Mixture Of Metabolites Research Articles

Fluorescent sensors for detection and quantification of bacterial siderophores and metal complexes

To proliferate in the host environment during colonization or infection, bacteria acquire iron from eukaryotic tissues, fluids, cells and proteins. To do so, they secrete siderophores that chelate iron, and they express membrane transporters that recognize and internalize ferric siderophores. The production of siderophores and the acquisition of ferric siderophores are determinants of microbial pathogenesis. For example, the E. coli outer membrane protein FepA actively transports ferric enterobactin, a prototypic catecholate iron complex of the Enterobacteriaceae, whose utilization promotes colonization of the mouse gut. We genetically engineered several fluorescent sensors to detect, discriminate and quantify ferric siderophores, in purified form or in complex mixtures of metabolites and other biochemicals. By substituting single Cys residues in TonB-dependent outer membrane transporters, and modifying them with maleimide fluorophores in living cells, we created sensors from different bacterial species that recognized different metal complexes: native, glucosylated, degraded ferric enterobactin; the hydroxamates ferric aerobactin, ferrichrome, ferric acinetobactin and ferrioxamine B: the porphyrins hemin and vitamin B12. In spectroscopic assays these constructs sensitively detected and quantified the different metal chelates in solution. These sensors facilitate assays of biochemical specificity, affinity, and membrane transport. They may also detect the presence and activities of bacterial pathogens, that often show a particular profile of siderophore production or ferric siderophore utilization. The sensors are useful for both basic research and drug discovery, because they rapidly detect and identifysiderophores in both clinical and food samples.

Rapid Development of Improved Data-Dependent Acquisition Strategies.

Tandem mass spectrometry (LC-MS/MS) is widely used to identify unknown ions in untargeted metabolomics. Data-dependent acquisition (DDA) chooses which ions to fragment based upon intensities observed in MS1 survey scans and typically only fragments a small subset of the ions present. Despite this inefficiency, relatively little work has addressed the development of new DDA methods, partly due to the high overhead associated with running the many extracts necessary to optimize approaches in busy MS facilities. In this work, we first provide theoretical results that show how much improvement is possible over current DDA strategies. We then describe an in silico framework for fast and cost-efficient development of new DDA strategies using a previously developed virtual metabolomics mass spectrometer (ViMMS). Additional functionality is added to ViMMS to allow methods to be used both in simulation and on real samples via an Instrument Application Programming Interface (IAPI). We demonstrate this framework through the development and optimization of two new DDA methods that introduce new advanced ion prioritization strategies. Upon application of these developed methods to two complex metabolite mixtures, our results show that they are able to fragment more unique ions than standard DDA strategies.

The Sorghum bicolor Root Exudate Sorgoleone Shapes Bacterial Communities and Delays Network Formation.

ABSTRACTPrimary and secondary metabolites exuded from roots are key drivers of root-soil microbe interactions that contribute to the structure and function of microbial communities. Studies with model plants have begun to reveal the complex interactions between root exudates and soil microbes, but little is known about the influence of specialized exudates from crop plants. The aims of this work were to understand whether sorgoleone, a unique lipophilic secondary benzoquinone exuded only from the root hairs of sorghum, influences belowground microbial community structure in the field, to assess the effect of purified sorgoleone on the cultured bacteria from field soils, and to determine whether sorgoleone inhibits nitrification under field conditions. Studies were conducted comparing wild-type sorghum and lines with genetically reduced sorgoleone exudation. In the soil near roots and rhizosphere, sorgoleone influenced microbial community structure as measured by β-diversity and network analysis. Under greenhouse conditions, the soil nitrogen content was an important factor in determining the impacts of sorgoleone. Sorgoleone delayed the formation of the bacterial and archaeal networks early in plant development and only inhibited nitrification at specific sampling times under field conditions. Sorgoleone was also shown to both inhibit and promote cultured bacterial isolate growth in laboratory tests. These findings provide new insights into the role of secondary metabolites in shaping the composition and function of the sorghum root-associated bacterial microbiomes. Understanding how root exudates modify soil microbiomes may potentially unlock an important tool for enhancing crop sustainability and yield in our changing environment.IMPORTANCE Plant roots exude a complex mixture of metabolites into the rhizosphere. Primary and secondary metabolites exuded from roots are key drivers of root-soil microbe interactions that contribute to the structure and function of microbial communities in agricultural and natural ecosystems. Previous work on plant root exudates and their influence on soil microbes has mainly been restricted to model plant species. Plant are a diverse group of organisms and produce a wide array of different secondary metabolites. Therefore, it is important to go beyond studies of model plants to fully understand the diverse repertoire of root exudates in crop plant species that feed human populations. Extending studies to a wider array of root exudates will provide a more comprehensive understanding of how the roots of important food crops interact with highly diverse soil microbial communities. This will provide information that could lead to tailoring root exudates for the development of more beneficial plant-soil microbe interactions that will benefit agroecosystem productivity.

