Identification of sulfation sites of metabolites and prediction of the compounds' biological effects

Pan-cancer single-cell landscape of drug-metabolizing enzyme genes

OBJECTIVE

Varied expression of drug-metabolizing enzymes (DME) genes dictates the intensity and duration of drug response in cancer treatment. This study aimed to investigate the transcriptional profile of DMEs in tumor microenvironment (TME) at single-cell level and their impact on individual responses to anticancer therapy.

METHODS

Over 1.3 million cells from 481 normal/tumor samples across 9 solid cancer types were integrated to profile changes in the expression of DME genes. A ridge regression model based on the PRISM database was constructed to predict the influence of DME gene expression on drug sensitivity.

RESULTS

Distinct expression patterns of DME genes were revealed at single-cell resolution across different cancer types. Several DME genes were highly enriched in epithelial cells (e.g. GPX2, TST and CYP3A5 ) or different TME components (e.g. CYP4F3 in monocytes). Particularly, GPX2 and TST were differentially expressed in epithelial cells from tumor samples compared to those from normal samples. Utilizing the PRISM database, we found that elevated expression of GPX2, CYP3A5 and reduced expression of TST was linked to enhanced sensitivity of particular chemo-drugs (e.g. gemcitabine, daunorubicin, dasatinib, vincristine, paclitaxel and oxaliplatin).

CONCLUSION

Our findings underscore the varied expression pattern of DME genes in cancer cells and TME components, highlighting their potential as biomarkers for selecting appropriate chemotherapy agents.

Metabolism of the 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor, Mesotrione, in Multiple-Herbicide-Resistant Palmer amaranth (Amaranthus palmeri)

Metabolic resistance to the maize-selective, HPPD-inhibiting herbicide, mesotrione, occurs via Phase I ring hydroxylation in resistant waterhemp and Palmer amaranth; however, mesotrione detoxification pathways post-Phase I are unknown. This research aims to (1) evaluate Palmer amaranth populations for mesotrione resistance via survivorship, foliar injury, and aboveground biomass, (2) determine mesotrione metabolism rates in Palmer amaranth populations during a time course, and (3) identify mesotrione metabolites including and beyond Phase I oxidation. The Palmer amaranth populations, SYNR1 and SYNR2, exhibited higher survival rates (100%), aboveground biomass (c.a. 50%), and lower injury (25-30%) following mesotrione treatment than other populations studied. These two populations also metabolized mesotrione 2-fold faster than sensitive populations, PPI1 and PPI2, and rapidly formed 4-OH-mesotrione. Additionally, SYNR1 and SYNR2 formed 5-OH-mesotrione, which is not produced in high abundance in waterhemp or naturally tolerant maize. Metabolite features derived from 4/5-OH-mesotrione and potential Phase II mesotrione-conjugates were detected and characterized by liquid chromatography-mass spectrometry (LCMS).

Identification of Sulfur-Containing Chlorinated Paraffin Structural Analogues in Human Serum: Origination from Biotransformation or Bioaccumulation?

Chlorinated paraffins (CPs) are manufactured and used in high quantities and have diverse structural analogues. It is generally recognized that sulfur-containing structural analogues of CPs are mainly derived from sulfate-conjugated phase II metabolism. In this study, we non-targeted identified three classes of sulfur-containing CP structural analogues (CPs-S) in human serum, including 44 CP sulfates (CPs-SO4H/CPs-SO4H-OH), 14 chlorinated benzene sulfates (CBs-SO4H), and 19 CP sulfite esters (CPs-SO3/CPs-S2O6), which were generated during the production of commercial mixtures of CPs and, thus, bioaccumulated via environmental exposures. We first wrote a program to screen CPs-S, which were baseline-separated from CPs according to their polar functional groups. Then, mass spectral analyses of alkalization-acidification liquid-liquid extracts of serum samples and Orbitrap mass spectrometry analyses in the presence and absence of tetraphenylphosphonium chloride (Ph4PCl), respectively, were performed to determine the ionization forms ([M + Cl]- or [M - H]-) of CPs-S. The presence of fragment ions (SO4H-, SO3-, SO2Cl-, and HSO3-) revealed the structures of CPs-S, which were validated by their detections in commercial mixtures of CPs. The estimated total concentrations of CPs-S in the human serum samples were higher than the concentrations of medium- and long-chain CPs. The profiles of CPs-S in human serum were similar to those detected in CP commercial mixtures and rats exposed to the commercial mixtures, but CPs-S were not detected in human liver S9 fractions or rat tissues after exposure to CP standards. These results, together with the knowledge of the processes used to chemically synthesize CPs, demonstrate that CPs-S in humans originates from environmental bioaccumulation.

Metabolism of natural and synthetic bioactive compounds in Cunninghamella fungi and their applications in drug discovery

Investigation of xenobiotic metabolism is a key step for drug discovery. Since the in vivo investigations may be associated with harmful effects attributed to production of toxic metabolites, it is deemed necessary to predict their structure especially at the preliminary clinical studies. Furthermore, the application of microorganisms that are capable of metabolizing drugs mimic human metabolism and consequently may predict possible metabolites. The genus Cunninghamella has been proven to be a potential candidate, which mimics xenobiotic metabolism occurring inside the human body, including phase I and II metabolic reactions. Moreover, biotransformation with Cunninghamella showed chemical diversity, where a lot of products were detected in relation to the initial substrates after being modified by oxidation, hydroxylation, and conjugation reactions. Some of these products are more bioactive than the parent compounds. The current review presents a comprehensive literature overview regarding the Cunninghamella organisms as biocatalysts, which simulate mammalian metabolism of natural secondary and synthetic compounds.

Metabolomics and Self-Reported Depression, Anxiety, and Phobic Symptoms in the VA Normative Aging Study

Traditional approaches to understanding metabolomics in mental illness have focused on investigating a single disorder or comparisons between diagnoses, but a growing body of evidence suggests substantial mechanistic overlap in mental disorders that could be reflected by the metabolome. In this study, we investigated associations between global plasma metabolites and abnormal scores on the depression, anxiety, and phobic anxiety subscales of the Brief Symptom Inventory (BSI) among 405 older males who participated in the Normative Aging Study (NAS). Our analysis revealed overlapping and distinct metabolites associated with each mental health dimension subscale and four metabolites belonging to xenobiotic, carbohydrate, and amino acid classes that were consistently associated across all three symptom dimension subscales. Furthermore, three of these four metabolites demonstrated a higher degree of alteration in men who reported poor scores in all three dimensions compared to men with poor scores in only one, suggesting the potential for shared underlying biology but a differing degree of perturbation when depression and anxiety symptoms co-occur. Our findings implicate pathways of interest relevant to the overlap of mental health conditions in aging veterans and could represent clinically translatable targets underlying poor mental health in this high-risk population.

Energy-Resolved Fragmentation Aiding the Structure Elucidation of Steroid Biomarkers

The identification and confirmation of steroid sulfate metabolites in biological samples are essential to various fields, including anti-doping analysis and clinical sciences. Ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) is the leading method for the detection of intact steroid conjugates in biofluids, but because of the inherent complexity of biological samples and the low concentration of many targets of interest, metabolite identification based solely on mass spectrometry remains a major challenge. The confirmation of new metabolites typically depends on a comparison with synthetically derived reference materials that encompass a range of possible conjugation sites and stereochemistries. Herein, energy-resolved collision-induced dissociation (CID) is used as part of UHPLC-HRMS/MS analysis to distinguish between regio- and stereo-isomeric steroid sulfate compounds. This wholly MS-based approach was employed to guide the synthesis of reference materials to unambiguously confirm the identity of an equine steroid sulfate biomarker of testosterone propionate administration.

