Identification of substances formed by decomposition of peak E substance in tryptophan

Peak E substance, a trace impurity in L-tryptophan, has been associated epidemiologically with an outbreak of eosinophilia-myalgia syndrome (EMS) in the USA in 1989. After fractionation and purification of this substance, nuclear magnetic resonance and fast-atom-bombardment mass spectroscopy were used to identify the molecular structures of peak X/X' (formed by the decomposition of peak E substance in a simulated gastric fluid) and peak Y/Y' substances (which are believed to be the intermediates in the transformation of peak E substance to peak X/X' substances). The analyses were also performed on synthesized peak E substance obtained from the reaction of tryptophan with acetaldehyde. The results indicated that the synthesized substance was of high purity and was suitable for use in studies investigating the relationship between peak E substance and EMS onset.