Exposure to volatile organic compounds – acrolein, 1,3-butadiene, and crotonaldehyde – is associated with vascular dysfunction

BackgroundCardiovascular disease (CVD) is the leading cause of mortality worldwide. Exposure to air pollution, specifically particulate matter of diameter ≤2.5 μm (PM2.5), is a well-established risk factor for CVD. However, the contribution of gaseous pollutant exposure to CVD risk is less clear. ObjectiveTo examine the vascular effects of exposure to individual volatile organic compounds (VOCs) and mixtures of VOCs. MethodsWe measured urinary metabolites of acrolein (CEMA and 3HPMA), 1,3-butadiene (DHBMA and MHBMA3), and crotonaldehyde (HPMMA) in 346 nonsmokers with varying levels of CVD risk. On the day of enrollment, we measured blood pressure (BP), reactive hyperemia index (RHI – a measure of endothelial function), and urinary levels of catecholamines and their metabolites. We used generalized linear models for evaluating the association between individual VOC metabolites and BP, RHI, and catecholamines, and we used Bayesian Kernel Machine Regression (BKMR) to assess exposure to VOC metabolite mixtures and BP. ResultsWe found that the levels of 3HPMA were positively associated with systolic BP (0.98 mmHg per interquartile range (IQR) of 3HPMA; CI: 0.06, 1.91; P = 0.04). Stratified analysis revealed an increased association with systolic BP in Black participants despite lower levels of urinary 3HPMA. This association was independent of PM2.5 exposure and BP medications. BKMR analysis confirmed that 3HPMA was the major metabolite associated with higher BP in the presence of other metabolites. We also found that 3HPMA and DHBMA were associated with decreased endothelial function. For each IQR of 3HPMA or DHBMA, there was a −4.4% (CI: −7.2, −0.0; P = 0.03) and a −3.9% (CI: −9.4, −0.0; P = 0.04) difference in RHI, respectively. Although in the entire cohort the levels of several urinary VOC metabolites were weakly associated with urinary catecholamines and their metabolites, in Black participants, DHBMA levels showed strong associations with urinary norepinephrine and normetanephrine levels. DiscussionExposure to acrolein and 1,3-butadiene is associated with endothelial dysfunction and may contribute to elevated risk of hypertension in participants with increased sympathetic tone, particularly in Black individuals.

Chemical characterization and in vitro anthelmintic activity of Citrus bergamia Risso and Citrus X paradisii Macfad essential oil against Haemonchus contortus Kirby isolate