Synthesis of stable isotope labelled steroid bis(sulfate) conjugates and their behaviour in collision induced dissociation experiments

Steroid bis(sulfate) metabolites derived from the two-fold sulfation of unconjugated precursors represent an important yet understudied portion of the steroid profile. The investigation of these compounds in fields such as medicine or anti-doping science relies on mass spectrometry (MS) as the principal tool to identify and quantify biomarkers of interest and depends in turn on access to steroid reference materials and their stable isotope labelled (SIL) derivatives. A new [¹⁸O] stable isotope label for sulfate metabolites is reported, which allows for the selective, late-stage and 'one-pot' synthesis of a variety of SIL-steroid conjugates suitable as MS probes and internal standards. The method is applied to more comprehensively study the MS behaviour of steroid bis(sulfate) compounds through collision-induced dissociation (CID) experiments.

Profiling Urinary Sulfate Metabolites With Mass Spectrometry

The study of urinary phase II sulfate metabolites is central to understanding the role and fate of endogenous and exogenous compounds in biological systems. This study describes a new workflow for the untargeted metabolic profiling of sulfated metabolites in a urine matrix. Analysis was performed using ultra-high-performance liquid chromatography-high resolution tandem mass spectrometry (UHPLC-HRMS/MS) with data dependent acquisition (DDA) coupled to an automated script-based data processing pipeline and differential metabolite level analysis. Sulfates were identified through k-means clustering analysis of sulfate ester derived MS/MS fragmentation intensities. The utility of the method was highlighted in two applications. Firstly, the urinary metabolome of a thoroughbred horse was examined before and after administration of the anabolic androgenic steroid (AAS) testosterone propionate. The analysis detected elevated levels of ten sulfated steroid metabolites, three of which were identified and confirmed by comparison with synthesised reference materials. This included 5α-androstane-3β,17α-diol 3-sulfate, a previously unreported equine metabolite of testosterone propionate. Secondly, the hydrolytic activity of four sulfatase enzymes on pooled human urine was examined. This revealed that Pseudomonas aeruginosa arylsulfatases (PaS) enzymes possessed higher selectivity for the hydrolysis of sulfated metabolites than the commercially available Helix pomatia arylsulfatase (HpS). This novel method provides a rapid tool for the systematic, untargeted metabolic profiling of sulfated metabolites in a urinary matrix.

Site-specific protein modification by 3-n-butylphthalide in primary hepatocytes: Covalent protein adducts diminished by glutathione and N-acetylcysteine

AIMS

3-n-Butylphthalide (NBP) is widely used for the treatment of cerebral ischaemic stroke but can causeliver injury in clinical practice. This study aims to elucidate the underlying mechanisms and propose potential preventive strategies.

MAIN METHODS

NBP and its four major metabolites, 3-hydroxy-NBP (3-OH-NBP), 10-hydroxy-NBP, 10-keto-NBP and NBP-11-oic acid, were synthesized and evaluated in primary human or rat hepatocytes (PHHs, PRHs). NBP-related substances or amino acid adducts were identified and semi-quantitated by ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). The target proteins and binding sites were identified by shotgun proteomics based on peptide mass fingerprinting coupled with tandem mass spectrometry and verified by molecular docking.

KEY FINDINGS

The toxicity of NBP and its four major metabolites were compared in both PHHs and PRHs, and 3-OH-NBP was found to be the most toxic metabolite. 3-OH-NBP induced remarkable cell death and oxidative stresses in hepatocytes, which correlated well with the levels of glutathione and N-acetylcysteine adducts (3-GSH-NBP and 3-NAC-NBP) in cell supernatants. Additionally, 3-OH-NBP covalently conjugated with intracellular Cys, Lys and Ser, with preferable binding to Cys sites at Myh9 Cys1380, Prdx4 Cys53, Vdac2 Cys48 and Vdac3 Cys36. Furthermore, we found that CYP3A4 induction by rifampicin augmented NBP-induced cell toxicity and supplementing with GSH or NAC alleviated the oxidative stresses and reactive metabolites caused by 3-OH-NBP.

SIGNIFICANCE

Our work suggests that glutathione depletion, mitochondrial injury and covalent protein modification are the main causes of NBP-induced hepatotoxicity, which may be prevented by exogenous GSH or NAC supplementation and avoiding concomitant use of CYP3A4 inducers.

Biomarkers of Deoxynivalenol Toxicity in Chickens with Special Emphasis on Metabolic and Welfare Parameters

Deoxynivalenol (DON), a trichothecene mycotoxin produced by Fusarium species, is the most widespread mycotoxin in poultry feed worldwide. Long term-exposure from low to moderate DON concentrations can produce alteration in growth performance and impairment of the health status of birds. To evaluate the efficacy of mycotoxin-detoxifying agent alleviating the toxic effects of DON, the most relevant biomarkers of toxicity of DON in chickens should be firstly determined. The specific biomarker of exposure of DON in chickens is DON-3 sulphate found in different biological matrices (plasma and excreta). Regarding the nonspecific biomarkers called also biomarkers of effect, the most relevant ones are the impairment of the productive parameters, the intestinal morphology (reduction of villus height) and the enlargement of the gizzard. Moreover, the biomarkers of effect related to physiology (decrease of blood proteins, triglycerides, hemoglobin, erythrocytes, and lymphocytes and the increase of alanine transaminase (ALT)), immunity (response to common vaccines and release of some proinflammatory cytokines) and welfare status of the birds (such as the increase of Thiobarbituric acid reactive substances (TBARS) and the stress index), has been reported. This review highlights the available information regarding both types of biomarkers of DON toxicity in chickens.

An activity-based fluorescent sensor for the detection of the phenol sulfotransferase SULT1A1 in living cells

Human phenol sulfotransferases mediate the transfer of a sulfuryl moiety from the activated sulfate donor PAPS to hydroxy-containing substrates, altering substrate solubility and charge to affect phase II metabolism and cell signaling. Here, we present the development, computational modeling, in vitro enzymology, and biological application of STS-3, an activity-based fluorescent sensor for the SULT1A1 isoform.

Effects of Deoxynivalenol-Contaminated Diets on Metabolic and Immunological Parameters in Broiler Chickens

The current study was conducted to examine the effects of deoxynivalenol (DON) at different levels (5 and 15 mg/kg feed) on the metabolism, immune response and welfare parameters of male broiler chickens (Ross 308) at 42 days old. Forty-five 1 day-old broiler chickens were randomly distributed into three different dietary treatments: (1) control, (2) DON-contaminated diet with 5 mg DON/kg of feed (guidance level), and (3) DON-contaminated diet with 15 mg DON/kg of feed. Five replicated cages with three birds each were used for each treatment in a randomized complete block design. The results showed that DON was detected in excreta of birds fed contaminated diets compared with controls. The metabolite DON-3 sulphate (DON-3S) was detected in plasma and excreta in both treated groups, as well as in the liver (but only at 15 mg/kg feed). The increase in the level of DON decreased the hemoglobin concentration (p < 0.001), whereas the erythrocyte counts were only decreased at 15 mg DON/kg feed. No effect of DON on the responses to common vaccines was observed. In plasma, interleukin 8 levels in both contaminated groups were significantly higher than in the control group. The expression of interleukin 6, interleukin 1β and interferon-γ increased in jejunum tissues of broilers fed 5 mg/kg of DON compared with controls. The stress index (heterophil to lymphocyte ratio) was not affected by DON-contaminated diets compared with controls. The plasma corticosterone level was significantly lower in both DON groups compared with controls. In conclusion, DON-3S could be used as a specific biomarker of DON in different biological matrices, while the immune response in broiler chickens is stimulated by the presence of DON at the guidance level, but no adverse effect was observed on physiological stress parameters.

