L-Ornithine

Absorption

Absorbed from the small intestine via a sodium-dependent active transport process

Toxicity

Oral, rat LD50 = 10000 mg/kg

The Uses of L-Ornithine

hepatoprotectant, anticholesteremic

Background

Produced during the urea cycle, ornithine is an amino acid produced from the splitting off of urea from arginine. L-Ornithine allows for the disposal of excess nitrogen and acts as a precursor of citrulline and arginine.

Indications

Used for nutritional supplementation, also for treating dietary shortage or imbalance. It has been claimed that ornithine improves athletic performance, has anabolic effects, has wound-healing effects, and is immuno-enhancing.

Definition

ChEBI: An optically active form of ornithine having L-configuration.

Synthesis Reference(s)

Canadian Journal of Chemistry, 31, p. 1060, 1953 DOI: 10.1139/v53-139

Pharmacokinetics

A non-essential and nonprotein amino acid, ornithine is critical for the production of the body's proteins, enzymes and muscle tissue. Ornithine plays a central role in the urea cycle and is important for the disposal of excess nitrogen (ammonia). Ornithine is the starting point for the synthesis of many polyamines such as putrescine and spermine. Ornithine supplements are claimed to enhance the release of growth hormone and to burn excess body fat. Ornithine is necessary for proper immune function and good liver function.

Safety Profile

Mutation data reported. When heated to decomposition it emits toxic vapors of NOx.

Metabolism

Ornithine undergoes extensive metabolism in the liver to L-arginine, polyamines, and proline, and several other metabolites.

Purification Methods

Crystallise L-ornithine from water containing 1mM EDTA (to remove metal ions). [Perrin J Chem Soc 3125 1958, Rivard Biochemical Preparations 3 97 1955, Greenstein & Winitz The Chemistry of the Amino Acids J. Wiley, Vol 3 pp 2477-2491 1961, Beilstein 4 III 1346, 4 IV 2644.]