Haemonchus contortus, a blood-sucking parasite of small ruminants, produces very important economic losses in the productive sector. This abomasum parasite has become resistant to most commercial drugs worldwide, and alternatives to fight this problem are urgently needed. Essential oils (EO) are a complex mixture of volatile secondary metabolites, composed mainly by terpenoids and phenolic compounds, from plants that have several pharmacological properties, including anthelmintic activity. Particularly, citrus peel is a source of cold-pressed EO, where limonene is its major component, and can be used as an additional food component for ruminants. The aim of the present work was to determine the in vitro anthelmintic activity of EO from Citrus bergamia (EOB), C. x paradisii (EOG) and limonene against the benzimidazole-susceptible Kirby isolate of H. contortus, using the egg hatch test (EHT) and the exsheathed third stage larval motility test (XLMT) using a WMicroTracker equipment. Albendazole (ABZ) and monepantel (MON) were used as positive controls. The 50% inhibitory concentrations (IC50) in XLMT were 8.77 and 13.88 µg/ml for EOB and EOG respectively, after an incubation of 72 h. An interesting observation on XLMT resulted when the positive controls were tested on the same plate, but in different well of the EOB. The volatile components of the EO significantly influenced (P < 0.05) the percentage of larval motility, reducing values from 66.9 to 19.6% for ABZ, and from 72.8 to 33.7% for MON, when comparing the activity of positive controls in a control plate without EO. The in vitro anthelmintic activity of EOB and EOG shows that they could be interesting candidates for nematode control. It is still necessary additional studies against the adult stage of H. contortus in efficacy trials in infected animals to validate their anthelmintic activity.

The plant metabolome guides fitness-relevant foraging decisions of a specialist herbivore.

Plants produce complex mixtures of primary and secondary metabolites. Herbivores use these metabolites as behavioral cues to increase their fitness. However, how herbivores combine and integrate different metabolite classes into fitness-relevant foraging decisions in planta is poorly understood. We developed a molecular manipulative approach to modulate the availability of sugars and benzoxazinoid secondary metabolites as foraging cues for a specialist maize herbivore, the western corn rootworm. By disrupting sugar perception in the western corn rootworm and benzoxazinoid production in maize, we show that sugars and benzoxazinoids act as distinct and dynamically combined mediators of short-distance host finding and acceptance. While sugars improve the capacity of rootworm larvae to find a host plant and to distinguish postembryonic from less nutritious embryonic roots, benzoxazinoids are specifically required for the latter. Host acceptance in the form of root damage is increased by benzoxazinoids and sugars in an additive manner. This pattern is driven by increasing damage to postembryonic roots in the presence of benzoxazinoids and sugars. Benzoxazinoid- and sugar-mediated foraging directly improves western corn rootworm growth and survival. Interestingly, western corn rootworm larvae retain a substantial fraction of their capacity to feed and survive on maize plants even when both classes of chemical cues are almost completely absent. This study unravels fine-grained differentiation and combination of primary and secondary metabolites into herbivore foraging and documents how the capacity to compensate for the lack of important chemical cues enables a specialist herbivore to survive within unpredictable metabolic landscapes.

Biological activity and safety evaluation of monoterpenes against the peach aphid (Myzus persicae Sulzer) (Hemiptera: Aphididae)

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is an economically important cosmopolitan crop pest. Essential oils (EOs) are complex mixtures of secondary metabolites that exhibit a wide range of biological activities, including antioxidant, antimicrobial and anti-inflammatory activities. Monoterpenes, as the major constituents of EOs, are well known for having a range of biological activities. In this study, 9 monoterpenes were screened for fumigant toxicity against M. persicae, and the safety of monoterpenes to natural enemies was evaluated. The results of the bioassays indicated that 9 monoterpenes showed promising fumigant toxicity against M. persicae. Carvacrol was the most toxic compound based on the LC50 value, which was 1.566 mg/L, followed by bornyl acetate, terpinolene, and terpinyl acetate, which had higher toxicities towards aphids, with LC50 values of 2.648 mg/L, 2.759 mg/L, and 2.832 mg/L, respectively. In addition, the safety evaluation assays of carvacrol against Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) larvae (LC50 = 43.851 mg/L) did not affect nontarget invertebrates at concentrations that effectively controlled aphids. Carvacrol was safer than chlorpyrifos to natural enemy H. axyridis larvae (toxicity ratio = 28.00 > 2.93). These results identified several high-activity monoterpenes that can be used against this pest in greenhouses as botanical insecticides.

GC-MS of some lycorine-type Amaryllidaceae alkaloids.

