Aromatic Amino Acid Metabolism Research Articles

Metabolomics-based assessment of nanoparticles (nZnO) toxicity in an infaunal marine annelid, the lugworm Arenicola marina (Annelida: Sedentaria)

Nanopollutants such as nZnO gain importance as contaminants of emerging concern due to their high production volume and potential toxicity. Coastal sediments serve as sinks for nanoparticles but the impacts and the toxicity mechanisms of nZnO in sediment-dwelling organisms are not well understood. We used metabolomics to assess the effects of nZnO-contaminated sediments on a benthic ecosystem engineer, an infaunal polychaete Arenicola marina. The worms were exposed to unpolluted (control) sediment or to the sediment spiked with 100 or 1000 μg Zn kg−1 of nZnO. Oxidative lesions (lipid peroxidation and protein carbonyls) were measured in the body wall as traditional biomarkers of nanopollutant toxicity. Metabolite profiles (including amino acids, tricarboxylic acid (TCA) cycle and urea cycle intermediates) were determined in the body wall and the coelomic fluid. Exposure to nZnO altered metabolism of the lugworms via suppression of the metabolism of gluconeogenic and aromatic amino acids, and altered the TCA cycle likely via suppression of fumarase activity. These metabolic changes may negatively affect carbohydrate metabolism and energy storage, and impair hormonal signaling in the worms. The total pool of free amino acids was depleted in nZnO exposures with potentially negative consequences for osmoregulation and protein synthesis. Exposure to nZnO led to accumulation of the lipid peroxidation products demonstrating high susceptibility of the cellular membranes to nZnO-induced oxidative stress. The nZnO-induced shifts in the metabolite profiles were more pronounced in the coelomic fluid than the body wall. This finding emphasizes the important metabolic role of the coelomic fluid as well as its suitability for assessing the toxic impacts of nZnO and other metabolic disruptors. The metabolic disruptions caused by environmentally relevant concentrations of nZnO can have negative effects on the organisms' fitness impairing growth and reproduction of the populations of marine bioturbators like the lugworms in nanoparticle-polluted sediments.

OR14-5 Branched-chain Amino Acid and Tryptophan Metabolism and the Pathogenesis of Youth-Onset Type 2 Diabetes Mellitus (T2D)

Abstract Objectives We have previously demonstrated that insulin resistance (IR) in youth is associated with elevated levels of branched-chain amino acids (BCAAs). BCAAs compete with aromatic amino acids (AAA) including tryptophan, the precursor of serotonin, for uptake into β-cells and other tissues via the large neutral amino acid transporter. Serotonin has been reported to increase β-cell mass and glucose-dependent insulin secretion. In this study we have explored how BCAA, tryptophan (one of the AAA), and a subset of their metabolites are modulated in youth-onset T2D. Based on our prior studies in neuronal BCAA metabolism, we hypothesized that elevated BCAA could induce diversion of tryptophan metabolism towards production of kynurenine rather than serotonin in youth with T2D. To test this, we analyzed 24-hour urine samples and compared levels of byproducts of BCAAs and tryptophan metabolism in obese youth with T2D with those in non-diabetic obese and lean youth of comparable age, pubertal status and ethnicity. Methods 56 non-diabetic adolescents with overweight/obesity ("obese"), 42 adolescents with T2D ("T2D"), and 43 normal weight controls ("lean"), ages 12-21 years-old were studied. Weight, height, BMI, BMI% were extracted from medical charts. Body fat percent (BF%) was measured by TANITA. We also measured metabolites derived from BCAA catabolism, including the branched-chain ketoacids (BCKAs), and tryptophan metabolism, including intermediates of the serotonergic and kynurenine pathways, in spot and 24-hour urine samples by liquid chromatography/tandem-mass spectrometry (LC/MS-MS). Levels were normalized to urine creatinine. Group differences were assessed by Kruskal Wallis or ANOVA. Results Groups were comparable for age (obese 14.8 +/- 1.9; T2D 15.7 +/- 2.1 and lean 14.9 +/- 1.9-yr), pubertal status, and ethnicity. Youth with T2D were predominantly female (T2D, 28 F, 14 M; obese 33 F, 23 M and lean, 17 F, 26 M), and had highest BF% (obese 37.3 +/- 9.5; T2D 42.9 +/- 9.9; lean 20.1 +/- 6.3%; p=2.58e-22). In 24-hour urine samples, BCKAs, tryptophan, and kynurenine levels were higher in T2D (p=0.0002, p= 0.0045 and p= 0.00009 respectively) than in either lean controls or nondiabetic youth with obesity; in contrast, there were no differences between lean controls and non-diabetic youth with obesity. The levels of 5-HIAA, the principal metabolite of serotonin, were comparable across groups; however, the ratio of kynurenine/tryptophan was higher (p= 0.0112) in youth with T2D and the ratios of 5-HIAA/ tryptophan (p=0.027) and 5-HIAA/Kynurenine (p=0.0067) were lower compared to the other two groups. Those ratios were comparable between lean controls and non-diabetic youth with obesity. Conclusions Increased BCKAs are accompanied by diversion of tryptophan metabolism from the serotonin pathway to the kynurenine pathway, suggesting perturbations in both BCAA and AAA metabolism in youth-onset T2D. These alterations could contribute to development of beta-cell dysfunction and progression to T2D in youth. Presentation: Sunday, June 12, 2022 12:00 p.m. - 12:15 p.m.

