Tracking lipid synthesis using 2H2O and 2H-NMR spectroscopy in black soldier fly (Hermetia illucens) larvae fed with macroalgae

Black soldier fly (Hermetia illucens) larvae are used to upcycle biowaste into insect biomass for animal feed. Previous research on black soldier fly has explored the assimilation of dietary fatty acids (FAs), but endogenous FA synthesis and modification remain comparatively unexplored. This study presents a 1H/2H-NMR methodology for measuring lipid synthesis in black soldier fly larvae using diluted deuterated water (2H2O) as a stable isotopic tracer delivered through the feeding media. This approach was validated by measuring 2H incorporation into the larvae's body water and consequent labelling of FA esterified into triacylglycerols. A 5% 2H enrichment in the body water, adequate to label the FA, is achieved after 24 h in a substrate with 10% 2H2O. A standard feeding trial using an invasive macroalgae was designed to test this method, revealing de novo lipogenesis was lower in larvae fed with macroalgae, probably related to the poor nutritional value of the diet.

Electroreduction of unactivated alkenes using water as hydrogen source

Herein, we report an electroreduction of unactivated alkyl alkenes enabled by [Fe]-H, which is provided through the combination of anodic iron salts and the silane generated in situ via cathodic reduction, using H2O as an H-source. The catalytic amounts of Si-additive work as an H-carrier from H2O to generate a highly active silane species in situ under continuous electrochemical conditions. This approach shows a broad substrate scope and good functional group compatibility. In addition to hydrogenation, the use of D2O instead of H2O provides the desired deuterated products in good yields with excellent D-incorporation (up to >99%). Further late-stage hydrogenation of complex molecules and drug derivatives demonstrate potential application in the pharmaceutical industry. Mechanistic studies are performed and provide support for the proposed mechanistic pathway.

Heavy water (D2O) induces autophagy-dependent apoptotic cell death in non-small cell lung cancer A549 cells by generating reactive oxygen species (ROS) upon microtubule disruption

OBJECTIVE

Deuterium oxide (D2O) or heavy water is known to have diverse biological activities and have a few therapeutic applications due to its limited toxicity to human subjects. In the present study, we investigated the mechanism of D2O-induced cytotoxicity in non-small cell lung cancer A549 cells.

RESULTS

We found that D2O-treatment resulted in cytotoxicity, cell cycle arrest, and apoptosis in A549 cells in a dose-dependent fashion. In contrast, limited cytotoxicity was observed in lung fibroblasts WI38 cells. Moreover, D2O-treatment resulted in the disruption of the cellular microtubule network, accompanied by the generation of ROS. On further investigation, we observed that the intracellular ROS triggered autophagic responses in D2O-treated cells, leading to apoptosis by inhibiting the oncogenic PI3K/ Akt/ mTOR signaling. D2O-treatment was also found to enhance the efficacy of paclitaxel in A549 cells.

SIGNIFICANCE

D2O induces autophagy-dependent apoptosis in A549 cells via ROS generation upon microtubule depolymerization and inhibition of PI3K/ Akt/ mTOR signaling. It augments the efficacy of other microtubule-targeting anticancer drug taxol, which indicates the potential therapeutic importance of D2O as an anticancer agent either alone or in combination with other chemotherapeutic drugs.

Clinically Translatable Hyperpolarized 13C Bicarbonate pH Imaging Method for Use in Prostate Cancer

Solid tumors such as prostate cancer (PCa) commonly develop an acidic microenvironment with pH 6.5-7.2, owing to heterogeneous perfusion, high metabolic activity, and rapid cell proliferation. In preclinical prostate cancer models, disease progression is associated with a decrease in tumor extracellular pH, suggesting that pH imaging may reflect an imaging biomarker to detect aggressive and high-risk disease. Therefore, we developed a hyperpolarized carbon-13 MRI method to image the tumor extracellular pH (pHe) and prepared it for clinical translation for detection and risk stratification of PCa. This method relies on the rapid breakdown of hyperpolarized (HP) 1,2-glycerol carbonate (carbonyl-13C) via base-catalyzed hydrolysis to produce HP 13CO32-, which is neutralized and converted to HP H13CO3-. After injection, HP H13CO3- equilibrates with HP 13CO2 in vivo and enables the imaging of pHe. Using insights gleaned from mechanistic studies performed in the hyperpolarized state, we solved issues of polarization loss during preparation in a clinical polarizer system. We successfully customized a reaction apparatus suitable for clinical application, developed clinical standard operating procedures, and validated the radiofrequency pulse sequence and imaging data acquisition with a wide range of animal models. The results demonstrated that we can routinely produce a highly polarized and safe HP H13CO3- contrast agent suitable for human injection. Preclinical imaging studies validated the reliability and accuracy of measuring acidification in healthy kidney and prostate tumor tissue. These methods were used to support an Investigational New Drug application to the U.S. Food and Drug Administration. This methodology is now ready to be implemented in human trials, with the ultimate goal of improving the management of PCa.

Rapid detection of antimicrobial resistance in methicillin-resistant Staphylococcus aureus using MALDI-TOF mass spectrometry

Antimicrobial resistance is a growing problem in modern healthcare. Most antimicrobial susceptibility tests (AST) require long culture times which delay diagnosis and effective treatment. Our group has previously reported a proof-of-concept demonstration of a rapid AST in Escherichia coli using deuterium labeling and MALDI mass spectrometry. Culturing bacteria in D2O containing media incorporates deuterium in newly synthesized lipids, resulting in a mass shift that can be easily detected by mass spectrometry. The extent of new growth is measured by the average mass of synthesized lipids that can be correlated with resistance in the presence of antimicrobials. In this work, we adapt this procedure to methicillin-resistant Staphylococcus aureus using the Bruker MALDI-TOF Biotyper, a low-cost instrument commonly available in diagnostic laboratories. The susceptible strain showed a significant decrease in average mass in on-target microdroplet cultures after 3 hours of incubation with 10 µg/mL methicillin, while the resistant strain showed consistent labeling regardless of methicillin concentration. This assay allows us to confidently detect methicillin resistance in S. aureus after only 3 hours of culture time and minimal sample processing, reducing the turn-around-time significantly over conventional assays. The success of this work suggests its potential as a rapid AST widely applicable in many clinical microbiology labs with minimal additional costs.

