https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Seaweed is more than the wrap that keeps rice together in sushi. Seaweed biomass is already used for a wide range of other products in food, including stabilising agents. Biorefineries with seaweed as feedstock are attracting worldwide interest and include low-volume, high value-added products and vice versa. Scientific research on bioactive compounds in seaweed usually takes place on just a few species and compounds. This paper reviews worldwide research on bioactive compounds, mainly of nine genera or species of seaweed, which are also available in European temperate Atlantic waters, i.e. Laminaria sp., Fucus sp., Ascophyllum nodosum, Chondrus crispus, Porphyra sp., Ulva sp., Sargassum sp., Gracilaria sp. and Palmaria palmata. In addition, Undaria pinnatifida is included in this review as this is globally one of the most commonly produced, investigated and available species. Fewer examples of other species abundant worldwide have also been included. This review will supply fundamental information for biorefineries in Atlantic Europe using seaweed as feedstock. Preliminary selection of one or several candidate seaweed species will be possible based on the summary tables and previous research described in this review. This applies either to the choice of high value-added bioactive products to be exploited in an available species or to the choice of seaweed species when a bioactive compound is desired. Data are presented in tables with species, effect and test organism (if present) with examples of uses to enhance comparisons. In addition, scientific experiments performed on seaweed used as animal feed are presented, and EU, US and Japanese legislation on functional foods is reviewed.

Bioactive compounds in seaweed: functional food applications and legislation

Global demand for macroalgal and microalgal foods is growing, and algae are increasingly being consumed for functional benefits beyond the traditional considerations of nutrition and health. There is substantial evidence for the health benefits of algal-derived food products, but there remain considerable challenges in quantifying these benefits, as well as possible adverse effects. First, there is a limited understanding of nutritional composition across algal species, geographical regions, and seasons, all of which can substantially affect their dietary value. The second issue is quantifying which fractions of algal foods are bioavailable to humans, and which factors influence how food constituents are released, ranging from food preparation through genetic differentiation in the gut microbiome. Third is understanding how algal nutritional and functional constituents interact in human metabolism. Superimposed considerations are the effects of harvesting, storage, and food processing techniques that can dramatically influence the potential nutritive value of algal-derived foods. We highlight this rapidly advancing area of algal science with a particular focus on the key research required to assess better the health benefits of an alga or algal product. There are rich opportunities for phycologists in this emerging field, requiring exciting new experimental and collaborative approaches.

https://link.springer.com/content/pdf/10.1007%2Fs10811-016-0974-5.pdf

Algae as nutritional and functional food sources: revisiting our understanding

Sulfated polysaccharides and their lower molecular weight oligosaccharide derivatives from marine macroalgae have been shown to possess a variety of biological activities. The present paper will review the recent progress in research on the structural chemistry and the bioactivities of these marine algal biomaterials. In particular, it will provide an update on the structural chemistry of the major sulfated polysaccharides synthesized by seaweeds including the galactans (e.g., agarans and carrageenans), ulvans, and fucans. It will then review the recent findings on the anticoagulant/antithrombotic, antiviral, immuno-inflammatory, antilipidemic and antioxidant activities of sulfated polysaccharides and their potential for therapeutic application.

Chemical Structures and Bioactivities of Sulfated Polysaccharides from Marine Algae

Biological activities and potential health benefits of sulfated polysaccharides derived from marine algae

Fucoidan refers to a type of polysaccharide which contains substantial percentages of L-fucose and sulfate ester groups, mainly derived from brown seaweed. For the past decade fucoidan has been extensively studied due to its numerous interesting biological activities. Recently the search for new drugs has raised interest in fucoidans. In the past few years, several fucoidans' structures have been solved, and many aspects of their biological activity have been elucidated. This review summarizes the research progress on the structure and bioactivity of fucoidan and the relationships between structure and bioactivity.

