TY - JOUR T1 - Structural characterization of a case-implicated contaminant, "Peak X," in commercial preparations of 5-hydroxytryptophan. JF - The Journal of Rheumatology JO - J Rheumatol SP - 89 LP - 95 VL - 30 IS - 1 AU - Klaus Klarskov AU - Kenneth L Johnson AU - Linda M Benson AU - Jennifer D Cragun AU - Gerald J Gleich AU - Monika Wrona AU - Xiang-Rong Jiang AU - Glenn Dryhurst AU - Stephen Naylor Y1 - 2003/01/01 UR - http://www.jrheum.org/content/30/1/89.abstract N2 - OBJECTIVE: To determine the chemical structure of a contaminant, X1, previously found in eosinophilia myalgia syndrome case-implicated 5-hydroxytryptophan (5-OHTrp), and also present in over-the-counter (OTC) commercially available 5-OHTrp. METHODS: Case-implicated 5-OHTrp as well as 6 OTC samples were subjected to accurate mass HPLC-mass spectrometry and HPLC-electrochemical detection, and reacted with reduced glutathione. Peak X1 was subsequently subjected to HPLC-tandem mass spectrometry (MS/MS), as well as the resulting nucleophilic glutathione product. All these data were compared with analysis carried out under identical conditions on authentic 4,5-tryptophan-dione (Trp-4,5D). RESULTS: Based on accurate mass, tandem mass spectrometric analysis, and comparision with authentic standard compound analysis, X1 was determined to be 4,5-tryptophan-dione, a putative neurotoxin. The presence of X1 in OTC samples varied from 0.5 to 10.3% of the amount of Trp-4,5D present in case-implicated 5-OHTrp. CONCLUSION: Peak X1 was identified as the putative neurotoxin Trp-4,5D. It was found in case-implicated 5-OHTrp as well as 6 OTC samples. This gives some cause for concern in terms of the safety of such commercial preparations of 5-OHTrp. ER -