Comparison of two arylsulfatases for targeted mass spectrometric analysis of microbiota-derived metabolites

Sulfation of metabolites is the second highest phase II modification in humans, which plays a critical role in the xenobiotics clearance process and gut microbiota-host co-metabolism. Besides the main function to remove xenobiotics from the body, sulfated metabolites have also been linked to inflammation, bacterial pathogenesis and metabolic disorders. A better understanding of how these metabolites impact the human body has turned into an important research area. Analytical methods for selective identification of this metabolite class are scarce. We have recently developed an assay utilizing the arylsulfatase from Helix pomatia due to a high substrate promiscuity combined with state-of-the-art metabolomics bioinformatic analysis for the selective identification of O-sulfated metabolites in human samples. This enzyme requires a multistep purification process as highest purity is needed for the developed mass spectrometric assay. In this study, we have utilized a new and recombinant overexpressed arylsulfatase (ASPC) for the selective identification of organic sulfate esters in human urine samples. We have compared the substrate conversion in urine samples and substrate specificity of this enzyme with purified arylsulfatase from Helix pomatia. Our analysis of urine samples revealed that both enzymes can be utilized for the selective analysis and discovery of sulfated metabolites with high promiscuity as demonstrated by equal hydrolysis of 108 substrates including sulfated conjugates of 27 metabolites of microbial origin. Importantly, we also identified 21 substrates in human urine samples that are exclusively hydrolyzed by ASPC and application of this enzyme increases the discovery of unknown sulfated metabolites with a higher scaffold diversity.

Rapid Preparation of a Large Sulfated Metabolite Library for Structure Validation in Human Samples

Metabolomics analysis of biological samples is widely applied in medical and natural sciences. Assigning the correct chemical structure in the metabolite identification process is required to draw the correct biological conclusions and still remains a major challenge in this research field. Several metabolite tandem mass spectrometry (MS/MS) fragmentation spectra libraries have been developed that are either based on computational methods or authentic libraries. These libraries are limited due to the high number of structurally diverse metabolites, low commercial availability of these compounds, and the increasing number of newly discovered metabolites. Phase II modification of xenobiotics is a compound class that is underrepresented in these databases despite their importance in diet, drug, or microbiome metabolism. The O-sulfated metabolites have been described as a signature for the co-metabolism of bacteria and their human host. Herein, we have developed a straightforward chemical synthesis method for rapid preparation of sulfated metabolite standards to obtain mass spectrometric fragmentation pattern and retention time information. We report the preparation of 38 O-sulfated alcohols and phenols for the determination of their MS/MS fragmentation pattern and chromatographic properties. Many of these metabolites are regioisomers that cannot be distinguished solely by their fragmentation pattern. We demonstrate that the versatility of this method is comparable to standard chemical synthesis. This comprehensive metabolite library can be applied for co-injection experiments to validate metabolites in different human sample types to explore microbiota-host co-metabolism, xenobiotic, and diet metabolism.

Metabolic studies of selective androgen receptor modulators RAD140 and S-23 in horses

This paper describes the studies of the in vitro biotransformation of two selective androgen receptor modulators (SARMs), namely, RAD140 and S-23, and the in vivo metabolism of RAD140 in horses using ultra-high performance liquid chromatography-high resolution mass spectrometry. in vitro metabolic studies of RAD140 and S-23 were performed using homogenised horse liver. The more prominent in vitro biotransformation pathways for RAD140 included hydrolysis, hydroxylation, glucuronidation and sulfation. Metabolic pathways for S-23 were similar to those for other arylpropionamide-based SARMs. The administration study of RAD140 was carried out using three retired thoroughbred geldings. RAD140 and the majority of the identified in vitro metabolites were detected in post-administration urine samples. For controlling the misuse of RAD140 in horses, RAD140 and its metabolite in sulfate form gave the longest detection time in hydrolysed urine and could be detected for up to 6 days post-administration. In plasma, RAD140 itself gave the longest detection time of up to 13 days. Apart from RAD140 glucuronide, the metabolites of RAD140 described herein have never been reported before.

Differentiation of Deprotonated Acyl-, N-, and O-Glucuronide Drug Metabolites by Using Tandem Mass Spectrometry Based on Gas-Phase Ion-Molecule Reactions Followed by Collision-Activated Dissociation

Glucuronidation, a common phase II biotransformation reaction, is one of the major in vitro and in vivo metabolism pathways of xenobiotics. In this process, glucuronic acid is conjugated to a drug or a drug metabolite via a carboxylic acid, a hydroxy, or an amino group to form acyl-, O-, and/or N-glucuronide metabolites, respectively. This process is traditionally thought to be a detoxification pathway. However, some acyl-glucuronides react with biomolecules in vivo, which may result in immune-mediated idiosyncratic drug toxicity (IDT). In order to avoid this, one may attempt in early drug discovery to modify the lead compounds in such a manner that they then have a lower probability of forming reactive acyl-glucuronide metabolites. Because most drugs or drug candidates bear multiple functionalities, e.g., hydroxy, amino, and carboxylic acid groups, glucuronidation can occur at any of those. However, differentiation of isomeric acyl-, N-, and O-glucuronide derivatives of drugs is challenging. In this study, gas-phase ion-molecule reactions between deprotonated glucuronide metabolites and BF₃ followed by collision-activated dissociation (CAD) in a linear quadrupole ion trap mass spectrometer were demonstrated to enable the differentiation of acyl-, N-, and O-glucuronides. Only deprotonated N-glucuronides and deprotonated, migrated acyl-glucuronides form the two diagnostic product ions: a BF₃ adduct that has lost two HF molecules, [M - H + BF₃ - 2HF]^-, and an adduct formed with two BF₃ molecules that has lost three HF molecules, [M - H + 2BF₃ - 3HF]^-. These product ions were not observed for deprotonated O-glucuronides and unmigrated, deprotonated acyl-glucuronides. Upon CAD of the [M - H + 2BF₃ - 3HF]^- product ion, a diagnostic fragment ion is formed via the loss of 2-fluoro-1,3,2-dioxaborale (MW of 88 Da) only in the case of deprotonated, migrated acyl-glucuronides. Therefore, this method can be used to unambiguously differentiate acyl-, N-, and O-glucuronides. Further, coupling this methodology with HPLC enables the differentiation of unmigrated 1-β-acyl-glucuronides from the isomeric acyl-glucuronides formed upon acyl migration. Quantum chemical calculations at the M06-2X/6-311++G(d,p) level of theory were employed to probe the mechanisms of the reactions of interest.

