Excretion patterns of tryptamine, indoleacetic acid, and 5-hydroxyindoleacetic acid, and their correlation with mental changes in schizophrenic patients under medication with alpha-methyldopa

Design, Synthesis and Bioactivity Evaluation of Novel Chalcone Derivatives Possessing Tryptophan Moiety with Dual Activities of Anti-cancer and Partially Restoring the Proliferation of Normal Kidney Cells Pre-treated with Cisplatin

BACKGROUND

Chalcone is a broad-spectrum natural product with anti-cancer and anti-inflammatory activities. However, low potency, low selectivity, and serious side effects limit its druggability. L-Tryptophan is an essential precursor molecule of an anti-cancer active substance. Also, the indole moiety inhibits the proliferation of tumor cells by binding to colchicine sites. A decrease in kidney cell activity caused by kidney inflammation is the primary side effect of cancer therapy.

OBJECTIVE

The purpose of this work was to design, synthesize, and perform bioactivity evaluation of novel chalcone derivatives possessing tryptophan moiety with dual activities of anti-cancer and partially restoring the proliferation of normal kidney cells pre-treated with cisplatin.

METHODS

A series of novel chalcone derivatives possessing tryptophan moiety (5a-5g, 6a-6o) were designed, synthesized, and evaluated for anti-cancer activity against four cancer cell lines (gastric (HGC-27), colon (HCT-116), prostate (PC-3), and lung (A549)), and a human normal cell line (gastric mucosal epithelial (GES-1)). The activity of restoring the proliferation of normal kidney cells pre-treated with cisplatin was evaluated by MTT assay. Cell cycle, apoptosis, and apoptosis proteins (Bax and Bcl-2) were used to evaluate the anti-cancer mechanism of the most potent compound. Moreover, a docking study was performed to explain the high anti-cancer activity of 6n. The expressions of TNF-α, IL-6, and MCP-1 were detected by ELISA.

RESULTS

Most of the compounds exhibited high anti-cancer activity against the HGC-27 cell line and exhibited low toxicity against the normal cell line. Based on three rounds of a structure optimization, 6n was discovered as the most potent compound against HGC-27 cells with an IC50 value of 2.02 μM and an SI value of 28.47. Further studies demonstrated that 6n could induce cell cycle arrest at the G2/M phase and the apoptosis of the HGC-27 cell line by reducing the expression of Bcl-2 and improving the expression level of Bax. Molecular docking result displayed 6n bound to the colchicine site. At the same time, 6n also exhibited moderate activity of restoring the proliferation of normal kidney cells pre-treated with cisplatin by reducing the expression of inflammatory substances.

CONCLUSION

Our findings collectively suggested that 6n should be further studied as a potential anti-cancer agent that could partially restore the proliferation of normal kidney cells pre-treated with cisplatin in gastric cancer patients by an anti-inflammatory pathway.

Accessing Bioactive Natural Products from the Human Microbiome

Natural products have long played a pivotal role in the development of therapeutics for a variety of diseases. Traditionally, soil and marine environments have provided a rich reservoir from which diverse chemical scaffolds could be discovered. Recently, the human microbiome has been recognized as a promising niche from which secondary metabolites with therapeutic potential have begun to be isolated. In this Review, we address how the expansive history of identifying bacterial natural products in other environments is informing the approaches being brought to bear on the study of the human microbiota. We also touch on how these tools can lead to insights about microbe-microbe and host-microbe interactions and help generate biological hypotheses that may lead to developments of new therapeutic modalities.

