Øystein Arlov

Cadmium and inorganic arsenic are potentially toxic elements in seaweed. They accumulate in body tissues and may cause cancer, osteoporosis, kidney and DNA damage. Because cadmium is not removed by standard blanching for iodine reduction in seaweed (80°C, 120 s), alternative methods are needed. This study presents an acidic blanching method to reduce cadmium in freshly harvested Alaria esculenta and Saccharina latissima, while preserving composition. Alginate, a structural polysaccharide in brown seaweed, binds divalent cations such as Cd²⁺. Lowering pH below its pKa protonates alginate, releasing bound metals. Blanching at pH <3.6 (80°C, 120 s) reduced cadmium from 1700 to 700 µg kg⁻¹ in A. esculenta and from 700 to 200 µg kg⁻¹ in S. latissima. The content of arsenic decreased with blanching at pH 2.0–7.0. Arsenic speciation revealed that the toxic inorganic species, As(III) and As(V), constituted only 0.10–2.75% of total arsenic in the seaweed water extracts.

Two commercially utilized kelp species, winged kelp (Alaria esculenta) and sugar kelp (Saccharina latissima), can accumulate high amounts of iodine and thereby pose a health concern if consumed in excess. Water blanching is used industrially to reduce the iodine content. This study aimed to optimize the blanching conditions to reduce the energy consumption and environmental impact by investigating the parameters of temperature, duration, use of sea or fresh water, biomass-to-water ratio, and recycling of water. The study investigated the impact of the blanching conditions on composition of the biomass, including nutrient content and potential toxic elements. The iodine content was reduced to 5% of the initial content for S. latissima and to 8% for A. esculenta at the optimal conditions in the present study, which was blanching in seawater at 80 °C for 2 min. Using tap water at the same conditions resulted in a reduction to 7 and 11% of the initial content. The content of arsenic in blanched winged kelp was reduced to levels below the maximum allowed content in feed, whereas the content in blanched sugar kelp remained above this level. This study provides a comprehensive set of data on blanching of the two kelp species, with high relevance for the industrial scale-up of kelp processing.

Sulfated polysaccharides are ubiquitous in living systems and have central roles in biological functions such as organism development, cell proliferation and differentiation, cellular communication, tissue homeostasis, and host defense. Engineered sulfated polysaccharides (ESPs) are structural derivatives not found in nature but generated through chemical and enzymatic modification of natural polysaccharides, as well as chemically synthesized oligo‐ and polysaccharides. ESPs exhibit novel and augmented biological properties compared with their unmodified counterparts, mainly through facilitating interactions with other macromolecules. These interactions are closely linked to their sulfation patterns and backbone structures, providing a means to fine‐tune biological properties and characterize structural–functional relationships by employing well‐characterized polysaccharides and strategies for regioselective modification. The following review provides a comprehensive overview of the synthesis and characterization of ESPs and of their biological properties. Through the pioneering research presented here, key emerging application areas for ESPs, which can lead to novel breakthroughs in biomedical research and clinical treatments, are highlighted.

Heparin is widely recognized for its potent anticoagulating effects, but has an additional wide range of biological properties due to its high negative charge and heterogeneous molecular structure. This heterogeneity has been one of the factors in motivating the exploration of functional analogues with a more predictable modification pattern and monosaccharide sequence, that can aid in elucidating structure-function relationships and further be structurally customized to fine-tune physical and biological properties toward novel therapeutic applications and biomaterials. Alginates have been of great interest in biomedicine due to their inherent biocompatibility, gentle gelling conditions, and structural versatility from chemo-enzymatic engineering, but display limited interactions with cells and biomolecules that are characteristic of heparin and the other glycosaminoglycans (GAGs) of the extracellular environment. Here, we review the chemistry and physical and biological properties of sulfated alginates as structural and functional heparin analogues, and discuss how they may be utilized in applications where the use of heparin and other sulfated GAGs is challenging and limited.