title: On-line HPLC-tandem mass spectrometry structural characterization of case-associated contaminants of L-tryptophan implicated with the onset of eosinophilia myalgia syndrome.
abstract: The eosinophilia-myalgia syndrome (EMS) outbreak that occurred in the USA in 1989 was caused by the intake of L-tryptophan (Trp) produced from one manufacturer, Showa Denko K.K. of Japan. Six compounds present in the Trp were reported to be case-associated contaminants. However, three of these compounds, Peaks C, FF and AAA have remained unidentified. Here, we successfully employ on-line HPLC-electrospray ionization multistage mass spectrometry to structurally characterize Peak C and Peak FF. Peak C was determined by accurate mass-LC-MS to have a protonated molecular ion MH+ = 221.0919 with an empirical formula of C11H13N2O3. By comparing the LC-MS-MS spectra with authentic 5-OHTrp and other structurally similar compounds, as well as considering the chemical reactivity of the indole ring, the structure of Peak C was consistent with 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo-[2,3-b]-indole-2-carboxy lic acid. Peak FF was also subjected to accurate mass-LC-MS and shown to have MH+ = 338.1524, corresponding to an empirical formula of C19H20N3O3. Comparison of the LC-MS-MS and LC-sCID-MS-MS of spectra derived from Peak FF with a previously characterized contaminant of Trp, namely P31, was consistent with Peak FF being 2-(2-hydroxy indoline)-Trp. Unlike the majority of the contaminants identified in EMS implicated tryptophan, both Peaks C and FF possess an indoline ring. This is significant since a case-associated contaminant found in 5-hydroxy-Trp also contains an indoline ring, and the chemical reactivity of this ring system may possibly play a role in the etiology of EMS.
authors.affiliation: Biomedical Mass Spectrometry Facility and Department of Biochemistry and Molecular Biology, Mayo Clinic/Mayo Foundation, Rochester, MN 55905, USA.
authors.forename: B L
authors.initials: BL
authors.lastname: Williamson
authors.forename: K L
authors.initials: KL
authors.lastname: Johnson
authors.forename: A J
authors.initials: AJ
authors.lastname: Tomlinson
authors.forename: G J
authors.initials: GJ
authors.lastname: Gleich
authors.forename: S
authors.initials: S
authors.lastname: Naylor
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004340:Drug Contamination; D016603:Eosinophilia-Myalgia Syndrome / Q000139:chemically induced*; D006801:Humans; D013058:Mass Spectrometry; D014364:Tryptophan / Q000009:adverse effects / Q000031:analogs & derivatives / Q000032:analysis*
chemical_list: D014364:Tryptophan