The emerging roles of human trace amines and human trace amine-associated receptors (hTAARs) in central nervous system

Human trace amines (TAs) are endogenous compounds, previously almost ignored in human pathology for many reasons (difficulty of their measurement in biological fluids, unknown receptors for elusive amines), are now considered to play a significant role in synaptic transmission within the central nervous system (CNS) acting as neuromodulators. The recent discovery of a novel family of G-protein-coupled receptors (GPCRs) that includes individual members that are highly specific for TAs indicates a potential role for TAs as vertebrate neurotransmitters or neuromodulators, although the majority of these GPCRs so far have not been demonstrated to be activated by TAs. Human trace amine receptors (including TAAR1 TAAR2 TAAR5 TAAR6 TAAR8 TAAR9) are expressed in the brain and play significant physiological and neuropathological roles by activation of trace amines. We herein discuss the recent findings that provide insights into the functional roles of human trace amines (including P-Octopamine, β phenylethylamine, Tryptamine, Tyramine, Synephrine, 3-Iodothyronamine, 3-Methoxytyramine, N-Methyltyramine, N-Methylphenethylamine) in brain. Furthermore, we discuss the known functions of human trace amine receptors in brain.

Acetaldehyde and parkinsonism: role of CYP450 2E1

The present review update the relationship between acetaldehyde (ACE) and parkinsonism with a specific focus on the role of P450 system and CYP 2E1 isozyme particularly. We have indicated that ACE is able to enhance the parkinsonism induced in mice by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, a neurotoxin able to damage the nigrostriatal dopaminergic pathway. Similarly diethyldithiocarbamate, the main metabolite of disulfiram, a drug widely used to control alcoholism, diallylsulfide (DAS) and phenylisothiocyanate also markedly enhance the toxin-related parkinsonism. All these compounds are substrate/inhibitors of CYP450 2E1 isozyme. The presence of CYP 2E1 has been detected in the dopamine (DA) neurons of rodent Substantia Nigra (SN), but a precise function of the enzyme has not been elucidated yet. By treating CYP 2E1 knockout (KO) mice with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, the SN induced lesion was significantly reduced when compared with the lesion observed in wild-type animals. Several in vivo and in vitro studies led to the conclusion that CYP 2E1 may enhance the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine toxicity in mice by increasing free radical production inside the dopaminergic neurons. ACE is a good substrate for CYP 2E1 enzyme as the other substrate-inhibitors and by this way may facilitate the susceptibility of dopaminergic neurons to toxic events. The literature suggests that ethanol and/or disulfiram may be responsible for toxic parkinsonism in human and it indicates that basal ganglia are the major targets of disulfiram toxicity. A very recent study reports that there are a decreased methylation of the CYP 2E1 gene and increased expression of CYP 2E1 mRNA in Parkinson's disease (PD) patient brains. This study suggests that epigenetic variants of this cytochrome contribute to the susceptibility, thus confirming multiples lines of evidence which indicate a link between environmental toxins and PD.

Tryptamine: a metabolite of tryptophan implicated in various neuropsychiatric disorders

Although early interest in the biomedical relevance of tryptamine has waned in recent years, it is clear from the above discussion that the study of tryptamine is worthy of serious consideration as a factor in neuropsychiatric disorders. The study of [3H]-tryptamine binding sites indicates an adaptive responsiveness characteristic of functional receptors. The question raised by Jones (1982d) on whether tryptamine is acting centrally as a neurotransmitter or a neuromodulator still remains mostly unanswered, although the evidence cited within this review strongly suggests a modulatory role for this neuroactive amine (see also Juorio and Paterson, 1990). The synthesis and degradative pathways of tryptamine, as well as the intricate neurochemical and behavioral consequences of altering these pathways, are now more fully understood. It is not yet clear what the role of tryptamine is under normal physiological [homeostatic] conditions, however, its role during pathological conditions such as mental and physical stress, hepatic dysfunction and other disorders of metabolism (i.e. electrolyte imbalance, increased precursor availability, enzyme induction or alterations in enzyme co-factor availability) may be quite subtle, perhaps accounting for various sequelae hitherto considered idiopathic. The evidence for a primary role for tryptamine in the etiology of mental or neurological diseases is still relatively poor, although the observations that endogenous concentrations of tryptamine are particularly susceptible to pharmacological as well as physiological manipulations serve to reinforce the proposition that this indoleamine is not simply a metabolic accident but rather a neuroactive compound in its own right. Finally, one might wonder what proportion of the data attributed to modifications of 5-HT metabolism might, in fact, involve unrecognized changes in the concentrations of other neuroactive metabolites of tryptophan such as tryptamine.

