|CAS number||, R , S|
|PubChem||, R, S|
|ChemSpider||, R , S|
|RTECS number||CF1934200 S|
|ATC code||B05 S|
|Beilstein Reference||1725411, 1725412 R, 1725413 S|
|Gmelin Reference||364938 R|
|Jmol-3D images||Image 1
|Molar mass||174.20 g mol−1|
260 °C, 533 K, 500 °F
|Solubility in water||87.1 g L−1 (at 20 °C)|
|Std enthalpy of
|−624.9–−622.3 kJ mol−1|
|Std enthalpy of
|−3.7396–−3.7370 MJ mol−1|
|250.6 J K−1 mol−1|
|Specific heat capacity, C||232.8 J K−1 mol−1 (at 23.7 °C)|
|GHS signal word||WARNING|
|GHS hazard statements||H319|
|GHS precautionary statements||P305+351+338|
|Related alkanoic acids|
|Supplementary data page|
|n, εr, etc.|
Solid, liquid, gas
|Spectral data||UV, IR, NMR, MS|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Arginine (abbreviated as Arg or R) is an α-amino acid. It was first isolated in 1886. The L-form is one of the 20 most common natural amino acids. At the level of molecular genetics, in the structure of the messenger ribonucleic acid mRNA, CGU, CGC, CGA, CGG, AGA, and AGG, are the triplets of nucleotide bases or codons that code for arginine during protein synthesis. In mammals, arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual. Preterm infants are unable to synthesize or create arginine internally, making the amino acid nutritionally essential for them. There are some conditions that put an increased demand on the body for the synthesis of L-arginine, including surgical or other trauma, sepsis and burns. Arginine was first isolated from a lupin seedling extract in 1886 by the Swiss chemist Ernst Schultze.
In general, most people do not need to take arginine supplements because the body usually produces enough.
With a pKa of 12.48, the guanidinium group is positively charged in neutral, acidic and even most basic environments, and thus imparts basic chemical properties to arginine. Because of the conjugation between the double bond and the nitrogen lone pairs, the positive charge is delocalized, enabling the formation of multiple H-bonds.
Dietary sources 
Arginine is a conditionally nonessential amino acid, meaning most of the time it can be manufactured by the human body, and does not need to be obtained directly through the diet. The biosynthetic pathway however does not produce sufficient arginine, and some must still be consumed through diet. Individuals who have poor nutrition or certain physical conditions may be advised to increase their intake of foods containing arginine. Arginine is found in a wide variety of foods, including:
- Animal sources
- dairy products (e.g., cottage cheese, ricotta, milk, yogurt, whey protein drinks), beef, pork (e.g., bacon, ham), gelatin , poultry (e.g. chicken and turkey light meat), wild game (e.g. pheasant, quail), seafood (e.g., halibut, lobster, salmon, shrimp, snails, tuna)
- Plant sources
- wheat germ and flour, buckwheat, granola, oatmeal, peanuts, nuts (coconut, pecans, cashews, walnuts, almonds, Brazil nuts, hazelnuts, pinenuts), seeds (pumpkin, sesame, sunflower), chick peas, cooked soybeans, Phalaris canariensis (canaryseed or ALPISTE)
Arginine is synthesized from citrulline by the sequential action of the cytosolic enzymes argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL). In terms of energy, this is costly, as the synthesis of each molecule of argininosuccinate requires hydrolysis of adenosine triphosphate (ATP) to adenosine monophosphate (AMP), i.e., two ATP equivalents. Taking an excess of arginine essentially gives more energy by saving ATPs that can be used elsewhere.
Citrulline can be derived from multiple sources:
- from arginine via nitric oxide synthase (NOS)
- from ornithine via catabolism of proline or glutamine/glutamate
- from asymmetric dimethylarginine (ADMA) via DDAH
On a whole-body basis, synthesis of arginine occurs principally via the intestinal–renal axis, wherein epithelial cells of the small intestine, which produce citrulline primarily from glutamine and glutamate, collaborate with the proximal tubule cells of the kidney, which extract citrulline from the circulation and convert it to arginine, which is returned to the circulation. As a consequence, impairment of small bowel or renal function can reduce endogenous arginine synthesis, thereby increasing the dietary requirement.
