Targeted Metabolic Investigation of Ligandrol and Analytical Methods Validation for Its Main Long-term Metabolite

Prompted by the need for related analytical reference material in the frame of the fight against doping in sports, synthetic efforts towards the main long-term bishydroxylated metabolite (LGD-LTM1) of the nonsteroidal selective androgen receptor modulator (SARM) ligandrol have produced related derivatives that were exploited for a targeted metabolite analysis of urine samples obtained in the course of previous excretion studies of this SARM. Further clarifying ligandrol's metabolic profile, the availability of synthetic reference material permitted the structural elucidation of a previously reported pyrrolidinone-type metabolite and revealed its potential analytical utility as an additional long-term marker. Moreover, synthetic reference material enabled the comparison and validation of liquid chromatography coupled with mass spectrometry (LC-MS)-based and gas chromatography coupled with mass spectrometry (GC-MS)-based detection and identification methods focusing on the LGD-LTM1 marker.

Solid-State Glass Nanopipettes: Functionalization and Applications

Solid-state glass nanopipettes provide a promising confined space that offers several advantages such as controllable size, simple preparation, low cost, good mechanical stability, and good thermal stability. These advantages make them an ideal choice for various applications such as biosensors, DNA sequencing, and drug delivery. In this review, we first delve into the functionalized nanopipettes for sensing various analytes and the methods used to develop detection means with them. Next, we provide an in-depth overview of the advanced functionalization methodologies of nanopipettes based on diversified chemical kinetics. After that, we present the latest state-of-the-art achievements and potential applications in detecting a wide range of targets, including ions, molecules, biological macromolecules, and single cells. We examine the various challenges that arise when working with these targets, as well as the innovative solutions developed to overcome them. The final section offers an in-depth overview of the current development status, newest trends, and application prospects of sensors. Overall, this review provides a comprehensive and detailed analysis of the current state-of-the-art functionalized nanopipette perception sensing and development of detection means and offers valuable insights into the prospects for this exciting field.

Tapping the Full Potential of Infrared Spectroscopy for the Analysis of Technical Lignins

We present an approach to overcome the challenges associated with the increasing demand of high-throughput characterization of technical lignins, a key resource in emerging bioeconomies. Our approach offers a resort from the lack of direct, simple, and low-cost analytical techniques for lignin characterization by employing multivariate calibration models based on infrared (IR) spectroscopy to predict structural properties of lignins (i. e., functionality, molar mass). By leveraging a comprehensive database of over 500 well-characterized technical lignin samples - a factor of 10 larger than previously used sets - our chemometric models achieved high levels of quality and statistical confidence for the determination of different functional group contents (RMSEPs of 4-16 %). However, the statistical moments of the molar mass distribution are still best determined by size-exclusion chromatography. Analyses of over 500 technical lignins offered also a great opportunity to provide information on the general variability in kraft lignins and lignosulfonates (from different origins). Overall, the effected savings in analysis time (>7 h), resources, and required sample mass combined with non-destructiveness of the measurement satisfy key demands for efficient high-throughput lignin analyses. Finally, we discuss the advantages, disadvantages, and limitations of our approach, along with critical insights into the associated chemical-analytical and spectroscopic challenges.

Common Methods of Extraction and Determination of Phytomelatonin in Plants

The presence of melatonin in plants, called phytomelatonin, has gained great interest in recent years. The determination of phytomelatonin levels in plant extracts for both physiological and plant foodstuff studies requires sophisticated techniques due to the low endogenous levels of this indolic compound with hormonal nature. This chapter presents the most common and advanced techniques in the determination of phytomelatonin, with special emphasis on the techniques of extraction, cleaning, separation, detection, identification, and quantification. Multiple examples and recommendations are presented for a clear overview of the pros and cons of phytomelatonin determinations in plant tissues, seeds, and fruits, mainly.

