Contaminants in L-tryptophan associated with eosinophilia myalgia syndrome

Toxicology and safety study of L-tryptophan and its impurities for use in broiler feed

L-tryptophan has been utilized as a feed additive in animal nutrition to improve growth performance, as well as a dietary supplement to alleviate various emotional symptoms in humans. Despite its benefits, concerns regarding its safety arose following the outbreak of eosinophilia-myalgia syndrome (EMS) among individuals who consumed L-tryptophan. The causative material of EMS was determined to be not L-tryptophan itself, but rather L-tryptophan impurities resulting from a specific manufacturing process. To investigate the effect of L-tryptophan and its impurities on humans who consume meat products derived from animals that were fed L-tryptophan and its impurities, an animal study involving broiler chickens was conducted. The animals in test groups were fed diet containing 0.065%-0.073% of L-tryptophan for 27 days. This study aimed to observe the occurrence of toxicological or EMS-related symptoms and analyze the residues of L-tryptophan impurities in meat products. The results indicated that there was no evidence of adverse effects associated with the test substance in the investigated parameters. Furthermore, most of the consumed EMS-causing L-tryptophan impurities did not remain in the meat of broiler chickens. Thus, this study demonstrated the safety of L-tryptophan and some of its impurities as a feed additive.

Safety concerns regarding impurities in L-Tryptophan associated with eosinophilia myalgia syndrome

L-tryptophan is one of the essential amino acids in humans and across the animal kingdom. It has been widely used as a feed additive for domestic animals and is also administered through dietary supplements in humans. Safety concerns have been raised however since a disease known as eosinophilia-myalgia syndrome (EMS) was reported to be related to L-tryptophan supplements. EMS is a rare condition characterized by inflammation in various organ systems including the muscles, skin, and lungs. Through several studies, it has been speculated that the six components generated during the process of L-tryptophan synthesis are related to the induction of EMS. In this review, we discuss the history of EMS and its controversial correlation with L-tryptophan use reported in several studies. Many in vitro and in vivo studies have been conducted to assess the putative correlation between impurities in L-tryptophan preparations and EMS, but no clear and convincing conclusions have been drawn so far.

Simultaneous determination of L-tryptophan impurities in meat products

L-tryptophan has been used as a feed additive for swine and poultry and as a nutrient supplement for humans. However, some impurities in L-tryptophan have been reported as causative components of eosinophilia-myalgia syndrome. Therefore, from a safety perspective, it is important to analyze meat samples for these impurities. This study aims to develop an analytical method for the simultaneous detection of L-tryptophan impurities in meat products using LC-MS/MS. Among the various impurities, detection methods for (S)-2-amino-3-(5-hydroxy-1H-indol-3-yl)propanoic acid (5-hydroxytryptophan) (HTP), 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA), 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo-[2,3-b]-indole-2-carboxylic acid (PIC), and 1,1'-ethylidenebistryptophan (EBT) and 2-(3-indoylmethyl)-L-tryptophan (IMT) were developed. The developed method allowed simultaneous determination of these four impurities in 5 min. No interferences from the matrix were observed, and the method showed good sensitivity to each analyte. The method detection limit and limit of quantification in meat matrices were below 11.2 and 35.7 μg/kg, respectively.

Reactivity and degradation products of tryptophan in solution and proteins

Tryptophan is one of the essential mammalian amino acids and is thus a required component in human nutrition, animal feeds, and cell culture media. However, this aromatic amino acid is highly susceptible to oxidation and is known to degrade into multiple products during manufacturing, storage, and processing. Many physical and chemical processes contribute to the degradation of this compound, primarily via oxidation or cleavage of the highly reactive indole ring. The central contributing factors are reactive oxygen species, such as singlet oxygen, hydrogen peroxide, and hydroxyl radicals; light and photosensitizers; metals; and heat. In a multi-component mixture, tryptophan also commonly reacts with carbonyl-containing compounds, leading to a wide variety of products. The purpose of this review is to summarize the current state of knowledge regarding the degradation and interaction products of tryptophan in complex liquid solutions and in proteins. For the purposes of context, a brief summary of the key pathways in tryptophan metabolism will be included, along with common methods and issues in tryptophan manufacturing. The review will focus on the conditions that lead to tryptophan degradation, the products generated in these processes, their known biological effects, and methods which may be applied to stabilize the amino acid.