Challenges Related to Acquisition of Physiological Data for Physiologically Based Pharmacokinetic (PBPK) Models in Postpartum, Lactating Women and Breastfed Infants-A Contribution from the ConcePTION Project

Physiologically based pharmacokinetic (PBPK) modelling is a bottom-up approach to predict pharmacokinetics in specific populations based on population-specific and medicine-specific data. Using an illustrative approach, this review aims to highlight the challenges of incorporating physiological data to develop postpartum, lactating women and breastfed infant PBPK models. For instance, most women retain pregnancy weight during the postpartum period, especially after excessive gestational weight gain, while breastfeeding might be associated with lower postpartum weight retention and long-term weight control. Based on a structured search, an equation for human milk intake reported the maximum intake of 153 mL/kg/day in exclusively breastfed infants at 20 days, which correlates with a high risk for medicine reactions at 2-4 weeks in breastfed infants. Furthermore, the changing composition of human milk and its enzymatic activities could affect pharmacokinetics in breastfed infants. Growth in breastfed infants is slower and gastric emptying faster than in formula-fed infants, while a slower maturation of specific metabolizing enzymes in breastfed infants has been described. The currently available PBPK models for these populations lack structured systematic acquisition of population-specific data. Future directions include systematic searches to fully identify physiological data. Following data integration as mathematical equations, this holds the promise to improve postpartum, lactation and infant PBPK models.

Organo-Mediator Enabled Electrochemical Deuteration of Styrenes

Despite widespread use of the deuterium isotope effect, selective deuterium labeling of chemical molecules remains a major challenge. Herein, a facile and general electrochemically driven, organic mediator enabled deuteration of styrenes with deuterium oxide (D2 O) as the economical deuterium source was reported. Importantly, this transformation could be suitable for various electron rich styrenes mediated by triphenylphosphine (TPP). The reaction proceeded under mild conditions without transition-metal catalysts, affording the desired products in good yields with excellent D-incorporation (D-inc, up to >99 %). Mechanistic investigations by means of isotope labeling experiments and cyclic voltammetry tests provided sufficient support for this transformation. Notably, this method proved to be a powerful tool for late-stage deuteration of biorelevant compounds.

Heavy Water Reduces the Electronic Conductance of Protein Wires via Deuteron Interactions with Aromatic Residues

Proteins are versatile, self-assembling nanoelectronic components, but their hopping conductivity is expected to be influenced by solvent fluctuations. The role of the solvent was investigated by measuring the single molecule conductance of several proteins in both H2O and D2O. The conductance of a homologous series of protein wires decreases more rapidly with length in D2O, indicating a 6-fold decrease in carrier diffusion constant relative to the same protein in H2O. The effect was found to depend on the specific aromatic amino acid composition. A tryptophan zipper protein showed a decrease in conductance similar to that of the protein wires, whereas a phenylalanine zipper protein was insensitive to solvent changes. Tryptophan contains an indole amine, whereas the phenylalanine aromatic ring has no exchangeable protons, so the effect of heavy water on conductance is a consequence of specific D- or H-interactions with the aromatic residues.

Imaging ocular water inflow in the mouse with deuterium oxide MRI

Abnormal intraocular fluid flow or clearance is involved with a variety of eye diseases such as glaucoma and diabetic retinopathy, but measurement of water exchange dynamics in the vitreous and aqueous remain challenging. 2H MRI can be used to image deuterium oxide (D₂O) as a tracer, but the signal-to-noise ratio for deuterium is low due to its low concentration, which has hampered its application to imaging the eye. To overcome this challenge, we investigated the feasibility of direct D2O MRI to measure water dynamics in the mouse eye. The balanced steady-state free precession (bSSFP) sequence provided substantially higher signal-to-noise ratio for imaging D2O in fluid compared to standard gradient echo and spin echo sequences. bSSFP allowed dynamic imaging of intraocular water inflow in the mouse with 41 s temporal resolution. The inflow rate in the vitreous was found to be faster than in the aqueous. These studies demonstrate the feasibility of in vivo imaging of water inflow dynamics into the both the vitreous and aqueous in mice, which could be useful in studies of abnormal fluid exchange in rodent models of eye disease.

Bioactive Natural Product Discovery via Deuterium Adduct Bioactivity Screening

The discovery of bioactive natural products lies at the forefront of human medicine. The continued discovery of these molecules is imperative in the fight against infection and disease. While natural products have historically dominated the drug market, discovery in recent years has slowed significantly, partly due to limitations in current discovery methodologies. This work demonstrates a new workflow, deuterium adduct bioactivity screening (DABS), which pairs untargeted isotope labeling with whole cell binding assays for bioactive natural product discovery. DABS was validated and led to the discovery of a new isoprenyl guanidine alkaloid, zillamycin, which showed anti-cancer and anti-microbial activities. DABS thus represents a new workflow to accelerate discovery of natural products with a wide range of bioactive potentials.

Systemic deuteration of SCID mice using the water-isotopologue deuterium oxide (D2 O) inhibits tumor growth in an orthotopic bioluminescent model of human pancreatic ductal adenocarcinoma

Since its initial discovery as a natural isotopologue of dihydrogen oxide (1 H2 O), extensive research has focused on the biophysical, biochemical, and pharmacological effects of deuterated water (2 H2 O [D2 O, also referred to as "heavy water"]). Using a panel of cultured human pancreatic ductal adenocarcinoma (PDAC) cells we have profiled (i) D2 O-induced phenotypic antiproliferative and apoptogenic effects, (ii) redox- and proteotoxicity-directed stress response gene expression, and (iii) phosphoprotein-signaling related to endoplasmic reticulum (ER) and MAP-kinase stress response pathways. Differential array analysis revealed early modulation of stress response gene expression in both BxPC-3 and PANC-1 PDAC cells elicited by D2 O (90%; ≤6 h; upregulated: HMOX1, NOS2, CYP2E1, CRYAB, DDIT3, NFKBIA, PTGS1, SOD2, PTGS2; downregulated: RUNX1, MYC, HSPA8, HSPA1A) confirmed by independent RT-qPCR analysis. Immunoblot-analysis revealed rapid (≤6 h) onset of D2 O-induced MAP-kinase signaling (p-JNK, p-p38) together with ER stress response upregulation (p-eIF2α, ATF4, XBP1s, DDIT3/CHOP). Next, we tested the chemotherapeutic efficacy of D2 O-based drinking water supplementation in an orthotopic PDAC model employing firefly luciferase-expressing BxPC-3-FLuc cells in SCID mice. First, feasibility and time course of systemic deuteration (30% D2 O in drinking water; 21 days) were established using time-resolved whole-body proton magnetic resonance imaging and isotope-ratio mass spectrometry-based plasma (D/H)-analysis. D2 O-supplementation suppressed tumor growth by almost 80% with downregulated expression of PCNA, MYC, RUNX1, and HSP70 while increasing tumor levels of DDIT3/CHOP, HO-1, and p-eIF2α. Taken together, these data demonstrate for the first time that pharmacological induction of systemic deuteration significantly reduces orthotopic tumor burden in a murine PDAC xenograft model.

