The effect of selected amino acids on gelatin-induced inflammation in adult male mice.

Several studies have indicated to us that certain amino acids may exhibit antiinflammatory activity. In the present study we attempted to evaluate the inhibitory effect of various amino acids on gelatin-induced abdominal inflammation in mice using peritoneal fluid cytology as the diagnostic tool. The L-amino acids tested were tryptophan, phenylalanine, alanine, cystine, hydroxyproline, tyrosine, citrulline, leucine, and valine. Hydrocortisone was used as an antiphlogistic steroid control. Tryptophan, phenylalanine, alanine, cystine, hydroxyproline, and tyrosine all significantly decreased the inflammation. Citrulline and valine, however, both exhibited strong antiiflammatory responses. Based on these results, three related dipeptides were also screened: L-valy-L-alanine, L-valyl-L-tryptophan, and L-tyrosl-L-valine. Valyl alanine was found to produce a strong antiinflammatory effect. In a final test, the combination of the steroid, hydrocortisone, and the amino acid, cystine, was screened for a synergistic effect. The combined treatment inhibited the gelatin-induced inflammation more than either the amino acid or the steroid administered alone.