GABA (Gamma-Aminobutyric Acid)

Gamma‑aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system of mammals.

• It is synthesized from the amino acid glutamate.
• It functions primarily to reduce neuronal excitability by binding to GABA‑type receptors.
• This regulates brain‑wide excitatory‑inhibitory balance.
• It promotes relaxation and sleep.

• IUPAC name: 4‑Aminobutanoic acid
• Molecular formula: C₄H₉NO₂
• Molar mass: 103.12 g·mol⁻¹
• Structure:
  • A four‑carbon linear chain.
  • Terminating in a primary amine (–NH₂) at the γ‑position.
  • A carboxylic acid (–COOH) at the α‑position.
  • The central carbon chain confers the “γ‑amino” designation.
• Physical properties:
  • White, crystalline powder.
  • Water‑soluble (≈1 g mL⁻¹ at 25 °C).
  • pKa ≈ 4.2 (carboxyl) and ≈9.6 (amine), giving a zwitterionic form at physiological pH (≈7.4).
• Stability: Stable under neutral pH and ambient temperature; susceptible to oxidation under strong alkaline conditions.
• Solubility & Bioavailability:
  • Oral bioavailability is modest (~5 % in humans) due to limited transport across the blood–brain barrier.
  • Formulation strategies (e.g., liposomal encapsulation, co‑administration with vitamin B6) aim to improve CNS delivery.

• Commercial GABA is most commonly produced by microbial fermentation (e.g., Lactobacillus spp.) using glucose or glycerol as substrates, yielding a high‑purity (>99 %) product.
• Chemical synthesis (via the Strecker reaction) is also employed, though it may introduce residual solvents.
• Natural food sources contain trace amounts: fermented foods (kimchi, miso, tempeh), sprouted legumes, and certain teas (e.g., green tea) provide dietary GABA.
• For supplements, pharmaceutical‑grade GABA is typically produced under GMP (Good Manufacturing Practice) with certifications for heavy‑metal and microbiological limits.
• Quality considerations include:
  • Verification of >95 % purity by HPLC.
  • Absence of residual fermentation by‑products.
  • Stability testing (e.g., moisture content <0.5 %).
• Third‑party testing (e.g., USP, NSF) is recommended to ensure product integrity and to avoid contamination with allergens or heavy metals.