L-Tryptophan

L‑Tryptophan (Trp) is an essential aromatic amino acid that humans must obtain from the diet because the body cannot synthesize it. Once absorbed, it serves as a precursor for several biologically active compounds, most notably the neurotransmitter serotonin and the hormone melatonin, which together influence mood, sleep, and a range of physiological processes.

• Molecular Formula and Name: L‑Tryptophan (L‑2‑amino‑3‑(indol‑3‑yl)propanoic acid) has the molecular formula C₁₁H₁₂N₂O₂, molecular weight 204.23 g/mol. IUPAC name: (2S)-2‑amino‑3‑(indol‑3‑yl)propanoic acid.
• Structure: It features an indole ring (a fused benzene‑pyrrole system) attached to the α‑carbon of an amino acid backbone, giving it a distinct aromatic side chain.
• Chirality: The compound is chiral, with the natural L‑configuration (S‑enantiomer) being biologically active.
• Zwitterion Properties: It is a zwitterion at physiological pH (≈7.4) with a pKa of 2.2 (carboxyl) and 9.4 (amino).
• Solubility and Stability: Soluble in water (≈50 mg/mL) and stable under neutral conditions, but it can oxidize under light/heat, forming indole‑derived degradation products; hence, supplements are often encapsulated to protect stability.

• Primary Source: Commercial L‑tryptophan is primarily obtained via microbial fermentation (e.g., Corynebacterium glutamicum or E. coli strains engineered for high‑yield production) followed by crystallization.
• Alternative Sources: Traditional extraction from protein‑rich foods (e.g., soy, turkey, nuts) yields low concentrations and is not economical for supplement manufacture. Synthetic routes using a protected indole intermediate are also employed, but most high‑purity products use fermentation for cost-effectiveness and sustainability.
• Quality Considerations:
  • Verification of >99 % purity by HPLC.
  • Absence of contaminants such as 1‑ethyl‑3‑phenyl‑2‑hydroxy‑propyl‑urea (a historical EMS‑causing impurity).
  • Compliance with GMP, USP‑NF, or EFSA standards.
• Third-Party Testing: Third‑party testing (e.g., NSF, Informed‑Choice) helps ensure the product is free from heavy metals, microbiological contaminants, and allergens.