The search for novel bioactive compounds and the identification of known ones in the plant kingdom are a challenge for the scientists working in different fields of plant science. In the recent years, mass spectrometry is the most frequently applied method for analysis of complex mixtures of plant metabolites. Twenty-two alkaloids of different lycorine skeleton subtypes (with a Δ3,4 double bond, with a Δ4,11 double bond, with saturated rings C and D, and with aromatic ring C) were subjected to separation with gas chromatography and studied with electron impact mass spectrometry including single quadropole (GC-EIMS), tandem mass (GC-EIMS/MS) and high resolution mass (EI-HRMS) detectors in order to determine their fragmentation pattern. The compounds showed excellent separation and specific MS fragmentation allowing structural determination. The GC-MS can be successfully applied for searching new and identification of known bioactive molecules, chemotaxonomical and chemoecological studies, among others, within the Amaryllidoideae subfamily.

Fluorescence Sensors for Detection, Discrimination and Quantification of Siderophores

To proliferate in the host environment during colonization or infection, bacteria acquire iron from eukaryotic tissues, fluids, cells and proteins. To do so, they secrete siderophores that chelate iron, and they express membrane transporters that recognize and internalize ferric siderophores. The production of siderophores and the acquisition of ferric siderophores are determinants of microbial pathogenesis. For example, the E. coli outer membrane protein FepA actively transports ferric enterobactin, a prototypic catecholate iron complex of the Enterobacteriaceae, whose utilization promotes colonization of the mouse gut. We genetically engineered several fluorescent sensors to detect, discriminate and quantify ferric siderophores, in purified form or in complex mixtures of metabolites and other biochemicals. By substituting single Cys residues in TonB-dependent outer membrane transporters, and modifying them with maleimide fluorophores in living cells, we created sensors that recognized different metal complexes: native, glucosylated and degraded ferric enterobactin; the hydroxamates ferric aerobactin, ferrichrome and ferrioxamine B: the porphyrins hemin and vitamin B12. In spectroscopic assays these constructs sensitively detected and quantified the different metal chelates in solution. These sensors facilitate assays of biochemical specificity, affinity, and membrane transport. They may also detect the presence and activities of bacterial pathogens, that often show a particular profile of siderophore production or ferric siderophore utilization. The sensors are useful for both basic research and drug discovery, because they rapidly detect and identify siderophores in both clinical and food samples

Environmentally relevant mixtures of phthalates and phthalate metabolites differentially alter the cell cycle and apoptosis in mouse neonatal ovaries†.

Phthalates are a group of chemicals used as additives in various consumer products, medical equipment, and personal care products. Phthalates and their metabolites are consistently detected in humans, indicating widespread and continuous exposure to multiple phthalates. Thus, environmentally relevant mixtures of phthalates and phthalate metabolites were investigated to determine the effects of phthalates on the function of the ovary during the neonatal period of development. Neonatal ovaries from CD-1 mice were cultured with dimethyl sulphoxide (DMSO; vehicle control), phthalate mixture (0.1-100μg/mL), or phthalate metabolite mixture (0.1-100μg/mL). The phthalate mixture was composed of 35% diethyl phthalate, 21% di(2-ethylhexyl) phthalate, 15% dibutyl phthalate, 15% diisononyl phthalate, 8% diisobutyl phthalate, and 5% benzylbutyl phthalate. The phthalate metabolite mixture was composed of 37% monoethyl phthalate, 19% mono(2-ethylhexyl) phthalate, 15% monobutyl phthalate, 10% monoisononyl phthalate, 10% monoisobutyl phthalate, and 8% monobenzyl phthalate. After 96h of culture, ovaries were harvested for histological analysis of folliculogenesis, gene expression analysis of cell cycle and apoptosis regulators, and immune staining for cell proliferation and apoptosis. The metabolite mixture significantly decreased the number and percentage of abnormal follicles (100μg/mL) compared to controls. The metabolite mixture also significantly increased the expression of cell cycle inhibitors (100μg/mL) and the antiapoptotic factor Bcl2l10 (10μg/mL) compared to controls. The phthalate mixture did not significantly alter gene expression or follicle counts, but ovaries exposed to the phthalate mixture (0.1μg/mL) exhibited marginally significantly increased apoptosis as revealed by DNA fragmentation staining. Overall, these data show that parent phthalates and phthalate metabolites differentially impact ovarian function.