Time-restricted feeding affects transcriptomic profiling of hypothalamus in pigs through regulating aromatic amino acids metabolism.

Time-restricted feeding (TRF) is an effective means that can efficiently regulate the metabolism and health of animals and humans. However, the effect of TRF on hypothalamic function remains unclear. Results showed that TRF significantly increased the activities of digestive enzymes lipase, maltase in the duodenum and lipase, trypsin in the pancreas whereas significantly decreased serum gastrointestinal hormones gastrin, glucagon-like peptide-1, cholecystokinin, peptide YY, and ghrelin. Metabolites related to amino acid metabolism, including citrulline, kynurenine, N-acetylleucine, l-tryptophan, and l-tyrosine, significantly increased in the TRF group. Differential metabolites were mainly enriched in phenylalanine, tyrosine, and tryptophan biosynthesis and tryptophan metabolism. Transcriptomic analysis of hypothalamus showed that a total of 462 differentially expressed genes (DEGs) were significantly changed by TRF. In particular, DEGs such as DDC, TH, GOT2, and DBH involved in aromatic amino acid metabolism pathways were significantly downregulated, whereas the expression of CYP1B1 was significantly upregulated. Moreover, DEGs (PDYN and PPP3CA) involved in amphetamine addiction and cocaine addiction were also downregulated in the TRF group. Taken together, these results suggested that TRF improved the digestion and absorption of nutrients and thus increased the accessibilities of aromatic amino acids. The increasing of circulating aromatic amino acids might mediate the regulatory neuroendocrine effects of TRF regimes on the hypothalamus functions, especially on drug addictions. This study reveals a possible mechanism underlying the effects of regulating feeding patterns on the function of the hypothalamus by altering aromatic amino acids metabolism. © 2022 Society of Chemical Industry.

Metabolomic Signatures of Autism Spectrum Disorder.

Autism Spectrum Disorder (ASD) is associated with many variations in metabolism, but the ex-act correlates of these metabolic disturbances with behavior and development and their links to other core metabolic disruptions are understudied. In this study, large-scale targeted LC-MS/MS metabolomic analysis was conducted on fasting morning plasma samples from 57 children with ASD (29 with neurodevelopmental regression, NDR) and 37 healthy controls of similar age and gender. Linear model determined the metabolic signatures of ASD with and without NDR, measures of behavior and neurodevelopment, as well as markers of oxidative stress, inflammation, redox, methylation, and mitochondrial metabolism. MetaboAnalyst ver 5.0 (the Wishart Research Group at the University of Alberta, Edmonton, Canada) identified the pathways associated with altered metabolic signatures. Differences in histidine and glutathione metabolism as well as aromatic amino acid (AAA) biosynthesis differentiated ASD from controls. NDR was associated with disruption in nicotinamide and energy metabolism. Sleep and neurodevelopment were associated with energy metabolism while neurodevelopment was also associated with purine metabolism and aminoacyl-tRNA biosynthesis. While behavior was as-sociated with some of the same pathways as neurodevelopment, it was also associated with alternations in neurotransmitter metabolism. Alterations in methylation was associated with aminoacyl-tRNA biosynthesis and branched chain amino acid (BCAA) and nicotinamide metabolism. Alterations in glutathione metabolism was associated with changes in glycine, serine and threonine, BCAA and AAA metabolism. Markers of oxidative stress and inflammation were as-sociated with energy metabolism and aminoacyl-tRNA biosynthesis. Alterations in mitochondrial metabolism was associated with alterations in energy metabolism and L-glutamine. Using behavioral and biochemical markers, this study finds convergent disturbances in specific metabolic pathways with ASD, particularly changes in energy, nicotinamide, neurotransmitters, and BCAA, as well as aminoacyl-tRNA biosynthesis.