A Novel Method for Identification and Quantification of Sulfated Flavonoids in Plants by Neutral Loss Scan Mass Spectrometry

Sulfur is present in plants in a large range of essential primary metabolites, as well as in numerous natural products. Many of these secondary metabolites contain sulfur in the oxidized form of organic sulfate. However, except of glucosinolates, very little is known about other classes of such sulfated metabolites, mainly because of lack of specific and quantitative analytical methods. We developed an LC-MS method to analyze sulfated flavonoids, a group of sulfated secondary metabolites prominent, e.g., in plants of the genus Flaveria. The method uses a linear gradient of methanol/formic acid in water on a Restek Raptor C₁₈ Core-Shell column for separation of the compounds. The sulfated flavonoids are detected by mass spectrometry (MS) in a negative mode, using a neutral loss of 80 Da after a collision induced dissociation. With this method we were also able to quantify the sulfated flavonoids. We could detect all (mono)sulfated flavonoids described before in Flaveria plus a number of new ones, such as isorhamnetin-sulfate-glycoside. In addition, we showed that sulfated flavonoids represent a substantial sulfur pool in Flaveria, larger than the thiols glutathione and cysteine. The individual species possess different sulfated flavonoids, but there is no correlation between the qualitative pattern and type of photosynthesis. Similar to other sulfur-containing secondary compounds, the concentration of sulfated flavonoids in leaves is reduced by sulfur starvation. The new LC-MS method will enable qualitative and quantitative detection of these secondary metabolites in plants as a pre-requisite to addressing their functions.

Characteristics of Colon-Derived Uremic Solutes

BACKGROUND AND OBJECTIVES

Colon microbial metabolism produces solutes that are normally excreted in the urine and accumulate in the plasma when the kidneys fail. This study sought to further identify and characterize human colon-derived uremic solutes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Colon-derived solutes normally excreted in the urine were identified by comparing urine from controls (n=17) and patients with total colectomies (n=12), using an established metabolomic platform. Colon-derived solutes that accumulate in kidney failure were then identified by comparing the plasma of the control patients with that of patients on dialysis (n=14).

RESULTS

Ninety-one urinary solutes were classified as colon-derived on the basis of the finding of a urine excretion rate at least four-fold higher in control patients than in patients with total colectomies. Forty-six were solutes with known chemical structure, 35 of which had not previously been identified as colon-derived. Sixty of the colon-derived solutes accumulated in the plasma of patients with ESKD to a degree greater than urea and were therefore classified as uremic. The estimated urinary clearance for 27 out of the 32 colon-derived solutes for which clearance could be calculated exceeded that of creatinine, consistent with tubular secretion. Sulfatase treatment revealed that 42 out of the 91 colon-derived solutes detected were likely conjugates.

CONCLUSIONS

Metabolomic analysis identified numerous colon-derived solutes that are normally excreted in human urine. Clearance by tubular secretion limits plasma levels of many colon-derived solutes.

Metabolic Engineering of Escherichia coli for Enhanced Production of Naringenin 7-Sulfate and Its Biological Activities

Flavonoids are one of the predominant groups of plant polyphenols, and these compounds have significant effects on human health and nutrition. Sulfated flavonoids have more favorable attributes compared to their parent compounds such as increased solubility, stability, and bioavailability. In this research, we developed a microbial system to produce sulfated naringenin using Escherichia coli expressing a sulfotransferase (ST) from Arabidopsis thaliana (At2g03770). This wild-type strain was used as a model system for testing clustered regularly interspaced short palindromic repeats (CRISPR) interference (CRISPRi) metabolic engineering strategies. Using synthetic sgRNA to mediate transcriptional repression of cysH, a gene encoding 3'-phosphoadenosine-5'-phosphosulfate (PAPS) ST, which is involved in sulfur metabolism, resulted in an increase in intracellular PAPS accumulation by over 3.28-fold without impairing cell growth. Moreover, naringenin 7-sulfate production by engineering E. coli with its cysH gene repressed in the open reading frame through CRISPRi was enhanced by 2.83-fold in compared with the wild-type control. To improve the efficiency of biotransformation, the concentration of SO42- , glucose, and substrate were optimized. The bioproductivity of naringenin 7-sulfate was 135.49 μM [∼143.1 mg (47.7 mg L^-1)] in a 3-L fermenter at 36 h. These results demonstrated that the CRISPRi system was successfully applied for the first time in E. coli to develop an efficient microbial strain for production of a sulfated flavonoid. In addition, antibacterial and anticancer activities of naringenin 7-sulfate were investigated and found to be higher than the parent compound.

High resolution mass spectrometry-based methodologies for identification of Etravirine bioactivation to reactive metabolites: In vitro and in vivo approaches

Drug bioactivation to reactive metabolites capable of covalent adduct formation with bionucleophiles is a major cause of drug-induced adverse reactions. Therefore, elucidation of reactive metabolites is essential to unravel the toxicity mechanisms induced by drugs and thereby identify patient subgroups at higher risk. Etravirine (ETR) was the first second-generation Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI) to be approved, as a therapeutic option for HIV-infected patients who developed resistance to the first-generation NNRTIs. Additionally, ETR came into market aiming to overcome some adverse effects associated with the previously used efavirenz (neurotoxicity) and nevirapine (hepatotoxicity) therapies. Nonetheless, post-marketing reports of severe ETR-induced skin rash and hypersensitivity reactions have prompted the U.S. FDA to issue a safety alert on ETR. Taking into consideration that ETR usage may increase in the near future, due to the possible use of the drug for coinfection with malaria and HIV, the development of reliable prognostic tools for early risk/benefit estimations is urgent. In the current study, high resolution mass spectrometry-based methodologies were integrated with MS³ experiments for the identification of reactive ETR metabolites/adducts: 1) in vitro incubation of the drug with human and rat liver S9 fractions in the presence of Phase I and II co-factors, including glutathione, as a trapping bionucleophile; and 2) in vivo, using urine samples from HIV-infected patients on ETR therapy. We obtained evidence for multiple bioactivation pathways leading to the formation of covalent adducts with glutathione and N-acetyl-L-cysteine. These results suggest that similar reactions may occur with cysteine residues of proteins, supporting a role for ETR bioactivation in the onset of the toxic effects elicited by the drug. Additionally, ETR metabolites stemming from amine oxidation, with potential toxicological significance, were identified in vitro and in vivo. Also noteworthy is the fact that new metabolic conjugation pathways of glucuronide metabolites were demonstrated for the first time, raising questions about their potential toxicological implications. In conclusion, these results represent not only a contribution towards the elucidation of new metabolic pathways of drugs in general but also an important step towards the elucidation of potentially toxic ETR pathways, whose understanding may be crucial for reliable risk/benefit estimations of ETR-based regimens.

Persulfate Reaction in a Hair-Bleaching Formula: Unveiling the Unconventional Reactivity of 1,13-Diamino-4,7,10-Trioxatridecane

The stability and unconventional reactivity of 1,13‐diamino‐4,7,10‐trioxatridecane in the presence of NH₃, H₂O₂, and (NH₄)₂S₂O₈ are described. The ether‐diamine is an ingredient marketed to hair salons and consumers for so‐called “plex” services to compensate for hair damage during bleaching. The main reaction product identified is an unexpected azanyl ester derivative. This is considered relevant for the safety evaluation when used in cosmetic products. The mechanism of reaction was explored through DFT calculations. This study represents the first attempt to assess the stability of a plex active in an oxidative environment.

