWE (6.0-8.0%). Briefly, KWE facilitated to enhance the biomass productivity and lipid content of Chlorella strains, also improved the fatty acid compositions for biodiesel production.

An approach for identification and determination of arsenic species in the extract of kelp

The National Institute of Standards and Technology is developing a kelp powder standard reference material (SRM) in support of dietary supplement measurements. Edible seaweeds such as kelp and laver consumed as diet or dietary supplement contain tens of mg/kg arsenic. The speciation information of arsenic in the seaweed should be provided because the total arsenic alone does not fully address the safety issue of the dietary supplement as the value assignment is originally intended. The inability to avail all arsenic species for value assignment measurements prevented the certification of arsenic species in the candidate SRM; however, approximately 70 % of total arsenic extracted with a 1:1 volume fraction of methanol:water mixture allowed arsenic speciation values to be assigned to a procedure-defined extract, which may be used for method validation in research to improve upon current extraction and measurement practices. Arsenic species in kelp and laver were identified using electrospray ionization ion trap time of flight mass spectrometry (ESI-IT-TOF). Arsenosugars As(328), As(482), and As(392) were found in the kelp candidate SRM while As(328) and As(482) were found in GBW 08521, a certified reference material (CRM) of laver produced by the National Institute of Metrology of China (NIM). A discovery that the digests of kelp and laver contained only dimethylarsinic acid led to the conclusion that the seaweeds did not contain detectible levels of arsenobetaine, arsenocholine or trimethylarsine oxide that could overlap with the peaks of arsenosugars in the separation. The mean ± s of (5.68 ± 0.28) mg/kg and (13.43 ± 0.31) mg/kg found for As(482) and As(392) in kelp, respectively, using instrumental neutron activation analysis (INAA) demonstrated that value assignment measurement of arsenosugars was possible without arsenosugar calibration standards.

[Metabolomic approach to evaluating the effect of the mixed decoction of kelp and licorice on system metabolism of SD rats]

The aim of the study is to evaluate the effects of the single and mixed decoction of Thallus laminariae (kelp) and Glycyrrhiza glabra (licorice) on the metabolism and their difference. The mixed decoction of kelp and licorice and the single decoction were made and intragastrically administered to the SD rats. The effect on system metabolism, the toxicity of liver and kidney were assessed by GC-MS profiling of the endogenous molecules in serum, routine biochemical assays and histographic inspection of tissues from SD rats, separately. The mixed decoction of kelp and licorice induced more obvious pathological abnormalities in SD rats than a single decoction of kelp, while the extracts of licorice did not show any pathological change. Neither the mixed, nor the single decoction showed abnormal histopathology. After intragastric administration of extracts for 5 days, the mixed decoction induced a decrease of ALT (no significant change in the groups of single decoction) and an increase of BUN (so did the single decoction of kelp). Metabolomic profile of the molecules in serum revealed that the metabolic patterns were all obviously affected for the three groups, i.e., the mixed and single decoction of kelp and licorice. The rats given with the single decoction of kelp showed a similar pattern to that of the mixed decoction, indicating that the kelp primarily contributed the perturbation of metabolism for the mixed decoction. All three groups induced a decrease of branched chain amino acids, TCA cycle intermediates and glycolysis intermediates (e.g., pyruvic acid and lactic acid) and an increase of 3-hydroxybutyric acid. Kelp decoction showed stronger potential in reducing TCA cycle intermediates and glycolysis intermediates than the other two groups, while the levels of branched chain amino acids were the lowest after licorice extracts were given. These results suggested that the effect of the mixed decoction on metabolism was closely associated with both kelp and licorice. The continuous administration of single decoction of kelp and the mixed decoction of licorice and kelp resulted in pathological abnormalities in kidney of SD rats. The mixed decoction of kelp and licorice distinctly perturbed sera molecules and hence system metabolism, which showed associated with those of kelp and licorice. Although the metabolic effect was associated with both kelp and licorice, the results suggested kelp contributed to it primarily.

