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L-Arginine Monochloride is a crystalline salt form of the semi-essential amino acid L-Arginine, combined with hydrochloric acid.
It has attracted considerable attention in nutrition, medicine, biochemistry, and pharmaceutical sciences due to its involvement in nitric oxide (NO) synthesis, cardiovascular health, protein metabolism, and therapeutic applications.
Chemical Name: L-Arginine Hydrochloride
CAS Number: 1119-34-2
Molecular Formula: C₆H₁₄N₄O₂·HCl
Molar Mass: 210.66 g/mol
Synonyms:
L-Arginine HCl,Arginine Hydrochloride,L-(+)-Arginine Monohydrochloride
Arginine Hydrochloridum
As a hydrochloride salt, L-Arginine Monochloride offers better stability, solubility, and bioavailability compared to the free base form.
It is widely used in dietary supplements, medical nutrition, parenteral solutions, and biochemical research.
Historical Background and Development
The discovery of arginine dates back to 1886 when Ernst Schulze first isolated it from lupin seedlings. Later studies demonstrated its critical role in the urea cycle, amino acid metabolism, and nitric oxide biosynthesis.
The hydrochloride salt form, L-Arginine Monochloride, was developed to overcome the instability of free L-Arginine in various formulations.
By the mid-20th century, it became a standard component in parenteral nutrition and clinical therapy.
Chemical Properties
Molecular Structure
L-Arginine Monochloride is the protonated hydrochloride salt of the amino acid L-Arginine.
Structure:
Guanidino group (–C(=NH)NH₂)
Alpha-amino group (–NH₂)
Alpha-carboxylic acid group (–COOH)
Side chain containing a three-carbon aliphatic chain terminated with a guanidinium group.
Physical and Chemical Characteristics
Appearance: White crystalline powder
Taste: Slightly bitter, characteristic amino acid taste
Solubility: Freely soluble in water; practically insoluble in ethanol, ether, and chloroform
pKa values: 2.17 (α-COOH), 9.04 (α-NH₃⁺), 12.48 (guanidino group)
Melting Point: 225–230 °C (decomposes)
Hygroscopic nature: Stable under dry conditions; may absorb moisture
Stability
Stable in neutral aqueous solutions.
Sensitive to strong oxidizing agents.
The hydrochloride form improves shelf life and stability in formulations.
Biosynthesis and Natural Occurrence
Although L-Arginine is classified as semi-essential, its requirement increases under conditions such as growth, stress, wound healing, and metabolic disorders.
Natural Sources: Meat, poultry, fish, dairy products, nuts, soybeans, chickpeas, lentils.
Biosynthesis: Derived from citrulline via the urea cycle in the liver and kidney.
Dietary Contribution: L-Arginine Monochloride supplementation provides a direct source of arginine in an easily absorbable salt form.
Industrial and Laboratory Production
Raw Materials
Fermentation substrates: Glucose, molasses, sucrose.
Microorganisms: Corynebacterium glutamicum, Escherichia coli engineered strains.
Production Methods
Microbial Fermentation
Engineered bacteria overproduce L-Arginine.
Purification and crystallization yield L-Arginine Monochloride.
Chemical Synthesis
Rarely used due to cost and complexity.
Fermentation is the most economical method.
Purification
Ion-exchange chromatography.
Crystallization with hydrochloric acid to obtain the salt form.
Applications
Medical and Pharmaceutical Applications
Cardiovascular Health: Enhances nitric oxide production, improves vasodilation, reduces hypertension.
Wound Healing: Promotes collagen synthesis and tissue repair.
Immune Support: Enhances T-cell function and immune modulation.
Parenteral Nutrition: Essential component in IV amino acid solutions.
Drug Formulation: Used as a stabilizer in peptide and protein-based drugs.
Nutritional Supplements
Widely included in sports nutrition supplements for performance, endurance, and muscle growth.
Supports protein metabolism and growth.
Biochemical Research
Used as a stabilizer in protein crystallization.
Facilitates solubilization of recombinant proteins.
Applied in cell culture media formulations.
Cosmetic Industry
Used in skin care formulations for hydration, repair, and anti-aging properties.
Mechanisms of Action
Nitric Oxide Pathway
L-Arginine serves as a substrate for nitric oxide synthase (NOS), producing nitric oxide (NO) and citrulline.
NO acts as a signaling molecule regulating:
Vascular tone
Platelet aggregation
Neurotransmission
Protein and Creatine Synthesis
Arginine contributes to muscle protein turnover and creatine biosynthesis, enhancing energy metabolism.
Hormonal Regulation
Stimulates release of growth hormone and insulin.
Benefits
Improved vascular function.
Enhanced physical performance.
Faster recovery after surgery or injury.
Strengthened immune response.
Versatile use in pharmaceuticals, nutraceuticals, and cosmetics.
SAFETY INFORMATION ABOUT L-ARGININE MONOCHLORIDE
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