Structural elucidation of major selective androgen receptor modulator (SARM) metabolites for doping control

Elucidated and validated structure of the major SARM doping drug metabolites.

Constant Ion Loss Method for the Untargeted Detection of Bis-sulfate Metabolites

The untargeted detection of phase II metabolites is a key issue for the study of drug metabolism in biological systems. Sensitive and selective mass spectrometric (MS) techniques coupled to ultrahigh performance liquid chromatographic (UHPLC) systems are the most effective for this purpose. In this study, we evaluate different MS approaches with a triple quadrupole instrument for the untargeted detection of bis-sulfate metabolites. Bis-sulfates of 23 steroid metabolites were synthesized and their MS behavior was comprehensively studied. Bis-sulfates ionized preferentially as the dianion ([M - 2H]^2-) with a small contribution of the monoanion ([M - H]^-). Product ion spectra generated from the [M - 2H]^2- precursor ions were dominated by the loss of HSO₄^- to generate two product ions, that is, the ion at m/z 97 (HSO₄^-) and the ion corresponding to the remaining monosulfate fragment. Other product ions were found to be specific for some structures. As an example, the loss of [CH₃ + SO₃]^- was found to be important for several compounds with unsaturation adjacent to the sulfate. On the basis of the common behavior of the bis-sulfate metabolites two alternatives were evaluated for the untargeted detection of bis-sulfate metabolites (i) a precursor ion scan method using the ion at m/z 97 and (ii) a constant ion loss (CIL) method using the loss of HSO₄^-. Both methods allowed for the untargeted detection of the model compounds. Eight steroid bis-sulfates were synthesized in high purity in order to quantitatively evaluate the developed strategies. Lower limits of detection (2-20 ng/mL) were obtained using the CIL method. Additionally, the CIL method was found to be more specific in the detection of urinary bis-sulfates. The applicability of the CIL approach was demonstrated by determining progestogens altered during pregnancy and by detecting the bis-sulfate metabolites of tibolone.

Biotransformation of 2,4-dinitroanisole by a fungal Penicillium sp

Insensitive munitions explosives are new formulations that are less prone to unintended detonation compared to traditional explosives. While these formulations have safety benefits, the individual constituents, such as 2,4-dinitroanisole (DNAN), have an unknown ecosystem fate with potentially toxic impacts to flora and fauna exposed to DNAN and/or its metabolites. Fungi may be useful in remediation and have been shown to degrade traditional nitroaromatic explosives, such as 2,4,6-trinitrotoluene and 2,4-dinitrotoluene, that are structurally similar to DNAN. In this study, a fungal Penicillium sp., isolated from willow trees and designated strain KH1, was shown to degrade DNAN in solution within 14 days. Stable-isotope labeled DNAN and an untargeted metabolomics approach were used to discover 13 novel transformation products. Penicillium sp. KH1 produced DNAN metabolites resulting from ortho- and para-nitroreduction, demethylation, acetylation, hydroxylation, malonylation, and sulfation. Incubations with intermediate metabolites such as 2-amino-4-nitroanisole and 4-amino-2-nitroanisole as the primary substrates confirmed putative metabolite isomerism and pathways. No ring-cleavage products were observed, consistent with other reports that mineralization of DNAN is an uncommon metabolic outcome. The production of metabolites with unknown persistence and toxicity suggests further study will be needed to implement remediation with Penicillium sp. KH1. To our knowledge, this is the first report on the biotransformation of DNAN by a fungus.

Sulfate metabolites as alternative markers for the detection of 4-chlorometandienone misuse in doping control

Sulfate metabolites have been described as long-term metabolites for some anabolic androgenic steroids (AAS). 4-chlorometandienone (4Cl-MTD) is one of the most frequently detected AAS in sports drug testing and it is commonly detected by monitoring metabolites excreted free or conjugated with glucuronic acid. Sulfation reactions of 4Cl-MTD have not been studied. The aim of this work was to evaluate the sulfate fraction of 4Cl-MTD metabolism by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to establish potential long-term metabolites valuable for doping control purposes. 4Cl-MTD was administered to two healthy male volunteers and urine samples were collected up to 8 days after administration. A theoretical selected reaction monitoring (SRM) method working in negative mode was developed. Ion transitions were based on ionization and fragmentation behaviour of sulfate metabolites as well as specific neutral losses (NL of 15 Da and NL of 36 Da) of compounds with related chemical structure. Six sulfate metabolites were detected after the analysis of excretion study samples. Three of the identified metabolites were characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). Results showed that five out of the six identified sulfate metabolites were detected in urine up to the last collected samples from both excretion studies. Copyright © 2016 John Wiley & Sons, Ltd.

Urinary Metabolomics Identifies a Molecular Correlate of Interstitial Cystitis/Bladder Pain Syndrome in a Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network Cohort

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a poorly understood syndrome affecting up to 6.5% of adult women in the U.S. The lack of broadly accepted objective laboratory markers for this condition hampers efforts to diagnose and treat this condition. To identify biochemical markers for IC/BPS, we applied mass spectrometry-based global metabolite profiling to urine specimens from a cohort of female IC/BPS subjects from the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network. These analyses identified multiple metabolites capable of discriminating IC/BPS and control subjects. Of these candidate markers, etiocholan-3α-ol-17-one sulfate (Etio-S), a sulfoconjugated 5-β reduced isomer of testosterone, distinguished female IC/BPS and control subjects with a sensitivity and specificity > 90%. Among IC/BPS subjects, urinary Etio-S levels are correlated with elevated symptom scores (symptoms, pelvic pain, and number of painful body sites) and could resolve high- from low-symptom IC/BPS subgroups. Etio-S-associated biochemical changes persisted through 3–6 months of longitudinal follow up. These results raise the possibility that an underlying biochemical abnormality contributes to symptoms in patients with severe IC/BPS.

•

Unbiased small molecule profiling identified an interstitial cystitis/bladder pain syndrome associated metabolite.

•

This urinary metabolite independently identified patients with severe symptoms scores.

•

Associated biochemical changes persisted over 3–6 months and hint at broader metabolic dysfunction in patients.

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a poorly understood syndrome associated with chronic bladder or pelvic pain, often accompanied by frequent urination. Identifying biochemical pathways associated with IC/BPS is necessary to understand the disease processes and suggest new therapeutic targets. Here we applied a biochemical approach to compare all detectable urinary metabolites from human subjects with and without IC/BPS. This analysis identified a steroid hormone metabolite that corresponds to patients that report the most severe symptoms. This result offers insight into IC/BPS pathophysiology, and provides a new biochemical clue to guide future investigation into this mysterious condition.

New long term metabolite in human urine for metenolone misuse by liquid chromatography quadrupole time-of-flight mass spectrometry

In this study, metenolone metabolic profiles were investigated. Metenolone was administered to one healthy male volunteer. Liquid-liquid extraction and direct-injection were applied to processing urine samples. Urinary extracts were analyzed by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOFMS) using full scan and product ion scan with accurate mass measurement for the first time. Due to the lack of useful fragment ion for structural elucidation, GC-MS instrumentation was employed to obtain structural details of the trimethylsilylated phase I metabolite released after hydrolysis, and the EI mass spectrum was always informative in steroidal structure studies owing to more useful fragment ions than the ESI mass spectrum. 16 metabolites including 6 glucuronide and 9 unreported sulfate conjugates were characterized and tentatively identified. All the metabolites were evaluated in terms of how long they could be detected. The sulfate conjugate S6 (1-methylen-5α-androst-3,17-dione-2ξ-sulfate) was considered to be a new long term metabolite for metenolone misuse that could be detected 40 days by liquid-liquid extraction and up to 30 days by direct-injection analysis after oral administration.