Assessment of microwave cooking on the bioaccessibility of cadmium from various food matrices using an in vitro digestion model

Bioaccessibility represents the maximum amount of pollutant ingested with food that is available for intestinal absorption. The measurement of bioaccessibility can achieve a more accurate risk assessment. Thus, in this study, the bioaccessibility of raw/microwave-cooked store-bought food including carrot, potato, white radish, lotus root, sweet corn, long grain rice, soybean, fleshy prawn, eastern oyster, kelp, and common carp were investigated by applying an in vitro digestion method. A validated microwave digestion/ICP-MS method was applied for determining the concentration of Cd. In this study, the concentration of Cd ranged 3.7-215.8 μg/kg fw in which carrot contained the lowest Cd while the fleshy prawn contained the highest Cd. There are no statistical differences of Cd content in microwave-cooked food and raw food except potato, lotus root, and eastern oyster. Cd in most of the cooked food materials was less bioaccessible than in raw food except sweet corn, potato, and kelp. The bioaccessibility of Cd was around 100 % in either raw or cooked potatoes. Microwave cooking caused the decreasing of bioaccessibility around 0-68 %, depending on different food matrix. Maximal decreasing of Cd bioaccessibility occurred in common carp. Thus, microwave cooking could be a feasible strategy for decreasing Cd bioaccessibility. In addition, the Cd dissolution in oral, gastric, and small intestine phase was different in different food matrix. For most of the investigated food items, Cd was largely migrated either into the oral phase (carrot, potato, white radish, lotus root, raw soybean, kelp, and common carp) or into the gastric phase (sweet corn, cooked soybean, rice, fleshy prawn, and eastern oyster). Our findings will have significant implications for food processing aiming to decrease the absorption of Cd and risk assessment analysis improvements. Further study is needed to use the animal model to validate these results.

Purification of a fucoidan from kelp polysaccharide and its inhibitory kinetics for tyrosinase

High-speed countercurrent chromatography (HSCCC) was used to separate kelp polysaccharide. HSCCC was performed using an aqueous two-phase solvent system composed of PEG1000-K₂HPO₄-KH₂PO₄-H₂O (0.5:1.25:1.25:7.0, w/w) by eluting a lower aqueous phase at 2.0 mL/min at 600 rpm, yielding two separate fractions, KPS-1 and KPS-2. The KPS-2 fraction was further purified by DEAE-Sepharose fast flow anion-exchange column chromatography to provide 3 fractions, KPS-2-1, KPS-2-2 and KPS-2-3. GPC-HPLC analysis indicated that KPS-2-1 fraction was a purified fucoidan. FT-IR analysis showed that KPS-2-1 was a sulphated polysaccharide. An analysis of enzymatic kinetics showed that the purified fucoidan was a competitive inhibitor of tyrosinase toward l-tyrosine, and the inhibitory constant Ki obtained from double-reciprocal plots was 0.9907 mg/mL.

Anti-inflammatory activity of edible brown alga Eisenia bicyclis and its constituents fucosterol and phlorotannins in LPS-stimulated RAW264.7 macrophages

Although individual phlorotannins contained in the edible brown algae have been reported to possess strong anti-inflammatory activity, the responsible components of Eisenia bicyclis have yet to be fully studied. Thus, we evaluated their anti-inflammatory activity via inhibition against production of lipopolysaccharide (LPS)-induced nitric oxide (NO) and tert-butylhydroperoxide (t-BHP)-induced reactive oxygen species (ROS), along with suppression against expression of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), in RAW 264.7 cells. The anti-inflammatory activity potential of the methanolic extract and its fractions of E. bicyclis was in the order of dichloromethane>methanol>ethyl acetate>n-butanol. The strong anti-inflammatory dichloromethane fraction was further purified to yield fucosterol. From the ethyl acetate fraction, six known phlorotannins were isolated: phloroglucinol, eckol, dieckol, 7-phloroeckol, phlorofucofuroeckol A and dioxinodehydroeckol. We found that these compounds, at non-toxic concentrations, dose-dependently inhibited LPS-induced NO production. Fucosterol also inhibited t-BHP-induced ROS generation and suppressed the expression of iNOS and COX-2. These results indicate that E. bicyclis and its constituents exhibited anti-inflammatory activity which might attribute to inhibition of NO and ROS generation and suppression of the NF-κB pathway and can therefore be considered as a useful therapeutic and preventive approach to various inflammatory and oxidative stress-related diseases.

