Types of fucoidan: F, U, L, G, GA

Fucoidan is not the name of a chemical substance but a generic name for a class of chemical substances. The chemical formula and physiological activity of a fucoidan varies depending on the particular seaweed and extraction method. It was not until 1996 that the chemical structure and physiological activity of fucoidan were analyzed, which became possible due to the development of enzymes capable of splitting fucoidan into oligosaccharide units. These enzymes were obtained by screening many marine microorganisms and making extracts from them. One of the first academic reports on fucoidan was presented in 1996 at the General Assembly of the Japan Cancer Association and was titled: "Apoptosis in human gastric and intestinal cancer cells induced by fucoidan extracted from kagome kombu (scientific name Kjellmaniella crassifolia miyabe)". This report was the result of joint research conducted by the Sugar Chain Engineering Laboratory and Takara Bio Laboratory. The Sugar Chain Engineering Laboratory (糖鎖工学研究所) was established in 1990 as a collaboration between industry, academia and local government with funding for seven years from the Biological Industries Promotion Organization (and it received special approval from the Ministry of Finance and the Ministry of Agriculture of Japan), Aomori Prefectural Government (Japan), and 11 private businesses with the purpose of promoting research into glycobiology to boost the development of useful glucides.

The research results are as follows:

1. A method for refining polysaccharides containing sulfated fucose, which were extracted from dried kagome kombu seaweed, was established. Using this method it became possible to collect fucoidan and other polysaccharides, which contain sulfated fucose.
2. It was discovered that the polysaccharide fraction containing sulfated fucose and obtained with the above-mentioned method, has two types of sulfated polysaccharides. One of these is a polysaccharide almost completely composed of sulfated fucose, which was named F-fucoidan (the official name is sulfated fucan). The other one is composed of a repeating structure of three oligosaccharides: sulfated fucose, sulfated mannose and glucuronic acid. This was named U-fucoidan (the official name is sulfated fucoglucuromannan). Also, G-fucoidan, which contains sulfated galactose as its main component, was isolated. In total three types of fucoidan were discovered and the chemical structure of each was determined. The estimated chemical structure of another type of fucoidan, which is found in the Okinawan seaweed mozuku (Cladosiphon okamuranus), was proposed in 1999 by Nagaoka et al. Later Kato et al. discovered enzymes capable of decomposing Okinawan mozuku fucoidan and thus the structure of this kind of fucoidan was determined experimentally.
3. Microorganisms able to assimilate F-fucoidan and U-fucoidan, using enzymes capable of decomposing these two types of fucoidan, were discovered and the enzymes were refined. The amino-acid sequences of the refined enzymes were analyzed and from each of the microorganisms the genes for the fucoidan-degrading enzymes were cloned.
4. F-fucoidan and U-fucoidan were decomposed enzymatically and the oligosaccharides in each were refined and analyzed using MS and NMR.
5. The apoptosis-inducing ability of these fucoidans for leukemia, intestinal and gastric cancerous cells was studied. The main result was that hydrophobic substances firmly attached to fucoidan (U-fucoidan and Okinawan mozuku fucoidan) perform the large part of this function. When separated, these hydrophobic substances do not dissolve in water, but when attached to U-fucoidan they become readily soluble, and in an aqueous solution they induce apoptosis in cancerous cells.
6. Fucoidan was added to the diet of rats and mice with transplanted human colon cancer cells. A prolongation of life and contraction of the tumors was observed. The results of these experiments suggested an antiangiogenic effect (i.e. reducing the growth of new blood vessels) by fucoidan on the cancerous cells, giving rise to the possibility of using fucoidan for treating cancer.

There are six known types of fucoidan:

1. F-fucoidan: The main component is sulfated fucose.
2. U-fucoidan: Besides sulfated fucose, it contains glucuronic acid and mannose.
3. G-fucoidan: Besides sulfated fucose, it contains galactose.
4. L-fucoidan: Besides sulfated fucose, it contains galactose. This type of fucoidan is found in the root and leaves of kombu seaweed (Laminaria japonica).
5. GA-fucoidan: Besides sulfated fucose, it contains saccharides such as galactose, xylose, mannose and glucose. Uronic acid is also found in this type of fucoidan.
6. Okinawan mozuku seaweed fucoidan: Uronic acid is linked to the sulfated fucose in this type of fucoidan. Okinawan mozuku is also known to contain U-fucoidan.

Please have a look at our fucoidan products.

For reference:

1. 酒井武ら　2003.　藻類　５１、19－25
2. M. Nagaoka et al. 1999. Glycoconjugate J., 16, 19-26