Comparative Metagenomics and Metabolomes Reveals Abnormal Metabolism Activity Is Associated with Gut Microbiota in Alzheimer's Disease Mice.

A common symptom in Alzheimer’s disease (AD) is cognitive decline, of which the potential pathogenesis remains unclear. In order to understand the mechanism of gut microbiota in AD, it is necessary to clarify the relationship between gut microbiota and metabolites. Behavioral tests, pathological examination, metagenomics, and metabolomics were applied to analyze the difference of gut microbiota and metabolome between APPswe/PS1ΔE9 (PAP) mice with cognitive decline and age-matched controls, and their possible correlations. Our results showed that PAP mice and health mice had different structures of the bacterial communities in the gut. The abundances and diversities of the bacterial communities in health mice were higher than in PAP mice by metagenomics analysis. The abundances of Libanicoccus massiliensis, Paraprevotella clara, and Lactobacillus amylovorus were significantly increased in PAP mice, while the abundances of Turicibacter sanguinis, Dubosiella newyorkensis, and Prevotella oris were greatly reduced. Furthermore, PAP mice possessed peculiar metabolic phenotypes in stool, serum, and hippocampus relative to WT mice, as is demonstrated by alterations in neurotransmitters metabolism, lipid metabolism, aromatic amino acids metabolism, energy metabolism, vitamin digestion and absorption, and bile metabolism. Microbiota–host metabolic correlation analysis suggests that abnormal metabolism in stool, serum, and hippocampus of PAP mice may be modulated by the gut microbiota, especially T. sanguinis, D. newyorkensis, and P. oris. Therefore, abnormal metabolism activity is associated with gut microbiota in Alzheimer’s disease mice. Our results imply that modifying host metabolism through targeting gut microbiota may be a novel and viable strategy for the prevention and treatment of AD in the future.

Colchicine increases intestinal toxic load by disturbing fecal metabolome homeostasis in mice

Colchicine (COL) has been used to treat gout for over a millennium, but its medicinal use has been controversial due to its potent toxicity in the gastrointestinal tract. Nausea, vomiting, and diarrhea are the most prominent external manifestations of COL gastrointestinal toxicity, but the cause of these adverse events remains obscure. In this study, the mice were exposed to COL (2.5 mg/kg b.w./day) for one week to study the mechanism of COL-induced diarrhea from the perspective of intestinal metabolism. The results showed that COL exposure disturbed intestinal metabolic homeostasis, resulting in a significant accumulation of 116 metabolites and, conversely, significant depletion of 64 metabolites, with the number of differential metabolites being one-eighth of the total metabolites (180/1445). Also, it was found that cAMP, Adenosine 5′-monophosphate, GDP, Inositol, and Cortisol are core metabolites that play crucial roles in COL-induced metabolic disorders. These metabolites could be used as biomarkers to differentiate control and COL-treated groups, implying that these metabolites may be closely related to COL-induced diarrhea. Furthermore, changes in the metabolic pathways (Purine metabolism, biosynthesis and metabolism of aromatic amino acids, and Bile secretion) involved in these five core metabolites increased the toxic load in the gut, which was the culprit leading to intestinal metabolic disorders. In addition, the abnormal bile secretion caused by COL exposure may play an important role in COL-induced diarrhea. In conclusion, our study opens new avenues for understanding the mechanisms of COL-induced gastrointestinal adverse reactions and broadens the scientific horizon on the interactions between COL and host metabolism.

