半乳糖二酸, 黏酸,Galactaric acid; Mucic Acid

Mucic acid is a metal chelate that stimulates the metabolism of carbohydrates, fats and proteins. It also plays a role in the production of energy in the body. Mucic acid has been shown to have a protective effect against infectious diseases, as it activates toll-like receptor 2 (TLR2) and TLR4, which are molecules involved in innate immunity. Mucic acid has been shown to protect against influenza virus infection by increasing the expression of interferon-gamma (IFN-γ) and IL-12, which are cytokines that inhibit viral replication. Mucic acid can be used as a fluorescence probe for detection of polymorphonuclear leucocytes in blood samples.

Mucic acid is a white crystalline substance commonly used in various fields of research and industries such as analytical chemistry, pharmaceuticals, manufacturing, and food industries. It is a hexo-aldonic acid that is formed by the oxidation of various types of sugars such as glucose, fructose, and galactose. This paper aims to provide an in-depth understanding of mucic acid, including its definition and background, physical and chemical properties, synthesis, and characterization techniques. It also evaluates the analytical methods used in detecting mucic acid, biological properties, toxicity, safety in scientific experiments, and potential applications in various fields of research and industry.

Definition and Background

Mucic acid, also known as galactaric acid, is a sugar derivative that belongs to the chemical family of hexonic acids. It has a chemical formula of C6H10O8 and a molar mass of 194.14 g/mol. Mucic acid is formed by the oxidation of sugar or other aldoses like arabinose, galactose, glucose, and ribose. The sugar is converted to aldaric acid, which is then further oxidized to mucic acid. Mucic acid has two distinct diastereomers, which are called threo and erythro forms.

Mucic acid has multifaceted applications in industries, including manufacturing, pharmaceuticals, and analytical chemistry. It's commonly used as a standard reagent for various analytical methods, including titration and chromatography techniques. It's also utilized in the manufacturing of dyes and pigments, coatings, plasticizers, and antioxidants.

Physical and Chemical Properties

Mucic acid is a white, crystalline, and odorless solid that has a sweet taste. It has a melting point of 210-214 °C and decomposes at temperatures above 220 °C. Mucic acid is highly soluble in water, methanol, ethanol, and acetone; it has a solubility rate of about 160 g/L at 25 °C in water. It is relatively stable at room temperatures and possesses good thermal stability.

Mucic acid can form a hydrate by absorbing water molecules, and this water is lost when it is heated above 110 °C. This may lead to a diminution in both the crystallinity and solubility of the compound. Additionally, mucic acid can undergo esterification reactions to form mono, di, and tri-esters, which have important applications in various fields.

Mucic acid possesses two primary functional groups, carboxyl and hydroxyl groups. The carboxyl group can dissociate at neutral pH due to the presence of an alcoholic group in the compound, making it a weak acid. The dissociation constant Ka of mucic acid is 1.7×10⁻⁵. The hydroxyl group creates a chiral center in the molecule, leading to the formation of diastereomers or stereoisomers with similar physical and chemical properties.

Synthesis and Characterization

Mucic acid can be synthesized by the oxidation of various sugars using a variety of oxidants. Potassium permanganate, sodium periodate, and lead tetraacetate are commonly used oxidants in the synthesis of mucic acid. The choice of oxidant depends on factors such as reaction time, reaction temperature, cost, and the yield of the reaction.

Various analytical techniques are used to characterize mucic acid in solution and in the solid-state. Classical wet chemical methods include titration and colorimetry. Modern techniques such as high-performance liquid chromatography (HPLC), mass spectroscopy (MS), nuclear magnetic resonance spectroscopy (NMR), and X-ray crystallography are used to determine the chemical structure, molecular weight, and shape of mucic acid.

Analytical Methods

Several analytical methods exist for the detection and quantification of mucic acid. These methods include chromatographic techniques such as HPLC, gas chromatography (GC), and thin-layer chromatography (TLC).

Gas chromatography is a widely used technique in which mucic acid is derivatized to produce its corresponding trimethylsilyl (TMS) derivative. The TMS derivative is then analyzed using a gas chromatograph, which separates the compounds of the mixture into their individual components.

HPLC is another widely used method for the identification and quantification of mucic acid. This method utilizes a chromatographic column which separates the components based on their molecular weight and polarity. The advantage of using HPLC is that it can separate different isomers and detect the minor components in the mixture.

Nuclear magnetic resonance spectroscopy (NMR) and infrared spectrometry (IR) are non-destructive methods that are used for the identification and quantification of mucic acid in solution. These methods are highly sensitive and can provide detailed information about the chemical structure and composition of mucic acid.

