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CAS no: 74-79-3
EC / List no: 200-811-1
Chemical formula: C6H14N4O2
Synonyms: Arginine, (2S)-2-Amino-5-(diaminomethylideneamino)pentanoic acid, (2S)-2-amino-5-carbamimidamidopentanoic acid, (2S)-2-Amino-5-guanidinopentanoic acid, (S)-2-Amino-5-guanidino-valeriansäure, (S)-2-Amino-5-guanidinopentanoic acid, L-2-Amino-5-guanidino-pentanoic acid, 2-amino-5-carbamimidamidopentanoic acid, 2-Amino-5-guanidinopentanoic acid, Arginin, L-ARGININE, L-Arginin, L-Arginine
L-Arginine is a basic, proteinogenic alpha-amino acid containing a unique guanidino functional group on its side chain. Characterized by possessing four nitrogen atoms per molecule, L-Arginine is the most nitrogen-rich of all standard amino acids.
Classified physiologically as a semi-essential (conditionally essential) amino acid, adults can synthesize L-Arginine endogenously via the urea cycle and citrulline conversion. However, during periods of rapid growth, pregnancy, severe infection, physical trauma, or cardiovascular stress, metabolic demand outpaces endogenous production, requiring dietary intake or supplementation. Found naturally in protein-rich foods (red meat, poultry, seafood, dairy, nuts, legumes, and soy), L-Arginine is manufactured industrially via glucose bio-fermentation using high-yield bacterial strains such as Corynebacterium glutamicum or Escherichia coli.
Key Properties of L-Arginine
Molar Mass: 174.20 g/mol
Appearance: White crystalline powder or white crystals
Odor: Odorless to faint characteristic odor
Density: ~1.3 g/cm³ (bulk density ~0.7–1.1 g/cm³)
Boiling Point: Not applicable; decomposes before boiling
Melting Point: ~244 °C (decomposes upon heating)
Solubility: Highly soluble in water (~148–180 g/L at 20–25 °C); slightly soluble in ethanol; insoluble in ether
pH: Alkaline in aqueous solution (typically pH ~10.5–12.0 depending on concentration)
Ionic Character: Basic amino acid; cationic (positively charged) at physiological pH due to its side-chain guanidino group
Molecular Weight: 174.20 g/mol
Isoelectric Point (pI): ~10.76
Hygroscopicity / Water Absorption: Slightly hygroscopic
Stability: Stable under recommended dry, ambient storage conditions; decomposes under high temperatures or exposure to strong oxidizing agents
Core Mechanisms of Action & Biological Functions
Precursor to Nitric Oxide (NO): Serves as the primary substrate for endothelial Nitric Oxide Synthase (eNOS). Enzymatic oxidation converts L-Arginine into L-citrulline and Nitric Oxide (NO), a potent signaling gas that triggers smooth muscle relaxation, vasodilation, and blood flow regulation.
Urea Cycle & Nitrogen Detoxification: Acts as an intermediate metabolite in the hepatic urea cycle (ornithine cycle). Enzymatic degradation converts L-Arginine into ornithine and urea via arginase, facilitating the clearance of toxic metabolic ammonia from the bloodstream.
Endocrine & Hormone Stimulation: Stimulates the pituitary gland and pancreas to release key hormones, including insulin, human growth hormone (hGH), and glucagon, by NO-dependent mechanisms.
Biosynthetic Building Block: Serves as a vital biochemical precursor for the endogenous synthesis of creatine, polyamines (spermidine/spermine), L-proline, glutamate, and sarcosine.
Tissue Regeneration & Collagen Synthesis: Promotes collagen deposition and cell proliferation, accelerating wound healing, tissue repair, and post-surgical recovery.
Spermatogenesis Support: Constitutes a major structural portion of sperm proteins, supporting sperm maturation, motility, and cellular energy provision.
Immune Modulation: Supports the proliferation and function of T-lymphocytes and macrophages, reinforcing immune defense during catabolic stress.