Use of high-resolution metabolomics to assess the biological perturbations associated with maternal exposure to Bisphenol A and Bisphenol F among pregnant African American women

BackgroundHuman and animal exposure to bisphenol A (BPA) has been associated with adverse developmental and reproductive effects. The molecular mechanisms by which BPA exposure exerts its effects are not well-understood, even less known about its analogues bisphenol F (BPF). To address these knowledge gaps, we conducted an untargeted metabolome-wide association study (MWAS) to identify metabolic perturbations associated with BPA/BPF exposures in a pregnant African American cohort. MethodsFrom a subset of study participants enrolled in the Atlanta African American Maternal-Child cohort, we collected both urine samples, for targeted exposure assessment of BPA (N = 230) and BPF (N = 48), and serum samples, for high-resolution metabolomics (HRM) profiling (N = 230), during early pregnancy (8–14 weeks’ gestation). Using an established untargeted HRM workflow consisting of MWAS modeling, pathway enrichment analysis, and chemical annotation and confirmation, we investigated the potential metabolic pathways and features associated with BPA/BPF exposures. ResultsThe geometric mean creatinine-adjusted concentrations of urinary BPA and BPF were 0.85 ± 2.58 and 0.70 ± 4.71 µg/g creatinine, respectively. After false positive discovery rate correction at 20 % level, 264 and 733 unique metabolic features were significantly associated with urinary BPA and BPF concentrations, representing 10 and 12 metabolic pathways, respectively. Three metabolic pathways, including steroid hormones biosynthesis, lysine and lipoate metabolism, were significantly associated with both BPA and BPF exposure. Using chemical standards, we have confirmed the chemical identity of 16 metabolites significantly associated with BPA or BPF exposure. ConclusionsOur findings support that exposure to BPA and BPF in pregnant women is associated with the perturbation of aromatic amino acid metabolism, xenobiotics metabolism, steroid biosynthesis, and other amino acid metabolism closely linked to stress responses, inflammation, neural development, reproduction, and weight regulation.

Unearthing the mechanisms underlying calcium carbonate therapies for eliminating pathogens during composting

The elimination of pathogens during composting is crucial for safe utilization of organic fertilizers and food security. Nevertheless, simple, low-cost and eco-friendly techniques for pathogen elimination are extremely scarce. The current study was aimed to explore mechanisms underlying the effects of calcium carbonate (CaCO3) addition on pathogen elimination during composting. High throughput sequencing and metabolomic analysis were adopted to determine the efficiency of CaCO3 in pathogen elimination. CaCO3 addition significantly decreased the abundance of pathogens along with increased temperature, pH, electrical conductivity, and extracellular enzyme activities of composting. CaCO3 strongly changed fungal community composition and increased fungal Shannon index and Phylogenetic diversity at the mesophilic phase with Shannon index positively related to pathogen abundance. The fungal function of Plant Pathogen significantly decreased at the thermophilic phase under CaCO3 addition. Antipathogenic metabolites were significantly increased under CaCO3 addition, including 8-iso Prostaglandin F2-Ethanolamide from Fatty acids degradation, Xanthium, 5-(3,4-dihydroxybenzylidene) hexahydropyrimidine-2,4,6-trione and Evernic acid from Aromatic amino acids metabolism, which were responsible for the elimination of Fusarium, Erysiphe, Colletotrichum, Pseudocercospora, Pythium, and Verticillium at the thermophilic phase. Our findings demonstrate that CaCO3 addition could efficiently eliminate pathogens during composting, so that benefit agricultural disease control and food security.