Chemical exposure-induced systemic fibrosing disorders: Novel insights into systemic sclerosis etiology and pathogenesis

Numerous drugs and chemical substances are capable of inducing exaggerated tissue fibrotic responses. The vast majority of these agents cause localized fibrotic tissue reactions or fibrosis confined to specific organs. Although much less frequent, chemically-induced systemic fibrotic disorders have been described, sometimes occurring as temporally confined outbreaks. These include the Toxic Oil Syndrome (TOS), the Eosinophilia-Myalgia Syndrome (EMS), and Nephrogenic Systemic Fibrosis (NSF). Although each of these disorders displays some unique characteristics, they all share crucial features with Systemic Sclerosis (SSc), the prototypic idiopathic systemic fibrotic disease, including vasculopathy, chronic inflammatory cell infiltration of affected tissues, and cutaneous and visceral tissue fibrosis. The study of the mechanisms and molecular alterations involved in the development of the chemically-induced systemic fibrotic disorders has provided valuable clues that may allow elucidation of SSc etiology and pathogenesis. Here, we review relevant aspects of the TOS, EMS, and NSF epidemic outbreaks of chemically-induced systemic fibrosing disorders that provide strong support to the hypothesis that SSc is caused by a toxic or biological agent that following its internalization by endothelial cells induces in genetically predisposed individuals a series of molecular alterations that result in the development of SSc clinical and pathological alterations.

Peak AAA fatty acid homolog contaminants present in the dietary supplement l-Tryptophan associated with the onset of eosinophilia-myalgia syndrome

The eosinophilia-myalgia syndrome (EMS) outbreak that occurred in the USA and elsewhere in 1989 was caused by the ingestion of Showa Denko K.K. (SD) L-tryptophan (L-Trp). "Six compounds" detected in the L-Trp were reported as case-associated contaminants. Recently the final and most statistically significant contaminant, "Peak AAA" was structurally characterized. The "compound" was actually shown to be two structural isomers resulting from condensation reactions of L-Trp with fatty acids derived from the bacterial cell membrane. They were identified as the indole C-2 anteiso (AAA₁-343) and linear (AAA₂-343) aliphatic chain isomers. Based on those findings, we utilized a combination of on-line HPLC-electrospray ionization mass spectrometry (LC-MS), as well as both precursor and product ion tandem mass spectrometry (MS/MS) to facilitate identification of a homologous family of condensation products related to AAA₁-343 and AAA₂-343. We structurally characterized eight new AAA₁-XXX/AAA₂-XXX contaminants, where XXX represents the integer molecular ions of all the related homologs, differing by aliphatic chain length and isomer configuration. The contaminants were derived from the following fatty acids of the bacterial cell membrane, 5-methylheptanoic acid (anteiso-C8:0) for AAA₁-315; n-octanoic acid (n-C8:0) for AAA₂-315; 6-methyloctanoic acid (anteiso-C9:0) for AAA₁-329; n-nonanoic acid (n-C9:0) for AAA₂-329; 10-methyldodecanoic acid (anteiso-C13:0) for AAA₁-385; n-tridecanoic acid (n-C13:0) for AAA₂-385; 11-methyltridecanoic acid (anteiso-C14:0) for AAA₁-399; and n-tetradecanoic acid (n-C14:0) for AAA₂-399. The concentration levels for these contaminants were estimated to be 0.1-7.9 μg / 500 mg of an individual SD L-Trp tablet or capsule The structural similarity of these homologs to case-related contaminants of Spanish Toxic Oil Syndrome (TOS) is discussed.

Structure determination of disease associated peak AAA from l-Tryptophan implicated in the eosinophilia-myalgia syndrome

The eosinophilia-myalgia syndrome (EMS) outbreak of 1989 that occurred in the USA and elsewhere was caused by the ingestion of l-Tryptophan (L-Trp) solely manufactured by the Japanese company Showa Denko K.K. (SD). Six compounds present in the SD L-Trp were reported to be case-associated contaminants. However, "one" of these compounds, Peak AAA has remained structurally uncharacterized, despite the fact that it was described as "the only statistically significant (p=0.0014) contaminant". Here, we employ on-line microcapillary-high performance liquid chromatography-electrospray ionization mass spectrometry (LC-MS), and tandem mass spectrometry (MS/MS) to determine that Peak AAA is in fact two structurally related isomers. Peak AAA₁ and Peak AAA₂ differed in LC retention times, and were determined by accurate mass-LC-MS to both have a protonated molecular ion (MH⁺⁾ of mass 343.239Da (Da), corresponding to a molecular formula of C₂₁H₃₀N₂O_2, and possessing eight degrees of unsaturation (DoU) for the non-protonated molecule. By comparing the LC-MS and LC-MS-MS retention times and spectra with authentic synthetic standards, Peak AAA₁ was identified as the intermolecular condensation product of L-Trp with anteiso 7-methylnonanoic acid, to afford (S)-2-amino-3-(2-((S,E)-7-methylnon-1-en-1-yl)-1H-indol-3-yl)propanoic acid. Peak AAA₂ was determined to be a condensation product of L-Trp with decanoic acid, which produced (S)-2-amino-3-(2-((E)-dec-1-en-1-yl)-1H-indol-3-yl)propanoic acid.

