L-Arginine is semiessential amino acid. In most cases the human body can produce enough L-arginine on its own making supplementation unnecessary.

Pyrrolidine Production

L-Arginine which is unabsorbed in the small intestine, is converted by colonic bacteria to pyrrolidine in the large intestine (colon), and this is then partly absorbed and excreted unchanged in the urine (Asatoor et al, 1962).[1]

It can take 3 or more hours for food to reach the colon (this varies dramatically from person to person, and depends highly on other contents in the digestive system). For this reason excess L-arginine supplements will not normally begin to produce pyrrolidine until several hours have passed.


The therapeutic dosage (maximum dose considered to be safe) is 400-6,000 milligrams.

Chemical Properties

PubChem Compound ID: 6322
Molecular Weight: 174.20096 [g/mol]
Molecular Formula: C6H14N4O2
XLogP3: -4.2
IUPAC Name: (2S)-2-amino-5-(diaminomethylideneamino)pentanoic acid
InChI: InChI=1S/C6H14N4O2/c7-4(5(11)12)2-1-3-10-6(8)9/h4H,1-3,7H2,(H,11,12)(H4,
Canonical SMILES: C(CC(C(=O)O)N)CN=C(N)N
Isomeric SMILES: C(C[C@@H](C(=O)O)N)CN=C(N)N

1. Asatoor AM, Harrison BD, Milne MD, Prosser DI.
Intestinal absorption of an arginine-containing peptide in cystinuria Medical Unit, Westminster Medical School, London; Gut. 1972 Feb;13(2):95-8; PubMed PMID 5045711 (Download Attached PDF Document)
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