Presence of Blastocystis in gut microbiota is associated with cognitive traits and decreased executive function

Growing evidence implicates the gut microbiome in cognition. Blastocystis is a common gut single-cell eukaryote parasite frequently detected in humans but its potential involvement in human pathophysiology has been poorly characterized. Here we describe how the presence of Blastocystis in the gut microbiome was associated with deficits in executive function and altered gut bacterial composition in a discovery (n = 114) and replication cohorts (n = 942). We also found that Blastocystis was linked to bacterial functions related to aromatic amino acids metabolism and folate-mediated pyrimidine and one-carbon metabolism. Blastocystis-associated shifts in bacterial functionality translated into the circulating metabolome. Finally, we evaluated the effects of microbiota transplantation. Donor’s Blastocystis subtypes led to altered recipient’s mice cognitive function and prefrontal cortex gene expression. In summary, Blastocystis warrant further consideration as a novel actor in the gut microbiome-brain axis.

Novel Plasma Metabolomic Markers Associated with Diabetes Progression in Older Puerto Ricans.

We assessed longitudinal associations between plasma metabolites, their network-derived clusters, and type 2 diabetes (T2D) progression in Puerto Rican adults, a high-risk Hispanic subgroup with established health disparities. We used data from 1221 participants free of T2D and aged 40–75 years at baseline in the Boston Puerto Rican Health and San Juan Overweight Adult Longitudinal Studies. We used multivariable Poisson regression models to examine associations between baseline concentrations of metabolites and incident T2D and prediabetes. Cohort-specific estimates were combined using inverse-variance weighted fixed-effects meta-analyses. A cluster of 13 metabolites of branched chain amino acids (BCAA), and aromatic amino acid metabolism (pooled IRR = 1.87, 95% CI: 1.28; 2.73), and a cell membrane component metabolite cluster (pooled IRR = 1.54, 95% CI: 1.04; 2.27) were associated with a higher risk of incident T2D. When the metabolites were tested individually, in combined analysis, 5 metabolites involved in BCAA metabolism were associated with incident T2D. These findings highlight potential prognostic biomarkers to identify Puerto Rican adults who may be at high risk for diabetes. Future studies should examine whether diet and lifestyle can modify the associations between these metabolites and progression to T2D.

The formation mechanisms of key flavor substances in stinky tofu brine based on metabolism of aromatic amino acids

Understanding the formation mechanism of the flavor compounds in stinky tofu brine is crucial for controlling the flavor quality of Changsha stinky tofu. Dynamic changes in associated bacteria, enzymes, and differential metabolites in the metabolic pathway of aromatic amino acids in brine were investigated. Results showed that phenol (0.39～89.96 μg/mL), p-cresol (0.19～389.62 μg/mL), indole (1.14～242.97 μg/mL), 3-methylindole (0.14～3.00 μg/mL) were the key flavor substances of brine. The main associated bacteria Clostridiales bacterium SYSU GA17129, Aneurinibacillus aneurinilyticus, and Anaerosalibacter massiliensis were significantly positively correlated with key flavor substances (P < 0.05). The main associated enzymes were transaminase, decarboxylase, and lyase. In summary, phenol and p-cresol were formed by the metabolism of tyrosine and phenylalanine through five reaction chains, and indole and 3-methylindole were formed by the metabolism of tryptophan through one and three reaction chains, respectively.

Sex differences in global metabolomic profiles of COVID-19 patients

Coronavirus disease (COVID-19), caused by SARS-CoV-2, leads to symptoms ranging from asymptomatic disease to death. Although males are more susceptible to severe symptoms and higher mortality due to COVID-19, patient sex has rarely been examined. Sex-associated metabolic changes may implicate novel biomarkers and therapeutic targets to treat COVID-19. Here, using serum samples, we performed global metabolomic analyses of uninfected and SARS-CoV-2-positive male and female patients with severe COVID-19. Key metabolic pathways that demonstrated robust sex differences in COVID-19 groups, but not in controls, involved lipid metabolism, pentose pathway, bile acid metabolism, and microbiome-related metabolism of aromatic amino acids, including tryptophan and tyrosine. Unsupervised statistical analysis showed a profound sexual dimorphism in correlations between patient-specific clinical parameters and their global metabolic profiles. Identification of sex-specific metabolic changes in severe COVID-19 patients is an important knowledge source for researchers striving for development of potential sex-associated biomarkers and druggable targets for COVID-19 patients.