/pdf/fucoidan-structure-and-bioactivity-4ietpbi8g1.pdf

Fucoidan: Structure and Bioactivity

Compact atomic magnetometer has become an important approach for noise measurement of magnetic shielding systems as well as biomagnetic measurement. In this study, we propose a novel method that enables time-shard triaxial magnetic field measurements in near-zero magnetic field through a compact high-performance atomic magnetometer with femtotesla sensitivity. With pump–probe orthogonal configuration, the magnetometer can be operated without optical and magnetic modulation. The <italic>y</italic>-axis magnetic field measurement was realized in zero field, whereas the <italic>x</italic>- and <italic>z</italic>- axes magnetic fields were measured by the cross-application of the bias magnetic fields operating in near-zero field. The maximum response amplitude and sensitivity with bandwidths of 46.8 Hz (<italic>x</italic>- axis), 10.5 Hz (<italic>y</italic>-axis), and 10.9 Hz (<italic>z</italic>-axis) are achieved under bias magnetic fields of <inline-formula> <tex-math notation="LaTeX">$B_{z-\mathrm {offset}}= 8$ </tex-math></inline-formula> nT and <inline-formula> <tex-math notation="LaTeX">$B_{x-\mathrm {offset}} = 2$ </tex-math></inline-formula> nT. The bandwidth along <italic>x</italic>- axis was extended to 232 Hz under <inline-formula> <tex-math notation="LaTeX">$B_{z-\mathrm {offset}} = 32$ </tex-math></inline-formula> nT, which can further be improved by increasing <inline-formula> <tex-math notation="LaTeX">$B_{z-\mathrm {offset}}$ </tex-math></inline-formula>. The linear interval of measurable magnetic field are between −11.7 to +11.7 nT (<italic>x</italic>- axis), −0.8 to +0.8 nT (<italic>y</italic>-axis), and −28.2 to +28.2 nT (<italic>z</italic>-axis). For <italic>x</italic>- and <italic>z</italic>-axes, the measurable interval can further be improved by increasing <inline-formula> <tex-math notation="LaTeX">$B_{z-\mathrm {offset}}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$B_{x-\mathrm {offset}}$ </tex-math></inline-formula>, respectively. The triaxial sensitivities achieved through our method reached 3.1 ± 0.3 fT/Hz1/2 (<italic>x</italic>- axis), 2.0 ± 0.1 fT/Hz1/2(<italic>y</italic>- axis), and 6.0 ± 0.5 fT/Hz1/2 (<italic>z</italic>- axis). This system is measured in a low-noise ferrite magnetic shield to ensure extra-low magnetic noise condition. Furthermore, the non-modulation triaxial vector operation demonstrated in this study is advantageous for reducing interference and spin-exchange relaxation caused by magnetic field modulation.

Triaxial Vector Operation in Near-Zero Field of Atomic Magnetometer With Femtotesla Sensitivity

Spin-exchange relaxation-free (SERF) atomic magnetometers operated under a near-zero magnetic field are used for vector magnetic field measurements with high sensitivity. Previously, the cross-axis coupling error evoked by a nonzero background magnetic field has been verified to be adverse in modulated single-beam magnetometers. Here, in a dual-beam unmodulated SERF magnetometer, we propose a somewhat different solution model for the cross-axis coupling effect where the field of interest couples with the interference field. Considering two cases where the transverse or longitudinal background field exists, the cross-axis coupling effect dependence on multiple factors is investigated here based on the dynamic response under a background magnetic field within ±5 nT. The theoretical and experimental investigation suggests that it has an adverse impact on the output response amplitude and phase and tilts the sensitive axis by several degrees, causing a measurement error on the dual-beam magnetometer. To suppress this effect, the background magnetic field is compensated through the PI closed-loop control. The coupling effect is effectively suppressed by 1.5 times at the 10–40 Hz low-frequency band and the sensitivity reaches 2.4 fT/Hz1/2.

/pdf/analysis-and-suppression-of-the-cross-axis-coupling-effect-204lruwy.pdf

Analysis and Suppression of the Cross-Axis Coupling Effect for Dual-Beam SERF Atomic Magnetometer

The emerging multi-channel spin-exchange relaxation-free (SERF) atomic magnetometer is a promising candidate for non-intrusive biomagnetism imaging. In this study, we propose a scanning 9-channel SERF magnetometer based on an acousto-optic modulator (AOM). Using the diffraction light of the AOM as the probe laser (with a low laser power of 1.7 mW), 9 channels were rapidly scanned by altering the diffraction angle. The scanning imaging scheme provides a new, to the best of our knowledge, approach for multi-channel magnetic field measurement and realizes a single-channel sensitivity of about 3 fT/Hz1/2, a spatial resolution of 0.6 mm, and a time resolution of about 2.7 ms, which is well suited for real-time extremely weak magnetic field imaging.

Scanning a multi-channel spin-exchange relaxation-free atomic magnetometer with high spatial and time resolution.

This publisher's note contains a correction to Opt. Lett.47, 3908 (2022)10.1364/OL.465832.

Bo Li

Papers

Fucoidan: Structure and Bioactivity

Triaxial Vector Operation in Near-Zero Field of Atomic Magnetometer With Femtotesla Sensitivity

Analysis and Suppression of the Cross-Axis Coupling Effect for Dual-Beam SERF Atomic Magnetometer

Scanning a multi-channel spin-exchange relaxation-free atomic magnetometer with high spatial and time resolution.

Scanning multi-channel spin-exchange relaxation-free atomic magnetometer with high spatial and time resolution: publisher's note.