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DNA adductomics is a relatively new omics approach aiming to measure known and unknown DNA modifications, called DNA adducts. Liquid chromatography–tandem mass spectrometry (LC-MS/MS) has become the most common method for analyzing DNA adducts. Recent advances in the field of mass spectrometry have allowed the possibility to perform a comprehensive analysis of adducts, for instance, by using a nontargeted data-independent acquisition method, with multiple precursor m/z windows as an inclusion list. However, the generated data are large and complex, and there is a need to develop algorithms to simplify and automate the time-consuming manual analysis that has hitherto been used. Here, a graphical user interface (GUI) program was developed, with the purpose of tracking a characteristic neutral loss reaction from tandem mass spectrometry of the nucleoside adducts. This program, called nLossFinder, was developed in the MATLAB platform, available as open-source code. Calf thymus DNA was used as a model for method optimization, and the overall adductomics approach was applied to DNA from amphipods (Monoporeia affinis) collected within the Swedish National Marine Monitoring Program. In the amphipod DNA, over 150 putative adducts were found in comparison to 18 using a manual approach in a previous study. The developed program can improve the processing time for large MS data, as it processes each sample in a few seconds, and hence can be applicable for high-throughput screening of adducts.
Pedro Sousa; Giulia Martella; K. Åberg; Bahare Esfahani; Hitesh Motwani. nLossFinder—A Graphical User Interface Program for the Nontargeted Detection of DNA Adducts. Toxics 2021, 9, 78 .
AMA StylePedro Sousa, Giulia Martella, K. Åberg, Bahare Esfahani, Hitesh Motwani. nLossFinder—A Graphical User Interface Program for the Nontargeted Detection of DNA Adducts. Toxics. 2021; 9 (4):78.
Chicago/Turabian StylePedro Sousa; Giulia Martella; K. Åberg; Bahare Esfahani; Hitesh Motwani. 2021. "nLossFinder—A Graphical User Interface Program for the Nontargeted Detection of DNA Adducts." Toxics 9, no. 4: 78.
The instability of electrophilic reactive metabolites in in vitro metabolism studies makes their accurate analysis challenging. To stabilise the reactive compounds prior to their analysis, different trapping agents, such as thiols, amines and cob(I)alamin, have earlier been tested depending on the metabolites to be analysed and the type of study. In the present work, DNA is introduced as a trapping agent for measuring the formation of bulky electrophilic metabolites. Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon (PAH), was used as a model compound in a rat liver S9 metabolic system. Under physiological incubation conditions, B[a]P metabolises to diol epoxide (BPDE) metabolites which were trapped by DNA resulting in the formation of covalently bound DNA adducts. The methodology for analysis of these adducts included extraction of the DNA from the metabolic system, digestion of the DNA to yield nucleosides and analysis of the BPDE-adduct to deoxyguanosine (BPDE-dG) by liquid chromatography coupled to high resolution mass spectrometry (HRMS). The chromatographic conditions in combination with the high mass accuracy data (±3 ppm) was useful in resolving BPDE-dG in its protonated form from the complex set of ions present in the metabolic matrix. The method was validated in terms of sensitivity, specificity, accuracy, precision and recovery, and applied to provide a preliminary estimate of BPDE-dG levels from the metabolism of B[a]P in rat S9. The use of DNA as a trapping agent for in vitro metabolites has a potential to aid in cancer risk assessment procedure of PAHs, for instance, in inter-species comparison of metabolism to reactive metabolites and can be adapted for screening of genotoxic metabolites, e.g., from emerging environmental contaminants.
Hitesh V. Motwani. DNA as an in vitro trapping agent for detection of bulky genotoxic metabolites. Journal of Chromatography B 2020, 1152, 122276 .
AMA StyleHitesh V. Motwani. DNA as an in vitro trapping agent for detection of bulky genotoxic metabolites. Journal of Chromatography B. 2020; 1152 ():122276.
Chicago/Turabian StyleHitesh V. Motwani. 2020. "DNA as an in vitro trapping agent for detection of bulky genotoxic metabolites." Journal of Chromatography B 1152, no. : 122276.
Linking exposure to environmental stress factors with diseases is crucial for proposing preventive and regulatory actions. Upon exposure to anthropogenic chemicals, covalent modifications on the genome can drive developmental and reproductive disorders in wild populations, with subsequent effects on the population persistence. Hence, screening of chemical modifications on DNA can be used to provide information on the probability of such disorders in populations of concern. Using a high-resolution mass spectrometry methodology, we identified DNA nucleoside adducts in gravid females of the Baltic amphipods Monoporeia affinis, and linked the adduct profiles to the frequency of embryo malformations in the broods. Twenty-three putative nucleoside adducts were detected in the females and their embryos, and eight modifications were structurally identified using high-resolution accurate mass data. To identify which adducts were significantly associated with embryo malformations, partial least squares regression (PLSR) modelling was applied. The PLSR model yielded three adducts as the key predictors: methylation at two different positions of the DNA (5-methyl-2′-deoxycytidine and N6-methyl-2′-deoxyadenosine) representing epigenetic marks, and a structurally unidentified nucleoside adduct. These adducts predicted the elevated frequency of the malformations with a high classification accuracy (84%). To the best of our knowledge, this is the first application of DNA adductomics for identification of contaminant-induced malformations in field-collected animals. The method can be adapted for a broad range of species and evolve as a new omics tool in environmental health assessment.
