Arsenic Speciation in Sargassum fusiforme by Microwave-Assisted Extraction and LC-ICP-MS

Micropollutant content of Sargassum drifted ashore: arsenic and chlordecone threat assessment and management recommendations for the Caribbean

Massive Sargassum beachings occurred since 2011 on Caribbean shores. Sargassum inundation events currently involve two species, namely S. fluitans and S. natans circulating and blooming along the North Atlantic subtropical gyre and in the entire Caribbean region up to the Gulf of Mexico. Like other brown seaweeds, Sargassum have been shown to bioaccumulate a large number of heavy metals, alongside with some organic compounds including the contamination by historical chlordecone pollution in French West Indies (FWI), an insecticide used against the banana's weevil Cosmopolites sordidus. The present study reports, during two successive years, the concentration levels of heavy metals including arsenic in Martinique and Guadeloupe (FWI). We found that Sargassum can also accumulate a high concentration of chlordecone. Sargassum contamination by chlordecone is observed in areas close to contaminated river mouth but can be partly due to chlordecone desorption when secondary drifted on chlordecone-free shore. Our results further demonstrate that algae bleaching raises a number of questions about inorganic and organic pollutant (i) bioaccumulation, at sea for arsenic and close to river plumes for chlordecone, (ii) transport, and (iii) dissemination, depending the shoreline and the speciation for arsenic and/or metabolization for both.

Distribution, accumulation and health risk assessment of trace elements in Sargassum fusiforme

This study compared the ability of Sargassum fusiforme to accumulate As, Cd, Cr, Cu, Ni, Pb and Zn in its five tissues (main branch, lateral branch, leaf, receptacles and pneumathode). The concentrations of these trace elements in seawater, surface sediments and different tissues of S. fusiforme were analyzed in different areas in Dongtong County (Wenzhou City, China). The presence of receptacle at all sites indicated that S. fusiforme had entered the mature stage. However, the proportion of each tissue in S. fusiforme in different sites was varied, indicating subtle differences in growth. S. fusiforme has a great capacity to accumulate trace elements, showing relatively high levels of As (28.2-64.2 mg kg-1) and Zn (19.9-80.8 mg kg-1). The elements are mainly stored in leaf, receptacles and pneumathode. Compared to element concentrations in the surrounding environment, the seaweed exhibited stronger bioconcentration capacity for As and Cd than for other elements. According to our health risk assessment results, the hazard index and carcinogenic risk were below the limit, suggesting that the S. fusiforme ingestion would not pose any health risk and the potential risk of intake branches was even lower than that of other tissues.

The Complete Plastid Genomes of Seven Sargassaceae Species and Their Phylogenetic Analysis

Sargassum is one of the most important genera of the family Sargassaceae in brown algae and is used to produce carrageenan, mannitol, iodine, and other economic substances. Here, seven complete plastid genomes of Sargassum ilicifolium var. conduplicatum, S. graminifolium, S. phyllocystum, S. muticum, S. feldmannii, S. mcclurei, and S. henslowianum were assembled using next-generation sequencing. The sizes of the seven circular genomes ranged from 124,258 to 124,563 bp, with two inverted regions and the same set of plastid genes, including 139 protein-coding genes (PCGs), 28 transfer (t)RNAs, and 6 ribosomal (r)RNAs. Compared with the other five available plastid genomes of Fucales, 136 PCGs were conserved, with two common ones shared with Coccophora langsdorfii, and one with S. fusiforme and S. horneri. The co-linear analysis identified two inversions of trnC(gca) and trnN(gtt) in ten Sargassum species, against S. horneri and C. langsdorfii. The phylogenetic analysis based on the plastid genomes of 55 brown algae (Phaeophyceae) showed four clades, whose ancient ancestor lived around 201.42 million years ago (Mya), and the internal evolutionary branches in Fucales started to be formed 92.52 Mya, while Sargassum species were divided into two subclades 14.33 Mya. Our novel plastid genomes provided evidence for the speciation of brown algae and plastid genomic evolution events.

Analytical Methodologies for the Determination of Organoarsenicals in Edible Marine Species: A Review

Setting regulatory limits for arsenic in food is complicated, owing to the enormous diversity of arsenic metabolism in humans, lack of knowledge about the toxicity of these chemicals, and lack of accurate arsenic speciation data on foodstuffs. Identification and quantification of the toxic arsenic compounds are imperative to understanding the risk associated with exposure to arsenic from dietary intake, which, in turn, underscores the need for speciation analysis of the food. Arsenic speciation in seafood is challenging, owing to its existence in myriads of chemical forms and oxidation states. Interconversions occurring between chemical forms, matrix complexity, lack of standards and certified reference materials, and lack of widely accepted measurement protocols present additional challenges. This review covers the current analytical techniques for diverse arsenic species. The requirement for high-quality arsenic speciation data that is essential for establishing legislation and setting regulatory limits for arsenic in food is explored.

Toxicological Evaluation of Low Molecular Weight Fucoidan in Vitro and in Vivo

For a long time, fucoidan has been well known for its pharmacological activities, and recently low molecular weight fucoidan (LMF) has been used in food supplements and pharmaceutical products. In the present study, LMF was extracted from Laminaria japonica by enzyme hydrolysis. The toxicity of LMF in mouse and rat models was determined by many methods, such as total arsenic content, bacterial reverse mutation assay, chromosome aberration assay, and in vivo micronucleus assay. The present findings showed that LMF at 5000 μg/mL exhibited no mutagenicity. It also produced no formatting disruption of red blood cells in vivo. At 2000 mg/kg BW/day there were no toxicological indications. LMF is expected to be used as a safe food supplement.

