The Second Life of Marine Resources: The Multidimensional Functions of Chitosan and Deacetylated Chitosan

Chitosan (chitin) and deacetylated chitosan are components of the skeletons of crustaceans such as crabs and shrimp, and mollusks such as squid and shellfish. One hundred billion tons can be produced annually, but this has not been effectively utilized to date. Deacetylated chitosan is the product of removing one acetyl group from the chemical structure of chitosan. It is easily soluble in dilute acids and even easier to utilize than chitosan, but chitosan is more abundant in nature. This type of substance is also found in mushrooms and cheese. It can be said that chitosan and deacetylated chitosan are among the last biological resources on Earth that can be utilized in large quantities.

Chitosan and deacetylated chitosan, which have been overlooked, have been discovered to have a wide range of functions. They can form electrolyte complexes for recovering water-soluble proteins from wastewater in food processing plants and purifying drinking water; they can also be used to lower blood cholesterol, have antibacterial and antifungal properties, and promote the growth of bifidobacteria. Furthermore, they can form integrase to add essential nutrients such as iron to food or remove toxic heavy metals. Their adsorption, water retention, molecular recognition, and gelation properties make them suitable as immobilization carriers for nutrients, enzymes, and beneficial microorganisms.

Chitosan is a natural high-molecular-weight compound composed of acetylated glucosamines with a molecular weight of over 5000. It is an indigestible animal dietary fiber. Professor Shigeo Suzuki of Tohoku Pharmaceutical University has long been engaged in research on the anti-cancer and immune-activating effects of polysaccharides. According to Professor Suzuki's report, chitosan and deacetylated chitosan have inhibitory effects on transplanted cancer and ascites tumors in mice. Experimental observations revealed that deacetylated chitosan has a particularly significant inhibitory effect on cancer cells. Professor Suzuki also studied which component of deacetylated chitosan and why it effectively inhibits cancer cell proliferation.

The results showed that N-acetylated chitosan oligosaccharide and chitosan oligosaccharide, the main components of chitosan polysaccharides, have immune-activating effects and therefore anti-cancer effects. Although these oligosaccharide molecules are small, their immune-enhancing and anti-cancer effects are similar to those of high-molecular-weight mushroom polysaccharides (anti-cancer drugs extracted from shiitake mushrooms), and they exhibit extremely low pyrogenicity and toxicity. Further research is needed to determine how to further enhance their activity and develop superior anti-cancer drugs and treatments for immunodeficiency.