In vivo speciation studies and antioxidant properties of bromine in Laminaria digitata reinforce the significance of iodine accumulation for kelps

The metabolism of bromine in marine brown algae remains poorly understood. This contrasts with the recent finding that the accumulation of iodide in the brown alga Laminaria serves the provision of an inorganic antioxidant - the first case documented from a living system. The aim of this study was to use an interdisciplinary array of techniques to study the chemical speciation, transformation, and function of bromine in Laminaria and to investigate the link between bromine and iodine metabolism, in particular in the antioxidant context. First, bromine and iodine levels in different Laminaria tissues were compared by inductively coupled plasma MS. Using in vivo X-ray absorption spectroscopy, it was found that, similarly to iodine, bromine is predominantly present in this alga in the form of bromide, albeit at lower concentrations, and that it shows similar behaviour upon oxidative stress. However, from a thermodynamic and kinetic standpoint, supported by in vitro and reconstituted in vivo assays, bromide is less suitable than iodide as an antioxidant against most reactive oxygen species except superoxide, possibly explaining why kelps prefer to accumulate iodide. This constitutes the first-ever study exploring the potential antioxidant function of bromide in a living system and other potential physiological roles. Given the tissue-specific differences observed in the content and speciation of bromine, it is concluded that the bromide uptake mechanism is different from the vanadium iodoperoxidase-mediated uptake of iodide in L. digitata and that its function is likely to be complementary to the iodide antioxidant system for detoxifying superoxide.

Statistics-based optimization of the extraction process of kelp polysaccharide and its activities

Statistics-based response surface methodology (RSM) was used to optimize the extraction process of kelp polysaccharide and its activities were evaluated. Single factor experiment was first designed for determining the optimal range of each of four factors and these factors were further optimized using RSM with a CCD design. The optimal conditions were as follows: pH 3.4, temperature 83 °C, extraction time 3.95 h and ratio of water to kelp 1:23. Under the above conditions, the yield of kelp polysaccharide obtained was 1.26%. Scavenging percentages of free radicals OH, O(2)(-) and DPPH by kelp polysaccharide were up to 90.8% (1.6 mg/mL), 85% (1 mg/mL) and 23.8% (1 mg/mL), respectively. An increase of 86% in the biosynthetic activity of collagen was obtained at a kelp polysaccharide concentration of 0.25%. All these results indicate that kelp polysaccharide may be a good candidate as an effective ingredient of cosmetics for future use.

Vascular barrier protective effects of phlorotannins on HMGB1-mediated proinflammatory responses in vitro and in vivo

The phlorotannins (phloroglucinol, eckol, and dieckol) are active compounds found in Eisenia bicyclis, and have been widely investigated for their antioxidant, anti-tumor, and anti-cancer activities. In this study, we investigated the protective effects of these phlorotannins against pro-inflammatory responses in human umbilical vein endothelial cells (HUVECs) and in mice treated by high mobility group box 1 protein (HMGB1), and the signaling pathways involved. The protective activities of the phlorotannins were determined by measuring permeability, leukocyte adhesion and migration, and the activations of pro-inflammatory proteins in HMGB1-activated HUVECs. We found that the phlorotannins inhibited; lipopolysaccharide (LPS)-induced HMGB1 release, HMGB1-mediated barrier disruption, the expressions of cell adhesion molecules (CAMs), and the adhesion/transendothelial migration of leukocytes to human endothelial cells. The phlorotannins also suppressed acetic acid induced-hyperpermeability and carboxymethylcellulose-induced leukocytes migration in vivo. Further studies revealed that the hydroxyl groups on dieckol positively regulated these vascular barrier protective effects. Collectively, these results suggest that phloroglucinol, eckol, and dieckol protect vascular barrier integrity by inhibiting hyperpermeability, the expressions of CAMs, and the adhesion and migration of leukocytes, which confirms their potential usefulnesses for the treatment of vascular inflammatory diseases.

