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 pivo...
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