D-Galactose, D-半乳糖

D-galactose is a monosaccharide that is an intermediate in the pentose phosphate pathway and the synthesis of ribose. It is also a substrate for glycosyltransferases, which are enzymes that use it to form glycosides. D-Galactose has been shown to be involved in mitochondrial functions, brain functions, and complex enzyme activities. D-Galactose inhibits glycolysis by inhibiting cell lysis and blocking the formation of disulfide bonds. This sugar has been shown to have inhibitory levels in rats at doses of 10 g/kg body weight a day or higher. D-galactose also has neurotrophic effects and can be used for cardiac protection.

The free sugar has been detected in ivy berries, some fruits and heartwood of Chamaecyparis lawsonia . It is a constit. of the oligosaccharides Lactose, L-13, 6-O-a- D-Galactopyranosyl-D-glucose, G-145 and Raffinose, R-1, the glycosides Idaein and Myritillin and the cerebrosides and gangliosides of brain and nerve tissue. It is one of the few sugars, other than D-Glucose and 2-Deoxy-D-ribose, found to any great extent in the animal kingdom, a common constit. of glycoproteins and the galactans of beef lung, frog spawn and snail (Helix pomatia) albumin gland. Polysaccharides agar, gum arabic, mesquite gum, western larch gum and many plant mucilages and gums contain galactose. Can be prepd. by
acid hydrol. of lactose, being isol. after the glucose has been removed by yeast fermentation. Inexpensive starting material for synthesis. Mp 118-1208 (monohydrate).

Title: D-Galactose

CAS Registry Number: 59-23-4

Additional Names: Cerebrose; brain sugar

Molecular Formula: C6H12O6

Molecular Weight: 180.16

Percent Composition: C 40.00%, H 6.71%, O 53.28%

Literature References: Constituent of many oligo- and polysaccharides occurring in pectins, gums, and mucilages. Prepn: Kent, Tollens, Ann. 227, 224 (1885); E. P. Clark, J. Biol. Chem. 47, 2 (1921). Mutarotation and purification of b-form: C. S. Hudson, E. Yanosky, J. Am. Chem. Soc. 39, 1021 (1917). Structural configuration: J. Pryde, J. Chem. Soc. 123, 1809 (1923); W. Charlton et al., ibid. 1926, 94; W. N. Haworth et al., ibid. 1927, 2428; E. L. Jackson, C. S. Hudson, J. Am. Chem. Soc. 59, 994 (1937); R. M. Hann et al., ibid. 66, 1912 (1944). Isoln in the processing of the red algae, Porphyra umbilicalis: S. Peat et al., J. Chem. Soc. 1961, 1590. Review: W. Pigman, The Carbohydrates (Academic Press, New York, 1957) pp 88-90. Review of diagnostic use: W. J. Schirmer et al., J. Surg. Res. 41, 543 (1986).

Derivative Type: a-Form

Properties: Prisms from water or ethanol, mp 167°. [a]D +150.7° ® +80.2° (water). Soluble in about 0.5 parts water; freely sol in hot water; final soly in water at 25° = 68%; sol in pyridine; slightly sol in alcohol.

Melting point: mp 167°

Optical Rotation: [a]D +150.7° ® +80.2° (water)

Derivative Type: b-Form

Properties: Crystals, mp 167°. [a]D +52.8° ® +80.2° (water). Sol in 1.7 parts water at 17°.

Melting point: mp 167°

Optical Rotation: [a]D +52.8° ® +80.2° (water)

Derivative Type: Monohydrate

Properties: Prisms from water, mp 118-120°.

Melting point: mp 118-120°

Derivative Type: Microparticulate Form

CAS Registry Number: 90881-70-2

Manufacturers' Codes: SH U 454

Trademarks: Echovist (Schering)

Literature References: Suspension of galactose microparticle granules in a galactose solution. Prepn: J. S. Rasor, E. G. Tickner, EP 131540 (1985 to Schering). Series of articles on in vivo use in echocardiography: Arzneim.-Forsch. 36, 1030-1040 (1986). Review of formulations and clinical diagnostic use: R. Schürmann, R. Schlief, Radiol. Med. 87, Suppl. 1, 15-23 (1994).

Derivative Type: Transpulmonary Microparticulate Form

CAS Registry Number: 144046-30-0

Manufacturers' Codes: SH U 508A

Trademarks: Levovist (Schering)

Literature References: Suspension of galactose microparticle granules containing 0.1% physiologic palmitic acid in a sterile water solution.

Therap-Cat: Diagnostic aid (hepatic function). Microparticulate forms as diagnostic aid (ultrasound contrast agent).

Keywords: Diagnostic Aid.