The use of kelp sieve tube sap metal composition to characterize urban runoff in southern California coastal waters

This study introduces an innovative method for biomonitoring using giant kelp (Macrocystis pyrifera) sieve tube sap (STS) metal concentrations as an indication of pollution influence. STS was sampled from fronds collected from 10 southern California locations, including two reference sites on Santa Catalina Island. Using ICP-MS methodology, STS concentrations of 17 different metals were measured (n=495). Several metals associated with pollution showed the highest STS concentrations and most seasonal variation from populations inside the Port of Los Angeles/Long Beach. Lowest concentrations were measured at less-urbanized areas: Santa Catalina Island and Malibu. Some metals showed a spatial gradient in STS metal concentration with increasing distance from point sources (i.e. Los Angeles River). Cluster analyses indicate that polluted seawater may affect kelp uptake of metals essential for cellular function. Results show that this method can be useful in describing bioavailable metal pollution with implications for accumulation within an important ecosystem.

Cd(II) biosorption using Lessonia kelps

Lessonia kelps (L. trabeculata and L. nigrescens) have been successfully used for the recovery of Cd(II) from near neutral solutions. The biomass was pre-treated with calcium chloride for stabilization of alginate-based compounds. SEM-EDAX analysis and FT-IR spectrometry analysis were used for identifying the modifications of the biomass. Sorption isotherms were performed at the optimum pH (i.e., pH 6) and the maximum sorption capacity reached up to 1 and 1.5 mmol Cd g(-1) for L. nigrescens (L.n.) and L. trabeculata (L.t.), respectively. The Langmuir equation fits well experimental data. The temperature (in the range 20-40 °C) had a more marked effect on affinity coefficient than on maximum sorption capacity. The influence of particle size, sorbent dosage, metal concentration and temperature was evaluated on uptake kinetics. The kinetic profiles that were modeled using the Crank equation (i.e., the resistance to intraparticle diffusion) were hardly affected by the temperature and the particle size contrary to the sorbent dosage and the metal concentration, which show greater impact. The pseudo-second order rate equation was also tested for the modeling of uptake kinetics.

Microbiological evaluation of the efficacy of two new biodetergents on multidrug-resistant nosocomial pathogens

BACKGROUND

In the last few years, several outbreaks of nosocomial infections caused by multidrug-resistant pathogenic agents have been observed, and various biocides products were developed in order to control this phenomenon. We investigated the efficacy of two natural biodetergents composed of plants and kelps extracts, BATT1 and BATT2, against multidrug-resistant strains.

METHODS

In-vitro antibacterial efficacy of BATT1 and BATT2 against nosocomial multidrug-resistant isolates was assessed using a suspension-inhibition test, with and without bovine serum albumin (BSA). The test was also carried out on glass surfaces with and without BSA.

RESULTS

In vitro tests with both biocidal disinfectants at 25% concentration demonstrated an overall drop in bacterial, mould and yeast counts after 10 min of contact with or without organic substances. For Pseudomonas aeruginosa, it was necessary to use undiluted disinfectants with and without an organic substance. The same results were obtained in tests carried out on glass surfaces for all strains.

CONCLUSIONS

The natural products BATT1 and BATT2 behave like good biocides even in presence of organic substances. The use of both disinfectants may be beneficial for reducing hospital-acquired pathogens that are not susceptible to disinfectants.However, it has to be stressed that all these experiments were carried out in vitro and they still require validation from use in clinical practice.

Glutamate: from discovery as a food flavor to role as a basic taste (umami)

In 1908 Kikunae Ikeda identified the unique taste component of konbu (kelp) as the salt of glutamic acid and coined the term umami to describe this taste. After Ikeda's discovery, other umami taste substances, such as inosinate and guanylate, were identified. Over the past several decades, the properties of these umami substances have been characterized. Recently, umami has been shown to be the fifth basic taste, in addition to sweet, sour, salty, and bitter.

