Bioactivity and Applications of Polysaccharides from Marine Microalgae

Abstract

Marine microorganisms have been under research for the last decades, as sources of different biocompounds, each with various applications. Polysaccharides (PSs) are among these chemicals being produced and released by marine microalgae. These are very heterogeneous, including cyanobacteria and eukaryotic microalgae from several divisions/phyla, each of which with different characteristics. The PSs, sulfated or not, that they produce have already proved to be promising agents in various fields, such as food, feed, pharmaceutical, and biomedical. They can also be applied in wastewater and/or soil treatment and in some engineering areas, as naval engineering. After a brief introduction on the general types of biopolymers produced by marine microalgae and cyanobacteria, this chapter starts by presenting the species of these microorganisms and the types of PSs they produce, as well as the respective chemical composition; goes into the production of PSs and the effect of specific compounds; and focuses on the physicochemical properties of these PSs and their composition and structure, approaching the rheological properties relevant for their functions and behavior. The bioactivity of PSs and their applications are, next, presented, including therapeutic applications based on their antiviral and antibacterial activities, antioxidant properties, anti-inflammatory and immunomodulatory characteristics, antitumoral activity, and antilipidemic and antiglycemic properties, among others. The potential use of PSs from marine microalgae as it is or incorporated in health foods is also considered. The mechanisms behind their antiviral and antibacterial activities are explained. Toxicological and safety issues are also disclosed, and there is a brief mention of the bioavailability of PSs from microalgae. The chapter ends by listing some preclinical studies with this type of polymers.

Variability in nutrient composition and in vitro crude protein digestibility of 16 microalgae products

“…We prefer to not term this fraction as “starch” because the applied assay included acid hydrolysis followed by enzymatic hydrolysis using the enzyme amyloglucosidase, cleaving α‐1,4 and α‐1,6‐glucan bonds of polysaccharides. Microalgae have been described to contain glucose as monosaccharides besides starch (de Jesus Raposo, de Morais, & de Morais, , ; Sui, Gizaw, & BeMiller, ) and with α‐1,4 or α‐1,6‐glucan bonds (e.g., chrysolaminarin in Phaeodactylum ) (Goo et al., ; Gügi et al., ). Such polysaccharides might have been degraded to glucose by acid hydrolysis or amyloglucosidase or both and hence might have mimicked starch.…”

Exocellular Polysaccharides in Microalgae and Cyanobacteria: Chemical Features, Role and Enzymes and Genes Involved in Their Biosynthesis

“…Microalgae and cyanobacteria have simple growth requirements, consisting in a source of nitrogen (apart from the nitrogen-fi xing organisms), phosphate, iron, magnesium, calcium and other minor salts. Harvesting is independent from climate and season and polymers with similar and reproducible properties can be more easily obtained (de Jesus Raposo et al 2013 ).…”

Equilibrium, kinetic and thermodynamic biosorption studies of Hg(II) on red algal biomass ofPorphyridium cruentum

“…Marine red unicellular micro algae from the genus Porphridium (Porphyridiales, Rhodophyta) are characterized by extracellular sulfated polysaccharides with acidic characteristics and found potential application as therapeutic and nutraceutical agent (20). Porphridium cruentum is unicellular marine red micro algal (Rhodophyta) species (21).…”