Eosinophilia-myalgia syndrome case-associated contaminants in commercially available 5-hydroxytryptophan

Comparative assessment of toxic responses in 3D embryoid body differentiation model and mouse early embryos treated with 5-hydroxytryptophan

Pluripotent stem cells recapitulate in vitro the early developmental stages and are considered promising cell models for predictive developmental toxicity studies. To investigate the consistency between adverse drug effects on early development and the early stages of embryonic stem cell differentiation in three-dimensional (3D) in vitro culture, the toxic responses to 5-hydroxytryptophan (5-HTP; 0.5-2 mM) were evaluated in early mouse embryos and the embryoid body (EB) differentiation model. 3D architectures, developmental and differentiation dynamics and the cell death rates were analyzed in early mouse embryos (E2.5-E5.5) and EBs at 1 and 6 days of differentiation using a combination of confocal immunofluorescence microscopy with high content imaging analysis and quantitative gene expression analysis. Comparative analysis of toxic responses in early embryos and EBs revealed a similar dose- and stage-dependent decrease in the 5-HTP toxic effects during development and differentiation. The integral toxic responses in the early embryos and EBs were significantly dependent on their 3D architecture and cellular composition. Treatment with 5-HTP (1 mM and above) induced developmental arrest, growth inhibition, and increased cell death in the early embryos without the trophoblasts (E2.5) and those with impaired trophoblasts and in early EBs, whereas later embryos and EBs were more resistant due to the protection of the extraembryonic tissues. This study demonstrates that the EB differentiation model is a relevant 3D-model of early mammalian development and can be useful for the predictive evaluation of toxic and teratogenic effects in embryos at the preimplantation and early post-implantation developmental stages.

An Integrative Approach to Depression: Part 2—Assessment and Treatment

This article is the second of a two-part series presenting an integrative model for understanding and treating depression. In this part, the integrative model provides the basis for comprehensive assessment and treatment, guiding the application of a wide variety of treatments. Evidence-based complementary and conventional treatment modalities for depression are also reviewed.

A facile means for the identification of indolic compounds from plant tissues

The bulk of indole-3-acetic acid (IAA) in plants is found in the form of conjugated molecules, yet past research on identifying these compounds has largely relied on methods that were both laborious and inefficient. Using recent advances in analytical instrumentation, we have developed a simple yet powerful liquid chromatography-mass spectrometry (LC-MS)-based method for the facile characterization of the small IAA conjugate profile of plants. The method uses the well-known quinolinium ion (m/z 130.0651) generated in MS processes as a signature with high mass accuracy that can be used to screen plant extracts for indolic compounds, including IAA conjugates. We reinvestigated Glycine max (soybean) for its indoles and found indole-3-acetyl-trytophan (IA-Trp) in addition to the already known indole-3-acetyl-aspartic acid (IA-Asp) and indole-3-acetyl-glutamic acid (IA-Glu) conjugates. Surprisingly, several organic acid conjugates of tryptophan were also discovered, many of which have not been reported in planta before. These compounds may have important physiological roles in tryptophan metabolism, which in turn can affect human nutrition. We also demonstrated the general applicability of this method by identifying indolic compounds in different plant tissues of diverse phylogenetic origins. It involves minimal sample preparation but can work in conjunction with sample enrichment techniques. This method enables quick screening of IAA conjugates in both previously characterized as well as uncharacterized species, and facilitates the identification of indolic compounds in general.

Metabolomic study of insomnia and intervention effects of Suanzaoren decoction using ultra-performance liquid-chromatography/electrospray-ionization synapt high-definition mass spectrometry

Metabolomics is the comprehensive assessment of endogenous metabolites of a biological system in a holistic context, and its property consists with the global view of traditional Chinese medicine (TCM). Suanzaoren decoction (SZRD), an ancient TCM formulae, has been used for treating insomnia for centuries, and its mechanism remains unclear completely. This paper was designed to explore globally metabolomic characters of the insomnia and the therapeutic effects of SZRD. Ultra-performance liquid-chromatography/electrospray-ionization synapt high-definition mass spectrometry (UPLC/ESI-SYNAPT-HDMS) combined with pattern recognition approaches including principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA) were integrated to approximate the comprehensive metabolic signature and discover differentiating metabolites. The changes in metabolic profiling were restored to their baseline values after SZRD treatment according to the PCA score plots. Altogether, the current metabonomic approach based on UPLC/ESI-SYNAPT-HDMS indicate 20 ions (9 in the negative mode, 11 in the positive mode) as "differentiating metabolites". The alterations in these metabolites were associated with perturbations in amino acid and fatty acid metabolism, in response to insomnia through immune and nervous system. Of note, we found that SZRD increases sleep activity and exhibits binding affinity for serotonin receptors. These results implicate the therapeutic effects of SZRD may mediate through serotonergic activation. Our findings also show the robust UPLC/ESI-SYNAPT-HDMS techniques is promising for metabolites profiling analysis of TCM and open new perspectives to using metabolomics platform to resolve special TCM issues.

Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan

This paper reviews the preclinical and clinical evidence regarding the use of the dietary supplement 5-hydroxytryptophan (5-HTP) for the treatment of depression. In the absence of supplementation with exogenous 5-HTP, the amount of endogenous 5-HTP available for serotonin synthesis depends on the availability of tryptophan and on the activity of various enzymes, especially tryptophan hydroxylase, indoleamine 2,3-dioxygenase, and tryptophan 2,3-dioxygenase (TDO). Factors affecting each of these are reviewed. The amount of 5-HTP reaching the central nervous system (CNS) is affected by the extent to which 5-HTP is converted to serotonin in the periphery. This conversion is controlled by the enzyme amino acid decarboxylase, which, in the periphery, can be blocked by peripheral decarboxylase inhibitors (PDIs) such as carbidopa. Preclinical and clinical evidence for the efficacy of 5-HTP for depression is reviewed, with emphasis on double-blind, placebo-controlled (DB-PC) trials. Safety issues with 5-HTP are also reviewed, with emphasis on eosinophilia myalgia syndrome (EMS) and serotonin syndrome.

Safety of 5-hydroxy-L-tryptophan

5-Hydroxy-L-tryptophan (5-HTP) is the immediate precursor in the biosynthesis of 5-hydroxy-tryptamine (5-HT; serotonin) from the essential amino acid L-tryptophan (L-Trp). The use of L-Trp as a dietary supplement was discontinued in 1989 due to an outbreak of eosinophilia-myalgia syndrome (EMS) that was traced to a contaminated synthetic L-Trp from a single manufacturer. 5-HTP has since become a popular dietary supplement in lieu of the removal of L-Trp from the market. Because of its chemical and biochemical relationship to L-Trp, 5-HTP has been under vigilance by consumers, industry, academia and government for its safety. However, no definitive cases of toxicity have emerged despite the worldwide usage of 5-HTP for last 20 years, with the possible exception of one unresolved case of a Canadian woman. Extensive analyses of several sources of 5-HTP have shown no toxic contaminants similar to those associated with L-Trp, nor the presence of any other significant impurities. A minor chromatographic peak (peak X) reported in some 5-HTP samples lacks credibility due to chromatographic artifacts and infinitesimal concentrations, and has raised undue speculations concerning its chemistry and toxicity.