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.

This review discusses different forms of nanomaterials generated from chitosan and its derivatives for controlled drug delivery. Nanomaterials are drug carriers with multiple features, including target delivery triggered by environmental, pH, thermal responses, enhanced biocompatibility, and the ability to cross the blood-brain barrier. Chitosan (CS), a natural polysaccharide largely obtained from marine crustaceans, is a promising drug delivery vector for therapeutics and diagnostics, owing to its biocompatibility, biodegradability, low toxicity, and structural variability. This review describes various approaches to obtain novel CS derivatives, including their distinct advantages, as well as different forms of nanomaterials recently developed from CS. The advanced applications of CS-based nanomaterials are presented here in terms of their specific functions. Recent studies have proven that nanotechnology combined with CS and its derivatives could potentially circumvent obstacles in the transport of drugs thereby improving the drug efficacy. CS-based nanomaterials have been shown to be highly effective in targeted drug therapy.

Recently, fucoidan has been proposed as a potential prebiotic agent for functional food and pharmaceutical development. However, while previous studies illustrated favorable modulations of gut microbiota by fucoidan, changes in the overall microbial structure remain elusive. In the present study, modulations of gut microbiota by different fucoidans were studied using high throughput sequencing and bioinformatics analysis. We found that at the expense of opportunistic pathogenic bacteria such as Peptococcus, the abundance of beneficial bacteria including Lactobacillus and Ruminococcaceae was significantly increased in response to fucoidan treatment. Besides, by maintaining a more balanced composition of gut microbiota, dietary fucoidan also significantly reduced the antigen load and the inflammatory response in the host as evidenced by the decreased serum lipopolysaccharide-binding protein levels. Collectively, our results indicate that fucoidan can be used as a gut microbiota modulator for health promotion and treatment of intestinal dysbiosis.