Marine derived polysaccharides for biomedical applications: chemical modification approaches

Polysaccharide-based biomaterials are an emerging class in several biomedical fields such as tissue regeneration, particularly for cartilage, drug delivery devices and gelentrapment systems for the immobilization of cells. Important properties of the polysaccharides include controllable biological activity, biodegradability, and their ability to form hydrogels. Most of the polysaccharides used derive from natural sources; particularly, alginate and chitin, two polysaccharides which have an extensive history of use in medicine, pharmacy and basic sciences, and can be easily extracted from marine plants (algae kelp) and crab shells, respectively. The recent rediscovery of poly-saccharidebased materials is also attributable to new synthetic routes for their chemical modification, with the aim of promoting new biological activities and/or to modify the final properties of the biomaterials for specific purposes. These synthetic strategies also involve the combination of polysaccharides with other polymers. A review of the more recent research in the field of chemical modification of alginate, chitin and its derivative chitosan is presented. Moreover, we report as case studies the results of our recent work concerning various different approaches and applications of polysaccharide-based biomaterials, such as the realization of novel composites based on calcium sulphate blended with alginate and with a chemically modified chitosan, the synthesis of novel alginate-poly(ethylene glycol) copolymers and the development of a family of materials based on alginate and acrylic polymers of potential interest as drug delivery systems.

Protein extraction for 2-DE from the lamina of Ecklonia kurome (laminariales): recalcitrant tissue containing high levels of viscous polysaccharides

Extraction of proteins from the tissues of laminarialean algae, i.e. kelp, is difficult due to high levels of nonprotein interfering compounds, mainly viscous polysaccharides. To establish proteomic analysis of kelp species, an ethanol/phenol extraction method was developed and compared to other popular methods. Proteins were extracted with phenol from crude protein powder, obtained by homogenizing the kelp tissues in ice-cold ethanol. The ethanol/phenol method produced high-quality proteins of the highest purity from the lamina of Ecklonia kurome, one of the Japanese dominant laminarialean algae. This method gave well-resolved 1-D SDS-PAGE or 2-DE images with low background and the highest number of bands or spots. In particular, proteins with neutral to basic pI's were efficiently extracted. Furthermore, 27 spots on the 2-DE gel were extensively identified by MALDI-TOF/TOF analysis. To the best of our knowledge, this is the first report of a protocol for protein extraction from kelp tissues that gives satisfactory 2-D protein profiles. It is expected that the protocol can be applied to other algae tissues or other recalcitrant plant tissues containing high levels of nonprotein interfering compounds.

Kelp as a bioindicator: does it matter which part of 5 m long plant is used for metal analysis?

Kelp may be useful as a bioindicator because they are primary producers that are eaten by higher trophic level organisms, including people and livestock. Often when kelp or other algae species are used as bioindicators, the whole organism is homogenized. However, some kelp can be over 25 m long from their holdfast to the tip of the blade, making it important to understand how contaminant levels vary throughout the plant. We compared the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in five different parts of the kelp Alaria nana to examine the variability of metal distribution. To be useful as a bioindicator, it is critical to know whether levels are constant throughout the kelp, or which part is the highest accumulator. Kelp were collected on Adak Island in the Aleutian Chain of Alaska from the Adak Harbor and Clam Cove, which opens onto the Bering Sea. In addition to determining if the levels differ in different parts of the kelp, we wanted to determine whether there were locational or size-related differences. Regression models indicated that between 14% and 43% of the variation in the levels of arsenic, cadmium, chromium, manganese, mercury, and selenium was explained by total length, part of the plant, and location (but not for lead). The main contributors to variability were length (for arsenic and selenium), location (mercury), and part of the plant (for arsenic, cadmium, chromium and manganese). The higher levels of selenium occurred at Clam Cove, while mercury was higher at the harbor. Where there was a significant difference among parts, the holdfast had the highest levels, although the differences were not great. These data indicate that consistency should be applied in selecting the part of kelp (and the length) to be used as a bioindicator. While any part of Alaria could be collected for some metals, for arsenic, cadmium, chromium, and manganese a conversion should be made among parts. In the Aleutians the holdfast can be perennial while the blade, whipped to pieces by winter wave action, is regrown each year. Thus the holdfast may be used for longer-term exposure for arsenic, cadmium, chromium and manganese, while the blade can be used for short-term exposure for all metals. Cadmium, lead and selenium were at levels that suggest that predators, including people, may be at risk from consuming Alaria. More attention should be devoted to heavy metal levels in kelp and other algae from Adak, particularly where they may play a role in a subsistence diets.

