Arsenosugar phosphate extracted from seaweed: Isolation, quantification, characterization, and in vitro toxicological...

The increasing interest in seaweed as a potential feed and food source has prompted concerns regarding the presence of potentially toxic arsenic (As) species. Seaweed is known to contain the organic As species arsenosugars, but the toxicity of these compounds is not fully known due to a lack of scientific data. Nori (Porphyra spp.), a common red seaweed and potential feed and food candidate, contains arsenosugar-phosphate (As-Sug-PO₄) as a primary As species. In this study, As-Sug-PO₄ was isolated from nori by solid-phase extraction (SPE) and subsequently evaluated for in vitro toxicity in primary salmon hepatocytes. The As-Sug-PO₄ isolate, alongside As reference standards (arsenite As(III) and dimethylarsinic acid (DMA(V)), and arsenic-containing hydrocarbon (AsHC-360)), were assessed for cytotoxicity (mitochondrial activity) and for transcriptional effects on genes associated with lipid biosynthesis, inflammation and oxidative stress by reverse transcription-quantitative polymerase chain reaction (RT‑qPCR). Impacts on total As and As speciation were quantified in both cell pellets and culture medium using high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). High concentrations of As-Sug-PO₄ caused cytotoxicity and mitochondrial damage, while lower levels influenced triglyceride biosynthesis, indicating impaired lipid deposition. As(III) was the most toxic As species, followed by As-Sug-PO₄ and DMA(V) and unlike As(III), As-Sug-PO₄ and DMA(V) did not alter total As levels and speciation profile in samples after 48 h of exposure. Follow-up in vivo studies with commercial standards are needed to confirm effects on lipid deposition and to support the establishment of regulatory limits for As-Sug-PO₄ in feed and food.