Measurement of the Heterocyclic Amines 2-Amino-9H-pyrido[2,3-b]indole and 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in Urine: Effects of Cigarette Smoking

2-Amino-9H-pyrido[2,3-b]indole (AαC) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) are carcinogenic heterocyclic aromatic amines (HAAs) formed during the combustion of tobacco and during the high-temperature cooking of meats. Human enzymes biotransform AαC and PhIP into reactive metabolites, which can bind to DNA and lead to mutations. We sought to understand the relative contribution of smoking and diet to the exposure of AαC and PhIP, by determining levels of AαC, its ring-oxidized conjugate 2-amino-9H-pyrido[2,3-b]indole-3-yl sulfate (AαC-3-OSO3H), and PhIP in urine of smokers on a free-choice diet before and after a six week tobacco smoking cessation study. AαC and AαC-3-OSO3H were detected in more than 90% of the urine samples of all subjects during the smoking phase. The geometric mean levels of urinary AαC during the smoking and cessation phases were 24.3 pg/mg creatinine and 3.2 pg/mg creatinine, and the geometric mean levels of AαC-3-OSO3H were 47.3 pg/mg creatinine and 3.7 pg/mg creatinine. These decreases in the mean levels of AαC and AαC-3-OSO3H were, respectively, 87% and 92%, after the cessation of tobacco (P < 0.0007). However, PhIP was detected in <10% of the urine samples, and the exposure to PhIP was not correlated to smoking. Epidemiological studies have reported that smoking is a risk factor for cancer of the liver and gastrointestinal tract. It is noteworthy that AαC is a hepatocellular carcinogen and induces aberrant crypt foci, early biomarkers of colon cancer, in rodents. Our urinary biomarker data demonstrate that tobacco smoking is a significant source of AαC exposure. Further studies are warranted to examine the potential role of AαC as a risk factor for hepatocellular and gastrointestinal cancer in smokers.

Toxicokinetic study and oral bioavailability of deoxynivalenol in turkey poults, and comparative biotransformation between broilers and turkeys

The aim of present study was to reveal the toxicokinetic properties and absolute oral bioavailability of deoxynivalenol (DON) in turkey poults. Six turkey poults were administered this Fusarium mycotoxin per os and intravenously in a two-way cross-over design. Based on non-compartmental analysis, DON was absorbed rapidly (Tmax= 0.57 h) but incomplete, as the oral bioavailability was only 20.9%. DON was rapidly eliminated as well, both after oral (T1/2elimination PO=0.86 h) as well as intravenous (IV) (T1/2elimination IV = 0.62 h) administration. Furthermore, semi-quantitative analysis using high-resolution mass spectrometry revealed that DON-3α-sulphate is the major metabolite of DON in turkeys after IV as well as oral administration, with DON-3α-sulphate/DON ratios between 1.3-12.6 and 32.4-140.8 after IV and oral administration, respectively. Glucuronidation of DON to DON-3α-glucuronide is a minor pathway in turkey poults, with DON-3α-glucuronide/DON ratios between 0.009-0.065 and 0.020-0.481 after IV and oral administration, respectively. Only trace amounts of other metabolites were found including 10-DON-sulphonate, de-epoxydeoxynivalenol and 10-de-epoxydeoxynivalenol-sulphonate. In addition, a similar two-way cross-over study was performed in three broiler chickens, in order to compare the biotransformation of DON in both poultry species. High-resolution mass spectrometry revealed that DON-3α-sulphate was the major metabolite of DON in broiler chickens as well, with DON-3α-sulphate/DON ratios between 243-453 and 1,365-29,624 after IV and oral administration, respectively. These ratios indicate that broiler chickens metabolise DON even more extensively to the sulphate conjugate compared to turkey poults. Only trace amounts of other metabolites were detected in broiler chickens. In conclusion, it can be stated that the toxicokinetic behaviour of DON in broiler chickens and turkey poults is comparable (low absolute oral bioavailability, rapid absorption and elimination, extensive biotransformation to DON-3α-sulphate), however, relative differences in DON-3α-sulphate/DON ratios exist between both species which might explain the hypothesised difference in sensitivity of both poultry species to DON.

Comparison of sulfo-conjugated and gluco-conjugated urinary metabolites for detection of methenolone misuse in doping control by LC-HRMS, GC-MS and GC-HRMS

Methenolone (17β-hydroxy-1-methyl-5α-androst-1-en-3-one) misuse in doping control is commonly detected by monitoring the parent molecule and its metabolite (1-methylene-5α-androstan-3α-ol-17-one) excreted conjugated with glucuronic acid using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography mass spectrometry (LC-MS) for the parent molecule, after hydrolysis with β-glucuronidase. The aim of the present study was the evaluation of the sulfate fraction of methenolone metabolism by LC-high resolution (HR)MS and the estimation of the long-term detectability of its sulfate metabolites analyzed by liquid chromatography tandem mass spectrometry (LC-HRMSMS) compared with the current practice for the detection of methenolone misuse used by the anti-doping laboratories. Methenolone was administered to two healthy male volunteers, and urine samples were collected up to 12 and 26 days, respectively. Ethyl acetate extraction at weak alkaline pH was performed and then the sulfate conjugates were analyzed by LC-HRMS using electrospray ionization in negative mode searching for [M-H](-) ions corresponding to potential sulfate structures (comprising structure alterations such as hydroxylations, oxidations, reductions and combinations of them). Eight sulfate metabolites were finally detected, but four of them were considered important as the most abundant and long term detectable. LC clean up followed by solvolysis and GC/MS analysis of trimethylsilylated (TMS) derivatives reveal that the sulfate analogs of methenolone as well as of 1-methylene-5α-androstan-3α-ol-17-one, 3z-hydroxy-1β-methyl-5α-androstan-17-one and 16β-hydroxy-1-methyl-5α-androst-1-ene-3,17-dione were the major metabolites in the sulfate fraction. The results of the present study also document for the first time the methenolone sulfate as well as the 3z-hydroxy-1β-methyl-5α-androstan-17-one sulfate as metabolites of methenolone in human urine. The time window for the detectability of methenolone sulfate metabolites by LC-HRMS is comparable with that of their hydrolyzed glucuronide analogs analyzed by GC-MS. The results of the study demonstrate the importance of sulfation as a phase II metabolic pathway for methenolone metabolism, proposing four metabolites as significant components of the sulfate fraction.