β-Escin: An Updated Review of Its Analysis, Pharmacology, Pharmacokinetics, and Toxicity

[Formula: see text]-Escin is an oleanane-type pentacyclic triterpenoid saponin extracted from the seeds of Aesculus hippocastanum (AH), which is more widely distributed. [Formula: see text]-Escin sodium has been approved by the American FDA for clinical usage. This paper is intended to summarize an updated and comprehensive review of the pharmacological activities, pharmacokinetic properties, toxicity, and analytical methods of [Formula: see text]-escin. Studies have shown that [Formula: see text]-escin has significant antitumor, antiviral, anti-inflammatory, and other activities alongside less adverse effects and higher safety than other compounds. The review shows that the pharmacological effects of [Formula: see text]-escin involve mechanisms such as ATM/[Formula: see text]H2AX, RhoA/Rock, GSK-3[Formula: see text]/[Formula: see text]-Catenin, HER2/HER3/Akt, and PI3K/Akt signaling pathways, and Cyclin A, p21[Formula: see text], survivin, Bcl-2, Mcl-1, Caspases, TGF-[Formula: see text], MMPs, and TNF-[Formula: see text] among other inflammatory factors. [Formula: see text]-Escin has significant cytotoxicity; the use of the chitosan/xanthan gum-based polyelectrolyte complexes PA1 and PC-11 to modify it not only to reduces its toxicity, but also improves its drug efficacy. Because of this, these compounds may become a new research hotspot. [Formula: see text]-Escin in vivo metabolism can be converted by the CYP1A2 enzyme in the intestinal flora to produce [Formula: see text]-escin, deacylated, deglycosylated, and 21[Formula: see text]-[Formula: see text]-crotonoyl-protoescin, and the binding rate of the plasma proteins is higher than 90%. These are mainly metabolized by the liver, kidneys, and other organs, and excreted in the form of urine and feces. The number of reports on the specific mediators of the metabolism of [Formula: see text]-escin and their mechanisms and metabolites is relatively small; furthermore, the results are vague. Therefore, a complete and in-depth exploration of the pharmacokinetic characteristics of [Formula: see text]-escin is needed to provide a more complete and effective theoretical reference for the study of its pharmacodynamic activity.

The Eschenmoser's Salt as a Formylation Agent for the Synthesis of Indolizinecarbaldehydes and Their Use for Colorimetric Nitrite Detection

C-H bond formylation is the most immediate way to incorporate the versatile formyl group into (hetero)aromatics. However, the type of reagents and severe conditions involved in the classical formylation methods often curtail their application, especially in the presence of other functional groups. Herein, we present the Eschenmoser's salt, a commercially available (dimethylamino)methylating chemical, as a useful reagent for the C-H formylation of indolizines and other compounds. The method is straightforward and mild, furnishing indolizinecarbaldehydes in modest-to-good yields with exclusive and remote regioselectivity. Furthermore, these compounds can be easily transformed into push-pull dyes and are highly selective in the colorimetric detection of nitrite, a substance extensively employed as preservative in the food industry, the concentration of which is crucial to control to prevent harmful effects in living organisms. The assay is simple, allowing the naked-eye detection of nitrite in solution or on a cotton swab for a wide range of concentrations.

Infrared Diffusion-Ordered Spectroscopy Reveals Molecular Size and Structure

Inspired by ideas from NMR, we have developed Infrared Diffusion-Ordered Spectroscopy (IR-DOSY), which simultaneously characterizes molecular structure and size. We rely on the fact that the diffusion coefficient of a molecule is determined by its size through the Stokes-Einstein relation, and achieve sensitivity to the diffusion coefficient by creating a concentration gradient and tracking its equilibration in an IR-frequency resolved manner. Analogous to NMR-DOSY, a two-dimensional IR-DOSY spectrum has IR frequency along one axis and diffusion coefficient (or equivalently, size) along the other, so the chemical structure and the size of a compound are characterized simultaneously. In an IR-DOSY spectrum of a mixture, molecules with different sizes are nicely separated into distinct sets of IR peaks. Extending this idea to higher dimensions, we also perform 3D-IR-DOSY, in which we combine the conformation sensitivity of femtosecond multi-dimensional IR spectroscopy with size sensitivity.