Determining and interpreting protein lifetimes in mammalian tissues

The orchestration of protein production and degradation, and the regulation of protein lifetimes, play a central role in the majority of biological processes. Recent advances in proteomics have enabled the estimation of protein half-lives for thousands of proteins in vivo. What is the utility of these measurements, and how can they be leveraged to interpret the proteome changes occurring during development, aging, and disease? This opinion article summarizes leading technical approaches and highlights their strengths and weaknesses. We also disambiguate frequently used terminology, illustrate recent mechanistic insights, and provide guidance for interpreting and validating protein turnover measurements. Overall, protein lifetimes, coupled to estimates of protein levels, are essential for obtaining a deep understanding of mammalian biology and the basic processes defining life itself.

Enrichment of hepatic glycogen and plasma glucose from H₂18 O informs gluconeogenic and indirect pathway fluxes in naturally feeding mice

Deuterated water (2 H2 O) is a widely used tracer of carbohydrate biosynthesis in both preclinical and clinical settings, but the significant kinetic isotope effects (KIE) of 2 H can distort metabolic information and mediate toxicity. 18 O-water (H2 18 O) has no significant KIE and is incorporated into specific carbohydrate oxygens via well-defined mechanisms, but to date it has not been evaluated in any animal model. Mice were given H2 18 O during overnight feeding and 18 O-enrichments of liver glycogen, triglyceride glycerol (TG), and blood glucose were quantified by 13 C NMR and mass spectrometry (MS). Enrichment of oxygens 5 and 6 relative to body water informed indirect pathway contributions from the Krebs cycle and triose phosphate sources. Compared with mice fed normal chow (NC), mice whose NC was supplemented with a fructose/glucose mix (i.e., a high sugar [HS] diet) had significantly higher indirect pathway contributions from triose phosphate sources, consistent with fructose glycogenesis. Blood glucose and liver TG 18 O-enrichments were quantified by MS. Blood glucose 18 O-enrichment was significantly higher for HS versus NC mice and was consistent with gluconeogenic fructose metabolism. TG 18 O-enrichment was extensive for both NC and HS mice, indicating a high turnover of liver triglyceride, independent of diet. Thus H2 18 O informs hepatic carbohydrate biosynthesis in similar detail to 2 H2 O but without KIE-associated risks.

Highly Effective H2/D2 Separation within the Stable Cu(I)Cu(II)-BTC: The Effect of Cu(I) Structure on Quantum Sieving

Realizing ideal deuterium separation from isotopic mixtures remains a daunting challenge because of their almost identical sizes, shapes, and physicochemical properties. Using the quantum sieving effect in porous materials with suitable pore size and open metal sites (OMSs) enables efficient hydrogen isotope separation. Herein, synthetic HKUST-1-derived microporous mixed-valence Cu(I)Cu(II)-BTC (BTC = benzene-1,3,5-tricarboxylate), featuring a unique network of distinct Cu(I) and Cu(II) coordination sites, can remarkably boost the D₂/H₂ isotope separation, which has a high selectivity (S_D2/H2) of 37.9 at 30 K, in comparison with HKUST-1 and other porous materials. Density functional theory (DFT) calculations indicate that the introduction of Cu(I) macrocycles in the framework decreases the pore size and further leads to relatively enhanced interaction of H₂/D₂ molecules on Cu(II) sites. The significantly enhanced selectivity of Cu(I)Cu(II)-BTC at 30 K can be mainly attributed to the synergistic effect of kinetic quantum sieving (KQS) and chemical affinity quantum sieving (CAQS). The results reveal that Cu(I) OMSs exhibit counterintuitive behaviors and play a crucial role in tuning quantum sieving without a complex structural design, which provides a deeper insight into quantum sieving mechanisms and a new strategy for the intelligent design of highly efficient isotope systems.

Electroreductively Induced Radicals for Organic Synthesis

Organic electrochemistry has attracted tremendous interest within the novel sustainable methodologies that have not only reduced the undesired byproducts, but also utilized cleaner and renewable energy sources. Particularly, oxidative electrochemistry has gained major attention. On the contrary, reductive electrolysis remains an underexplored research direction. In this context, we discuss advances in transition-metal-free cathodically generated radicals for selective organic transformations since 2016. We highlight the electroreductive reaction of alkyl radicals, aryl radicals, acyl radicals, silyl radicals, fluorosulfonyl radicals and trifluoromethoxyl radicals.

Atom-economical synthesis of 1,2-bis(phosphine oxide)ethanes from calcium carbide with straightforward access to deuterium- and 13C-labeled bidentate phosphorus ligands and metal complexes

Straightforward access to bidentate phosphorus ligands and bis(phosphineoxide)ethanes is described based on atom-economic addition reaction. A practical approach was developed to incorporate 2H and 13C labels using easily available reagents.