Synthesis of arginine from citrulline also occurs at a low level in many other cells, and cellular capacity for arginine synthesis can be markedly increased under circumstances that also induce iNOS. Thus, citrulline, a coproduct of the NOS-catalyzed reaction, can be recycled to arginine in a pathway known as the citrulline-NO or arginine-citrulline pathway. This is demonstrated by the fact that in many cell types, citrulline can substitute for arginine to some degree in supporting NO synthesis. However, recycling is not quantitative because citrulline accumulates along with nitrate and nitrite, the stable end-products of NO, in NO-producing cells.
The benefits and functions attributed to oral supplementation of L-arginine include:
- Precursor for the synthesis of nitric oxide (NO)
- Reduces healing time of injuries (particularly bone)
- Quickens repair time of damaged tissue
- Helps decrease blood pressure in clinical hypertensive subjects 
The distributing basics of the moderate structure found in geometry, charge distribution and ability to form multiple H-bonds make arginine ideal for binding negatively charged groups. For this reason, arginine prefers to be on the outside of the proteins where it can interact with the polar environment.
Incorporated in proteins, arginine can also be converted to citrulline by PAD enzymes. In addition, arginine can be methylated by protein methyltransferases.
Arginine is the immediate precursor of nitric oxide (NO), urea, ornithine, and agmatine; is necessary for the synthesis of creatine; and can also be used for the synthesis of polyamines (mainly through ornithine and to a lesser degree through agmatine), citrulline, and glutamate. As a precursor of nitric oxide, arginine may have a role in the treatment of some conditions where vasodilation is required. The presence of asymmetric dimethylarginine (ADMA), a close relative, inhibits the nitric oxide reaction; therefore, ADMA is considered a marker for vascular disease, just as L-arginine is considered a sign of a healthy endothelium.
Treatment of dentin hypersensitivity 
Arginine (8%) in dental products (e.g., toothpaste) provides effective relief from sensitive teeth by depositing a dentin-like mineral, containing calcium and phosphate, within the dentin tubules and in a protective layer on the dentin surface.
Treatment of herpes simplex virus 
Possible increased risk of death after supplementation following heart attack 
A clinical trial found that patients taking an L-arginine supplement following a heart attack found no change in the heart's vascular tone or decrease in the symptoms of congestive heart failure (the heart's ability to pump). In fact, six more patients who were taking L-arginine died than those taking a placebo resulting in early termination of the study with the recommendation that the supplement not be used by heart attack patients. These findings suggest L-arginine is not beneficial post-heart-attack.
Potential medical uses 
Lung inflammation and asthma 
Inhalation of L-arginine can increase lung inflammation and worsen asthma.
Growth hormone 
Intravenously-administered arginine stimulates the secretion of growth hormone, and is used in growth hormone stimulation tests. Research suggests that oral preparations of L-arginine are ineffective at increasing growth hormone levels despite being effective at increasing plasma levels of L-arginine.
MELAS syndrome 
Cellular arginine biosynthetic capacity determined by activity of argininosuccinate synthetase (AS) is induced by the same mediators of septic response — endotoxin and cytokines — that induce nitric oxide synthase (NOS), the enzyme responsible for nitric oxide synthesis.
Malate salt 
A preliminary study of supplementation with L-arginine and antioxidant vitamins showed that this combination may help to combat abnormally high blood pressure during high risk pregnancies.
Intravenous infusion of arginine reduces blood pressure in patients with hypertension as well as normal subjects.
A recent meta-analysis showed that L-arginine reduces blood pressure with pooled estimates of 5.4/2.7 mmHg for SBP/DBP.
Erectile dysfunction 
Dietary supplementation of L-arginine taken in combination with L-lysine has been shown potentially useful in treating people subjected to high levels of mental stress and anxiety, in a double-blind, placebo controlled and randomized study, involving 108 Japanese adults. Trait anxiety and state anxiety induced by cognitive stress battery was significantly reduced, and basal levels of the stress hormone cortisol were decreased. The study was funded by Ajinomoto, Co. Inc., an industrial manufacturer of lysine and arginine.