Variable-temperature NMR spectroscopy for metabolite identification in biological materials.

Nuclear magnetic resonance is a “workhorse technique” used in metabolomics, complementary to mass spectrometry. Unfortunately, only the most basic NMR methods are sensitive enough to allow fast medical screening. The most common of them, a simple 1H NMR, suffers from low dispersion of resonance frequencies, which often hampers the identification of metabolites. In this article we show that 1H NMR spectra contain previously overlooked parameters potentially helpful in metabolite identification, namely the rates of temperature-induced changes of chemical shifts. We prove that they are reproducible between various metabolite mixtures and can be determined quickly when Radon transform is used to process the data.

Advances in decomposing complex metabolite mixtures using substructure- and network-based computational metabolomics approaches.

Covering: up to the end of 2020Recently introduced computational metabolome mining tools have started to positively impact the chemical and biological interpretation of untargeted metabolomics analyses. We believe that these current advances make it possible to start decomposing complex metabolite mixtures into substructure and chemical class information, thereby supporting pivotal tasks in metabolomics analysis including metabolite annotation, the comparison of metabolic profiles, and network analyses. In this review, we highlight and explain key tools and emerging strategies covering 2015 up to the end of 2020. The majority of these tools aim at processing and analyzing liquid chromatography coupled to mass spectrometry fragmentation data. We start with defining what substructures are, how they relate to molecular fingerprints, and how recognizing them helps to decompose complex mixtures. We continue with chemical classes that are based on the presence or absence of particular molecular scaffolds and/or functional groups and are thus intrinsically related to substructures. We discuss novel tools to mine substructures, annotate chemical compound classes, and create mass spectral networks from metabolomics data and demonstrate them using two case studies. We also review and speculate about the opportunities that NMR spectroscopy-based metabolome mining of complex metabolite mixtures offers to discover substructures and chemical classes. Finally, we will describe the main benefits and limitations of the current tools and strategies that rely on them, and our vision on how this exciting field can develop toward repository-scale-sized metabolomics analyses. Complementary sources of structural information from genomics analyses and well-curated taxonomic records are also discussed. Many research fields such as natural products discovery, pharmacokinetic and drug metabolism studies, and environmental metabolomics increasingly rely on untargeted metabolomics to gain biochemical and biological insights. The here described technical advances will benefit all those metabolomics disciplines by transforming spectral data into knowledge that can answer biological questions.

Cardioprotective effect of H2S and glutathione synthesis modulation is mediated by inhibition mitochondrial permeability transition pore opening

Hydrogen sulfide (H2S) was recently classified as the third gaseous transmitter produces by two cytosolic cystathionine γ-lyase (CSE) and cystathionine β-synthase, and one mitochondrial enzyme – 3-mercaptopyruvate sulfurtransferase. It was clearly shown that H2S protects against cardiac ischemia/reperfusion (I/R) injury in a wide range of exogenously applied doses of H2S donors. Cell damage within I/R injury is caused by extensive reactive oxygen species (ROS) mainly produced by mitochondria. ROS fleshes are associated with massive opening of mitochondrial permeability transition (MPT) pores and contribute to deterioration of heart function. However, it may be prevented in case of pharmacological inhibition of MPT pores opening. Mixture of mitochondrial metabolites released through the opened MPT pores can be detected in situ as increased optical density of outflow solutions at a wavelength of 245-250 nm and was called mitochondrial factor (MF). One of the most powerful antioxidant agents that preserve redox status in tissues is tripeptide glutathione. It forms in two ATP-depended reactions and exists in two forms reduced and oxidized one. Glutathione and H2S have a common precursor – amino acid L-cysteine. In this study, we used Langendorff isolated rat heart model to investigate the effect of H2S and glutathione synthesis modulation on MPT pores opening in I/R injury. Rats were pretreated intraperitoneally with D,L-propargylglycine (11,3 mg/kg), an inhibitor of H2S-producing enzyme CSE, L-cysteine (121 mg/kg) and buthionine sulfoximine (BSO, 22,2 mg/kg) an inhibitor of first step of glutathione synthesis. Cardiac function, oxygen metabolism and MPT pores opening in situ were measured. We clearly showed that treatment with PAG and L-cysteine provided pharmacological precondition and exerted cardioprotective effect inhibiting MPT pores opening as greatly decreased MF release from isolated heart. Pretreatment with BSO abolished cardioprotective effect of PAG+L-cysteine combination. Absorbance spectra in L-cysteine pretreated group did not differ from the control. Thus, we demonstrate that PAG+L-cysteine induced cardioprotection mediated via inhibition of MPT pores opening.