Evaluation of Deutetrabenazine's Potential to Delay Cardiac Repolarization Using Concentration-QTc Analysis

Deutetrabenazine (Austedo) is indicated in adults for chorea associated with Huntington disease and tardive dyskinesia. Escalating deutetrabenazine doses were administered to healthy volunteers who were cytochrome P450 2D6 extensive/intermediate metabolizers (EMs) or poor metabolizers (PMs) to determine pharmacokinetic exposure of parent drug and active metabolites (α-dihydrotetrabenazine [α-HTBZ] and β-dihydrotetrabenazine [β-HTBZ]), and collect corresponding electrocardiograms (ECGs) for evaluation of the cardiodynamic effect using concentration-QTc (C-QTc) modeling. Participants (12 EMs, 24 PMs) received placebo or single doses of deutetrabenazine (24, 48, and 72 mg) to achieve plasma concentrations exceeding therapeutic range in both cohorts. Pharmacokinetic samples were obtained over 72 hours after dosing and were time matched with 12-lead ECGs extracted from continuous ECG recordings. C-QTc analysis, using linear mixed-effects modeling and model selection procedure, characterized the relationship between plasma concentrations of deutetrabenazine, deuterated α-HTBZ and β-HTBZ, and the change from baseline in QT interval corrected using Fridericia's formula. Deutetrabenazine exhibited linear kinetics, and a C-QTc model with deuterated α-HTBZ and β-HTBZ was selected to best describe the C-QTc relationship in pooled EM and PM data. This model predicted a placebo-corrected Fridericia corrected QT interval prolongation higher than 10 milliseconds can be excluded at concentrations associated with the maximum recommended doses in both populations. Adverse events increased with higher exposure as reflected by the higher event number in the PM cohort receiving 48 and 72 mg doses. No subject discontinued due to cardiac-related adverse events and no clinically relevant ECG findings were reported. Thus, this study found that deutetrabenazine does not have a clinically relevant effect on QT prolongation at maximum recommended doses in either cytochrome P450 2D6 EMs or PMs.

The T1R3 subunit of the sweet taste receptor is activated by D2O in transmembrane domain-dependent manner

Deuterium oxide (D2O) is water in which the heavier and rare isotope deuterium replaces both hydrogens. We have previously shown that D2O has a distinctly sweet taste, mediated by the T1R2/T1R3 sweet taste receptor. Here, we explore the effect of heavy water on T1R2 and T1R3 subunits. We show that D2O activates T1R3-transfected HEK293T cells similarly to T1R2/T1R3-transfected cells. The response to glucose dissolved in D2O is higher than in water. Mutations of phenylalanine at position 7305.40 in the transmembrane domain of T1R3 to alanine, leucine, or tyrosine impair or diminish activation by D2O, suggesting a critical role for T1R3 TMD domain in relaying the heavy water signal.

A Hydrophilic Mixed Lanthanide Metal-Organic Framework Monitoring H2O in D2O

Lanthanide metal-organic framework (Ln-MOF) luminescent sensors monitoring the H₂O content in D₂O are still rare. We designed and built a hydrophilic mixed Ln-MOF (Eu_0.4Tb_0.6-MOF) monitoring the H₂O content in D₂O. By designing a ligand and controlling the synthesis method, we achieved a balance between the structural stability and sensing capacity. When the H₂O content ranges from 0 to 100%, the photoluminescence color of Eu_0.4Tb_0.6-MOF can change from yellow to green, which can be observed by the naked eye. The mechanism is that the photoluminescence intensity of Eu³⁺ decreases faster than that of Tb³⁺ when the H₂O content increases. The sensing mechanism was studied further by transient fluorescence spectrometry.

Dietary intake of deuterium oxide decreases cochlear metabolism and oxidative stress levels in a mouse model of age-related hearing loss

Age-related hearing loss (ARHL) is the most prevalent sensory disorder in the elderly. Currently, no treatment can effectively prevent or reverse ARHL. Aging auditory organs are often accompanied by exacerbated oxidative stress and metabolic deterioration. Here, we report the effect of deuterated oxygen (D2O), also known as "heavy water", mouse models of ARHL. Supplementing the normal mouse diet with 10% D2O from 4 to 9 weeks of age lowered hearing thresholds at selected frequencies in treated mice compared to untreated control group. Oxidative stress levels were significantly reduced and in the cochlear duct of treated vs. untreated mice. Through metabolic flux analysis, we found that D2O mainly slowed down catabolic reactions, and may delay metabolic deterioration related to aging to a certain extent. Experiments confirmed that the Nrf2/HO-1/glutathione axis was down-regulated in treated mice. Thus, D2O supplementation can hinder ARHL progression in mouse models by slowing the pace of metabolism and reducing endogenous oxidative stress production in the cochlea. These findings open new avenues for protecting the cochlea from oxidative stress and regulating metabolism to prevent ARHL.

The transient expression of recombinant proteins in plant cell packs facilitates stable isotope labelling for NMR spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy can be used to determine the structure, dynamics and interactions of proteins. However, protein NMR requires stable isotope labelling for signal detection. The cells used for the production of recombinant proteins must therefore be grown in medium containing isotopically labelled substrates. Stable isotope labelling is well established in Escherichia coli, but bacteria are only suitable for the production of simple proteins without post-translational modifications. More complex proteins require eukaryotic production hosts, but their growth can be impaired by labelled media, thus reducing product yields and increasing costs. To address this limitation, we used media supplemented with isotope-labelled substrates to cultivate the tobacco-derived cell line BY-2, which was then cast into plant cell packs (PCPs) for the transient expression of a labelled version of the model protein GB1. Mass spectrometry confirmed the feasibility of isotope labelling with ¹⁵ N and ² H using this approach. The resulting NMR spectrum featured a signal dispersion comparable to recombinant GB1 produced in E. coli. PCPs therefore offer a rapid and cost-efficient alternative for the production of isotope-labelled proteins for NMR analysis, especially suitable for complex proteins that cannot be produced in microbial systems.

Cultivation of the microalgae Chlamydomonas reinhardtii and Desmodesmus quadricauda in highly deuterated media: Balancing the light intensity

The production of organic deuterated compounds in microalgal systems represents a cheaper and more versatile alternative to more complicated chemical synthesis. In the present study, we investigate the autotrophic growth of two microalgae, Chlamydomonas reinhardtii and Desmodesmus quadricauda, in medium containing high doses of deuterated water, D₂O. The growth of such cultures was evaluated in the context of the intensity of incident light, since light is a critical factor in the management of autotrophic algal cultures. Deuteration increases the light sensitivity of both model organisms, resulting in increased levels of singlet oxygen and poorer photosynthetic performance. Our results also show a slowdown in growth and cell division processes with increasing D₂O concentrations. At the same time, impaired cell division leads to cell enlargement and accumulation of highly deuterated compounds, especially energy-storing molecules. Thus, considering the specifics of highly deuterated cultures and using the growth conditions proposed in this study, it is possible to obtain highly deuterated algal biomass, which could be a valuable source of deuterated organic compounds.