Effects of age and of chronic antidepressant treatment on [3H]tryptamine and [3H]dihydroalprenolol binding to rat cortical membranes

1. The effects of age and of chronic antidepressant treatment on [3H]tryptamine and [3H]dihydroalprenolol binding site density were measured in brain cortical membranes from male Sprague-Dawley rats. 2. The density but not the affinity of [3H]tryptamine binding sites was increased in 18-month-old rats relative to 3-month-old rats. Neither the density nor the affinity of [3H]dihydroalprenolol binding sites was affected by age. 3. Chronic administration (28 days s.c. via Alzet osmotic minipumps) of tricyclic antidepressant drugs (daily doses: imipramine.HCl, 30 mg kg-1; desipramine.HCl, 10 mg kg-1; clomipramine.HCl, 10 mg kg-1) resulted in decreases in [3H]dihydroalprenolol binding site density but no changes in [3H]tryptamine binding site density; no changes in affinity of either site were observed. 4. Chronic administration (s.c. via Alzet osmotic minipumps) of monoamine oxidase inhibitor antidepressant drugs (daily doses: tranylcypromine.HCl, 0.5 and 1.0 mg kg-1; phenelzine sulfate, 5 and 10 mg kg-1, each for 28 days; clorgyline.HCl, 1.0 mg kg-1; (-)-deprenyl.HCl, 1.0 mg kg-1, each for 14 days) resulted in decreases in [3H]tryptamine binding site density, without any effects on the affinity of this site. In addition, each of these monoamine oxidase inhibitors except (-)-deprenyl resulted in a decrease in [3H]dihydroalprenolol binding site density. No affinity changes were observed. 5. These data indicate that the [3H]tryptamine binding site exhibits physiological changes with aging and is differentially sensitive to the actions of tricyclic antidepressants and monoamine oxidase inhibitor antidepressants, respectively.

Biogenic amines and their metabolites in body fluids of normal, psychiatric and neurological subjects

The biogenic monoamines and their metabolites have been isolated, identified and quantified in human body fluids over the past forty years using a wide variety of chromatographic separation and detection techniques. This review summarizes the results of those studies on normal, psychiatric and neurological subjects. Tables of normal values and the methods used to obtain them should prove to be useful as a reference source for benchmark amine and metabolite concentrations and for successful analytical procedures for their chromatographic separation, detection and quantification. Summaries of the often contradictory results of the application of these methods to psychiatric and neurological problems are presented and may assist in the assessment of the validity of the results of experiments in this field. Finally, the individual, environmental and the methodological factors affecting the concentrations of the amines and their metabolites are discussed.

Tryptamine: a neuromodulator or neurotransmitter in mammalian brain?

Tryptamine synthesized by decarboxylation of L-tryptophan occurs as an endogenous constituent of mammalian brain albeit at very low concentrations (low ng/g range). It is primarily metabolized by oxidative deamination by MAO and possesses an extremely rapid turnover and half-life. Subcellular localization appears to be in nerve terminals and it is releasable by electrical or potassium evoked depolarization. Neuropharmacological and electrophysiological data strongly suggest the existence of post-synaptic receptors for tryptamine independent of those for 5HT. There may exist a rostrally projecting neuronal tryptamine containing system arising from cell bodies in or close to the nucleus raphé medianus. The demonstration of specific receptors for tryptamine in the CNS strongly indicates a transmitter role, although a strong case can be made for a role as a modifier of central 5HT systems. The possibility also exists that 5HT and tryptamine may be mediators of functionally opposite neuronal pathways. Whatever the role of tryptamine in the CNS it is clear that it not simply present as an accident of metabolism or a "biological artefact." The indications are that it possesses important functions in central neurotransmission.

The dependence of tryptamine excretion on urinary pH

It is demonstrated that urinary tryptamine decreases significantly with increasing urinary pH. This effect becomes important at a urinary pH of 6.5 and over.