Eosinophilia in Rheumatologic/Vascular Disorders

Peripheral and tissue eosinophilia can be a prominent feature of several unique rheumatologic and vascular diseases. These diseases span a wide range of clinical features, histologic findings, therapeutic approaches, and outcomes. Despite the rare nature of these entities--which makes large-scale studies challenging--knowledge has continued to grow regarding their epidemiology, pathophysiology, and management. This review compares and contrasts 5 rheumatologic and vascular conditions in which eosinophilia can be seen: eosinophilic granulomatosis with polyangiitis (Churg-Strauss), immunoglobulin G4-related disease, diffuse fasciitis with eosinophilia, eosinophilia-myalgia syndrome, and eosinophilic myositis.

L-Tryptophan: Biochemical, nutritional and pharmacological aspects

Tryptophan is important both for protein synthesis and as a precursor of niacin, serotonin and other metabolites. Tryptophan is an unusual amino acid because of the complexity of its metabolism, the variety and importance of its metabolites, the number and diversity of the diseases it is involved in, and because of its use in purified form as a pharmacological agent. This review covers the metabolism of tryptophan, its presence in the diet, the disorders associated with low tryptophan levels due to low dietary intake, malabsorption, or high rates of metabolism, the therapeutic effects of tryptophan and the side effects of tryptophan when it is used as a drug including eosinophilia myalgia syndrome.

Post-epidemic eosinophilia-myalgia syndrome associated with L-tryptophan

Eosinophilia-myalgia syndrome (EMS) is characterized by subacute onset of myalgias and peripheral eosinophilia, followed by chronic neuropathy and skin induration. An epidemic of EMS in 1989 was linked to consumption of L-tryptophan that had originated from a single source. Following the ban by the Food and Drug Administration (FDA) on the sale of L-tryptophan, the incidence of EMS declined rapidly. Moreover, no new cases have been described since the FDA ban was lifted in 2005. We report the clinical, histopathologic, and immunogenetic features of a new case of L-tryptophan-associated EMS, along with evidence of activated transforming growth factor β and interleukin-4 signaling in the lesional skin.

The problem with nutritionally enhanced plants

Among the next generation of genetically modified (GM) plants are those that are engineered to produce elevated levels of nutritional molecules such as vitamins, omega-3 fatty acids, and amino acids. Based upon the U.S. current regulatory scheme, the plants and their products may enter our food supply without any required safety testing. The potential risks of this type of GM plant are discussed in the context of human health, and it is argued that there should be very careful safety testing of plants designed to produce biologically active molecules before they are commercially grown and consumed. This will require a mandatory, scientifically rigorous review process.

Health risks of genetically modified foods

As genetically modified (GM) foods are starting to intrude in our diet concerns have been expressed regarding GM food safety. These concerns as well as the limitations of the procedures followed in the evaluation of their safety are presented. Animal toxicity studies with certain GM foods have shown that they may toxically affect several organs and systems. The review of these studies should not be conducted separately for each GM food, but according to the effects exerted on certain organs it may help us create a better picture of the possible health effects on human beings. The results of most studies with GM foods indicate that they may cause some common toxic effects such as hepatic, pancreatic, renal, or reproductive effects and may alter the hematological, biochemical, and immunologic parameters. However, many years of research with animals and clinical trials are required for this assessment. The use of recombinant GH or its expression in animals should be re-examined since it has been shown that it increases IGF-1 which may promote cancer.

Generation of Quinoneimine Intermediates in the Bioactivation of 3-(N-Phenylamino)alanine (PAA) by Human Liver Microsomes: A Potential Link Between Eosinophilia-Myalgia Syndrome and Toxic Oil Syndrome

Eosinophilia-myalgia syndrome (EMS) was an intoxication episode that occurred in the US in 1989 and affected 1,500 people. EMS was associated with the ingestion of manufactured L-tryptophan, and 3-(N-phenylamino)alanine (PAA) was identified as one of the contaminants present in the L-tryptophan batches responsible for intoxication. In previous studies (Martínez-Cabot et al., Chem Res. Toxicol., in press), we have shown that the incubation of 3-(N-phenylamino)propane-1,2-diol (PAP), a toxic biomarker of the oil batches that caused Toxic Oil Syndrome in Spain, with human liver microsomes generates a reactive quinoneimine intermediate. The structural similarity between PAA and PAP led Mayeno and co-workers (Mayeno et al. (1995) Chem. Res. Toxicol. 8, 911-916) to hypothesize that both xenobiotics could be linked to a common etiologic agent. We thus set about to study the bioactivation of PAA by human liver microsomes. Under these conditions, PAA is converted to its 4'-hydroxy derivative, an unstable intermediate that is rapidly transformed into the final metabolites 4-aminophenol and formylglycine, which were identified in the incubations by GC/MS using the H2(18)O-labeled medium. We also provide evidence that 4-aminophenol and formylglycine are formed from a quinoneimine intermediate via a pathway similar to that demonstrated for PAP bioactivation. This quinoneimine, in the absence of nucleophiles in the incubation medium, could isomerize to give the corresponding imine, which could undergo hydrolysis to yield the aforementioned final products. These findings establish that EMS and TOS are linked by a common toxic metabolite (4-aminophenol) and that they may be further linked by the concomitant release of potentially hazardous carbonyl species.