In-Situ Analysis of Anionic Coordination Polymerizations by Electrospray-Ionization Mass Spectrometry

Anionic coordination polymerizations proceed via highly reactive intermediates, whose in situ analysis has remained difficult. Here, we show that electrospray-ionization mass spectrometry is a promising method to obtain detailed information on the polymerization process. Focusing on polymerization reactions of 1,3-dienes initiated by CoCl₂ /RLi (R=Me, nBu, tBu, Ph), we directly observe the growing polymer chains and characterize the active anionic cobalt centers by gas-phase fragmentation experiments. On the basis of these results, we suggest a plausible mechanism for the polymerization reaction. Moreover, the ESI mass spectra permit the determination of molecular weight distributions, which are in good agreement with those derived from NMR-spectroscopic as well as MALDI mass-spectrometric measurements, and afford a wealth of kinetic data.

Sensitive, Efficient and Portable Analysis of Molecular Exchange Processes by Hyperpolarized Ultrafast NMR

Molecular exchange processes are ubiquitous in nature. Here, we introduce a method to analyze exchange processes by using low-cost, portable, single-sided NMR instruments. The inherent magnetic field inhomogeneity of the single-sided instruments is exploited to achieve diffusion contrast of exchange sites and spatial encoding of 2D data. This so-called ultrafast diffusion exchange spectroscopy method shortens the experiment time by two to four orders of magnitude. Furthermore, because full 2D data are measured in a single scan (in a fraction of a second), the sensitivity of the experiment can be improved by several orders of magnitude using so-called nuclear spin hyperpolarization methods (in this case, dissolution dynamic nuclear polarization). As the first demonstration of the feasibility of the method in various applications, we show that the method enables quantification of intra- and extracellular exchange of water in a yeast cell suspension.

Trapping-Enrichment Multi-dimensional Liquid Chromatography with On-Line Deuterated Solvent Exchange for Streamlined Structure Elucidation at the Microgram Scale

At the forefront of chemistry and biology research, development timelines are fast-paced and large quantities of pure targets are rarely available. Herein, we introduce a new framework, which is built upon an automated, online trapping-enrichment multi-dimensional liquid chromatography platform (TE-Dt-mDLC) that enables: 1) highly efficient separation of complex mixtures in a first dimension (¹ D-UV); 2) automated peak trapping-enrichment and buffer removal achieved through a sequence of H₂ O and D₂ O washes using an independent pump setup; and 3) a second dimension separation (² D-UV-MS) with fully deuterated mobile phases and fraction collection to minimize protic residues for immediate NMR analysis while bypassing tedious drying processes and minimizing analyte degradation. Diverse examples of target isolation and characterization from organic synthesis and natural product chemistry laboratories are illustrated, demonstrating recoveries above 90 % using as little as a few micrograms of material.

Mediation by hormone concentrations on the associations between repeated measures of phthalate mixture exposure and timing of delivery

BACKGROUND

Phthalates are used in the manufacturing of consumer products, resulting in ubiquitous human exposure to phthalate mixtures. Previous work has suggested that phthalates display endocrine-disrupting capabilities, and exposure is associated with early delivery.

OBJECTIVE

To assess mediating effects of hormone concentrations on associations between phthalate mixtures and preterm birth (PTB).

METHODS

Repeated urinary phthalates and serum hormones were measured among 1011 women in the PROTECT Puerto Rico birth cohort from 2011-2019. We utilized ridge regression to create phthalate environmental risk scores (ERS), which represent weighted summaries of total phthalate exposure. Mediation analyses were conducted on a subset of 705 women. We additionally conducted fetal sex-specific analyses.

RESULTS

Free thyroxine (FT4) mediated 9.6% of the association between high molecular weight (HMW) ERS at 18 weeks and reduced gestational age at delivery (95%CI:1.07-29.9). Progesterone at 26 weeks mediated 21.1% and 16.2% of the association between HMW ERS at 18 and 22 weeks, and spontaneous PTB, respectively. Among male fetuses, corticotropin releasing hormone (CRH) at 18 weeks mediated 28.2% of the association between low molecular weight ERS and spontaneous PTB.

SIGNIFICANCE

We provide introductory evidence of hormone disruption on the causal pathway between phthalate exposure and early delivery. We also show differences by fetal sex, but larger sample size is necessary to validate our findings.

