Neuroactive and other free amino acids in seed and young plants of Panax ginseng

The seeds and one to three years old plants of Asian ginseng (Panax ginseng C.A. Meyer) were analyzed for their free amino acid contents. The neuro-excitatory beta-ODAP (beta-N-oxalyl-L-alpha,beta-diaminopropionic acid), suggested to be the cause of the crippling neurolathyrism, was the major component in the seed extract (70% of the total free amino acids detected) and showed the highest concentration (0.43% by wt) compared to that in the different parts of young plants. beta-ODAP concentration was higher in the shoots as compared to roots and declined in older plants. The amount of beta-ODAP in the roots may be considered as an indirect measure of age and quality. Another neuro-active non-protein amino acid, GABA (gamma-aminobutyric acid), increased dramatically after germination and reached highest concentration in different parts of 3 year-old plants. Glutamine and arginine were the two major free proteinogenic amino acids in the ginseng plants and together they constituted over 50% of all the free amino acids detected in the root.