STRUCTURAL CHARACTERIZATION OF CONTAMINANTS FOUND IN COMMERCIAL PREPARATIONS OF MELATONIN - SIMILARITIES TO CASE-RELATED COMPOUNDS FROM L-TRYPTOPHAN ASSOCIATED WITH EOSINOPHILIA-MYALGIA-SYNDROME

On-line HPLC/electrospray ionization-tandem mass spectrometry (LC/ESI- MS/MS) in conjunction with NMR has been successfully employed to ident ify and structurally characterize seven contaminants found in three di fferent commercial preparations of melatonin. Six of these contaminant s were identified as analogues of impurities found in contaminated L-t ryptophan (an over-the-counter dietary supplement) associated with the eosinophilia-myalgia syndrome (EMS) epidemic that. occurred in the Un ited States during 1989, In particular, our studies identified two com pounds with MH+ = 249 to be hydroxymelatonin isomers. Four other compo unds with MH+ = 477 were identified as melatonin-formaldehyde condensa tion products, These compounds are structural analogues of L-tryptopha n contaminants, namely, 'peak C' and 'peak E' that were previously imp licated as etiological agents causing EMS. It has been reported that m elatonin consumption has resulted in eosinophilia in some humans takin g high doses of this supplement. Although there has not been a major o utbreak of EMS-like symptoms from consumption of melatonin, this study clearly suggests that tighter control and regulation of nutritional s upplements sold and used as drugs is necessary.