IMPACT STATEMENT

This study provides introductory evidence that an alteration of hormone concentrations occurs on the causal pathway between gestational phthalate mixture exposure and subsequent PTB. In addition to the novel application of repeated biomarker measurements and mixtures methods in causal mediation analyses, we also explored differences between classes of phthalate compounds and between fetal sexes. We show that differential endocrine pathways may be disrupted with exposures to low versus HMW phthalate compounds, and that pregnancies with a male fetus may be more susceptible to endocrine disruption than those with a female fetus.

Recent Trends and Future Perspectives of Emergent Analytical Techniques for Mercury Sensing in Aquatic Environments

Environmental emissions of mercury from industrial waste and natural sources, even in trace amounts, are toxic to organisms and ecosystems. However, industrial-scale mercury detection is limited by the high cost, low sensitivity/specificity, and poor selectivity of the available analytical tools. This review summarizes the key sensors for mercury detection in aqueous environments: colorimetric-, electrochemical-, fluorescence-, and surface-enhanced Raman spectroscopy-based sensors reported between 2014-2021. It then compares the performances of these sensors in the determination of inorganic mercury (Hg²⁺ ) and methyl mercury (CH₃ Hg⁺ ) species in aqueous samples. Mercury sensors for aquatic applications still face serious challenges in terms of difficult deployment in remote areas and low robustness, reliability, and selectivity in harsh environments. We provide future perspectives on the selective detection of organomercury species, which are especially toxic and reactive in aquatic environments. This review is intended as a valuable resource for scientists in the field of mercury sensing.

Per- and polyfluoroalkyl substances (PFAS) and total fluorine in fire station dust

Per- and polyfluoroalkyl substances (PFAS) are a class of over 4700 fluorinated compounds used in industry and consumer products. Studies have highlighted the use of aqueous film-forming foams (AFFFs) as an exposure source for firefighters, but little is known about PFAS occurrence inside fire stations, where firefighters spend most of their shifts. In this study, we aimed to characterize PFAS concentrations and sources inside fire stations. We measured 24 PFAS (using LC-MS/MS) and total fluorine (using particle-induced gamma ray emission) in dust from multiple rooms of 15 Massachusetts stations, many of which (60%) no longer use PFAS-containing AFFF at all and the rest of which only use it very rarely. Compared to station living rooms, turnout gear locker rooms had higher dust levels of total fluorine (p < 0.0001) and three PFAS: perfluorohexanoate (PFHxA), perfluoroheptanoate (PFHpA), and perfluorodecanoate (PFDoDA) (p < 0.05). These PFAS were also found on six wipes of station turnout gear. By contrast, the dominant PFAS in living rooms was N-ethyl perfluorooctane sulfonamidoacetic acid (N-MeFOSAA), a precursor to perfluorooctane sulfonate (PFOS) that still persists despite phase-outs almost two decades ago. The Σ₂₄ PFAS accounted for less than 2% of fluorine in dust (n = 39), suggesting the potential presence of unknown PFAS. Turnout gear may be an important PFAS source in stations due to intentional additives and/or contamination from firefighting activities.

Recent approaches for the quantitative analysis of functional oligosaccharides used in the food industry: A review

Functional oligosaccharides (OS) are diverse groups of carbohydrates that confer several health benefits stemming from their prebiotic activity. Commonly used oligosaccharides, fructooligosaccharides and galactooligosaccharides, are used in a wide range of applications from food ingredients to mimic the prebiotic activity of human milk oligosaccharides (HMOs) in infant formula to sugar and fat replacers in dairy and bakery products. However, while consumption of these compounds is associated with several positive health effects, increased consumption can cause intestinal discomfort and aggravation of intestinal bowel syndrome symptoms. Hence, it is essential to develop rapid and reliable techniques to quantify OS for quality control and proper assessment of their functionality in food and food products. The present review will focus on recent analytical techniques used to quantify OS in different matrices such as food and beverage products.

Electrochemical Fluorescence Switch of Organic Fluorescent or Fluorogenic Molecules

This short review is aimed at emphasizing the most prominent recent works devoted to the fluorescence modulation of organic fluorescent or fluorogenic molecules by electrochemistry. This still expanding research field not only addresses the smart uses of known molecules or the design of new ones, but also investigates the development of instrumentation providing time- and space-resolved information at the molecular level. Important considerations including fluorescent/fluorogenic probes, reversible/irreversible fluorescence switch, direct/indirect fluorescence modulation, or environment properties are especially scrutinized in recent works dealing with bioanalysis perspectives.