Elena Gorokhova; Giulia Martella; Nisha H. Motwani; Natalia Y. Tretyakova; Brita Sundelin; Hitesh V. Motwani. DNA epigenetic marks are linked to embryo aberrations in amphipods. Scientific Reports 2020, 10, 1 -11.
AMA StyleElena Gorokhova, Giulia Martella, Nisha H. Motwani, Natalia Y. Tretyakova, Brita Sundelin, Hitesh V. Motwani. DNA epigenetic marks are linked to embryo aberrations in amphipods. Scientific Reports. 2020; 10 (1):1-11.
Chicago/Turabian StyleElena Gorokhova; Giulia Martella; Nisha H. Motwani; Natalia Y. Tretyakova; Brita Sundelin; Hitesh V. Motwani. 2020. "DNA epigenetic marks are linked to embryo aberrations in amphipods." Scientific Reports 10, no. 1: 1-11.
DNA adducts can be formed from covalent binding of electrophilic reactive compounds to the nucleophilic N- and O-atoms of the biomolecule. The O-sites on DNA, with nucleophilic strength (n) of ca. 2, is recognized as a critical site for mutagenicity. Characterization of the reactivity of electrophilic compounds at the O-sites can be used to predict their mutagenic potency in relative terms. In the present study, reaction kinetic experiments were performed for butadiene monoxide (BM) in accordance with the Swain-Scott relation using model nucleophiles representing N- and O-sites on DNA, and earlier for glycidamide (GA) using a similar approach. The epoxide from the kinetic experiments was trapped by cob(I)alamin, resulting in formation of an alkylcobalamin which was analyzed by liquid chromatography tandem mass spectrometry. The Swain-Scott relationship was used to determine selectivity constant (s) of BM and GA as 0.86 and 1.0, respectively. The rate constant for the reaction at n of 2 was extrapolated to 0.023 and 0.038 M−1 h−1 for BM and GA, respectively, implying a higher mutagenic potency per dose unit of GA compared to BM. The reaction kinetic parameters associated with mutagenic potency were also estimated by a density functional theory approach, which were in accordance to the experimental determined values. These types of reaction kinetic measures could be useful in development of a chemical reactivity based prediction tool that could aid in reduction of animal experiments in cancer risk assessment procedures for relative mutagenicity.
Hitesh V. Motwani; Lars Eriksson; Lisa Göpfert; Kristian Larsen. Reaction kinetic studies for comparison of mutagenic potency between butadiene monoxide and glycidamide. Chemico-Biological Interactions 2018, 288, 57 -64.
AMA StyleHitesh V. Motwani, Lars Eriksson, Lisa Göpfert, Kristian Larsen. Reaction kinetic studies for comparison of mutagenic potency between butadiene monoxide and glycidamide. Chemico-Biological Interactions. 2018; 288 ():57-64.
Chicago/Turabian StyleHitesh V. Motwani; Lars Eriksson; Lisa Göpfert; Kristian Larsen. 2018. "Reaction kinetic studies for comparison of mutagenic potency between butadiene monoxide and glycidamide." Chemico-Biological Interactions 288, no. : 57-64.
When employing metabolism studies of genotoxic compounds/metabolites and cancer tests for risk estimation, low exposure doses in humans are roughly extrapolated from high exposure doses in animals. An improvement is to measure the in vivo dose, i.e. area under concentration-time curve (AUC), of the causative genotoxic agent. In the present work, we propose and evaluate a parallelogram based approach for estimation of the AUC of genotoxic metabolites that incorporates in vitro metabolic data and existing knowledge from published in vivo data on hemoglobin (Hb) adduct levels, using glycidamide (GA) as a case study compound that is the genotoxic metabolite of acrylamide (AA). The estimated value of AUC of GA per AUC of AA from the parallelogram approach vs. that from Hb adduct levels measured in vivo were in good agreement; 0.087 vs. 0.23 in human and 1.4 vs. 0.53 in rat, respectively. The described parallelogram approach is simple, and can be useful to provide an approximate estimation of the AUC of metabolites in humans at low exposure levels for which sensitive methods for analyzing the metabolites are not available, as well as aid in reduction of animal experiments for metabolism studies that are to be used for cancer risk assessment.
Hitesh V. Motwani; Cecilia Frostne; Margareta Törnqvist. Parallelogram based approach for in vivo dose estimation of genotoxic metabolites in humans with relevance to reduction of animal experiments. Scientific Reports 2017, 7, 17560 .
