D-glucuronic acid is white or white like needle crystal or powder, sour taste, sensitive to humidity, can reduce Fehling's solution. Its aqueous solution is unstable and it is easy to form lactones. Soluble in water and ethanol.
D-Glucuronic acid is a glucuronic acid formed by the oxidation of the C-6 hydroxyl group of glucose to a carboxyl group. D-glucuronic acid does not generally exist in its free form, as this form is unstable, but in the more stable 3, 6-lactone form of the furan ring. D-glucopyranuronic acid is present in oligosaccharides at the junctions of glycosaminoglycan chains, as well as in heparin and chondroitin.
Glucuronic acid is a sugar acid derived from glucose, with its sixth carbon atom oxidized to a carboxylic acid. In living beings, this primary oxidation occurs with UDP-α-D-glucose (UDPG), not with the free sugar.
Glucuronic acid, like its precursor glucose, can exist as a linear (carboxo-)aldohexose (<1%), or as a cyclic hemiacetal (furanose or pyranose). Aldohexoses such as D-glucose are capable of forming two furanose forms (α and β) and two pyranose forms (α and β). By the Fischer convention, glucuronic acid has two stereoisomers (enantiomers), D- and L-glucuronic acid, depending on its configuration at C-5. Most physiological sugars are of the D-configuration. Due to ring closure, cyclic sugars have another asymmetric carbon atom (C-1), resulting in two more stereoisomers, named anomers. Depending on the configuration at C-1, there are two anomers of glucuronic acid, α- and β-form. In β-D-glucuronic acid the C-1 hydroxy group is on the same side of the pyranose ring as the carboxyl group. In the free sugar acid, the β-form is prevalent (~64%), whereas in the organism, the α-form UDP-α-D-glucuronic acid (UDPGA) predominates.
Carbohydrate stereoisomers, which differ in configuration at only one (other) asymmetric C-atom, are named epimers. For example, D-mannuronic (C-2), D-alluronic (C-3), D-galacturonic (C-4), and L-iduronic acid (C-5) are epimers of glucuronic acid.
The nonplanar pyranose rings can assume either chair (in 2 variants) or boat conformation. The preferred conformation depends on spatial interference or other interactions of the substituents. The pyranose form of D-glucose and its derivative D-glucuronic acid prefer the chair 4C1.
Additional oxidation at C-1 to the carboxyl level yields the dicarboxylic glucaric acid. Glucuronolactone is the self-ester (lactone) of glucuronic acid.
Direct oxidation of an aldose affects the aldehyde group first. A laboratory synthesis of a uronic acid from an aldose requires protecting the aldehyde and hydroxy groups from oxidation, for example by conversion to cyclic acetals (e. g., acetonides).
Gluconic acid widely exists in nature, especially in fruits and in sucrose-containing substances such as honey. Early methods of synthesizing gluconic acid from glucose included hypobromite oxidation and alkaline hydrolysis. Now it is commercially produced by using microbes such as Aspergillus niger to oxidize glucose enzymatically.
Gluconate, gluconic acid’s conjugate base, is useful as a metal-chelating agent in alkaline solutions. It is a component of many cleaning products; and it is used to prevent formation of solids in dairy processing and beer brewing.
D-glucuronic acid is characterized by high chemical instability and can undergo a variety of changes under many mild conditions. Monosaccharide-like tautometry (optical rotation change) in solution in the case of glucuronic acid is complicated by the formation of D-glucofuranyl 6, 3 lactones (ic-lactones). In equilibrium at room temperature, the composition ratio is 60% D-glucuronide and 40% D-glucuronolactone. Increasing the temperature and the presence of an acidic catalyst accelerate this equilibrium. When D-glucuronic acid is heated and strong acid is present, decarboxylation also easily occurs to produce carbon dioxide, furan and other dissociating products. In acidic, neutral and alkaline media, D-glucuronic acid is transformed into a carbon-2 heterostereoisomer, and then into the corresponding keto acid and D-glucuronic acid isomers.
D-glucuronic acid and its derivatives (lactones, salts, amides, etc.) are highly bioactive compounds. They are widely used in food additives, cosmetics, etc.
The main function of glucuronic acid in cosmetics and skin care products is chelating agent and moisturizing agent. The risk coefficient is 1, which is relatively safe and can be used with confidence. It generally has no effect on pregnant women, and glucuronic acid does not cause acne.
It is irritating to the skin and eyes. It has excellent decontamination, chelation and dispersion ability. As a stain remover. Buffering agent, chelating agent, moisturizing agent, etc., used in the field of personal care products.
Glucuronic acid ingredients suitable for dry skin, non-pigmented skin, firm skin, tolerant skin these 4 types of skin.
glucuronic acid is also widely used in the field of health care products. It can be used as an intermediate substance to synthesize calcium D-gluconate, D-gluconic acid 1, 4-lactone and L-ascorbic acid, etc., and can also be added to functional drinks as a food additive. Its advantage role is constantly being explored, there are huge potential economic benefits.
D-glucuronic acid is prepared as follows:
(1) Preparation of oxidized starch: take an appropriate amount of starch into the mixing cylinder, and then add an appropriate amount of pure water to the starch to stir, the ratio between the weight of pure water and the weight of starch is 5: 2, stir evenly to make starch milk, then add lye to the starch milk, adjust the PH value of starch milk to 8-10, then add hydrogen peroxide solution to the starch milk, and then add appropriate amount of water to it, and then wash, dehydrate and dry the starch milk to make oxidized starch products;
(2) Preparation of glucuronic acid: The starch milk prepared in step (1) was poured into the reaction cylinder, and then an appropriate amount of alpha -amylase was added to the reaction cylinder, and the reaction cylinder was placed in a water bath for heating at a temperature of 70-80 degrees Celsius. The hydrolysis reaction took place between Alpha -amylase and the starch milk, and the hydrolysate was produced after the glycosylation reaction. The content of glucuronic acid in the hydrolysate was increased, and then the glucuronic acid in the hydrolysate was extracted through a series of processes.
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