Evaluating inter-study variability in phthalate and trace element analyses within the Children's Health Exposure Analysis Resource (CHEAR) using multivariate control charts

BACKGROUND

The Children's Health Exposure Analysis Resource (CHEAR) program allows researchers to expand their research goals by offering the assessment of environmental exposures in their previously collected biospecimens. Samples are analyzed in one of CHEAR's network of six laboratory hubs with the ability to assess a wide array of environmental chemicals. The ability to assess inter-study variability is important for researchers who want to combine datasets across studies and laboratories.

OBJECTIVE

Herein we establish a process of evaluating inter-study variability for a given analytic method.

METHODS

Common quality control (QC) pools at two concentration levels (A and B) in urine were created within CHEAR for insertion into each batch of samples tested at a rate of three samples of each pool per 100 study samples. We assessed these QC pool results for seven phthalates analyzed for five CHEAR studies by three different lab hubs utilizing multivariate control charts to identify out-of-control runs or sets of samples associated with a given QC sample. We then tested the conditions that would lead to an out-of-control run by simulating outliers in an otherwise "in-control" set of 12 trace elements in blood QC samples (NIST SRM 955c).

RESULTS

When phthalates were assessed within study, we identified a single out-of-control run for two of the five studies. Combining QC results across lab hubs, all of the runs from these two studies were now in-control, while multiple runs from two other studies were pushed out-of-control. In our simulation study we found that 3-6 analytes with outlier values (5xSD) within a run would push that run out of control in 65-83% of simulations, respectively.

SIGNIFICANCE

We show how acceptable bounds of variability can be established for a given analytic method by evaluating QC materials across studies using multivariate control charts.

CSF xanthochromia: correlation with brain imaging and its usefulness as an out-of-hours test

BACKGROUND

Subarachnoid haemorrhage (SAH) is a spontaneous bleed into the subarachnoid space which is investigated by CT head and cerebrospinal fluid (CSF) xanthochromia. The aim of this study was to compare CSF xanthochromia with brain imaging and evaluate the need for out of hours (OOH) testing for CSF xanthochromia.

METHOD

Discharge summaries and brain imaging of patients with positive xanthochromia screen were reviewed over 12 months retrospectively. Timings of CSF xanthochromia and hospital discharge of 30 consecutive patients with negative xanthochromia screen were also examined.

RESULTS

From 289 xanthochromia requests, 23 were positive but only 2 patients had an actual bleed. In 30 consecutive negative xanthochromia results, all brain imaging results suggested no bleed. Eight of these requests were performed OOH, and as a result, 1 patient was discharged early.

CONCLUSIONS

CSF xanthochromia has a poor positive predictive value (8.7%) but has a good negative predictive value (100%) for SAH. Analysis of CSF xanthochromia OOH, in patients with negative CT head, did not speed up the discharge process from the hospital.

Fasting increases serum bilirubin levels in clinically normal, healthy males but not females: a retrospective study from phase I clinical trial participants

AIM

To examine if fasting affects serum bilirubin levels in clinically healthy males and females.

METHODS

We used retrospective data from phase I clinical trials where blood was collected in either a fed or fasting state at screening and predosing time points and analysed for total bilirubin levels as per standard clinical procedures. Participants were clinically healthy males (n=105) or females (n=30) aged 18-48 inclusive who participated in a phase I clinical trial in 2012 or 2013.

RESULTS

We found a statistically significant increase in total serum bilirubin levels in fasting males as compared with non-fasting males. The fasting time correlated positively with increased bilirubin levels. The age of the healthy males did not correlate with their fasting bilirubin level. We found no correlation between fasting and bilirubin levels in clinically normal females.

CONCLUSIONS

The recruitment and screening of volunteers for a clinical trial is a time-consuming and expensive process. This study clearly demonstrates that testing for serum bilirubin should be conducted on non-fasting male subjects. If fasting is required, then participants should not be excluded from a trial based on an elevated serum bilirubin that is deemed non-clinically significant.