Genetic analysis of potato tuber metabolite composition: Genome‐wide association studies applied to a nontargeted metabolome

AbstractPlant improvement requires a response to selection, which can be complicated when the biochemical bases of a trait are poorly understood, difficult to measure, genetically complex, or some combination of these common obstacles. We applied nontargeted metabolomic profiling to generate a deep (but largely anonymous) dataset of potato (Solanum tuberosum L.) tubers to increase our understanding of the genetic bases for compositional traits. We examined water–methanol extracts of cooked potato tuber cores from 185 clones that had previously been single nucleotide polymorphism (SNP) genotyped by the Solanaceae Coordinated Agricultural Project (SolCAP) and detected 981 features that represent a mixture of primary metabolites, specialized metabolites, and hydrolyzed fragments of abundant proteins. Using GWASpoly, an R package that considers gene dosage through a series of genetic models, 472 features could be associated with at least one SNP marker, markedly increasing the number of marker–trait associations that have been made in potato to date. An additive genetic model detected the most associations, where 301 compositional features were associated with SNPs; in contrast, a duplex‐dominant model detected the least (160 features). Unexpectedly, SNPs associated with features were not uniformly distributed throughout the genome but were instead clustered on chromosomes 3, 7, and 8, with dozens of features associated with several small (∼2 Mbp) regions. Also interesting was that the most significant SNPs for several glycoalkaloids (α‐chaconine, β‐chaconine, and α‐solamarine)—detected on chromosomes 2, 7, and 8—are unlinked to any known glycoalkaloid biosynthetic genes.

AAPH or Peroxynitrite-Induced Biorelevant Oxidation of Methyl Caffeate Yields a Potent Antitumor Metabolite.

Hydroxycinnamic acids represent a versatile group of dietary plant antioxidants. Oxidation of methyl-p-coumarate (pcm) and methyl caffeate (cm) was previously found to yield potent antitumor metabolites. Here, we report the formation of potentially bioactive products of pcm and cm oxidized with peroxynitrite (ONOO¯), a biologically relevant reactive nitrogen species (RNS), or with α,α′-azodiisobutyramidine dihydrochloride (AAPH) as a chemical model for reactive oxygen species (ROS). A continuous flow system was developed to achieve reproducible in situ ONOO¯ formation. Reaction mixtures were tested for their cytotoxic effect on HeLa, SiHa, MCF-7 and MDA-MB-231 cells. The reaction of pcm with ONOO¯ produced two fragments, an o-nitrophenol derivative, and a new chlorinated compound. Bioactivity-guided isolation from the reaction mixture of cm with AAPH produced two dimerization products, including a dihydrobenzofuran lignan that exerted strong antitumor activity in vitro, and has potent in vivo antimetastatic activity which was previously reported. This compound was also detected from the reaction between cm and ONOO¯. Our results demonstrate the ROS/RNS dependent formation of chemically stable metabolites, including a potent antitumor agent (5), from hydroxycinnamic acids. This suggests that diversity-oriented synthesis using ROS/RNS to obtain oxidized antioxidant metabolite mixtures may serve as a valid natural product-based drug discovery strategy.