See also 
- IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. "Nomenclature and Symbolism for Amino Acids and Peptides". Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. Archived from the original on 29 May 2007. Retrieved 2007-05-17.
- Mayo Clinic
- Tapiero, H.; et al. (November 2002). "L-Arginine". Biomedicine and Pharmacotherapy 56 (9): 439–445 REVIEW. PMID 12481980.
- Wu, G.; et al. (August 2004). "Arginine deficiency in preterm infants: biochemical mechanisms and nutritional implications". Journal of Nutritional Biochemistry 15 (8): 332–451 REVIEW. doi:10.1016/j.jnutbio.2003.11.010. PMID 15302078.
- "L-Arginine Supplements Nitric Oxide Scientific Studies Food Sources". Retrieved 2007-02-20.
- Morris Jr, SM (October 2004). "Enzymes of arginine metabolism.". The Journal of nutrition 134 (10 Suppl): 2743S–2747S. PMID 15465778.
- Stechmiller, J.K.; et al. (February 2005). "Arginine supplementation and wound healing". Nutrition in Clinical Practice 20 (13): 52–61 REVIEW. doi:10.1177/011542650502000152. PMID 16207646.
- Witte, M.B.; Barbul, A (Nov-Dec 2003). "Arginine physiology and its implication for wound healing". Wound Repair and Regeneration 11 (6): 419–423 REVIEW. doi:10.1046/j.1524-475X.2003.11605.x. PMID 14617280.
- Andrew, P.J.; Myer, B. (August 15 1999). "Enzymatic function of nitric oxide synthases". Cardiovascular Research 43 (3): 521–531 REVIEW. doi:10.1016/S0008-6363(99)00115-7. PMID 10690324. 
- Gokce, N.. (October 2004). "L-Arginine and hypertension". Journal of Nutrition 134 (10 Suppl): 2807S–2811S REVIEW. PMID 15465790.
- Rajapakse, N.W.; et al. (December 2008). "Exogenous L-arginine ameliorates angiotensin II-induced hypertension and renal damage in rats". Hypertension 52 (6): 1084–1090. doi:10.1161/HYPERTENSIONAHA.108.114298. PMC 2680209. PMID 18981330. Retrieved 2009-11-29. 
- Dong JY, Qin LQ, Zhang Z, Zhao Y, Wang J, Arigoni F, Zhang W. (2011). "Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized, double-blind, placebo-controlled trials". American Heart Journal 162 (6): 959–965. doi:10.1016/j.ahj.2011.09.012. PMID 22137067.
- Petrou, I.; et al. (2009). "A breakthrough therapy for dentin hypersensitivity: how dental products containing 8% arginine and calcium carbonate work to deliver effective relief of sensitive teeth.". The Journal of Clinical Dentisry 20 (1): 23–31. PMID 19489189.
- Takeshi Naito, Hiroshi Irie, Kazuko Tsujimoto, Keiko Ikeda, Tsutomu Arakawa, A. Hajime Koyama (April 2009). "Antiviral effect of arginine against herpes simplex virus type 1". International Journal of Molecular Medicine (International Journal of Molecular Medicine) 23 (4): 495–499. doi:10.3892/ijmm_00000156. PMID 19288025. Retrieved 2010-10-18.
- Medical College of Georgia. "Diabetes Makes It Hard For Blood Vessels To Relax." ScienceDaily 1 February 2008. 1 February 2008
- Schulman, SP, Becker, LC, Kass, DA, Champion, HC, Terrin, ML, Forman, S, Ernst, KV, Kelemen, MD et al. (January 2006). "L-arginine therapy in acute myocardial infarction: the Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial.". JAMA: the Journal of the American Medical Association 295 (1): 58–64. doi:10.1001/jama.295.1.58. PMID 16391217.
- This study has been discussed in some detail in : "Reverse Heart Disease Now" by Stephen T Sinatra MD and James C Roberts MD, publ. Wiley 2006 ISBN 0-471-74704-1 at pp 111-113.