Baseline arsenic levels in marine and terrestrial resources from a pristine environment: Isabel Island, Solomon Islands

Baseline records are crucial in understanding how chemicals of concern impact on the receiving environment. We analysed terrestrial and marine resources from a pristine site on Isabel Island, Solomon Islands, to provide environmental baseline levels for total arsenic and arsenic species composition for commonly consumed marine resources. Our data show that levels of the more toxic inorganic arsenic species were very low or below detectable limits, with the exception of the seaweed Sargassum sp. that contained pentavalent inorganic arsenic levels of 4.63 μg g(-1). Total arsenic concentrations in the majority of marine and terrestrial samples collected were below 2 μg g(-1). The less toxic arsenobetaine was the predominant arsenic species present in all marine fauna samples analysed. This work highlights the need for arsenic speciation analysis to accurately assess potential toxicity of marine resources and provides a crucial baseline to assess the impact of future development within this region.

Effects of Sargassum fusiforme polysaccharides on antioxidant activities and intestinal functions in mice

Sargassum fusiforme is a kind of brown algae that has been widely consumed not only as food, but also as herbal medicine for thousands of years. The purpose of this study was to investigate the antioxidant activities and intestinal functions of polysaccharides extracted from S. fusiforme (SFP) in normal and cyclophosphamide-induced immunosuppressed mice. The experiment was performed on six groups of ICR mice, which treated with cyclophosphamide (CY, 200 mg/kg) or different dosages of SFP for 14 days. The results showed that administration of SFP was able to overcome the immunosuppression, and significantly increased the spleen index and antioxidant activities in mice (P<0.05). It also remarkably improved the numbers of jejunal intraepithelial lymphocytes (IELs) and goblet cells in immunosuppressed mice (P<0.05). For normal mice, SFP increased both thymus index and intestinal function parameters such as villus length/crypt depth ratio and intestinal IELs and goblet cells (P<0.05). The results suggested that SFP, possessing pronounced antioxidant activities, may play an important role in the improvement of intestinal function in mice. This might be one of the possible mechanisms of SFP for the immunomodulatory effects.

The impact of marine shallow-water hydrothermal venting on arsenic and mercury accumulation by seaweed Sargassum sinicola in Concepcion Bay, Gulf of California

The influence of hydrothermal venting activity on arsenic (As) and mercury (Hg) accumulation was investigated in the shallow-water marine ecosystem of Concepcion Bay in the western Gulf of California. Geochemical data indicate that the marine shallow-water hydrothermal system of the Mapachitos site is a source of As and Hg for the water, sediment and algae collected along a transect moving across the western region of the bay. Although a small proportion of As and Hg precipitates close to the hydrothermal vent, both elements remain largely in the dissolved fraction, spreading a long distance from the source. The brown seaweed Sargassum sinicola thriving near the area of hydrothermal venting accumulates large quantities of As (above 600 mg kg (-1)), surpassing its typical concentration in the genus Sargassum by an order of magnitude. In contrast to As, the seaweed does not significantly accumulate Hg.

Microwave-assisted extraction and determination of citrus red 2 dye in oranges and orange juice by liquid chromatography-tandem mass spectrometry

A fast, simple, low cost, and high-throughput method has been developed for the determination of citrus red 2 dye in orange and orange juice samples. The procedure is based on microwave-assisted extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The method was optimized, and the analyte was efficiently extracted from the samples in 30 min using hexane/acetone (v/v, 3 : 1). The method was validated and showed good linearity and selectivity. The limits of quantification (LOQs) were 5 μg/kg (sample size of 2 g) for both orange and orange juice samples. The average recoveries, measured at 3 concentration levels (5, 10, and 20 μg/kg), were in the range 77.5% to 87.6% for the compound tested with relative standard deviations below 7.3%. The proposed method is rapid, accurate, and could be utilized for the routine analysis of citrus red 2 dye in orange and orange juice samples.

Determination of hexabromocyclododecane diastereoisomers in Sargassum fusiforme and comparison of the extraction efficiency of ultrasonication, microwave-assisted extraction, Soxhlet extraction and pressurised liquid extraction

The concentrations of hexabromocyclododecanes (HBCD) in Sargassum fusiforme, the common Chinese edible seaweed, were investigated by LC-MS/MS. For the recovery of HBCD, the efficiency levels of ultrasonic-assisted extraction, microwave-assisted extraction, Soxhlet extraction and pressurised liquid extraction were compared under different conditions. Pressurised liquid extraction and ultrasonic-assisted extraction resulted in complete extraction of HBCD (92.7-102.5% recovery). Microwave-assisted extraction and Soxhlet extraction, on the other hand, offered relatively low extraction recoveries (82.1-90.6%). The instrumental LODs on columns in this study were 1.0, 0.3 and 0.7 ng/g for α-HBCD, β-HBCD and γ-HBCD, respectively. Because of its accuracy, this straightforward method is particularly suitable for routine HBCD analysis.