Systematic overview of drug interactions with antidepressant medications

OBJECTIVE

Antidepressants are commonly used drugs with potential for numerous drug interactions. This study aims to systematically review the literature on drug interactions with antidepressants.

METHODS

We searched MEDLINE (1966 to November 2003) and EMBASE (1980 to 2003), using the heading drug interactions combined with individual antidepressant names. We restricted searches to English-language articles and human studies. We screened drug interaction texts and review articles for relevant studies. We included articles reporting original human data on drug interactions with antidepressants commonly used in North America. Articles were independently evaluated by 2 reviewers on clinical effect, clinical significance, and quality of evidence. Discrepancies were resolved by consensus.

RESULTS

There were 904 eligible interactions, involving 9509 patients, for a total of 598 summary interactions. Of these, 439 (73%) demonstrated an interaction, 148 (25%) had no effect, and 11 (2%) had conflicting evidence. For 510 interactions (85%), the quality of evidence was poor. It was fair for 67 (11%) interactions and good for 10 (2%) interactions. There were no interactions with excellent quality of evidence. There were 145 (24%) interactions of major clinical significance. These were predominantly hypertensive emergencies and serotonin syndrome. Most interacting drugs had central nervous system (CNS) activity. As expected, monoamine oxidase inhibitors (MAOIs) appear to be the most problematic family in terms of potential for serious drug interactions.

CONCLUSIONS

Drug interactions with antidepressants are an important cause for concern, but this concern is based primarily on poor evidence. We recommend caution when combining antidepressants with other CNS drugs, particularly when coadministering MAOIs with other substances.

An analytical perspective on favoured synthetic routes to the psychoactive tryptamines

Many tryptamine derivatives are known to induce altered states of consciousness and are increasingly of interest in forensic and neurobiological studies. The analytical chemistry of certain synthetic routes to the tryptamines is discussed and likely side products and impurities identified, where literature reports are available. Recent examples from the authors' laboratory are presented to highlight future prospects and implications for analytical procedures. The aim of this review is to provide the analytical chemist with the foundation chemistry and some analytical targets to be able to undertake direct characterisation of products and intermediates. These might become available from interdiction of clandestine operations in a forensic environment or during the synthesis of the tryptamines for investigative neurobiological and clinical procedures.

Evaluation of the impurity profile of amino acids by means of CE

The aim of this study was to develop a general approach for characterizing the impurity profile of amino acids at level 0.1% by means of capillary electrophoresis (CE). Checking a variety of labeling reagents revealed 9-fluorenylmethyl chloroformate to be favorable, due to the high stability of its derivatives and the fact that the reagent peaks do not interfere with the peaks of the impurities. After optimization, the method was sufficiently sensitive to evaluate impurities at a 0.1% level by UV detection. The method was representatively validated for phenylalanine (Phe) with regard to selectivity, precision, linearity and accuracy using model mixtures of potential impurities. The CE analyzes method was applied to Phe samples of different manufacturers and the capabilities of the strategy was also demonstrated by samples of tryptophan and serine.

Tetrahydro-beta-carboline-3-carboxylic acids and contaminants of L-tryptophan

Methods for the separation, identification, and quantitative assay of contaminants of L-tryptophan implicated in eosinophilia-myalgia syndrome (EMS) are described. Propylsulfonic acid (PRS), benzenesulfonic acid (SCX), and octyl-derivatized silica (C8) bonded-phase cartridges were used for the separation; LC-MS and GC-MS for identification; and HPLC-UV-fluorescence detection for quantitative analyses of norharman, harman, tetrahydro-beta-carboline-3-carboxylic acid (TCCA), 1-methyltetrahydro-beta-carboline-3-carboxylic acid (MTCA), 1,1'-ethylidenbis(tryptophan) (EBT), and 3-(phenylamino)alanine (PAA). The tissue distribution, excretion, and metabolism of these contaminants of L-tryptophan associated with EMS after acute and chronic dosage regimens are described. Considerable amounts of EBT were observed in the large intestine of rats administered EBT, showing a transfer without decomposition in gastric fluid. In addition, MTCA was detected in the blood and urine as well as the organs of rats treated with EBT, suggesting MTCA as a major metabolite of EBT. PAA accumulated markedly in the brain, among the organs of rats, after both acute and chronic administration of PAA, while MTCA accumulated in the kidneys of rats after chronic dosage of MTCA. Ethanol and/or acetaldehyde-induced formation of MTCA, as well as tryptophan-induced formation of TCCA, occurred endogenously in man and animals.

