L-ornithine (0–10 mM) influences Ca2+ signaling in HK-2 cells and, in a concentration-dependent manner, activates CaSR [2]. In HK-2 cells, L-ornithine (10 mM) stimulates the Ca2+ entry pathway mediated by the TRPC channel [2]. Via the ROCE pathway, L-ornithine (100 or 300 μM; 24 hours) demonstrated a protective effect against ROS generation in HK-2 cells [2]. When H2O2 is exposed to HK-2 cells, L-ornithine (10 μM) guards against ROS and oxidative damage [2].

Absorption, Distribution and Excretion
Ornithine is absorbed from the small intestine via sodium-dependent active transport. Metabolism/Metabolites Ornithine is extensively metabolized in the liver to L-arginine, polyamines, proline, and several other metabolites.

Toxicity Summary
L-ornithine is metabolized to L-arginine. L-arginine stimulates the pituitary gland to release growth hormone. Burns or other injuries can affect the level of L-arginine in tissues throughout the body. Because de novo synthesis of L-arginine is usually insufficient to maintain normal immune function and protein synthesis in these situations, L-ornithine may have immunomodulatory and wound-healing effects (due to its metabolism to L-arginine). Toxicity Data
Oral LD50 in rats = 10000 mg/kg

[1]. Effect of L-ornithine hydrochloride ingestion on intermittent maximal anaerobic cycle ergometer performance and fatigue recovery after exercise. Eur J Appl Physiol. 2011 Nov;111(11):2837-43.

[2]. l-ornithine activates Ca2+ signaling to exert its protective function on human proximal tubular cells. Cell Signal. 2020 Mar;67:109484.

L-Ornithine is an optically active ornithine with an L-configuration. It has hepatoprotective effects and is a metabolite in algae and rodents. It is an ornithine and a non-protein L-α-amino acid. It is the conjugate base of L-ornithine salt (1+), the conjugate acid of L-ornithine acid, and an enantiomer of D-ornithine. Ornithine is produced in the urea cycle and is an amino acid generated by the breakdown of urea from arginine. L-Ornithine helps excrete excess nitrogen from the body and serves as a precursor to citrulline and arginine. Ornithine is a metabolite found in or produced by Escherichia coli (K12, MG1655 strains). L-Ornithine has also been reported to be present in Euphorbia prostrata, soybean (Glycine max), and other organisms with relevant data. Ornithine is a naturally occurring amino acid found in meat, fish, dairy products, and eggs. It is a key reactant in the urea cycle, responsible for 80% of nitrogen excretion in the body. Ornithine can enhance liver function and aid in the detoxification of harmful substances. Ornithine is an amino acid produced from the breakdown of urea by arginine in the urea cycle. Ornithine is a core component of the urea cycle, which is responsible for removing excess nitrogen from the body. L-Ornithine is also a precursor to citrulline and arginine. Ornithine produced in the cytoplasm must first cross the inner mitochondrial membrane into the mitochondrial matrix, where it is carbamylated by ornithine transcarbamate to be converted to citrulline. This transport process is mediated by mitochondrial ornithine transporters (SLC25A15; AF112968; ORNT1). Mutations in mitochondrial ornithine transporters can lead to hyperammonemia, hyperornithineemia, homocitrullinuria (HHH syndrome), and urea cycle disorders. The pathophysiological mechanism of this disease may involve reduced ornithine transport to mitochondria, leading to ornithine accumulation in the cytoplasm and decreased ability to clear carbamoyl phosphate and ammonia load. (OMIM 838970). (A3420).
An amino acid produced by the cleavage of urea from arginine in the urea cycle.
See also: Lysine (note moved to).

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Pharmacological Indications
For nutritional supplementation, and also for the treatment of dietary deficiencies or imbalances. Ornithine is claimed to improve athletic performance, has anabolic effects, promotes wound healing, and enhances immunity.

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Mechanism of Action
L-ornithine is metabolized to L-arginine. L-arginine stimulates the pituitary gland to release growth hormone. Burns or other injuries can affect the level of L-arginine in tissues throughout the body. Since de novo synthesis of L-arginine is usually insufficient to maintain normal immune function and protein synthesis in these cases, L-ornithine may have immunomodulatory and wound-healing effects in these cases (due to its metabolism to L-arginine).

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Pharmacodynamics
Ornithine is a non-essential, non-protein amino acid that is crucial for the production of proteins, enzymes, and muscle tissue in the human body. Ornithine plays a central role in the urea cycle and is essential for the removal of excess nitrogen (ammonia). Ornithine is a starting material for the synthesis of many polyamines, such as putrescine and spermidine. It is claimed that ornithine supplementation can promote the release of growth hormone and burn excess body fat. Ornithine is essential for normal immune function and good liver function.

C5H12N2O2

132.16098

132.089

70-26-8

L-Ornithine hydrochloride;3184-13-2

6262

White to off-white solid powder

1.2±0.1 g/cm3

308.7±32.0 °C at 760 mmHg

140ºC

140.5±25.1 °C

0.0±1.4 mmHg at 25°C

1.508

-0.96

3

4

4

9

95

1

N[C@@H](CCCN)C(O)=O

AHLPHDHHMVZTML-BYPYZUCNSA-N

InChI=1S/C5H12N2O2/c6-3-1-2-4(7)5(8)9/h4H,1-3,6-7H2,(H,8,9)/t4-/m0/s1

(2S)-2,5-diaminopentanoic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~50 mg/mL (~378.33 mM)
DMSO : ~1.3 mg/mL (~9.84 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)