Diosgenin Ameliorates Non-alcoholic Fatty Liver Disease by Modulating the Gut Microbiota and Related Lipid/Amino Acid Metabolism in High Fat Diet-Fed Rats.

Non-alcoholic fatty liver disease (NAFLD) is a metabolic disease closely associated with dietary habits. Diosgenin is abundant in yam, a common food and traditional Chinese medicine. The molecular mechanism of diosgenin on NAFLD has been preliminarily explored. However, the effect of diosgenin on metabolism and gut microbiota in NAFLD has not been reported. This study confirmed that diosgenin could suppress excessive weight gain, reduce serum levels of total cholesterol and triglycerides, and decrease liver fat accumulation in high-fat diet-induced NAFLD rats. Moreover, fecal metabolomics analysis suggested diosgenin improved abnormal lipid and amino acid metabolism. Bile acids, including lithocholic acid and ursodeoxycholic acid 3-sulfate that function as excretion, absorption, and transport of fats, were remarkably regulated by diosgenin. Aromatic amino acid and lysine metabolism was regulated by diosgenin as well. 16S rRNA gene sequencing analysis demonstrated that diosgenin restored gut microbiota disorder, especially Globicatella, Phascolarctobacterium, Pseudochrobactrum, and uncultured_bacterium_f_Prevotellaceae at the genus level. Additionally, these regulated bacterial genera showed significant correlations with lipid and amino acid metabolism-related biomarkers. This study further confirmed the significant effect of diosgenin on NAFLD, and provided a new perspective for the mechanism.

De novo biosynthesis of diverse plant-derived styrylpyrones in Saccharomyces cerevisiae

Plant styrylpyrones exerting well-established neuroprotective properties have attracted increasing attention in recent years. The ability to synthesize each individual styrylpyrone in engineered microorganisms is important to understanding the biological activity of medicinal plants and the complex mixtures they produce. Microbial biomanufacturing of diverse plant-derived styrylpyrones also provides a sustainable and efficient approach for the production of valuable plant styrylpyrones as daily supplements or potential drugs complementary to the prevalent agriculture-based approach. In this study, we firstly demonstrated the heterogenous biosynthesis of two 7,8-saturated styrylpyrones (7,8-dihydro-5,6-dehydrokavain (DDK) and 7,8-dihydroyangonin (DHY)) and two 7,8-unsaturated styrylpyrones (desmethoxyyangonin (DMY) and yangonin (Y)), in Saccharomyces cerevisiae. Although plant styrylpyrone biosynthetic pathways have not been fully elucidated, we functionally reconstructed the recently discovered kava styrylpyrone biosynthetic pathway that has high substrate promiscuity in yeast, and combined it with upstream hydroxycinnamic acid biosynthetic pathways to produce diverse plant-derived styrylpyrones without the native plant enzymes. We optimized the de novo pathways by engineering yeast endogenous aromatic amino acid metabolism and endogenous double bond reductases and by CRISPR-mediated δ-integration to overexpress the rate-limiting pathway genes. These combinatorial engineering efforts led to the first three yeast strains that can produce diverse plant-derived styrylpyrones de novo, with the titers of DDK, DMY and Y at 4.40 μM, 1.28 μM and 0.10 μM, respectively. This work has laid the foundation for larger-scale styrylpyrone biomanufacturing and the complete biosynthesis of more complicated plant styrylpyrones.

Microbiome-metabolomics insights into the feces of high-fat diet mice to reveal the anti-obesity effects of yak (Bos grunniens) bone collagen hydrolysates

In this study, a twelve-week intervention was conducted to investigate the anti-obesity effects of yak bone collagen hydrolysates (YBCH) on mice with a high-fat diet. The obesity-associated phenotypes of mice were detected and the feces of mice were jointly analyzed by 16S rRNA gene sequencing and untargeted metabolomics. Results indicated that supplementation with YBCH could ameliorate the obesity-associated phenotypes of mice, especially with the medium dose (MD) and high dose (HD) of YBCH. Compared with the high-fat diet control (HC) group, the ratio of Firmicutes and Bacteroidetes in the fecal microbiota of the low dose (LD), MD, and HD groups was separately decreased by 29.83 %, 70.85 %, and 75.70 %. Lachnospiraceae and Muribaculaceae were the key bacteria for the YBCH intervention, which might be attributed to their different substrate preferences. The joint analysis of the 16S rRNA gene sequencing and untargeted metabolomics suggested that the anti-obesity effects of YBCH might be achieved by up-regulating the arginine and proline metabolism and down-regulating the aromatic amino acids metabolism via the gut microbiota.