Structural characterization of case-associated contaminants peak C and FF in L-tryptophan implicated in eosinophilia-myalgia syndrome

We have characterized the structures of two case-associated contaminants of the Showa Denko L-tryptophan known to cause eosinophilia-myalgia syndrome (EMS). A combination of on-line accurate mass HPLC-electrospray ionization-mass spectrometry (LC-MS), HPLC-tandem mass spectrometry (LC-MS-MS) and HPLC-in source collision induced dissociation-MS-MS (LC-sCID-MS-MS) allowed the structure determination of both Peak C and FF. Peak C is identified as 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo-[2-3b]-indole-2-carboxyl ic acid, whereas Peak FF is characterized as 2-(2-hydroxy-indoline)-tryptophan. Both contaminants contain indoline rings, and the significance of this finding is discussed.

Synthesis, formation, and occurrence of contaminants in biotechnologically manufactured L-tryptophan

The pattern of contaminants in pharmaceutical and feed grade L-tryptophan (Trp) was investigated in a market survey of 22 lots of 6 different manufacturers. To date, 5 case associated contaminants in Showa Denko tryptophan (SD-Trp) known to cause the autoimmune disease eosinophilia-myalgia syndrome (EMS) have been structurally elucidated: 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrroloindole-2-carboxylic acid (PIC), an indoline compound, is one of the most abundant degradation compounds of unbound Trp during oxidative treatment. 2-(3-indolylmethyl)-L-tryptophan (IMT) and 2-(2-hydroxyindoline)-tryptophan (HIT) are both 2-substituted Trp-derivatives. IMT was synthesized by the reaction of Trp and indole-3-methanol or indole-3-acetaldehyde, respectively. From this finding it is proposed that Trp-metabolites can decompose under formation of transitional, mesomerism-stabilized cations that react with excess Trp to yield 2-substituted Trp derivatives. The decomposition of Trp-metabolites could be induced by elevated or low pH-values that occur during the downstream processing of the Trp fermentation broth. IMT was detected in pharmaceutical-grade and feed-grade Trp in amounts of < 20-1,400 mg/kg. 1,1'-Ethylidenebis-(L-tryptophan) (EBT) is formed from acetaldehyde and Trp under acidic conditions and serves as a marker for EMS-suspicious Trp. 3-(Phenylamino)alanine (PAA) is the only not Trp derived case associated contaminant. Low amounts of PAA (20 mg/kg) could be detected in feed-grade Trp of one manufacturer. Non-EMS correlated 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids of Trp and formaldehyde, acetaldehyde and indole-3-acetaldehyde could be detected in the examined Trp raw materials (< 10-13,500 mg/kg). In order to guarantee the safety of Trp containing drugs the amount of EBT (< 10 mg/kg Trp) and the sum of UV220 nm detectable contaminants (< 400 mg/kg Trp) are limited by the European authorities.

Structural characterization of contaminants in commercial preparations of melatonin by on-line HPLC-electrospray ionization-tandem mass spectrometry

Three different commercially available melatonin preparations were analyzed by on-line HPLC-electrospray ionization-tandem mass spectrometry. All three samples contained the same impurities at the approximately 0.1-0.5% level of parent melatonin. Based on accurate mass-HPLC-MS and tandem mass spectrometric analyses, two contaminants (both MH+ = 249) were identified as hydroxylation products of melatonin. One compound (MH+ = 265) was determined to be a C-2 oxidation product of hydroxymelatonin and a group of four regioisomers (MH+ = 477) were identified as melatonin-formaldehyde condensation products. These latter contaminants are structural analogues of the case-associated peak "E" found in L-tryptophan implicated in onset of eosinophilia-myalgia syndrome. The significance of these findings is discussed.

