61-90-5

description

L-Leucine is an essential amino acid, one of the twenty types that constitute proteins, and it belongs to the aliphatic amino acid group. It forms part of the trio known as branched-chain amino acids, along with L-isoleucine and L-valine. As a white hexahedral crystal or crystalline powder, it is odorless and slightly bitter. L-Leucine exhibits stability in aqueous mineral acids in the presence of hydrocarbons.

Chemical Properties

White shiny hexahedral crystals or white crystalline powder. Slightly bitter (DL-leucine is sweet). Sublimation at 145~148 ℃. Melting point 293~295 ℃ (decomposition). It belongs to the essential amino acids,and adult men requirement is 2.2g/d (151 version). It is necessary in normal growth for infants and maintaining normal nitrogen balance for adults. Natural products are found in the spleen, heart, etc., and are present in a variety of plant and animal tissues in the form of the proteins, free out after decomposition and corruption.

Uses

toxicity

Safe for food (FDA, §172.3202000). LD505379mg/kg (rat, subcutaneously).

Occurrence

Reported found as a constituent in proteins; also present in the free state in the human body

Production Methods

Leucine is produced microbially by incubating an amino-acidproducing microorganism including but not exclusive to Pseudomonas, Escherichia, Bacillus, or Staphylococcus in the presence of oxygen and a hydrocarbon. The nutrient medium should contain an inhibitory amount of a growth inhibitor that is a chemically similar derivative of leucine (e.g. methylallylglycine, a-hydrozinoisocaproic acid, or b-cyclopentanealanine) to inhibit the growth of the organism except for at least one mutant that is resistant to the inhibitory effect. The resistant mutant is then isolated and grown in the presence of oxygen and the hydrocarbon in the absence of the inhibitor. The mutant cells are then harvested and a nutrient medium is formed that includes a hydrocarbon as the sole source of carbon. Finally, the harvested cells are incubated in the medium in the presence of oxygen.

Definition

ChEBI: The L-enantiomer of leucine.

Preparation

By bromination followed by amination of isocaproic acid; via the acetamidomalonic ester; by isolation from gluten, casein, keratin; from hydantoin.

Pharmaceutical Applications

Leucine is used in pharmaceutical formulations as a flavoring agent. It has been used experimentally as an antiadherent to improve the deagglomeration of disodium cromoglycate micro-particles and other compounds in inhalation preparations; and as a tablet lubricant. Leucine copolymers have been shown to successfully produce stable drug nanocrystals in water.

Safety

Leucine is an essential amino acid and is consumed as part of a normal diet. It is generally regarded as a nontoxic and nonirritant material. It is moderately toxic by the subcutaneous route. LD50 (rat, IP): 5.379 g/kg

storage

Leucine is sensitive to light and moisture, and should be stored in an airtight container in a cool, dark, dry place.

Incompatibilities

Leucine is incompatible with strong oxidizing agents.

Regulatory Status

Included in the FDA Inactive Ingredients Database (IV infusion; oral tablets). Included in nonparenteral medicines licensed in the UK.

Who Evaluation

Evaluation year: 2004

Consumer Uses

ECHA has no public registered data indicating whether or in which chemical products the substance might be used. ECHA has no public registered data on the routes by which this substance is most likely to be released to the environment.