Human Urinary Composition Controls Antibacterial Activity of Siderocalin

During Escherichia coli urinary tract infections, cells in the human urinary tract release the antimicrobial protein siderocalin (SCN; also known as lipocalin 2, neutrophil gelatinase-associated lipocalin/NGAL, or 24p3). SCN can interfere with E. coli iron acquisition by sequestering ferric iron complexes with enterobactin, the conserved E. coli siderophore. Here, we find that human urinary constituents can reverse this relationship, instead making enterobactin critical for overcoming SCN-mediated growth restriction. Urinary control of SCN activity exhibits wide ranging individual differences. We used these differences to identify elevated urinary pH and aryl metabolites as key biochemical host factors controlling urinary SCN activity. These aryl metabolites are well known products of intestinal microbial metabolism. Together, these results identify an innate antibacterial immune interaction that is critically dependent upon individualistic chemical features of human urine.

Hydrastine pharmacokinetics and metabolism after a single oral dose of goldenseal (Hydrastis canadensis) to humans

The disposition and metabolism of hydrastine was investigated in 11 healthy subjects following an oral dose of 2.7 g of goldenseal supplement containing 78 mg of hydrastine. Serial blood samples were collected for 48 hours, and urine was collected for 24 hours. Hydrastine serum and urine concentrations were determined by Liquid Chromatography-tandem mass spectrometry (LC-MS/MS). Pharmacokinetic parameters for hydrastine were calculated using noncompartmental methods. The maximal serum concentration (Cmax) was 225 ± 100 ng/ml, Tmax was 1.5 ± 0.3 hours, and area under the curve was 6.4 ± 4.1 ng ⋅ h/ml ⋅ kg. The elimination half-life was 4.8 ± 1.4 hours. Metabolites of hydrastine were identified in serum and urine by using liquid chromatography coupled to high-resolution mass spectrometry. Hydrastine metabolites were identified by various mass spectrometric techniques, such as accurate mass measurement, neutral loss scanning, and product ion scanning using Quadrupole-Time of Flight (Q-ToF) and triple quadrupole instruments. The identity of phase II metabolites was further confirmed by hydrolysis of glucuronide and sulfate conjugates using bovine β-glucuronidase and a Helix pomatia sulfatase/glucuronidase enzyme preparation. Hydrastine was found to undergo rapid and extensive phase I and phase II metabolism. Reduction, O-demethylation, N-demethylation, hydroxylation, aromatization, lactone hydrolysis, and dehydrogenation of the alcohol group formed by lactone hydrolysis to the ketone group were observed during phase I biotransformation of hydrastine. Phase II metabolites were primarily glucuronide and sulfate conjugates. Hydrastine undergoes extensive biotransformation, and some metabolites may have pharmacological activity. Further study is needed in this area.

New potential biomarkers for mesterolone misuse in human urine by liquid chromatography quadrupole time-of-flight mass spectrometry

In this paper, mesterolone metabolic profiles were investigated carefully. Mesterolone was administered to one healthy male volunteer. Urinary extracts were analyzed by liquid chromatography quadruple time-of-flight mass spectrometry (LC-QTOFMS) for the first time. Liquid-liquid extraction was applied to processing urine samples, and dilute-shoot analyses of intact metabolites were also presented. In LC-QTOFMS analysis, chromatographic peaks for potential metabolites were hunt down by using the theoretical [M-H](-) as target ions in full scan experiment, and their actual deprotonated ions were analyzed in targeted MS/MS mode. Ten metabolites including seven new sulfate and three glucuronide conjugates were found for mesterolone. Because of no useful fragment ion for structural elucidation, gas chromatography-mass spectrometry instrumentation was employed to obtain structural details of the trimethylsilylated phase I metabolite released after solvolysis. Thus, their potential structures were proposed particularly by a combined MS approach. All the metabolites were also evaluated in terms of how long they could be detected, and S1 (1α-methyl-5α-androst-3-one-17β-sulfate) together with S2 (1α-methyl-5α-androst-17-one-3β-sulfate) was detected up to 9 days after oral administration, which could be the new potential biomarkers for mesterolone misuse.

New clostebol metabolites in human urine by liquid chromatography time-of-flight tandem mass spectrometry and their application for doping control

In this study, clostebol metabolic profiles were investigated carefully. Clostebol was administered to one healthy male volunteer. Urinary extracts were analyzed by liquid chromatography quadrupole time-of-flight mass spectrometry (MS) using full scan and targeted MS/MS techniques with accurate mass measurement for the first time. Liquid-liquid extraction and direct injection were applied to processing urine samples. Chromatographic peaks for potential metabolites were found by using the theoretical [M-H](-) as target ion in full scan experiment, and their actual deprotonated ions were analyzed in targeted MS/MS mode. Fourteen metabolites were found for clostebol, and nine unreported metabolites (two free ones and seven sulfate conjugates) were identified by MS, and their potential structures were proposed based on fragmentation and metabolism pathways. Four glucuronide conjugates were also first reported. All the metabolites were evaluated in terms of how long they could be detected and S1 (4ξ-chloro-5ξ-androst-3ξ-ol-17-one-3ξ-sulfate) was considered to be the long-term metabolite for clostebol misuse detected up to 25 days by liquid-liquid extraction and 14 days by direct injection analysis after oral administration. Five conjugated metabolites (M2, M5, S2, S6 and S7) could also be the alternative biomarkers for clostebol misuse.

Characterization of polar organosulfates in secondary organic aerosol from the green leaf volatile 3-Z-hexenal

Evidence is provided that the green leaf volatile 3-Z-hexenal serves as a precursor for biogenic secondary organic aerosol through the formation of polar organosulfates (OSs) with molecular weight (MW) 226. The MW 226 C6-OSs were chemically elucidated, along with structurally similar MW 212 C5-OSs, whose biogenic precursor is likely related to 3-Z-hexenal but still remains unknown. The MW 226 and 212 OSs have a substantial abundance in ambient fine aerosol from K-puszta, Hungary, which is comparable to that of the isoprene-related MW 216 OSs, known to be formed through sulfation of C5-epoxydiols, second-generation gas-phase photooxidation products of isoprene. Using detailed interpretation of negative-ion electrospray ionization mass spectral data, the MW 226 compounds are assigned to isomeric sulfate esters of 3,4-dihydroxyhex-5-enoic acid with the sulfate group located at the C-3 or C-4 position. Two MW 212 compounds present in ambient fine aerosol are attributed to isomeric sulfate esters of 2,3-dihydroxypent-4-enoic acid, of which two are sulfated at C-3 and one is sulfated at C-2. The formation of the MW 226 OSs is tentatively explained through photooxidation of 3-Z-hexenal in the gas phase, resulting in an alkoxy radical, followed by a rearrangement and subsequent sulfation of the epoxy group in the particle phase.

Metabolism, distribution, and excretion of deoxynivalenol with combined techniques of radiotracing, high-performance liquid chromatography ion trap time-of-flight mass spectrometry, and online radiometric detection

Dispositions of deoxynivalenol (DON) in rats and chickens were investigated, using a radiotracer method coupled with a novel γ-accurate radioisotope counting (γ-ARC) radio-high-performance liquid chromatography ion trap time-of-flight tandem mass spectrometry (radio-HPLC-IT-TOF-MS/MS) system. 3β-(3)H-DON was chemically synthesized and orally administrated to both sexes of rats and chickens as single or multiple doses. The results showed that DON was widely distributed and quickly eliminated in all tissues. The highest concentration was found in the gastrointestinal tract at 6 h post-administration. Substantially lower levels were detected in the kidney, liver, heart, lung, spleen, and brain. Three new metabolites were identified tentatively as 10-deoxynivalenol-sulfonate, 10-deepoxy-deoxynivalenol (DOM-1)-sulfonate, and deoxynivalenol-3α-sulfate. Deoxynivalenol-3α-sulfate was a major metabolite in chickens, while the major forms in rats were DOM-1 and DON. Additionally, a higher excretion rate in urine was observed in female rats than in male rats. The differences in metabolite profiles and excretion rates, which suggested diverse ways to detoxify, may relate to the different tolerances in different genders or species.