Synthesis and formation of an EMS correlated contaminant in biotechnologically manufactured L-tryptophan

Contaminants in biotechnologically manufactured L-Tryptophan (Trp) are suspected to be responsible for the outbreak of an unknown autoimmune disease in 1989. The contaminants, found in Trp-lots of a Japanese manufacturer, are classified in EMS-correlated and non EMS-correlated substances. Up to now six EMS-correlated substances are known. One of these compounds is 2-(3'-indolylmethyl)-indole (IMT). IMT was detected as a major contaminant in two investigated EMS-associated trp-samples. In a seven step chemical synthesis IMT was obtained for use as a reference substance. A model system to investigate the formation of IMT was created using Trp and 3-indolylmethanol (IM). IMT formation was observed at acidic and alkaline pH-values and the optimal molar ratio of Trp to IM is 100:1. In addition an IMT formation was observed from indole, formaldehyde and Trp as well as from Trp and 3-indolylacetaldehyde.

Biologic effects of and clinical disorders caused by nonprotein amino acids

Despite the fact that nonprotein amino acids are present in many commonly eaten foods, the biologic and clinical significance of this class of molecules has been largely overlooked. This is owing in part to their relatively low concentrations and their negligible nutritive value. Many of these compounds have the ability to interfere with a wide range of fundamental biochemical processes and cause disease. It is likely that the clinical effects of the ingestion of some nonprotein amino acids are yet to be described. Serious disorders in humans have followed the ingestion of these compounds as the result of food faddism, prodded by the commercial promotion of inadequately tested products. In view of the current popularity of herbal remedies and alternative medicine, these facts serve as another reminder to health care providers and the public at large about the need for critical analysis of the alleged benefits and the risks of exotic remedies and nutritional supplements. Beyond the public health issues they raise, non-protein amino acids take on significance because their misincorporation into proteins can trigger vigorous autoimmune attacks. To what extent this mechanism is responsible for highly prevalent diseases of autoimmunity remains to be determined.

On-line HPLC-tandem mass spectrometry structural characterization of case-associated contaminants of L-tryptophan implicated with the onset of eosinophilia myalgia syndrome

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.

Rapid HPLC screening method for contaminants found in implicated L-tryptophan associated with eosinophilia myalgia syndrome and adulterated rapeseed oil associated with toxic oil syndrome

In 1981 a massive food-borne epidemic, termed the toxic oil syndrome (TOS), occurred in Spain. Eight years later a closely related disease, the eosinophilia myalgia syndrome (EMS), was reported in the USA with many additional cases being reported worldwide. Although EMS was linked to the ingestion of contaminated L-tryptophan and TOS to aniline denatured rapeseed oil, the etiological agent(s) responsible for both diseases remains unknown. However, contaminants in both the oil and the dietary supplement are believed to have triggered these diseases, and there has been much speculation that a common contaminant may have caused both epidemics. In this report, methods for the facile preparation and HPLC analysis of EMS-implicated L-tryptophan and adulterated rapeseed oil samples associated with TOS are described which allow a direct comparison between the contaminants of both foodstuffs. A combination of solvent and solid phase extraction methods are demonstrated along with the application of C18 reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with on-line UV and MS detection. These methods have allowed us to determine for the first time, based upon this work, that there are no detectable common contaminants that possess a UV response, between EMS implicated L-tryptophan and TOS implicated rapeseed oil samples.

Effects of a tryptophan-free amino acid drink challenge on normal human sleep electroencephalogram and mood

BACKGROUND

Serotonin has been implicated in the regulation of sleep and mood. In animals a tryptophan-free amino acid drink (TFD) challenge has been found to reduce brain serotonin. We hypothesized this TFD would produce alterations in electroencephalographic (EEG) sleep commonly associated with depression, i.e. an enhancement of rapid eye movement (REM) sleep, and adversely affect mood ratings in humans.

METHODS

We investigated the effects of a TFD challenge in 11 healthy male subjects on EEG sleep and mood (assessed by Profile of Mood States). All subjects received on separate occasions an experimental drink containing approximately 100 g of an amino acid mixture (100% TFD) and a control drink containing one fourth strength (25% TFD) of the experimental drink 5 hours prior to sleep (6:00 PM).

RESULTS

Both drinks significantly decreased plasma tryptophan levels 5 hours postchallenge (11:00 PM). Both drinks significantly decreased REM latency, and the 25% TFD also increased REM time and REM% compared to baseline. No significant changes were found in subjective ratings of depression; however, subjects reported confusion and tension and a decrease in elation, vigor, and friendliness compared with baseline.

CONCLUSIONS

These TFD findings further support the involvement of serotonin deficiency in EEG sleep findings commonly seen in depression.