Associations between urinary phthalate metabolite mixtures and oxidative stress biomarkers among male partners of couples undergoing fertility treatments

Background: Oxidative stress, the imbalance between reactive oxygen species and antioxidants, has been associated with sperm dysfunction in men. Phthalate exposure has been associated with increased oxidative stress; however, few studies have explored the joint association between exposure to multiple phthalate metabolites simultaneously and circulating oxidative stress measures. Methods: We addressed this question among men (n=235) in the Environment and Reproductive Health (EARTH) study, in which couples seeking infertility treatment were recruited from a clinic in Boston, MA, USA. For males, one urine sample was collected for each fertility treatment cycle. Samples were analyzed for a panel of 11 phthalate metabolites and 3 oxidative stress biomarkers, including 8-iso-prostaglandin F2α [8isoPGF2a], its primary metabolite, and prostaglandin F2α. All measures were corrected for specific gravity to account for urine dilution, and all estimates were adjusted for potential confounders and accounted for repeated exposure and outcome measures. Single pollutant models for each phthalate metabolite and oxidative stress marker were created using linear mixed effects models. The joint association with the overall mixture was assessed using Bayesian Kernel Machine Regression (BKMR). Results: In single pollutant models, most phthalate metabolites were associated with increases in 8isoPGF2a, but not other oxidative stress markers. For example, an interquartile range increase (IQR) in summed di-2-ethylhexyl phthalate metabolites was associated with a 7.5% (95% CI: 2.0% – 13.4%) increase in 8isoPGF2a. The BKMR model also demonstrated a 20.4% (95% credible interval: 8.8% – 33.2%) increase in the 8isoPGF2a concentration per a joint increase in all phthalate metabolites from the 1st to the 3rd quartile. Conclusions: Among men presenting at an infertility clinic, those with higher overall urinary concentrations of phthalate metabolites had elevated urinary 8isoPGF2a levels, indicative of oxidative stress or inflammation. This mechanism could be relevant to previously observed associations between phthalate metabolites and fertility measures in men.

Associations of Plasma Folate and Vitamin B6 With Blood DNA Methylation Age: An Analysis of One-Carbon Metabolites in the VA Normative Aging Study.

One-carbon metabolism is an important contributor to aging-related diseases; nevertheless, relationships of one-carbon metabolites with novel DNA methylation-based measures of biological aging remain poorly characterized. We examined relationships of one-carbon metabolites with 3 DNA methylation-based measures of biological aging: DNAmAge, GrimAge, and PhenoAge. We measured plasma levels of 4 common one-carbon metabolites (vitamin B6, vitamin B12, folate, and homocysteine) in 715 VA Normative Aging Study participants with at least 1 visit between 1999 and 2008 (observations = 1153). DNA methylation age metrics were calculated using the HumanMethylation450 BeadChip. We utilized Bayesian Kernel Machine Regression models adjusted for chronological age, lifestyle factors, age-related diseases, and study visits to determine metabolites important to the aging outcomes. Bayesian Kernel Machine Regression models allowed for the estimation of the relationships of single metabolites and the cumulative metabolite mixture with methylation age. Log vitamin B6 was selected as important to PhenoAge (β = -1.62 years, 95% CI: -2.28, -0.96). Log folate was selected as important to GrimAge (β = 0.75 years, 95% CI: 0.41, 1.09) and PhenoAge (β = 1.62 years, 95% CI: 0.95, 2.29). Compared to a model where each metabolite in the mixture is set to its 50th percentile, the log cumulative mixture with each metabolite at its 30th (β = -0.13 years, 95% CI: -0.26, -0.005) and 40th percentile (β = -0.06 years, 95% CI: -0.11, -0.005) was associated with decreased GrimAge. Our results provide novel characterizations of the relationships between one-carbon metabolites and DNA methylation age in a human population study. Further research is required to confirm these findings and establish their generalizability.

3,3'-Dichlorobiphenyl Is Metabolized to a Complex Mixture of Oxidative Metabolites, Including Novel Methoxylated Metabolites, by HepG2 Cells.

