Description
Lactobionic acid (C12H22O12) is a disaccharide obtained from the oxidation of lactose. Chemically, Lactobionic acid is made up of a galactose moiety that is bonded to a gluconic acid molecule through an ether-like bond. The compound can be dehydrated to a lactone. Lactobionic acid is widely used in the chemical, food and pharmaceutical industries due to its chelating, emulsifying, humectant and chelating properties. Lactobionic acid and its constituent salts are essential as food additives due to excellent solubility, good taste, and health-promoting aspects. The compound may also be essential in the synthesis of targetable and biocompatible drug delivery systems.
Properties
Lactobionic acid has a molecular weight of 358.296 g/mol and a monoisotopic mass of 358.111 g/mol, which is also its exact mass. The compound has a heavy atom count of 24.
Lactobionic acid has a melting point of 113-118°C and a boiling point of about 410.75°C. It is a white to off-white powder with a solubility of 10 g/100 mL in water and a density of about 1.4662. It is also slightly soluble in anhydrous methanol and ethanol.
Lactobionic acid is hygroscopic, and it has a good water retention potential hence its applicability to cosmetic products. The compound and its constituent mineral salts (Ca, Na, and K lactobionate) are produced commercially for medical and industrial applications and in some cases for research purposes.
Preparation
The selective transformation of lactose into Lactobionic acid entails the oxidation of the radical aldehyde category of glucose on the lactose molecule to the carboxylic classification. The production of Lactobionic acid entails various processes which may include enzymatic synthesis, microbial production, biocatalytic oxidation, electrochemical oxidation and heterogeneous catalytic oxidation.
Extraction and Purification
To enhance the productive capacity of Lactobionic acid, the enzymatic reaction can be cut off after several hours of activity and the unchanged substrates can be re-injected into the cycle after the elimination of useful products. The effective process of separation is through liquid chromatography particularly because the recovered species are pure.
Exposing the solution made of lactobionate ions through a sequence of ion-transfer resins produces a pure solution of Lactobionic acid with minimal amounts of calcium ions. Different techniques such as crystallization, evaporation, electrodialysis and ethanol precipitation can be employed to obtain Lactobionic acid.
Physiological & Commercial Applications
Lactobionic acid is an essential compound based on its chelating properties and its ability to form complex bonds with Ca, Fe, Cu, and Mn. Its incorporation into food additives can stimulate mineral absorption and Ca2+ in the intestines hence enhancing one’s health.
Lactobionic acid is unaffected by digestive enzymes hence it is a valuable ingredient in the preparation of functional foods. It is poorly absorbed into the linings of the intestines hence it can also be a Bifidus booster molecule for functional beverages and foods.
It enhances the healing process of wounds hence it is valuable in oral, skin, nail, hair and vaginal mucosa care. As an antioxidant, Lactobionic acid acts by suppressing the synthesis of hydroxyl radicals due to its iron chelating ability.
As a food additive, Lactobionic acid functions as an acidifier in products containing fermented milk, an aging suppressor for bread, an antioxidant, and as a gelling or stabilizing medium in desserts.
In cosmetics, Lactobionic acid is applied as an active ingredient in regenerative and antiaging skin-care products based on its therapeutic properties. Its metal chelation potential suppresses the degeneration potential of metalloproteinase enzymes, which decreases the appearance of aging wrinkles.
In the chemical industry, Lactobionic acid is an active ingredient (sugar-based surfactant) in biodegradable detergents. It may also be used in drug delivery systems, nanoparticle diagnosis and tissue engineering.
Chemical Properties
White to off-white crystalline powder
Uses
Lactobionic acid is mainly used in preservation solutions for organ transplantation. It is used to produce erythromycine lactobionate.
Uses
An inhibitor of matrix metalloproteinases
Uses
Arginine metabolite in bovine brain; clonidine-displacing substance activity
Definition
ChEBI: A disaccharide formed between beta-D-galactose and D-gluconic acid.
Biotechnological Production
Currently, lactobionic acid is produced by chemical synthesis using refined lactose
as feedstock. This process is expensive due to the energy demand. Alternatively,
Acidic Organic Compounds in Beverage, Food, and Feed Production 111
enzymatic processes have been suggested. For example, lactose could be reacted to
lactobionic acid using an enzymatic system with co-factor regeneration. First,
lactose is converted to lactobionolactone by a cellobiose dehydrogenase. This
reaction requires an electron acceptor, which is regenerated by a laccase reducing
oxygen to water. Finally, lactobionolactone spontaneously hydrolyzes to lactobionic
acid.
Moreover, microbial production of lactobionic acid has been described. In
a fed-batch cultivation of Burkolderia cepacia growing in a complex medium
(lactose, salts, peptone, and yeast extract), a final titer of 400 g.L-1, a yield of
approximately 1.0 g of lactobionic acid per gram of lactose, and a productivity of
1.67 g.L-1.h-1 have been achieved.
Another promising strategy for an inexpensive biotechnological process is the
utilization of cheap raw materials. For example, lactobionic acid could be obtained
from concentrated cheese whey by fermentation with Pseudomonas taetrolens. In
a fed-batch process, a product concentration of 164 g.L-1 with a productivity of
2.05 g.L-1.h-1 and a yield of 0.82 g of lactobionic acid per gram of lactose have
been observed. Furthermore, whole-cell biocatalysis using permeabilized
Zymonmonas mobilis cells and an equimolar mixture of lactose and fructose has
been tested. In a batch process, a maximum lactobionic acid concentration of
268 g.L-1 and a conversion rate of 72 % within 24 h have been measured. The
productivity of lactobionic acid was 11.2 g.L-1.h-1 .
Clinical Use
Erythromycin lactobionate is a salt with enhanced water solubility that is used for injections.
Purification Methods
Crystallise lactobionic acid from water by addition of EtOH. [NMR: Taga et al. Bull Chem Soc Jpn 51 2278 1978, Beilstein 17 III/IV 3392, 17/7 V 436.]