On-line HPLC-tandem mass spectrometry analysis of contaminants of L-tryptophan associated with the onset of the eosinophilia-myalgia syndrome

The structural characterization of a number of contaminants of L-tryptophan (Trp) associated with eosinophilia myalgia syndrome has been performed for the first time by the powerful structural elucidation technique of tandem mass spectrometry coupled with on-line HPLC (LC-ESI-MS/MS). The identity of the contaminants: peaks UV-5, 3-(phenylamino)alanine, (PAA); E 1,1'-ethylidenebis(tryptophan); 200, 2-(3-indolylmethyl)-L-tryptophan; (all identified as case related) and peaks 1, 3-carboxy-1,2,3,4-tetrahydro-beta-carboline; 2, 3-carboxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline; 100, 2-(2,3 dihydroxy-1-[3-indolyl]propyl)-L-tryptophan; and 300 and 400, diastereomers of 3-carboxy-1-[3-indolyl-methyl]-1,2,3,4-tetrahydro-beta-carboline, have been confirmed by this technique. By comparison of tandem MS (MS/MS) data from these compounds with the MS/MS data of several other impurities, we have structurally characterized peaks CC, KK and OO, as well as two previously unreported components labeled as peak P18 and peak P31. Peak P18 was unresolved from the large Trp peak and has been characterized as indole-3-ethylamine. Peak P31 was previously unresolved from peak 200, a case related compound and therefore its structure is of extreme importance. This compound has been tentatively identified as 2-(3-indolyl)-L-tryptophan.

Mouse strain and source of L-tryptophan affects hepatic nuclear tryptophan binding

This study describes that the affinity for specific L-tryptophan binding to hepatic nuclei in vitro is markedly decreased in NZBWF1 mice in comparison to that in Swiss mice. Also, the hepatic nuclei of NZBWF1 mice have a significantly decreased binding response in vitro to Showa Denko L-tryptophan (implicated in the eosinophilia-myalgia syndrome) or to its contaminants, 1,1'-ethylidenebis(tryptophan) or 3-phenylamino-L-alanine, when each is added to control, non-implicated L-tryptophan compared with hepatic nuclei of Swiss mice. Enhanced hepatic protein synthesis induced by tube-feeding control L-tryptophan is much less in NZBWF1 mice than in Swiss mice. Tube-feeding of Showa Denko L-tryptophan induced less stimulation of hepatic protein synthesis than did control L-tryptophan in Swiss mice but essentially none in NZBWF1 mice. NZBWF1 mice have a genetically altered response to L-tryptophan which may prove to be useful is studying the role of L-tryptophan in health and in disease.

Contaminants in biotechnologically manufactured L-tryptophan

The epidemic outbreak of a new disease, the eosinophilia-myalgia syndrome (EMS), was traced back to the intake of L-tryptophan (Trp) of certain lots from a single manufacturer. Since some trace contaminants were related to EMS, it appeared to be necessary to identify and find the origin of most trace contaminants in the EMS related Trp in order to apply this knowledge to a prospective manufacturing practice. Seventeen contaminants were determined in an implicated Trp lot by a single reversed-phase high-performance liquid chromatography run using UV and fluorescence detection. Most of these contaminants were classified as Trp metabolites, non-physiological oxidation or carbonyl condensation compounds of Trp. The amount and the pattern of contaminants were compared with recently manufactured Trp and Trp-containing preparations.

Clinical features of eosinophilia myalgia syndrome and related disorders

EMS, EF, and TOS are all relatively rare disorders. There are considerable data to suggest that most (if not all) of these cases may be due to toxin exposure, although the precise etiologic agent(s) has yet to be identified. It is likely that the pathogenic mechanisms responsible for disease are similar in these entities, and thus the distinctions between these illnesses may be largely semantic. Rational therapy includes the removal of an inciting agent if identified, and the application of symptom-based treatment based on the organ or tissue involved, and whether there is evidence of active inflammation is present.

Pathogenesis of L-tryptophan eosinophilia myalgia syndrome

Taken together, these studies suggest that many different etiologic agents alone or together may initiate the common final pathways of tissue pathologic response resulting in the clinical syndrome of eosinophilia, myalgias and fasciitis. Tryptophan itself may contribute to some of the scarring features of the illness, while impure L-tryptophan, and one or more of the impurities cause the characteristic features of the illness. The altered tryptophan metabolism in EMS is secondary to inflammation.

Enhanced collagen synthesis and transcription by peak E, a contaminant of L-tryptophan preparations associated with the eosinophilia myalgia syndrome epidemic