3,3'-Dichlorobiphenyl (PCB 11) is a byproduct of industrial processes and detected in environmental samples. PCB 11 and its metabolites are present in human serum, and emerging evidence demonstrates that PCB 11 is a developmental neurotoxicant. However, little is known about the metabolism of PCB 11 in humans. Here, we investigated the metabolism of PCB 11 and the associated metabolomics changes in HepG2 cells using untargeted high-resolution mass spectrometry. HepG2 cells were exposed for 24 h to PCB 11 in DMSO or DMSO alone. Cell culture media were analyzed with ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry. Thirty different metabolites were formed by HepG2 cells exposed to 10 μM PCB 11, including monohydroxylated, dihydroxylated, methoxylated-hydroxylated, and methoxylated-dihydroxylated metabolites and the corresponding sulfo and glucuronide conjugates. The methoxylated PCB metabolites were observed for the first time in a human-relevant model. 4-OH-PCB 11 (3,3'-dichlorobiphenyl-4-ol) and the corresponding catechol metabolite, 4,5-di-OH-PCB 11 (3',5-dichloro-3,4-dihydroxybiphenyl), were unambiguously identified based on liquid and gas chromatographic analyses. PCB 11 also altered several metabolic pathways, in particular vitamin B6 metabolism. These results demonstrate that complex PCB 11 metabolite profiles are formed in HepG2 cells that warrant further toxicological investigation, particularly since catechol metabolites are likely reactive and toxic.

Combination of essential oils in dairy products: A review of their functions and potential benefits

Essential oils are volatile hydrophobic liquids extracted from plants which are often rich in aroma. They are a mixture of secondary metabolites, often terpenoids that play an important role in plant defense system and possess strong anti-microbial activities. In recent years, there is a growing interest in essential oils and their application as preservatives in dairy products as suitable alternatives to synthetic preservatives. Various studies have reported the antibacterial activities of essential oils and their active components along with their mechanism of action. However, there has not been any extensive review on the essential oils combination with dairy products and their mechanism of action as preservatives for dairy products. The main aim of this review is to critically analyze the available scientific information regarding the combination of essential oils in dairy products and their functions. In conclusion, essential oils were found to be promising agents in dairy products for their bio-preservative, antioxidant, anti-microbial activities, and for increasing aroma. Further studies should focus on a more detailed mechanism of their action and other possible benefits.

Suppression of Trichothecene-Mediated Immune Response by the Fusarium Secondary Metabolite Butenolide in Human Colon Epithelial Cells.

Butenolide (BUT, 4-acetamido-4-hydroxy-2-butenoic acid gamma-lactone) is a secondary metabolite produced by several Fusarium species and is co-produced with the major trichothecene mycotoxin deoxynivalenol (DON) on cereal grains throughout the world. BUT has low acute toxicity and only very limited occurrence and exposure data are available. The intestinal epithelium represents the first physiological barrier against food contaminants. We aimed to elucidate the intestinal inflammatory response of the human, non-cancer epithelial HCEC-1CT cells to BUT and to characterize potential combinatory interactions with co-occurring trichothecenes, such as DON and NX-3. Using a reporter gene approach, BUT (≥5 μM, 20 h) was found to decrease lipopolysaccharide (LPS; 10 ng/mL) induced nuclear factor kappa B (NF-κB) activation in a dose-dependent manner, and in combinatory treatments BUT represses trichothecene-induced enhancement of this important inflammatory pathway. Analysis of transcription and secretion levels of NF-κB-dependent, pro-inflammatory cytokines, revealed a significant down-regulation of IL-1β, IL-6, and TNF-α in IL-1β-stimulated (25 ng/mL) HCEC-1CT cells after BUT exposure (10 μM). Trichothecene-induced expression of pro-inflammatory cytokines by the presence of 1 μM DON or NX-3 was substantially suppressed in the presence of 10 μM BUT. The emerging mycotoxin BUT has the ability to suppress NF-κB-induced intestinal inflammatory response mechanisms and to modulate substantially the immune responsiveness of HCEC-1CT cells after trichothecene treatment. Our results suggest that BUT, present in naturally occurring mixtures of Fusarium fungal metabolites, should be increasingly monitored, and the mechanism of inhibition of NF-κB that might affect the pathogenesis or progression of intestinal inflammatory disorders, should be further investigated.