A new sulphate metabolite as a long-term marker of metandienone misuse

Metandienone is one of the most frequently detected anabolic androgenic steroids in sports drug testing. Metandienone misuse is commonly detected by monitoring different metabolites excreted free or conjugated with glucuronic acid using gas chromatography mass spectrometry (GC-MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) after hydrolysis with β-glucuronidase and liquid-liquid extraction. It is known that several metabolites are the result of the formation of sulphate conjugates in C17, which are converted to their 17-epimers in urine. Therefore, sulphation is an important phase II metabolic pathway of metandienone that has not been comprehensively studied. The aim of this work was to evaluate the sulphate fraction of metandienone metabolism by LC-MS/MS. Seven sulphate metabolites were detected after the analysis of excretion study samples by applying different neutral loss scan, precursor ion scan and SRM methods. One of the metabolites (M1) was identified and characterised by GC-MS/MS and LC-MS/MS as 18-nor-17β-hydroxymethyl-17α-methylandrost-1,4,13-triene-3-one sulphate. M1 could be detected up to 26 days after the administration of a single dose of metandienone (5 mg), thus improving the period in which the misuse can be reported with respect to the last long-term metandienone metabolite described (18-nor-17β-hydroxymethyl-17α-methylandrost-1,4,13-triene-3-one excreted in the glucuronide fraction).

Emerging sulfated flavonoids and other polyphenols as drugs: nature as an inspiration

Nature uses sulfation of endogenous and exogenous molecules mainly to avoid potential toxicity. The growing importance of natural sulfated molecules, as modulators of a number of physiological and pathological processes, has inspired the synthesis of non-natural sulfated scaffolds. Until the 1990s, the synthesis of sulfated small molecules was almost restricted to derivatives of flavonoids and aimed mainly at structure elucidation and plant biosynthesis studies. Currently, the synthesis of this type of compounds concerns structurally diverse scaffolds and is aimed at the development of potential drugs and/or exploitation of the biological effects of sulfated metabolites. Some important hit compounds are emerging from sulfated flavonoids and other polyphenols mainly as anticoagulant and antiviral agents. When compared with polymeric macromolecules such as heparins, sulfated small molecules could be of value in therapeutics due to their hydrophobic nature that can contribute to improve the bioavailability. This review highlights the synthetic approaches that were applied to obtain monosulfated or polysulfated phenolic small molecules and compiles the diverse biological activities already reported for this type of derivatives. Toxicity and pharmacokinetic parameters of this emerging class of derivatives will also be considered, emphasizing their value for therapeutic applications.

Alternative long-term markers for the detection of methyltestosterone misuse

Methyltestosterone (MT) is one of the most frequently detected anabolic androgenic steroids in doping control analysis. MT misuse is commonly detected by the identification of its two main metabolites excreted as glucuronide conjugates, 17α-methyl-5α-androstan-3α,17β-diol and 17α-methyl-5β-androstan-3α,17β-diol. The detection of these metabolites is normally performed by gas chromatography-mass spectrometry, after previous hydrolysis with β-glucuronidase enzymes, extraction and derivatization steps. The aim of the present work was to study the sulphate fraction of MT and to evaluate their potential to improve the detection of the misuse of the drug in sports. MT was administered to healthy volunteers and urine samples were collected up to 30days after administration. After an extraction with ethyl acetate, urine extracts were analysed by liquid chromatography tandem mass spectrometry using electrospray ionisation in negative mode by monitoring the transition m/z 385 to m/z 97. Three diol sulphate metabolites (S1, S2 and S3) were detected. Potential structures for these metabolites were proposed after solvolysis and mass spectrometric experiments: S1, 17α-methyl-5β-androstan-3α,17β-diol 3α-sulphate; S2, 17β-methyl-5α-androstan-3α,17α-diol 3α-sulphate; and S3, 17β-methyl-5β-androstan-3α,17α-diol 3α-sulphate. Synthesis of reference compounds will be required in order to confirm the structures. The retrospectivity of these sulphate metabolites in the detection of MT misuse was compared with the obtained with previously described metabolites. Metabolite S2 was detected up to 21days after MT administration, improving between 2 and 3 times the retrospectivity of the detection compared to the last long-term metabolite of MT previously described, 17α-hydroxy-17β-methylandrostan-4,6-dien-3-one.

New potential markers for the detection of boldenone misuse

Boldenone is one of the most frequently detected anabolic androgenic steroids in doping control analysis. Boldenone misuse is commonly detected by the identification of the active drug and its main metabolite, 5β-androst-1-en-17β-ol-3-one (BM1), by gas chromatography-mass spectrometry (GC-MS), after previous hydrolysis with β-glucuronidase enzymes, extraction and derivatization steps. However, some cases of endogenous boldenone and BM1 have been reported. Nowadays, when these compounds are detected in urine at low concentrations, isotope ratio mass spectrometry (IRMS) analysis is needed to confirm their exogenous origin. The aim of the present study was to identify boldenone metabolites conjugated with sulphate and to evaluate their potential to improve the detection of boldenone misuse in sports. Boldenone was administered to a healthy volunteer and urine samples were collected up to 56h after administration. After a liquid-liquid extraction with ethyl acetate, urine extracts were analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS) using electrospray ionisation in negative mode by monitoring the transition of m/z 365-350, specific for boldenone sulphate. Boldenone sulphate was identified in the excretion study urine samples and, moreover, another peak with the same transition was observed. Based on the MS/MS behaviour the metabolite was identified as epiboldenone sulphate. The identity was confirmed by isolation of the LC peak, solvolysis and comparison of the retention time and MS/MS spectra with an epiboldenone standard. These sulphated metabolites have not been previously reported in humans and although they account for less than 1% of the administered dose, they were still present in urine when the concentrations of the major metabolites, boldenone and BM1, were at the level of endogenous origin. The sulphated metabolites were also detected in 10 urine samples tested positive to boldenone and BM1 by GC-MS. In order to verify the usefulness of these new metabolites to discriminate between endogenous and exogenous origin of boldenone, four samples containing endogenous boldenone and BM1, confirmed by IRMS, were analysed. In 3 of the 4 samples, neither boldenone sulphate nor epiboldenone sulphate were detected, confirming that these metabolites were mainly detected after exogenous administration of boldenone. In contrast, boldenone sulphate and, in some cases, epiboldenone sulphate were present in samples with low concentrations of exogenous boldenone and BM1. Thus, boldenone and epiboldenone sulphates are additional markers for the exogenous origin of boldenone and they can be used to reduce the number of samples to be analysed by IRMS. In samples with boldenone and BM1 at the concentrations suspicion for endogenous origin, only if boldenone and epiboldenone sulphates are present, further analysis by IRMS will be needed to confirm exogenous origin.

Synthesis and molecular structure of (Z)-1H-purin-6-ylideneaminooxysulfonic acid: a possible secondary metabolite of adenine

The reaction of 6-chloropurine (