Industry Applications
Pharmaceuticals & Clinical Diagnostics
Cardiovascular Therapeutics: Incorporated into clinical treatments for congestive heart failure (CHF), coronary artery disease, angina pectoris, hypertension, and pre-eclampsia due to its anti-atherogenic, anti-ischemic, anti-platelet, and antithrombotic properties.
Parenteral & Enteral Nutrition: Essential component of intravenous amino acid infusions and integrated total parenteral nutrition (TPN) solutions for post-operative recovery, trauma, and infant growth maintenance.
Endocrine Diagnostics: Administered intravenously to stimulate pituitary growth hormone release for diagnostic testing of pituitary function.
Specialized Medications: Used in the treatment of erectile dysfunction, interstitial cystitis, hyperammonemia, and head-lice preparations (as a non-toxic pharmaceutical vehicle).
Cosmetics & Personal Care
Natural Moisturizing Factor (NMF) & Anti-Aging: Functions as an amino-acid moisturizer and skin-conditioning agent, reinforcing the skin barrier, stimulating collagen synthesis, and improving elasticity.
Scalp & Hair Care: Enhances microcirculation to the hair follicles, promoting hair growth and reducing hair loss.
Formulation pH Regulator & Anti-Static Agent: Acts as a green, bio-based pH buffer and neutralizing agent for cosmetic formulas. Prevents static charge accumulation in hair care and personal hygiene products.
Oral Care: Key active ingredient in desensitizing toothpastes, sealing dentin tubules to provide instant and lasting relief for sensitive teeth.
Food, Beverage & Sports Nutrition
Flavors & Fragrance Enhancement (E/FL Numbering): Reacts with reducing sugars during thermal processing (Maillard/amino-carbonyl reaction) to generate rich, savory aroma profiles. Authorized as a food spice (GB 2760) and flavoring agent.
Nutritional Supplements & Functional Foods: Popular ingredient in athletic, bodybuilding, and pre-workout formulas to support nitric oxide synthesis, improve oxygen/nutrient delivery to working muscles, boost energy, reduce fatigue, and flush out muscle lactate and ammonia.
Infant Formula & Infant Nutrition: Essential dietary addition for premature infants and newborns who lack the enzymatic maturity to synthesize arginine endogenously.
Biotechnology & Cell Culture Media
Cell Culture Component: Vital nutrient in basal cell culture media (e.g., RPMI-1640, DMEM) for culturing peripheral blood mononuclear cells (PBMCs), tissue cultures, and biopharmaceutical production lines.
Proteomics & Mass Spectrometry: Standard component in Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC) for quantitative LC-MS/MS proteomic profiling.
Protein & Enzyme Stabilization: Used in downstream processing as a protein-refolding additive and solubilizing agent to prevent protein aggregation in biopharmaceutical manufacturing.
Agriculture & Animal Nutrition
Plant Growth & Stress Resilience: Functions as an organic nitrogen donor in agricultural biostimulants and bio-fertilizers, boosting plant resilience to drought, salinity, and temperature fluctuations.
Animal Feed Additive: Included in livestock and aquaculture diets to improve muscle growth, support immune health, and optimize nitrogen utilization.
Industrial & Fuel Applications
Charge Stabilizer & Fuel Additive: Utilized in diesel fuel and industrial materials as an anti-static agent/charge stabilizer to prevent electrostatic charge accumulation during handling and transport.
L-Arginine stands out as an indispensable semi-essential amino acid whose multifunctional biological profile bridges clinical medicine, sports nutrition, cosmetics, and industrial biotechnology. As the primary endogenous substrate for nitric oxide production and a crucial participant in the urea cycle, it offers unmatched physiological benefits ranging from cardiovascular support and wound healing to skin hydration and oral health. Produced sustainably through modern bio-fermentation, L-Arginine remains a fundamental biochemical resource, delivering high functional value across pharmaceutical formulations, functional foods, personal care products, and agricultural applications.