Facile and general electrochemical deuteration of unactivated alkyl halides

Herein, a facile and general electroreductive deuteration of unactivated alkyl halides (X = Cl, Br, I) or pseudo-halides (X = OMs) using D2O as the economical deuterium source was reported. In addition to primary and secondary alkyl halides, sterically hindered tertiary chlorides also work very well, affording the target deuterodehalogenated products with excellent efficiency and deuterium incorporation. More than 60 examples are provided, including late-stage dehalogenative deuteration of natural products, pharmaceuticals, and their derivatives, all with excellent deuterium incorporation (up to 99% D), demonstrating the potential utility of the developed method in organic synthesis. Furthermore, the method does not require external catalysts and tolerates high current, showing possible use in industrial applications.

Protein turnover models for LC-MS data of heavy water metabolic labeling

Protein turnover is vital for cellular functioning and is often associated with the pathophysiology of a variety of diseases. Metabolic labeling with heavy water followed by liquid chromatography coupled to mass spectrometry is a powerful tool to study in vivo protein turnover in high throughput and large scale. Heavy water is a cost-effective and easy to use labeling agent. It labels all nonessential amino acids. Due to its toxicity in high concentrations (20% or higher), small enrichments (8% or smaller) of heavy water are used with most organisms. The low concentration results in incomplete labeling of peptides/proteins. Therefore, the data processing is more challenging and requires accurate quantification of labeled and unlabeled forms of a peptide from overlapping mass isotopomer distributions. The work describes the bioinformatics aspects of the analysis of heavy water labeled mass spectral data, available software tools and current challenges and opportunities.

Metabolically-incorporated deuterium in myelin localized by neutron diffraction and identified by mass spectrometry

Myelin is a natural and dynamic multilamellar membrane structure that continues to be of significant biological and neurological interest, especially with respect to its biosynthesis and assembly during its normal formation, maintenance, and pathological breakdown. To explore the usefulness of neutron diffraction in the structural analysis of myelin, we investigated the use of in vivo labeling by metabolically incorporating non-toxic levels of deuterium (²H; D) via drinking water into a pregnant dam (D-dam) and her developing embryos. All of the mice were sacrificed when the pups (D-pups) were 55 days old. Myelinated sciatic nerves were dissected, fixed in glutaraldehyde and examined by neutron diffraction. Parallel samples that were unfixed (trigeminal nerves) were frozen for mass spectrometry (MS). The diffraction patterns of the nerves from deuterium-fed mice (D-mice) vs. the controls (H-mice) had major differences in the intensities of the Bragg peaks but no appreciable differences in myelin periodicity. Neutron scattering density profiles showed an appreciable increase in density at the center of the lipid-rich membrane bilayer. This increase was greater in D-pups than in D-dam, and its localization was consistent with deuteration of lipid hydrocarbon, which predominates over transmembrane protein in myelin. MS analysis of the lipids isolated from the trigeminal nerves demonstrated that in the pups the percentage of lipids that had one or more deuterium atoms was uniformly high across lipid species (97.6% ​± ​2.0%), whereas in the mother the lipids were substantially less deuterated (60.6% ​± ​26.4%) with levels varying among lipid species and subspecies. The mass distribution pattern of deuterium-containing isotopologues indicated the fraction (in %) of each lipid (sub-)species having one or more deuteriums incorporated: in the D-pups, the pattern was always bell-shaped, and the average number of D atoms ranged from a low of ∼4 in fatty acid to a high of ∼9 in cerebroside. By contrast, in D-dam most lipids had more complex, overlapping distributions that were weighted toward a lower average number of deuteriums, which ranged from a low of ∼3–4 in fatty acid and in one species of sulfatide to a high of 6–7 in cerebroside and sphingomyelin. The consistently high level of deuteration in D-pups can be attributed to their de novo lipogenesis during gestation and rapid, postnatal myelination. The widely varying levels of deuteration in D-dam, by contrast, likely depends on the relative metabolic stability of the particular lipid species during myelin maintenance. Our current findings demonstrate that stably-incorporated D label can be detected and localized using neutron diffraction in a complex tissue such as myelin; and moreover, that MS can be used to screen a broad range of deuterated lipid species to monitor differential rates of lipid turnover. In addition to helping to develop a comprehensive understanding of the de novo synthesis and turnover of specific lipids in normal and abnormal myelin, our results also suggest application to studies on myelin proteins (which constitute only 20–30% by dry mass of the myelin, vs. 70–80% for lipid), as well as more broadly to the molecular constituents of other biological tissues.

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Deuterium metabolically assimilated into gestating mouse pups via drinking water.

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Neutron diffraction localized deuterium to middle of myelin membrane bilayers.

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Mass spectrometry identified 26 deuterated lipid species as myelinic.

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Myelin of pups substantially more deuterated than that of their dam.

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Deuterium differentially distributed among lipid species and subspecies.

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De novo lipid biogenesis vs. steady-state maintenance readily distinguished.

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Novel paradigm suggests application to animal models of human myelinopathies.

Development of a selective matrix metalloproteinase 13 (MMP-13) inhibitor for the treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic disorder that causes damage to the cartilage and surrounding tissues and is characterized by pain, stiffness, and loss of function. Current treatments for OA primarily involve providing only relief of symptoms but does not affect the overall trajectory of the disease. A major goal for treating OA has been to slow down or reverse disease progression. Matrix metalloproteinase-13 (MMP-13) is expressed by chondrocytes and synovial cells in human OA and is thought to play a critical role in cartilage destruction. Herein we report a new, allosteric MMP-13 inhibitor, AQU-019, that has been optimized for potency, metabolic stability, and oral bioavailability through a combination of structure activity relationship (SAR) and deuterium substitution as a potential disease modifying OA drug (DMOAD). The inhibitor was demonstrated to be chondroprotective when injected intraarticular (IA) in the monoiodoacetic acid (MIA) rat model of OA.

