The Cause of the Eosinophilia–Myalgia Syndrome Associated with Tryptophan Use

To the Editor: With reference to the article of Belongia et al. (Aug. 9 issue),* we have isolated and identified the peak E component of tryptophan that the authors mention as having a strong epidemiologic relation with the eosinophilia—myalgia syndrome.The peak E material from a preparation of L-tryptophan was purified and analyzed by nuclear-magnetic-resonance spectroscopy, mass spectroscopy, and infrared spectroscopy. The results indicate that peak E has the chemical structure shown in Figure 1. This compound was subsequently synthesized from L-tryptophan and acetaldehyde, confirming the structure. This substance decomposes promptly to form L-tryptophan and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, in an acid solution . . .