Tetrahydrobiopterin in Cell Function and Death Mechanisms.

Significance: Tetrahydrobiopterin (BH4) is most well known as a required cofactor for enzymes regulating cellular redox homeostasis, aromatic amino acid metabolism, and neurotransmitter synthesis. Less well known are the effects dependent on the cofactor's availability, factors governing its synthesis and recycling, redox implications of the cofactor itself, and protein-protein interactions that underlie cell death. This review provides an understanding of the recent advances implicating BH4 in the mechanisms of cell death and suggestions of possible therapeutic interventions. Recent Advances: The levels of BH4 often reflect the sum of synthetic and recycling enzyme activities. Enhanced expression of GTP cyclohydrolase, the rate-limiting enzyme in biosynthesis, increases BH4, leading to improved cell function and survival. Pharmacologically increasing BH4 levels has similar beneficial effects, leading to enhanced production of neurotransmitters and nitric oxide or reducing oxidant levels. The GTP cyclohydrolase-BH4 pairing has been implicated in a type of cell death, ferroptosis. At the cellular level, BH4 counteracts anticancer therapies directed to enhance ferroptosis via glutathione peroxidase 4 (GPX4) activity inhibition. Critical Issues: Because of the multitude of intertwined mechanisms, a clear relationship between BH4 and cell death is not well understood yet. The possibility that the cofactor directly influences cell viability has not been excluded in previous studies when modulating BH4-producing enzymes. Future Directions: The importance of cellular BH4 variations and BH4 biosynthetic enzymes to cell function and viability makes it essential to better characterize temporal changes, cofactor activity, and the influence on redox status, which in turn would help develop novel therapies. Antioxid. Redox Signal. 37, 171-183.

Thermal Hydrolysis Pretreatment-Anaerobic Digestion Promotes Plant-Growth Biostimulants Production from Sewage Sludge by Upregulating Aromatic Amino Acids Transformation and Quinones Supply.

Micromolecular plant-growth biostimulants (micro-PBs) production from sewage sludge is attracting increasing interest, as it is expected to enhance the fertilizing effect of sludge for land application. This study attempted to promote effective micro-PBs production from sewage sludge through thermal hydrolysis pretreatment-anaerobic digestion (THP-AD) and explore the underpinning regulation mechanisms. Results showed that the highest effective micro-PB production in digested sludge was achieved in THP(160 °C)-AD by day 12, with 80.73 mg/kg volatile solid (VS) of phytohormones and 417.75 mg/kg VS of allelochemicals, and these effective micro-PBs all originated from aromatic amino acids (AAAs). The metabolomic and metagenomic results revealed that, as compared with THP(120 °C)-AD and AD without THP, THP(160°C)-AD uniquely upregulated AAAs biosynthesis and consequently improved AAAs metabolism toward effective micro-PBs production. Further exploration of related microbial pathways and metabolites suggested that the upregulated AAAs biosynthesis in THP(160 °C)-AD in the early stage was partially attributed to the enhanced carbohydrate release. More importantly, the results showed that the amount of quinones, which probably facilitate energy generation via acting as electron-transfer mediators, was significantly positively correlated with the abundance of AAAs biosynthesis genes (R2 = 0.93). Hence, the improved initial release and biosynthesis of quinones are critical in enhancing the AAAs biosynthesis in THP(160 °C)-AD. Moreover, the enhanced quinones supply and the consequent active AAAs transformation in THP(160 °C)-AD reinforced the humification process, highly supporting effective micro-PBs stabilization. The important roles of quinones in effective micro-PBs production and stabilization in sludge anaerobic digestion should be considered in technology development for micro-PBs recovery.

