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Record Information
Created at2005-11-16 15:48:42 UTC
Updated at2022-05-31 20:31:53 UTC
NP-MRD IDNP0000288
Secondary Accession NumbersNone
Natural Product Identification
Common NameL-Phenylalanine
DescriptionPhenylalanine (Phe), also known as L-phenylalanine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. L-phenylalanine is one of 20 proteinogenic amino acids, i.E., The amino acids used in the biosynthesis of proteins. Phenylalanine is found in all organisms ranging from bacteria to plants to animals. It is classified as an aromatic, non-polar amino acid. In humans, phenylalanine is an essential amino acid and the precursor of the amino acid tyrosine. Like tyrosine, phenylalanine is also a precursor for catecholamines including tyramine, dopamine, epinephrine, and norepinephrine. Catecholamines are neurotransmitters that act as adrenalin-like substances. Interestingly, several psychotropic drugs (mescaline, morphine, codeine, and papaverine) also have phenylalanine as a constituent. Phenylalanine is highly concentrated in the human brain and plasma. Normal metabolism of phenylalanine requires biopterin, iron, niacin, vitamin B6, copper, and vitamin C. An average adult ingests 5 g of phenylalanine per day and may optimally need up to 8 g daily. Phenylalanine is highly concentrated in a number of high protein foods, such as meat, cottage cheese, and wheat germ. An additional dietary source of phenylalanine is artificial sweeteners containing aspartame (a methyl ester of the aspartic acid/phenylalanine dipeptide). As a general rule, aspartame should be avoided by phenylketonurics and pregnant women. When present in sufficiently high levels, phenylalanine can act as a neurotoxin and a metabotoxin. A neurotoxin is a compound that disrupts or attacks neural cells and neural tissue. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of phenylalanine are associated with at least five inborn errors of metabolism, including Hartnup disorder, hyperphenylalaninemia due to guanosine triphosphate cyclohydrolase deficiency, phenylketonuria (PKU), tyrosinemia type 2 (or Richner-Hanhart syndrome), and tyrosinemia type III (TYRO3). Phenylketonurics have elevated serum plasma levels of phenylalanine up to 400 times normal. High plasma concentrations of phenylalanine influence the blood-brain barrier transport of large neutral amino acids. The high plasma phenylalanine concentrations increase phenylalanine entry into the brain and restrict the entry of other large neutral amino acids (PMID: 19191004 ). Phenylalanine has been found to interfere with different cerebral enzyme systems. Untreated phenylketonuria (PKU) can lead to intellectual disability, seizures, behavioural problems, and mental disorders. It may also result in a musty smell and lighter skin. Classic PKU dramatically affects myelination and white matter tracts in untreated infants; this may be one major cause of neurological disorders associated with phenylketonuria. Mild phenylketonuria can act as an unsuspected cause of hyperactivity, learning problems, and other developmental problems in children. It has been recently suggested that PKU may resemble amyloid diseases, such as Alzheimer's disease and Parkinson's disease, due to the formation of toxic amyloid-like assemblies of phenylalanine (PMID: 22706200 ). Phenylalanine also has some potential benefits. Phenylalanine can act as an effective pain reliever. Its use in premenstrual syndrome and Parkinson's may enhance the effects of acupuncture and electric transcutaneous nerve stimulation (TENS). Phenylalanine and tyrosine, like L-DOPA, produce a catecholamine-like effect. Phenylalanine is better absorbed than tyrosine and may cause fewer headaches. Low phenylalanine diets have been prescribed for certain cancers with mixed results. For instance, some tumours use more phenylalanine than others (particularly melatonin-producing tumours called melanomas).