Case report: potential arsenic toxicosis secondary to herbal kelp supplement

CONTEXT

Medicinal use of dietary herbal supplements can cause inadvertent arsenic toxicosis.

CASE PRESENTATION

A 54-year-old woman was referred to the University of California, Davis, Occupational Medicine Clinic with a 2-year history of worsening alopecia and memory loss. She also reported having a rash, increasing fatigue, nausea, and vomiting, disabling her to the point where she could no longer work full-time. A thorough exposure history revealed that she took daily kelp supplements. A urine sample showed an arsenic level of 83.6 microg/g creatinine (normal < 50 microg/g creatinine). A sample from her kelp supplements contained 8.5 mg/kg (ppm) arsenic. Within weeks of discontinuing the supplements, her symptoms resolved and arsenic blood and urine levels were undetectable.

DISCUSSION

To evaluate the extent of arsenic contamination in commercially available kelp, we analyzed nine samples randomly obtained from local health food stores. Eight of the nine samples showed detectable levels of arsenic higher than the Food and Drug Administration tolerance level of 0.5 to 2 ppm for certain food products. None of the supplements contained information regarding the possibility of contamination with arsenic or other heavy metals. The 1994 Dietary Supplement Health and Education Act (DSHEA) has changed the way dietary herbal therapies are marketed and regulated in the United States. Less regulation of dietary herbal therapies will make inadvertent toxicities a more frequent occurrence.

RELEVANCE TO CLINICAL PRACTICE

Clinicians should be aware of the potential for heavy metal toxicity due to chronic use of dietary herbal supplements. Inquiring about use of dietary supplements is an important element of the medical history.

Precursor ion scanning for the non-targeted detection of individual arsenosugars in extracts of marine organisms

Arsenosugars are a group of arsenic compounds reported to be present in a wide variety of marine organisms. Numerous such compounds have been identified and characterized in marine organisms; however, unknown arsenosugar species may also be present. This indicates the need for an analytical technique suitable for their non-targeted detection. One such technique is tandem mass spectrometry operated in the precursor ion scanning mode. This technique is based on scanning for precursor ions that give specific product ions, characteristic of the compounds under investigation. In the present study two subgroups of arsenosugar species were examined, the oxo- and the thioarsenosugars, the CID behavior of which is well known from previous studies. In the case of the oxoarsenosugars characteristic product ions were observed at m/z 237 and 97, and for the thioarsenosugars at m/z 253 and 97. Validation of this approach was carried out by analyzing extracts of two commercial kelp powders with known contents of arsenosugar species. All arsenosugars reported to exist in these materials were detected successfully using the precursor ion scanning approach. The limits of detection for the oxo- and the thioarsenosugar species, and the selectivity and sensitivity of the method, strongly indicate the suitability of this approach for the non-targeted detection of arsenosugars in extracts of marine origin.

Release of bioactive active iodine in kelp

The release process and influencing factors of bioactive iodine of kelp are systemically studied by leaching experiment. The results showed that the bioactive iodine of kelp can be released rapidly and the principal form of iodine in lixivium is I-. There is a dynamic process between the release and absorption of iodine. With the increase of leaching water, the gross amounts of released iodine rise. There also exists a transforming process among I-, IO3- and organic iodine in lixivium.

[Study on certified reference material of iodine in kelp]

Analytical reference material of iodine in kelp was designed and prepared for accurate analysis, monitor and evaluation of iodine in trade of farming, forestry, medicine and food hygiene can be used in technical training, technical assessing, monitoring, date arbitrating and analytic method verifying for professional supervisors. This reference material was certified by neutron activation, ICP-MS, PA, GC, IC, COL method. According to Gurbb's law to judge the date of each group, it was confirmed that all of six groups certified curde date were normal distribution by checking normality D. The arithmetic mean value of all data on certified reference material of low and moderate amount was 9.3 microg/g and 85.7 microg/g respectively and, standard deviation was 0.9 microg/g and 4.9 microg/g respectively.