As can be seen from its origin of the Greek word, “chondros” meaning “cartilage”, chondroitin is contained in the joint cartilage in a large quantity. Among mucopolysaccharides, chondroitin shows broader distribution (ubiquitously locating) in the body, and in addition to the hard tissues such as the joint cartilage and bones, it exists in almost all the organs and tissues such as a central nervous tissue, and plays important functions.
Chondroitin has several different structures: from the positions and the numbers of sulfuric acid moiety, 5 types of chondroitins have been known so far (A, B, C, D and E). Table 2 represents the tissue distribution of chondroitins. The joint cartilages contain chondroitins of type A and type C, which are respectively called chondroitin 4 sulfate and chondroitin 6 sulfate from the positions where the sulfate group is bound.
Table 2 Distributions of chondroitins in the body
| Name | Locations | Nature |
|---|---|---|
| chondroitin sulfate chondroitin sulfate A and chondroitin sulfate C chondroitin sulfate B (Dermartan sulfuric acid) chondroitin sulfate D |
contained in almost all tissues. Both are contained in the cartilage, cornea, aorta, cardiac valve, and pulpous nucleus in large quantities. Trace amount is present in human serum and brain. The skin contains it in a large quantity, and the cardiac valve and lung also contain it in a large amount, but it is not present in bones and the cartilage. Present in the shark cartilage in a large quantity. |
The fundamental structure of saccharide is the same for both, and only the positions of sulfate groups are different. The fundamental structure of saccharide is the same for both, and only the positions of sulfate groups are different. The structure is very similar to that of chondroitin sulfate A, but glucuronic acid is changed to isuronic acid. It has an action to prevent cellular adhersion. Very similar to chondroitin sulfate C, but the content of sulfate is higher. |
| hyaluronic acid (hyalronan) |
Hyalin body of eyes, crest of chicken, and synovia |
This is a mucopolysaccharide without any sulfuric acid group, and its structure is the simplest among mucosaccharides, and the length of the molecule is amazingly long, reaching 1/2 of the diameter of red blood cells (about 0.004mm) . |
| Heparan sulfate (heparitin sulfate) |
The intima and media of blood vessel, cell surface, and basal lamina of cells |
Its structure is similar to heparin, but it does not have any anti-coagulation activity. This is due to the low content of sulfuric acid. It accelerates the adhesion among cells. |
| Kerato sulfate | cornea, nucleus palposus of the discus intervertebralis, and cartilage |
In most cases, it is bound to proteins together with chondroitin sulfate to act. |
| heparin | Lung and mast cells | It has an extremely potent anti-blood coagulation action and it is an essential substance at the time of operations and dialysis treatments. Its structure is that of mucosaccharides, but its localization and physiological function are specific. |
*prepared by Prof. Eiichi Hasegawa based on "Structures and Functions of Muco-Polysaccharides" (Nankodo)
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