A Randomized Phase 1 Evaluation of Deupirfenidone, a Novel Deuterium-Containing Drug Candidate for Interstitial Lung Disease and Other Inflammatory and Fibrotic Diseases

LYT-100 (deupirfenidone) is a selectively deuterated form of pirfenidone under development for the treatment of inflammatory and fibrotic diseases, including interstitial lung disease. Adverse events associated with antifibrotics can be a barrier to adoption and persistence in patients with interstitial lung diseases, most of whom are not on standard-of-care therapy. LYT-100 is designed to have a differentiated pharmacokinetic (PK) profile from pirfenidone and could offer a differentiated safety profile compared to current standard-of-care drugs while retaining the biochemical potency and specificity of pirfenidone. We conducted a phase 1b study to ascertain the safety, tolerability, steady-state PK profile, and food effect of LYT-100. This was a 2-part study. Part 1 assessed multiple ascending doses of LYT-100 from 100, 250, 500, 750, and 1000 mg twice daily given over 5 days without titration. Part 2 assessed the effects of fed vs fasting conditions on the PK profile of a single 500-mg dose of LYT-100. All doses up to 1000 mg were well tolerated, with adverse events being mild and transient. Exposure was slightly lower in the fed condition. LYT-100 was well tolerated and has a dose-proportional PK profile. The ratio of parent to major metabolite concentration was higher than reported with pirfenidone, which is consistent with an effect of deuteration on metabolism. No maximum tolerated dose was identified up to 1000 mg twice-daily dosing. These results support further clinical development of LYT-100, particularly considering the adverse event profile of current standard-of-care drugs.

Analytical scientist in pharmaceutical company: My thirty years in analytical R&D

A "summing up" of ~30 years' experience of analytical scientist in R&D of pharmaceutical industry. Some examples provided of most interesting and challenging cases of practical troubleshooting which we faced - and were able to solve. The cases are discussed in details in intention to not only debrief what has happened, but also to provide learning material for young analysts.

Cells in Slow Motion: Apparent Undercooling Increases Glassy Behavior at Physiological Temperatures

Solvent conditions are unexpectedly sufficient to drastically and reversibly slow down cells. In vitro on the molecular level, protein-solvent interactions drastically change in the presence of heavy water (D2 O) and its stronger hydrogen bonds. Adding D2 O to the cell medium of living cells increases the molecular intracellular viscosity. While cell morphology and phenotype remain unchanged, cellular dynamics transform into slow motion in a changeable manner. This is exemplified in the slowdown of cell proliferation and migration, which is caused by a reversible gelation of the cytoplasm. In analogy to the time-temperature superposition principle, where temperature is replaced by D2 O, an increase in viscosity slows down the effective time. Actin networks, crucial structures in the cytoplasm, switch from a power-law-like viscoelastic to a more rubber-like elastic behavior. The resulting intracellular resistance and dissipation impair cell movement. Since cells are highly adaptive non-equilibrium systems, they usually respond irreversibly from a thermodynamic perspective. D2 O induced changes, however, are fully reversible and their effects are independent of signaling as well as expression. The stronger hydrogen bonds lead to glass-like, drawn-out intramolecular dynamics, which may facilitate longer storage times of biological matter, for instance, during transport of organ transplants.

IVUS\IVPA hybrid intravascular molecular imaging of angiogenesis in atherosclerotic plaques via RGDfk peptide-targeted nanoprobes

Current intravascular imaging modalities face hurdles in the molecular evaluation of progressed plaques. This study aims to construct a novel hybrid imaging system (intravascular ultrasound/intravascular photoacoustic, IVPA/IVUS) via RGDfk peptide-targeted nanoparticles for monitoring angiogenesis in progressed atherosclerotic plaques in a rabbit model. An atherosclerotic rabbit model was induced by abdominal aorta balloon de-endothelialization followed by a high-fat diet. A human serum albumin (HSA)-based nanoprobe modified with RGDfk peptide was constructed by encapsulating indocyanine green (ICG) via electrostatic force (ICG-HSA-RGDfk NPs, IHR-NPs). A hybrid intravascular imaging system that combined IVUS and IVPA was self-assembled for RGDfk visualization within atherosclerotic plaques in the rabbit abdominal aorta. Through IHR-NPs and the hybrid IVUS/IVPA imaging platform, multiple comprehensive pieces of information on progressed plaques, including anatomical information, composition information and molecular information, can be obtained simultaneously, which may improve the precise diagnosis of plaque characteristics and the evaluation of early interventions for atherosclerosis.

Low amounts of heavy water increase the phase separation propensity of a fragment of the androgen receptor activation domain

The phase equilibria of intrinsically disordered proteins are exquisitely sensitive to changes in solution conditions and this can be used to investigate the driving forces of phase separation in vitro as well as the biological roles of phase transitions in live cells. Here we investigate how using D₂ O as co-solvent in an aqueous buffer changes the phase equilibrium of a fragment of the activation domain of the androgen receptor, a transcription factor that plays a role in the development of the male phenotype and is a therapeutic target for castration resistant prostate cancer. We show how replacing even small fractions of H₂ O with D₂ O increases the propensity of this fragment to undergo liquid-liquid phase separation, likely reflecting a stabilization of the hydrophobic interactions that drive condensation. Our results indicate that it is necessary to take this effect into consideration when studying phase separation phenomena with biophysical methods that require using D₂ O as a co-solvent. In addition, they suggest that additions of D₂ O may be used to enhance phase separation phenomena in cells, facilitating their observation.

Deuterium Oxide (D2O) Induces Early Stress Response Gene Expression and Impairs Growth and Metastasis of Experimental Malignant Melanoma

There are two stable isotopes of hydrogen, protium (1H) and deuterium (2H; D). Cellular stress response dysregulation in cancer represents both a major pathological driving force and a promising therapeutic target, but the molecular consequences and potential therapeutic impact of deuterium (2H)-stress on cancer cells remain largely unexplored. We have examined the anti-proliferative and apoptogenic effects of deuterium oxide (D2O; 'heavy water') together with stress response gene expression profiling in panels of malignant melanoma (A375V600E, A375NRAS, G361, LOX-IMVI), and pancreatic ductal adenocarcinoma (PANC-1, Capan-2, or MIA PaCa-2) cells with inclusion of human diploid Hs27 skin fibroblasts. Moreover, we have examined the efficacy of D2O-based pharmacological intervention in murine models of human melanoma tumor growth and metastasis. D2O-induction of apoptosis was substantiated by AV-PI flow cytometry, immunodetection of PARP-1, and pro-caspase 3 cleavage, and rescue by pan-caspase inhibition. Differential array analysis revealed early modulation of stress response gene expression in both A375 melanoma and PANC-1 adenocarcinoma cells elicited by D2O (90%; ≤6 h) (upregulated: CDKN1A, DDIT3, EGR1, GADD45A, HMOX1, NFKBIA, or SOD2 (up to 9-fold; p < 0.01)) confirmed by independent RT-qPCR analysis. Immunoblot analysis revealed rapid onset of D2O-induced stress response phospho-protein activation (p-ERK, p-JNK, p-eIF2α, or p-H2AX) or attenuation (p-AKT). Feasibility of D2O-based chemotherapeutic intervention (drinking water (30% w/w)) was demonstrated in a severe combined immunodeficiency (SCID) mouse melanoma metastasis model using luciferase-expressing A375-Luc2 cells. Lung tumor burden (visualized by bioluminescence imaging) was attenuated by D2O, and inhibition of invasiveness was also confirmed in an in vitro Matrigel transwell invasion assay. D2O supplementation also suppressed tumor growth in a murine xenograft model of human melanoma, and median survival was significantly increased without causing adverse effects. These data demonstrate for the first time that systemic D2O administration impairs growth and metastasis of malignant melanoma through the pharmacological induction of deuterium (2H)-stress.