The pathogenesis of the eosinophilia myalgia syndrome (EMS) remains unclear. Several abnormal constituents have been found in the L-tryptophan lots responsible for the illness, particularly, 1,1-ethylidenebis[L-tryptophan], also called peak E or EBT, and 3-phenylamino-alanine or peak 5. However, the role of these contaminants in the pathogenesis of EMS and in the development of fibrosis is unknown. We now report that peak E, a dimer of L-tryptophan, is a potent stimulus for human dermal fibroblast DNA and collagen synthesis. Peak E (0.1-1.0 microM) increased DNA synthesis up to four-fold (P = 0.0001) in a dose-dependent manner (r = 0.987). When added to monolayer cultures for 2 to 24 h, peak E (0.5 to 100 microM) caused a progressive, more than threefold increase in alpha 1(I) procollagen mRNA levels and collagenous protein. No increase in procollagen mRNA levels was found after the addition of another major L-tryptophan contaminant, peak 5, or with L-tryptophan itself. Transient transfection with a 2.5-kb alpha 1(I) procollagen promoter-luciferase construct showed that peak E causes a twofold upregulation of promoter activity (P = 0.022). Contraction of collagen gels, consisting of human dermal fibroblasts incorporated into a type I collagen lattice, was enhanced two-fold by exposure to peak E (P = 0.001). We conclude that a major constituent of contaminated batches of L-tryptophan, peak E, is a potent stimulus for fibroblast activation and collagen synthesis. This stimulatory action of peak E may provide a direct mechanism for the development of fibrosis in EMS.

Multiple hypothesis tests in multiple investigations

Inferential statistical methods have traditionally been based on the assumption that one experiment is performed and that interest centres on one or more predetermined hypothesis tests. Exploratory research, on the other hand, often involves multiple hypotheses or repeated investigations under similar or different conditions or both. Several techniques have been proposed to deal with multiple or simultaneous hypothesis testing in single investigations, and procedures to combine observed significance levels for an individual hypothesis test from two or more investigations have been suggested. In this paper we propose a method for identifying important results from multiple statistical tests in multiple investigations. The method is illustrated by using high performance liquid chromatography to identify potential aetiologic contaminants in L-tryptophan samples.

Accumulation of 3-(phenylamino)alanine, a constituent in L-tryptophan products implicated in eosinophilia-myalgia syndrome, in blood and organs of the Lewis rats

3-(Phenylamino)alanine (PAA), a newly discovered impurity in case-associated L-tryptophan tablets, has been investigated as a possible contributing factor in the etiology of eosinophilia-myalgia syndrome (EMS). We have studied distribution and elimination of PAA in rats which were administered a single 5 mg/kg dose of PAA by gastric gavage. PAA concentrations in blood, brain, kidney and liver were measured by high-performance liquid chromatography (HPLC) with electrochemical detection. The concentration of PAA in each tissue reached a maximum at 5 h, and then gradually declined. A high level of PAA still remained at 24 h, indicating gradual elimination. The concentration of PAA in brain at 5 h was 2139 ng/g tissue, demonstrating passage through the blood-brain barrier. Consecutive administration of PAA (5 mg/kg) for 4 days resulted in approximately double the concentration in all tissues. Chronic treatment using PAA incorporated into food pellets for 6 weeks resulted in similar accumulations in each tissue, and following 12 days on a PAA free diet, levels of this drug were still detectable in all tissues.

Eosinophilia-myalgia syndrome and tryptophan production: a cautionary tale

An epidemic of a new disease, termed eosinophilia-myalgia syndrome, occurred in the USA in 1989. This syndrome was linked to the consumption of L-tryptophan manufactured by a single company utilizing a fermentation process. All the findings indicate that the illness was probably triggered by an impurity formed when the manufacturing conditions were modified. This outbreak highlights the need for close monitoring of the chemical purity of biotechnology-derived products, and for rigorous testing of such products following any significant changes to the manufacturing process.

Effect of 3-phenylamino-L-alanine on tryptophan binding to rat hepatic nuclear envelopes

We have determined that the addition of 3-phenylamino-L-alanine (PAA), a recently reported contaminant in L-tryptophan implicated in the eosinophilia-myalgia syndrome, affects tryptophan binding by utilizing an in vitro measurement of 3H-tryptophan binding to hepatic nuclei or nuclear envelopes. PAA (10(-10) to 10(-4) M) diminishes the inhibitory effect of binding due to excess unlabeled L-tryptophan (10(-4) M). PAA alone has no inhibitory effect on binding. The effect of PAA on in vitro tryptophan binding is in contrast to that of another contaminant, 1,1'-ethylidenebis(tryptophan), which together with excess unlabeled L-tryptophan does not appreciably affect the binding. In vitro addition of PAA and L-tryptophan to nuclei of rat brain or of cultured murine macrophages does not affect [3H]tryptophan binding in comparison to L-tryptophan alone as is the case with hepatic nuclear envelopes. Adding PAA to an in vitro protein synthesis system and measuring [3H]tryptophan or [3H]alanine incorporation into acid-precipitable proteins reveals that it competes similarly, but somewhat less, than does equimolar concentrations of unlabeled L-tryptophan or L-alanine, respectively. This suggests that PAA or a breakdown compound becomes incorporated into proteins. Speculation as to how PAA may affect tissues in experimental animals is presented.