(S)-2-Amino-3-phenylpropionic acidChEBI
(S)-alpha-Amino-beta-phenylpropionic acidChEBI
(S)-a-Amino-b-phenylpropionic acidGenerator
(S)-Α-amino-β-phenylpropionic acidGenerator
(S)-2-Amino-3-phenylpropanoic acidHMDB
(S)-alpha-Amino-benzenepropanoic acidHMDB
(S)-alpha-Aminobenzenepropanoic acidHMDB
(S)-alpha-Aminohydrocinnamic acidHMDB
alpha-Aminohydrocinnamic acidHMDB
L-2-Amino-3-phenylpropionic acidHMDB
L-Isomer phenylalanineHMDB
Phenylalanine, L isomerHMDB
Phenylalanine, L-isomerHMDB
(6S)-Tetrahydrofolic acidHMDB
5,6,7,8-Tetrahydrofolic acidHMDB
Chemical FormulaC9H11NO2
Average Mass165.1891 Da
Monoisotopic Mass165.07898 Da
IUPAC Name(2S)-2-amino-3-phenylpropanoic acid
Traditional NameL-phenylalanine
CAS Registry Number63-91-2
InChI Identifier
Spectrum TypeDescriptionDepositor IDDeposition DateView
1D NMR1H NMR Spectrum (1D, 500 MHz, H2O, experimental)Wishart Lab2021-06-20View Spectrum
2D NMR[1H, 13C]-HSQC NMR Spectrum (2D, 600 MHz, H2O, experimental)Wishart Lab2021-06-20View Spectrum
1D NMR13C NMR Spectrum (1D, 400 MHz, H2O, simulated)Varshavi.d262021-07-29View Spectrum
1D NMR1H NMR Spectrum (1D, 700 MHz, H2O, simulated)Ahselim2022-05-31View Spectrum
1D NMR1H NMR Spectrum (1D, 700 MHz, H2O, experimental)Ahselim2022-05-31View Spectrum
Species of Origin
Species NameSourceReference
Arabidopsis thalianaPlant
Cannabis sativaCannabisDB
      Not Available
Capsicum annuumPlant
Catharanthus roseusPlant
Escherichia coli K12Bacteria
Homo sapiens (Serum)Animalia
Homo sapiens (Urine)Animalia
Medicago sativaPlant
Melissa officinalis L.Plant
Ocimum basilicumPlant
Pinus spp.Plant
Populus spp.Plant
Sinocrassula indicaPlant
Solanum lycopersicum var.cerasiforme (DUNAL) ALEF.Plant
Taraxacum formosanumPlant
Ulva lactuca-
Zea mays L.Plant
Zyzzya fuliginosa-
Chemical Taxonomy
Description Belongs to the class of organic compounds known as phenylalanine and derivatives. Phenylalanine and derivatives are compounds containing phenylalanine or a derivative thereof resulting from reaction of phenylalanine at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom.
KingdomOrganic compounds
Super ClassOrganic acids and derivatives
ClassCarboxylic acids and derivatives
Sub ClassAmino acids, peptides, and analogues
Direct ParentPhenylalanine and derivatives
Alternative Parents
  • Phenylalanine or derivatives
  • 3-phenylpropanoic-acid
  • Alpha-amino acid
  • Amphetamine or derivatives
  • L-alpha-amino acid
  • Aralkylamine
  • Monocyclic benzene moiety
  • Benzenoid
  • Amino acid
  • Carboxylic acid
  • Monocarboxylic acid or derivatives
  • Organic nitrogen compound
  • Primary amine
  • Organooxygen compound
  • Organonitrogen compound
  • Hydrocarbon derivative
  • Primary aliphatic amine
  • Organic oxide
  • Carbonyl group
  • Organopnictogen compound
  • Organic oxygen compound
  • Amine
  • Aromatic homomonocyclic compound
Molecular FrameworkAromatic homomonocyclic compounds
External Descriptors
Physical Properties
Experimental Properties
Melting Point283 °CNot Available
Boiling PointNot AvailableNot Available
Water Solubility26.9 mg/mLNot Available
LogP-1.38Avdeef, A., Box, K. J., Comer, J. E. A., Hibbert, C., & Tam, K. Y. (1998). pH-Metric logP 10. Determination of liposomal membrane-water partition coefficients of lonizable drugs. Pharmaceutical research, 15(2), 209-215.
Predicted Properties
Water Solubility4.14 g/LALOGPS
pKa (Strongest Acidic)2.47ChemAxon
pKa (Strongest Basic)9.45ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count3ChemAxon
Hydrogen Donor Count2ChemAxon
Polar Surface Area63.32 ŲChemAxon
Rotatable Bond Count3ChemAxon
Refractivity45.12 m³·mol⁻¹ChemAxon
Polarizability17.03 ųChemAxon
Number of Rings1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterNoChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
DrugBank IDDB00120
Phenol Explorer Compound IDNot Available
FoodDB IDFDB004940
KNApSAcK IDC00001386
Chemspider ID5910
KEGG Compound IDC00079
BiGG ID33775
Wikipedia LinkPhenylalanine
PubChem Compound6140
PDB IDNot Available
ChEBI ID17295
Good Scents IDrw1036921
General References