- Sapienza MA, Kharitonov SA, Horvath I, Chung KF, Barnes PJ. "Effect of inhaled L-arginine on exhaled nitric oxide in normal and asthmatic subjects." Thorax. 1998 Mar;53(3):172-5.
- Alba-Roth J, Müller O, Schopohl J, von Werder K (1988). "Arginine stimulates growth hormone secretion by suppressing endogenous somatostatin secretion". J Clin Endocrinol Metab 67 (6): 1186–9. doi:10.1210/jcem-67-6-1186. PMID 2903866.
- U.S. National Library of Medicine (September 2009). Growth hormone stimulation test
- Forbes, SC; Bell, GJ (2011 Jun). "The acute effects of a low and high dose of oral L-arginine supplementation in young active males at rest.". Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme 36 (3): 405–11. doi:10.1139/h11-035. PMID 21574873.
- Koga Y, Akita Y, Junko N, Yatsuga S, Povalko N, Fukiyama R, Ishii M, Matsuishi T (June 2006). "Endothelial dysfunction in MELAS improved by l-arginine supplementation". Neurology 66 (11): 1766–9. doi:10.1212/01.wnl.0000220197.36849.1e. PMID 16769961.
- Koga Y (November 2008). "[L-arginine therapy on MELAS]". Rinsho Shinkeigaku (in Japanese) 48 (11): 1010–2. PMID 19198147.
- Koga Y, Akita Y, Nishioka J, Yatsuga S, Povalko N, Katayama K, Matsuishi T (2007). "MELAS and L-arginine therapy". Mitochondrion 7 (1–2): 133–9. doi:10.1016/j.mito.2006.11.006. PMID 17276739.
- Finsterer J (November 2009). "Management of mitochondrial stroke-like-episodes". Eur. J. Neurol. 16 (11): 1178–84. doi:10.1111/j.1468-1331.2009.02789.x. PMID 19780807.
- MORRIS SM (1995). ROLE OF ARGININE SYNTHESIS IN SURGICAL SEPSIS. Crisp Data Base National Institutes Of Health. Archived from the original on 26 February 2010. Retrieved 2010-02-22.
- Tissot-Favre A, Brette R (May–June 1970). "Therapeutic effects of arginine malate in alcoholic cirrhosis". Therapie 25 (3): 629–33. PMID 5431854.
- Vadillo-Ortega F et al. (2011). "Effect of supplementation during pregnancy with L-arginine and antioxidant vitamins in medical food on pre-eclampsia in high risk population: randomised controlled trial". British Medical Journal 342: d2901–d2901. doi:10.1136/bmj.d2901.
- Nakaki, T., Hishikawa, K., Suzuki, H., Saruta, T., Kato, R. (1990). "L-arginine-induced hypotension". Lancet 336 (8716): 696. doi:10.1016/0140-6736(90)92196-O. PMID 1975886.
- Stanislavov, R., Nikolova, V (2003). "Treatment of Erectile Dysfunction with Pycnogenol and L-arginine". Journal of Sex and Marital Therapy 29 (3): 207–213. doi:10.1080/00926230390155104. PMID 12851125.
- Lebret, T.; Hervéa, J. M.; Gornyb, P.; Worcelc, M.; Botto, H. (2002). "Efficacy and Safety of a Novel Combination of L-Arginine Glutamate and Yohimbine Hydrochloride: A New Oral Therapy for Erectile Dysfunction". European Urology 41 (6): 608–613. doi:10.1016/S0302-2838(02)00175-6. PMID 12074777.
- Smriga M, Ando T, Akutsu M, Furukawa Y, Miwa K, Morinaga Y. (2007). "Oral treatment with L-lysine and L-arginine reduces anxiety and basal cortisol levels in healthy humans". Institute of Life Sciences 28 (2): 85–90. PMID 17510493.
|Wikimedia Commons has media related to: arginine|
- NIST Chemistry Webbook
- Mayo Clinic discussion of Arginine.
- National Institute of Health discussion of Arginine.