Phenylalanine

AKA: L-phenylalanine, 63-91-2, (2S)-2-amino-3-phenylpropanoic acid, (S)-2-Amino-3-phenylpropanoic acid, 3-Phenyl-L-alanine, (S)-Phenylalanine, (L)-Phenylalanine, 3-Phenylalanine, Beta-Phenyl-L-alanine
Synthetic
Skin Conditioner
Hair Care
Clean
OriginPhenylalanine is synthesized from phenylethylamine precursors or derived from ammonia and cinnamic acid through chemical synthesis. It is produced via fermentation using genetically modified microorganisms or through chemical catalytic processes.
Phenylalanine is an essential amino acid and the precursor for the amino acid tyrosine. Like tyrosine, it is the precursor of catecholamines in the body (tyramine, dopamine, epinephrine and norepinephrine). The psychotropic drugs (mescaline, morphine, codeine, and papaverine) also have phenylalanine as a constituent. Phenylalanine is a precursor of the neurotransmitters called catecholamines, which are adrenalin-like substances. 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 high protein foods, such as meat, cottage cheese and wheat germ. A new dietary source of phenylalanine is artificial sweeteners containing aspartame. Aspartame appears to be nutritious except in hot beverages; however, it should be avoided by phenylketonurics an
Solubility 10 to 50 mg/mL at 77 °F (NTP, 1992)
Formula
C9H11NO2
Mol. Weight
165.19
CAS #
63-91-2, 150-30-1
Form
Powder
State
L-phenylalanine is an odorless white crystalline powder. Slightly bitter taste. pH (1% aqueous solution) 5.4 to 6. (NTP, 1992)
Skin Types
●all-skin-types
Best For
Dryness
Pregnancy & Breastfeeding Safe
Yes
Functions
Hair Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Locks in moisture
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
1
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not a Skin Irritant
1 study / 1 not irritating (CIR 607)
Not a Sensitizer
1 study / 1 not sensitizing (CIR 607)
Concentration Guide
Leave-on0.00009–0.03%
Rinse-off0.0004–0.0008%
0%50%100%
CIR reported use · report published 2013
Regulatory Agencies
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR
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