Application of glycosaminoglycan polysaccharides extracted from aquatic animals in medical science

Aquatic animals, due to their unique environment, are known as producers of natural products with specific structure and diverse biological activities. Aquatic wastes are rich in bioactive compounds, which are mostly wasted with limited use and low commercial value, and even cause resource wastage and environmental pollution. One of these compounds is sulfated glycosaminoglycans (GAGs). Glycosaminoglycan polysaccharides are extracted from various parts (whole fish, head, flesh, fins and tail, gut and bone) fish, shrimp, molluscs and algae by two enzymatic and chemical methods. GAGs are negatively charged linear polysaccharides composed of repetitive disaccharide units of hexosamine (glucosamine or galactosamine), uronic acid (glucuronic or iduronic acid), or galactose. The most common GAGs are chondroitin sulfate (CS), dermatan sulfate (DS), hyaluronic acid (HA), keratan sulfate (KS) heparin (HE), and heparan sulfate (HS(. GAGs have biological functions in medical science such as immunomodulators, antioxidants, antivirals, anti-inflammatories, neuroprotectors, antiproliferative, and anticoagulants. Heparin is a highly sulfated glycosaminoglycan that has natural anticoagulant properties. Heparin isolated from some molluscs has shown the same structural characteristics and anticoagulant activity as heparin isolated from mammals. Also, glycosaminoglycans extracted from fish swim bladder have shown good anticoagulation activity. GAGs can be extracted from fish cartilage. Although cartilage is a low-value material, it is rich in chondroitin sulfate, which has been reported as one of the GAGs for the treatment of osteoarthritis. Due to the various side effects of sulfated glycoaminoglycan extracted from pig intestine or cow lung, there is a need for alternative natural compounds, and aquatic animals are natural sources available for extracting these compounds. Therefore, the use of non-edible aquatic by-products can be useful as one of the added value sources for GAGs extraction. Recent research focuses on the use of GAGs in tissue engineering constructs for the regeneration of damaged tissue such as implants, nerve regeneration, bone repair and damaged cartilage repair.