DMSO/SOCl2-mediated C(sp2)-H amination: switchable synthesis of 3-unsubstituted indole and 3-methylthioindole derivatives

The reaction of 2-alkenylanilines with SOCl2 in DMSO was found to selectively afford 3-unsubstituted indoles and 3-methylthioindoles. This switchable approach was found to be temperature-dependent: at room temperature, the reaction afforded 3-unsubstituted indoles through intramolecular cyclization and elimination; while at higher temperature, the reaction gave 3-methylthioindoles via further electrophilic methylthiolation.

Hydrogen-Bond-Donor Solvents Enable Catalyst-Free (Radio)-Halogenation and Deuteration of Organoborons

A hydrogen bond donor solvent assisted (radio)halogenation and deuteration of organoborons has been developed. The reactions exhibited high functional group tolerance and needed only an ambient atmosphere. Most importantly, compared to literature methods, our conditions are more consistent with the principals of green chemistry (e.g., metal-free, strong oxidant-free, more straightforward conditions).

An Animal Able To Tolerate D2 O

It is possible to gain a deeper insight into the role of water in biology by using physicochemical variant molecules, such as deuterium oxide (D₂ O); however, D₂ O is toxic to multicellular organisms in high concentrations. By using a unique desiccation-rehydration process, we demonstrate that the anhydrobiotic nematode Panagrolaimus superbus is able to tolerate and proliferate in 99 % D₂ O. Moreover, we analysed P. superbus' water-channel protein (aquaporin; AQP), which is associated with dehydration/rehydration, by comparing its primary structure and modelling its tertiary structure in silico. Our data evidence that P. superbus' AQP is an aquaglyceroporin, a class of water channel known to display a wider pore; this helps to explain the rapid and successful organismal influx of D₂ O into this species. This is the first demonstration of an animal able to withstand high D₂ O levels, thus paving a way for the investigation of the effects D₂ O on higher levels of biological organization.

Imaging the invisible-Bioorthogonal Raman probes for imaging of cells and tissues

A revolutionary avenue for vibrational imaging with super-multiplexing capability can be seen in the recent development of Raman-active bioortogonal tags or labels. These tags and isotopic labels represent groups of chemically inert and small modifications, which can be introduced to any biomolecule of interest and then supplied to single cells or entire organisms. Recent developments in the field of spontaneous Raman spectroscopy and stimulated Raman spectroscopy in combination with targeted imaging of biomolecules within living systems are the main focus of this review. After having introduced common strategies for bioorthogonal labeling, we present applications thereof for profiling of resistance patterns in bacterial cells, investigations of pharmaceutical drug-cell interactions in eukaryotic cells and cancer diagnosis in whole tissue samples. Ultimately, this approach proves to be a flexible and robust tool for in vivo imaging on several length scales and provides comparable information as fluorescence-based imaging without the need of bulky fluorescent tags.

Current development of CFTR potentiators in the last decade

Cystic fibrosis (CF) is a genetic disorder produced by the loss of function of CFTR, a main chloride channel involved in transepithelial salt and water transport. CFTR function can be rescued by small molecules called "potentiators" which increase gating activity of CFTR on epithelial surfaces. High throughput screening (HTS) assays allowed the identification of new chemical entities endowed with potentiator properties, further improved through medicinal chemistry optimization. In this review, the most relevant classes of CFTR potentiators developed in the last decade were explored, focusing on structure-activity relationships (SAR) of the different chemical entities, as a useful tool for the improvement of their pharmacological activity.

Molecular imaging of extracellular vesicles in vitro via Raman metabolic labelling

Extracellular vesicles (EVs) are biologically-derived nanovectors important for intercellular communication and trafficking. As such, EVs show great promise as disease biomarkers and therapeutic drug delivery vehicles. However, despite the rapidly growing interest in EVs, understanding of the biological mechanisms that govern their biogenesis, secretion, and uptake remains poor. Advances in this field have been hampered by both the complex biological origins of EVs, which make them difficult to isolate and identify, and a lack of suitable imaging techniques to properly study their diverse biological roles. Here, we present a new strategy for simultaneous quantitative in vitro imaging and molecular characterisation of EVs in 2D and 3D based on Raman spectroscopy and metabolic labelling. Deuterium, in the form of deuterium oxide (D2O), deuterated choline chloride (d-Chol), or deuterated d-glucose (d-Gluc), is metabolically incorporated into EVs through the growth of parent cells on medium containing one of these compounds. Isolated EVs are thus labelled with deuterium, which acts as a bio-orthogonal Raman-active tag for direct Raman identification of EVs when introduced to unlabelled cell cultures. Metabolic deuterium incorporation demonstrates no apparent adverse effects on EV secretion, marker expression, morphology, or global composition, indicating its capacity for minimally obstructive EV labelling. As such, our metabolic labelling strategy could provide integral insights into EV biocomposition and trafficking. This approach has the potential to enable a deeper understanding of many of the biological mechanisms underpinning EVs, with profound implications for the design of EVs as therapeutic delivery vectors and applications as disease biomarkers.