The Biosynthesis and Metabolism of the N-Acylated Aromatic Amino Acids: N-Acylphenylalanine, N-Acyltyrosine, N-Acyltryptophan, and N-Acylhistidine.

The fatty acid amides are a family of lipids composed of two chemical moieties, a fatty acid and a biogenic amine linked together in an amide bond. This lipid family is structurally related to the endocannabinoid anandamide (N-arachidonoylethanolamine) and, thus, is frequently referred to as a family of endocannabinoid-related lipids. The fatty acid amide family is divided into different classes based on the conjugate amine; anandamide being a member of the N-acylethanolamine class (NAE). Another class within the fatty acid amide family is the N-acyl amino acids (NA-AAs). The focus of this review is a sub-class of the NA-AAs, the N-acyl aromatic amino acids (NA-ArAAs). The NA-ArAAs are not broadly recognized, even by those interested in the endocannabinoids and endocannabinoid-related lipids. Herein, the NA-ArAAs that have been identified from a biological source will be highlighted and pathways for their biosynthesis, degradation, enzymatic modification, and transport will be presented. Also, information about the cellular functions of the NA-ArAAs will be placed in context with the data regarding the identification and metabolism of these N-acylated amino acids. A review of the current state-of-knowledge about the NA-ArAAs is to stimulate future research about this underappreciated sub-class of the fatty acid amide family.

Serum Metabolomic and Lipidomic Profiling Reveals Novel Biomarkers of Efficacy for Benfotiamine in Alzheimer's Disease.

Serum metabolomics and lipidomics are powerful approaches for discovering unique biomarkers in various diseases and associated therapeutics and for revealing metabolic mechanisms of both. Treatment with Benfotiamine (BFT), a thiamine prodrug, for one year produced encouraging results for patients with mild cognitive impairment and mild Alzheimer’s disease (AD). In this study, a parallel metabolomics and lipidomics approach was applied for the first exploratory investigation on the serum metabolome and lipidome of patients treated with BFT. A total of 315 unique metabolites and 417 lipids species were confidently identified and relatively quantified. Rigorous statistical analyses revealed significant differences between the placebo and BFT treatment groups in 25 metabolites, including thiamine, tyrosine, tryptophan, lysine, and 22 lipid species, mostly belonging to phosphatidylcholines. Additionally, 10 of 11 metabolites and 14 of 15 lipid species reported in previous literature to follow AD progression changed in the opposite direction to those reported to reflect AD progression. Enrichment and pathway analyses show that significantly altered metabolites by BFT are involved in glucose metabolism and biosynthesis of aromatic amino acids. Our study discovered that multiple novel biomarkers and multiple mechanisms that may underlie the benefit of BFT are potential therapeutic targets in AD and should be validated in studies with larger sample sizes.

Salivary Metabolomics Reveals that Metabolic Alterations Precede the Onset of Schizophrenia.

Schizophrenia is a complex and highly heterogeneous mental illness with a prodromal period called clinical high risk (CHR) for psychosis before onset. Metabolomics is greatly promising in analyzing the pathology of complex diseases and exploring diagnostic biomarkers. Therefore, we conducted salivary metabolomics analysis in 83 first-episode schizophrenia (FES) patients, 42 CHR individuals, and 78 healthy controls with ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The mass spectrometry raw data have been deposited on the MetaboLights (ID: MTBLS3463). We found downregulated aromatic amino acid metabolism, disturbed glutamine and nucleotide metabolism, and upregulated tricarboxylic acid cycle in FES patients, which existed even in the CHR stage and became more intense with the onset of the schizophrenia. Moreover, differential metabolites can be considered as potential diagnostic biomarkers and indicate the severity of the different clinical stages of disease. Furthermore, three disordered pathways were closely related to peripheral indicators of inflammatory response, oxidative stress, blood-brain barrier damage, and salivary microbiota. These results indicate that the disorder of oral metabolism occurs earlier than the onset of schizophrenia and is concentrated and intensified with the onset of disease, which may originate from the dysbiotic salivary microbiota and cause the onset of schizophrenia through the peripheral inflammatory response and redox system, suggesting the importance of oral-brain connection in the pathogenesis of schizophrenia.