Biological Properties

Mucic acid has several interesting biological properties. It has been shown to possess antioxidant, anti-inflammatory, anti-tumor, and anti-diabetic properties. In vitro and in vivo experimental studies have revealed that mucic acid can reduce the level of inflammation in various tissues and prevent the growth of certain types of cancer cells. It has also been reported that mucic acid can reduce oxidative stress and control blood sugar levels in diabetic patients.

Toxicity and Safety in Scientific Experiments

Mucic acid has a low toxicity profile and is generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA). Acute oral toxicity studies have shown that mucic acid is not toxic, and the lethal dose is above 2000 mg/kg. Long-term toxicity studies have revealed that mucic acid is not carcinogenic, teratogenic, or mutagenic.

Applications in Scientific Experiments

Mucic acid has several applications in scientific experiments, including in the manufacturing of dyes and pigments, pharmaceuticals, and analytical chemistry. It is also used as a standard reagent for various analytical techniques such as titration, chromatography, and spectrometry.

Mucic acid is used as a reducing agent in the preparation of metal nanoparticles. Mucic acid-functionalized nanoparticles have potential applications in drug delivery, imaging, and sensors. Additionally, mucic acid can be used as a chiral auxiliary in asymmetric synthesis.

Current State of Research

Several studies have been performed on mucic acid in various fields, including analytical chemistry, food research, pharmaceuticals, and nanotechnology. Current research is focused on expanding the application of mucic acid in these fields, including the synthesis of new derivatives with improved properties.

Potential Implications in Various Fields of Research and Industry

Mucic acid has potential implications in various fields of research and industry, including pharmaceuticals, analytical chemistry, food research, and nanotechnology. Its antioxidant, anti-inflammatory, and anti-tumor properties make it an attractive candidate for the preparation of new drugs. Additionally, its unique chiral properties make it a suitable auxiliary for asymmetric synthesis.

In the analytical chemistry field, mucic acid is commonly used as a standard reagent for various analytical methods. Its high solubility in water and good thermal stability make it an ideal reagent for titration and chromatography techniques. Moreover, its property to form ester derivatives makes it a perfect candidate for use as a molecular probe for various analysis techniques.

In the food industry, mucic acid can be used as a chelating agent and antioxidant. It has been shown to have a high capacity to bind metal ions, reduce the growth of bacteria, and prevent lipid oxidation in food products. Its proven safety profile makes it an attractive candidate for use in food application.

In the nanotechnology field, mucic acid-functionalized nanoparticles have potential applications in drug delivery, imaging, and sensors. The mucic acid coating improves the biocompatibility and biodegradability of the nanoparticles and enhances their functional properties.

Limitations and Future Directions

While the use of mucic acid has many potential applications, there are certain limitations that must be considered. One limitation is the fact that mucic acid is relatively expensive compared to other standard reagents used in analytical chemistry. Additionally, while mucic acid has been found to have various biological activities, further studies are required to assess its safety and efficacy when used in human clinical trials.

Future directions in research may include the development of new methods for the synthesis of more stable and efficient mucic acid derivatives. Moreover, the use of mucic acid in biotechnology and nanoparticles preparation may open up new areas of research in nanomedicine and biomaterials. Finally, additional studies evaluating the safety and efficacy of mucic acid in human clinical trials are needed to expand its applicability in the pharmaceutical industry.

Title: Galactaric Acid

CAS Registry Number: 526-99-8

Additional Names: Mucic acid; galactosaccharic acid; tetrahydroxyadipic acid; saccharolactic acid; Schleimsäure (German)

Molecular Formula: C6H10O8

Molecular Weight: 210.14

Percent Composition: C 34.29%, H 4.80%, O 60.91%

Literature References: Prepd by oxidation of lactose and of galactose: Kent, Tollens, Ann. 227, 221 (1885); Maurer, Drefahl, Ber. 75B, 1489 (1942). Manuf from wood sawdust: Acree, GB 160777 (1921). Review: B. A. Lewis et al., "Galactaric Acid and Its Derivatives" in Whistler, Wolfrom, Methods in Carbohydrate Chemistry vol. II (Academic Press, New York, 1963) pp 38-46.

Properties: Cryst powder, dec ~255° when rapidly heated, also reported as 225°. Soluble in 300 parts cold water, 60 parts boiling water, alkalies; practically insol in alcohol, ether.

Derivative Type: Ammonium salt

Molecular Formula: (NH4)2C6H8O8

Molecular Weight: 244.20

Percent Composition: N 11.47%, H 6.60%, C 29.51%, O 52.41%

Properties: Acicular crystals. Soluble in water.

Use: Has been proposed to replace potassium bitartrate in baking powder and for manuf of granular effervescing salts.