Mutations in a Single Signaling Pathway Allow Cell Growth in Heavy Water

Life is completely dependent on water. To analyze the role of water as a solvent in biology, we replaced water with heavy water (D₂O) and investigated the biological effects by a wide range of techniques, using Schizosaccharomyces pombe as model organism. We show that high concentrations of D₂O lead to altered glucose metabolism and growth retardation. After prolonged incubation in D₂O, cells displayed gross morphological changes, thickened cell walls, and aberrant cytoskeletal organization. By transcriptomics and genetic screens, we show that the solvent replacement activates two signaling pathways: (1) the heat-shock response pathway and (2) the cell integrity pathway. Although the heat-shock response system upregulates various chaperones and other stress-relieving enzymes, we find that the activation of this pathway does not offer any fitness advantage to the cells under the solvent-replaced conditions. However, limiting the D₂O-triggered activation of the cell integrity pathway allows cell growth when H₂O is completely replaced with D₂O. The isolated D₂O-tolerant strains may aid biological production of deuterated biomolecules.

Pharmacokinetic and Metabolic Profile of Deutetrabenazine (TEV-50717) Compared With Tetrabenazine in Healthy Volunteers

Deutetrabenazine (Austedo, Teva Pharmaceuticals) is a deuterated form of tetrabenazine. It is the first deuterated drug to receive US regulatory approval and is approved for treatment of chorea in Huntington's disease and tardive dyskinesia. Two oral single dose studies comparing deutetrabenazine (25 mg) with tetrabenazine (25 mg) in healthy volunteers evaluated the impact of deuteration on pharmacokinetics of the active metabolites, alpha-dihydrotetrabenazine (α-HTBZ) and beta-dihydrotetrabenazine (β-HTBZ), metabolite profile, safety, and tolerability. In the two-way, cross-over study, the mean elimination half-life of deuterated total (α + β)-HTBZ was doubled compared with nondeuterated total (α + β)-HTBZ, with a twofold increase in overall mean exposure (area under the concentration-time curve from zero to infinity (AUC_0-inf )) and a marginal increase in mean peak plasma concentration (C_max ). In the mass balance and metabolite profiling study, there were no novel plasma or urinary metabolites of [¹⁴ C]-deutetrabenazine relative to [¹⁴ C]-tetrabenazine. Specific deuteration in deutetrabenazine resulted in a superior pharmacokinetic profile and an increased ratio of active-to-inactive metabolites, attributes considered to provide significant benefits to patients.

Analysis of the Physiological and Metabolic State of Leishmania Using Heavy Water Labeling

This protocol describes the use of heavy water (²H₂O) labeling to determine the growth rate and metabolic state of Leishmania parasites in culture and in infected animals. In vitro labeling studies are undertaken by cultivating defined parasite developmental stages in standard medium supplemented with 5% ²H₂O, resulting in the incorporation of deuterium (²H) into a range of metabolic precursors used in macromolecule (DNA, RNA, protein, lipid, and glycan) synthesis. The rate of turnover of different parasite macromolecules can subsequently be determined by analysis of deuterium enrichment in the different constituents of these macromolecules by gas chromatography-mass spectrometry (GC-MS). To measure the growth rate and physiological state of parasite stages in lesion tissue, infected mice were provided with 9% ²H₂O in their drinking water for various periods of time and ²H-enrichment in the macromolecular constituents of isolated lesion-derived parasite stages determined by GC-MS. This protocol provides quantitative information on key cellular processes, such as replication (DNA turnover), transcription (RNA turnover), translation (protein turnover), membrane biogenesis (lipid turnover), and central carbon metabolism (glycan turnover) that define the growth state and phenome of different parasite stages in vitro and in vivo. This approach can be used to assess the impact of host immune responses on parasite growth and physiology (using different Leishmania strains/species, mouse lines), characterize different parasite populations during chronic and acute infections, and assess parasite responses to drug treatments. It is also broadly applicable to other microbial pathogens.

Mild, Selective Ru-Catalyzed Deuteration Using D2 O as a Deuterium Source

A method for the selective deuteration of polyfunctional organic molecules using catalytic amounts of [RuCl2 (PPh3 )3 ] and D2 O as a deuterium source is presented. Through variation of additives like CuI, KOH, and various amounts of zinc powder, orthogonal chemoselectivities in the deuteration process are observed. Mechanistic investigation indicates the presence of different, defined Ru-complexes under the given specific conditions.

Impact of D2O on peptidization of l-proline

This is our follow-up study carried out in an order to collect experimental evidence regarding the impact of heavy water (D2O) on the spontaneous oscillatory peptidization of l-proline (l-Pro). Our earlier studies have been focused on the two sulfur-containing proteinogenic α-amino acids, i.e., l-cysteine (l-Cys) and l-methionine (l-Met), and it seemed interesting to assess the effect induced by D2O on one more proteinogenic α-amino acid, i.e., l-Pro. It needs to be added that unlike l-Met, but similar to l-Cys, the oscillatory peptidization of l-Pro dissolved in the organic-aqueous solvent characterizes with the circadian rhythm. As analytical techniques, we used high-performance liquid chromatography with the evaporative light-scattering detection (HPLC-ELSD), mass spectrometry (MS), scanning electron microscopy (SEM), and turbidimetry. The obtained results can in certain sense be viewed as analogous to those earlier reported for l-Cys and l-Met by demonstrating that heavy water considerably hampers the oscillatory peptidization of l-Pro. However, an unexpected observation was also made than unlike the cases with l-Cys and l-Met, the observed hampering effect of D2O on the oscillatory peptidization of l-Pro is not monotonously dependent on the concentration of D2O in the system, but it is the strongest pronounced for 10% (v/v) D2O in the employed binary methanol–water solvent (with the investigated proportions of D2O in this solvent changing from 0 to 30%). Although we have no rational explanation for this striking effect, we believe that it should not pass unnoticed and therefore it is emphasized in this study. Maybe this firm quantitative result will prove an inspiration for future researchers interested in getting a deeper insight into the role of D2O in life processes, and more specifically in the kinetic and the mechanistic aspects thereof.

Dehalogenative Deuteration of Unactivated Alkyl Halides Using D2O as the Deuterium Source

The general dehalogenation of alkyl halides with zinc using D₂O or H₂O as a deuterium or hydrogen donor has been developed. The method provides an efficient and economic protocol for deuterium-labeled derivatives with a wide substrate scope under mild reaction conditions. Mechanistic studies indicated that a radical process is involved for the formation of organozinc intermediates. The facile hydrolysis of the organozinc intermediates provides the driving force for this transformation.