L-巖藻糖 , L-Fucose

L-(?)-Fucose is a deoxyhexose monosaccharide found on N- and O-linked glycans and glycolipids of a wide variety of organisms. It can exist as a terminal modification of glycan structures or serve as a point of attachment for adding other sugars. In humans, L-(?)-fucose plays a role in A and B blood group antigen substructure determination, selectin-mediated leukocyte-endothelial adhesion, and host-microbe interactions.

Beta-D-Fucose, also known as b-D-fuc or beta-delta-fuc, belongs to the class of organic compounds known as hexoses. These are monosaccharides in which the sugar unit is a is a six-carbon containing moeity. Beta-D-Fucose is soluble (in water) and a very weakly acidic compound (based on its pKa). Within the cell, Beta-D-fucose is primarily located in the cytoplasm. Beta-D-Fucose can be converted into quercetin 3-O-beta-D-fucopyranoside.

Beta-D-fucose is a D-fucopyranose with a beta-configuration at the anomeric position. It is an enantiomer of a beta-L-fucose.

Fucose (Fuc, 6-deoxy L-galactose) has a methyl group at C6 in place of a hydroxyl group and this gives the molecule a greater degree of hydrophobicity than galactose (Collins, 2006). L-fucose is found in fucoidan, a polysaccharide that occurs in the brown seaweeds (Phaeophyceae) (Percival, 1967). Fucose is also a key component in many mammalian N- and O-linked glycans, glycolipids, blood group substances and Lewis antigens (Becker, 2003). In human milk, neutral (fucosylated) oligosaccharides (HMO) contain fucose at the terminal position (e.g. 2a?? -fucosyllactose and lactodifucopentaose). They represent 35% to 50% of the total HMO content and many in vitro studies suggest that HMOs directly modulate immune responses, acting either locally on cells of the mucosa-associated lymphoid tissues or systemically to inhibit the expression of inflammatory genes, mainly cytokines (Plaza-Diaz, 2018).

Title: L-Fucose

CAS Registry Number: 2438-80-4

CAS Name: 6-Deoxy-L-galactose

Additional Names: L-galactomethylose

Molecular Formula: C6H12O5

Molecular Weight: 164.16

Percent Composition: C 43.90%, H 7.37%, O 48.73%

Literature References: Occurs in seaweed: Ascophyllum nodosum (L.) Ledol. (Fucus nodosus L.), Fucus vesiculosus L., F. serratus L., F. virsoides (Don) J. Ag., Fucaceae, and in gum tragacanth. Isoln from seaweed: Clark, J. Biol. Chem. 54, 65 (1922); Hockett et al., J. Am. Chem. Soc. 61, 1658 (1939). Manuf from fucoidan: Schweiger, US 3240775 (1966 to Kelco). Synthesis from D-galactose: Dejterjuszynski, Flowers, Carbohydr. Res. 28, 144 (1973); from D-glucose: T. Chiba, S. Tejima, Chem. Pharm. Bull. 27, 2838 (1979); from D-mannose: J. Defaye et al., Carbohydr. Res. 94, 131 (1981). Review of chemistry and biochemistry: H. M. Flowers, Adv. Carbohydr. Chem. Biochem. 39, 279-345 (1981).

 Derivative Type: a-Form

Properties: Minute needles from abs alcohol, mp 140°. Shows mutarotation. [a]D20 -124.1° (10 min) ? -108.0° (20 min) ? -91.5° (36 min) ? -78.6° (70 min) ? -75.6° (final value, 24 hrs, c = 9). Soluble in water and alcohol.

Melting point: mp 140°

Optical Rotation: [a]D20 -124.1° (10 min) ? -108.0° (20 min) ? -91.5° (36 min) ? -78.6° (70 min) ? -75.6° (final value, 24 hrs, c = 9)

Name: L-Fucose   M.F.: C₆H₁₂O₅    M.W.: 164.16    CAS: 2438-80-4,6696-41-9

References:

1. Wong C-H, Alajarin R, Morfs-Varas F, Blanco O, Garcia-Junceda E, J. Org. Chem. 1995, 60, p7360-7363
2. Cappi MW, Moree WJ, Qiao L, Marron TG, Weitz G, Bioorg. Med. Chem. 1997, Vol5, No2, p283-296(14)