  1. Sreekumar A, Poisson LM, Rajendiran TM, Khan AP, Cao Q, Yu J, Laxman B, Mehra R, Lonigro RJ, Li Y, Nyati MK, Ahsan A, Kalyana-Sundaram S, Han B, Cao X, Byun J, Omenn GS, Ghosh D, Pennathur S, Alexander DC, Berger A, Shuster JR, Wei JT, Varambally S, Beecher C, Chinnaiyan AM: Metabolomic profiles delineate potential role for sarcosine in prostate cancer progression. Nature. 2009 Feb 12;457(7231):910-4. doi: 10.1038/nature07762. [PubMed:19212411 ]
  2. Silwood CJ, Lynch E, Claxson AW, Grootveld MC: 1H and (13)C NMR spectroscopic analysis of human saliva. J Dent Res. 2002 Jun;81(6):422-7. [PubMed:12097436 ]
  3. Nicholson JK, O'Flynn MP, Sadler PJ, Macleod AF, Juul SM, Sonksen PH: Proton-nuclear-magnetic-resonance studies of serum, plasma and urine from fasting normal and diabetic subjects. Biochem J. 1984 Jan 15;217(2):365-75. [PubMed:6696735 ]
  4. Engelborghs S, Marescau B, De Deyn PP: Amino acids and biogenic amines in cerebrospinal fluid of patients with Parkinson's disease. Neurochem Res. 2003 Aug;28(8):1145-50. [PubMed:12834252 ]
  5. Sjoberg S, Eriksson M, Nordin C: L-thyroxine treatment and neurotransmitter levels in the cerebrospinal fluid of hypothyroid patients: a pilot study. Eur J Endocrinol. 1998 Nov;139(5):493-7. [PubMed:9849813 ]
  6. Hagenfeldt L, Bjerkenstedt L, Edman G, Sedvall G, Wiesel FA: Amino acids in plasma and CSF and monoamine metabolites in CSF: interrelationship in healthy subjects. J Neurochem. 1984 Mar;42(3):833-7. [PubMed:6198473 ]
  7. Peng CT, Wu KH, Lan SJ, Tsai JJ, Tsai FJ, Tsai CH: Amino acid concentrations in cerebrospinal fluid in children with acute lymphoblastic leukemia undergoing chemotherapy. Eur J Cancer. 2005 May;41(8):1158-63. Epub 2005 Apr 14. [PubMed:15911239 ]
  8. Cynober LA: Plasma amino acid levels with a note on membrane transport: characteristics, regulation, and metabolic significance. Nutrition. 2002 Sep;18(9):761-6. [PubMed:12297216 ]
  9. Rainesalo S, Keranen T, Palmio J, Peltola J, Oja SS, Saransaari P: Plasma and cerebrospinal fluid amino acids in epileptic patients. Neurochem Res. 2004 Jan;29(1):319-24. [PubMed:14992292 ]
  10. Deng C, Shang C, Hu Y, Zhang X: Rapid diagnosis of phenylketonuria and other aminoacidemias by quantitative analysis of amino acids in neonatal blood spots by gas chromatography-mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci. 2002 Jul 25;775(1):115-20. [PubMed:12101068 ]
  11. Wannemacher RW Jr, Klainer AS, Dinterman RE, Beisel WR: The significance and mechanism of an increased serum phenylalanine-tyrosine ratio during infection. Am J Clin Nutr. 1976 Sep;29(9):997-1006. [PubMed:822705 ]
  12. Doellgast GJ, Meis PJ: Use of specific inhibitors to disciminate alkaline phosphatase isoenzymes originating from human liver, placenta and intestine: absence of meconial alkaline phosphatase in maternal serum. Clin Chem. 1979 Jul;25(7):1230-3. [PubMed:455643 ]
  13. Kersemans V, Cornelissen B, Kersemans K, Bauwens M, Achten E, Dierckx RA, Mertens J, Slegers G: In vivo characterization of 123/125I-2-iodo-L-phenylalanine in an R1M rhabdomyosarcoma athymic mouse model as a potential tumor tracer for SPECT. J Nucl Med. 2005 Mar;46(3):532-9. [PubMed:15750170 ]
  14. Klassen P, Furst P, Schulz C, Mazariegos M, Solomons NW: Plasma free amino acid concentrations in healthy Guatemalan adults and in patients with classic dengue. Am J Clin Nutr. 2001 Mar;73(3):647-52. [PubMed:11237944 ]
  15. van Spronsen FJ, Hoeksma M, Reijngoud DJ: Brain dysfunction in phenylketonuria: is phenylalanine toxicity the only possible cause? J Inherit Metab Dis. 2009 Feb;32(1):46-51. doi: 10.1007/s10545-008-0946-2. Epub 2009 Jan 13. [PubMed:19191004 ]
  16. Adler-Abramovich L, Vaks L, Carny O, Trudler D, Magno A, Caflisch A, Frenkel D, Gazit E: Phenylalanine assembly into toxic fibrils suggests amyloid etiology in phenylketonuria. Nat Chem Biol. 2012 Aug;8(8):701-6. doi: 10.1038/nchembio.1002. Epub 2012 Jun 17. [PubMed:22706200 ]
  17. Fatima SW, Alam S, Khare SK: Molecular and structural insights of beta-boswellic acid and glycyrrhizic acid as potent SARS-CoV-2 Envelope protein inhibitors. Phytomed Plus. 2022 May;2(2):100241. doi: 10.1016/j.phyplu.2022.100241. Epub 2022 Feb 12. [PubMed:35403092 ]