Technical Exploration of the Blue Ocean: Algal Polysaccharides

Exploration of the infinite blue drug storehouse

Du Guanhua, Vice President of the Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, said, “Marine drugs are very unique and irreplaceable to an extent.” With the deepening of the understanding and exploration of marine life, we can find that most marine life has unique genes after long biological evolution to meet requirements for survival, multiplying, and defense, etc. in the deep-sea environment, for example, some can withstand cold, heat, and high pressure, and some can produce marine natural products with peculiar structures and diverse activity. The ocean is not only a medicinal compound library for treating tumors and easing chemoradiotherapy side effects, immune diseases, cardiovascular and cerebrovascular diseases, inflammation, and nervous system diseases, etc. but also a raw material store of health-related functional foods against oxidation and aging and for beauty and whitening and energy boosting, etc.

China is a maritime power with the kelp processing industry already forming an industrial system based on products like sodium alginate, mannitol, alginate, and iodine. However, the wastes generated by this industrial system, such as a large number of kelp residues, do not only seriously affect the marine ecology, but also represent a huge waste of resources. How to improve products’ value-added has become a technical problem that urgently needs researching and solving, with the intensification of market competition. Thanks to the acceleration of marine drug research and the applied research of modern extraction technologies in China, the functional activity and medicinal and edible value of algal polysaccharides have been increasingly focused on and valued.

Marine essence: algal polysaccharides

Algal polysaccharides are formed by multiple same or different monosaccharides linked by glycosidic bonds and are a generic term of various carbohydrate polymers contained between and within algal cells. Accordingly, they can be divided into three types: firstly, storage polysaccharides that exist within cells; secondly, mucopolysaccharides that exist between cell wall polysaccharides; thirdly, cell wall polysaccharides that exist in the outermost layer of cells. Common polysaccharides mainly include red alga polysaccharides, brown alga polysaccharides, green alga polysaccharides, and blue-green algae polysaccharides. Algal polysaccharides are mostly water-soluble because they are mostly polar macromolecules and contain a large number of hydroxyl groups. And most algal polysaccharides contain sulfate groups, therefore, they have high viscosity and solidification.

Extraction technology of algal polysaccharides

The technological difficulty in the application development of algal polysaccharides is mainly in the extraction process. The extraction process of brown alga polysaccharides has been tried and modified most; wherein, the extraction process of laminarin is the most mature. Extraction processes in China and abroad mainly include hot-water extraction, weak-acid extraction, and weak-base extraction. Those extraction processes have a simple process and low requirements on equipment, however, the extraction yield is low, the extraction duration is long, and the loss of activity is big, which limits the large-scale production of algal polysaccharides to some extent. By contrast, the microwave technology, ultrasound technology, and enzymolysis method, etc. developed in recent years have advantages such as high efficiency, low energy consumption, and short production cycle. However, all the extraction processes must protect the unique natural high-level structure of algal polysaccharides because algal polysaccharides’ activity relies heavily on their such structure and especially sulfate groups play a pivotal role. The core and key technical points of the algal polysaccharide extraction process lie in how to better protect the natural chemical structure and avoid and reduce the falling off of sulfate groups as far as possible. Only by grasping those points can the high activity and high quality of algal polysaccharides be ensured.

Application value of algal polysaccharides

As naturally active marine polysaccharides with many sources that have no or low toxicity, algal polysaccharides are extensively researched and applied in terms of drugs, animal nutrition, and health. Wholesale medical supplies manufacturers have done a lot of researches on them.

Microcapsules prepared with algal polysaccharides: they serve as controlled release drug carriers, cell culture microreactors, gene delivery vehicles, artificial organs, and separating media, etc.

Antiviral drugs: According to the Japanese medical press, Mr. Yuto Kamei, a Saga University associate professor who specializes in marine biotechnology, extracted a new fucoidan substance called “MC26” using brown algae that has excellent anti-influenza virus effects and more significant effects in inhibiting viral replication compared to existing anti-influenza drugs (such as Tamiflu). According to an in vitro test, MC26 could directly kill many influenza virus variants and had strong killing effects against the annoying avian influenza virus. Owing to the inhibition of anti-influenza drugs against the SARS virus, the Japanese scholars held that MC26 could be a new drug to treat epidemic viral diseases including SARS in the future.

Lipid lowering and antioxidation of algal polysaccharides: The low molecular sulfated fucan (LMSF) extracted from Laminaria japoniea is an indigenous intercellular water-soluble sulfated polysaccharide in brown algae, which the Ocean University of China used to experiment on rats with experimental hyperlipidemia. The results showed that LMSF had a big potential application value in lowering lipid and preventing atherogenesis.

Skin care and moisturizing functions of algal polysaccharides: Algae are an excellent emollient not only because the active substances in algae can bind to skin protein to form moisturizing gel but also because algae can form a protective membrane on the skin surface through hydration to prevent water evaporation.

Application of algal polysaccharides in the breeding industry: An experimental study discovered that adding 1.5% algal polysaccharides to broiler diet could affect enzyme and protein expression levels, promote body growth metabolism, significantly boost weight, feed utilization rate, and growth performance, showing that algal polysaccharides could regulate gene expression and help improve broiler body energy metabolism and nutrient use.

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