AMA StyleHitesh V. Motwani, Cecilia Frostne, Margareta Törnqvist. Parallelogram based approach for in vivo dose estimation of genotoxic metabolites in humans with relevance to reduction of animal experiments. Scientific Reports. 2017; 7 (1):17560.
Chicago/Turabian StyleHitesh V. Motwani; Cecilia Frostne; Margareta Törnqvist. 2017. "Parallelogram based approach for in vivo dose estimation of genotoxic metabolites in humans with relevance to reduction of animal experiments." Scientific Reports 7, no. 1: 17560.
Carcinogenicity of benzo[a]pyrene {B[a]P, a polycyclic aromatic hydrocarbon (PAH)} involves DNA-modification by B[a]P diol epoxide (BPDE) metabolites. Adducts to serum albumin (SA) are not repaired, unlike DNA adducts, and therefore considered advantageous in assessment of in vivo dose of BPDEs. In the present work, kinetic experiments were performed in relation to the dose (i.e. concentration over time) of different BPDE isomers, where human SA (hSA) was incubated with respective BPDEs under physiological conditions. A liquid chromatography (LC) tandem mass spectrometry methodology was employed for characterising respective BPDE-adducts at histidine and lysine. This strategy allowed to structurally distinguish between the adducts from racemic anti- and syn-BPDE and between (+)- and (−)-anti-BPDE, which has not been attained earlier. The adduct levels quantified by LC-UV and the estimated rate of disappearance of BPDEs in presence of hSA gave an insight into the reactivity of the diol epoxides towards the N-sites on SA. The structure specific method and dosimetry described in this work could be used for accurate estimation of in vivo dose of the BPDEs following exposure to B[a]P, primarily in dose response studies of genotoxicity, e.g. in mice, to aid in quantitative risk assessment of PAHs.
Hitesh V. Motwani; Emelie Westberg; Margareta Törnqvist. Interaction of benzo[a]pyrene diol epoxide isomers with human serum albumin: Site specific characterisation of adducts and associated kinetics. Scientific Reports 2016, 6, 36243 .
AMA StyleHitesh V. Motwani, Emelie Westberg, Margareta Törnqvist. Interaction of benzo[a]pyrene diol epoxide isomers with human serum albumin: Site specific characterisation of adducts and associated kinetics. Scientific Reports. 2016; 6 (1):36243.
Chicago/Turabian StyleHitesh V. Motwani; Emelie Westberg; Margareta Törnqvist. 2016. "Interaction of benzo[a]pyrene diol epoxide isomers with human serum albumin: Site specific characterisation of adducts and associated kinetics." Scientific Reports 6, no. 1: 36243.
Glycidol (Gly) is an electrophilic low-molecular weight epoxide that is classified by IARC as probably carcinogenic to humans. Humans might be exposed to Gly from food, e.g. refined vegetable oils, where Gly has been found as a food process contaminant. It is therefore important to investigate and quantify the genotoxicity of Gly as a primary step towards cancer risk assessment of the human exposure. Here, quantification of the mutagenic potency per exposure dose (AUC: area under the concentration-time curve) of Gly has been performed in Chinese hamster ovary (CHO) cells, using the HPRT assay. The dose of Gly was estimated in the cell exposure medium by trapping Gly with a strong nucleophile, cob(I)alamin, to form stable cob(I)alamin adducts for analysis by LC-MS/MS. Gly was stable in the exposure medium during the time for cell treatment, and thus the dose in vitro is the initial concentration × cell treatment time. Gly induced mutations in the hprt-gene at a rate of 0.08 ± 0.01 mutations/105 cells/mMh. Through comparison with the effect of ionizing radiation in the same system a relative mutagenic potency of 9.5 rad-eq./mMh was obtained, which could be used for comparison of genotoxicity of chemicals and between test systems and also in procedures for quantitative cancer risk assessment. Gly was shown to induce strand breaks, that were repaired by base excision repair. Furthermore, Gly-induced lesions, present during replication, were found to delay the replication fork elongation. From experiments with repair deficient cells, homologous recombination repair and the ERCC1-XPF complex were indicated to be recruited to support in the repair of the damage related to the stalled replication elongation. The type of DNA damage responsible for the mutagenic effect of Gly could not be concluded from the present study.
Jenny Aasa; Daniel Vare; Hitesh V. Motwani; Dag Jenssen; Margareta Törnqvist. Quantification of the mutagenic potency and repair of glycidol-induced DNA lesions. Mutation Research/Genetic Toxicology and Environmental Mutagenesis 2016, 805, 38 -45.
AMA StyleJenny Aasa, Daniel Vare, Hitesh V. Motwani, Dag Jenssen, Margareta Törnqvist. Quantification of the mutagenic potency and repair of glycidol-induced DNA lesions. Mutation Research/Genetic Toxicology and Environmental Mutagenesis. 2016; 805 ():38-45.
Chicago/Turabian StyleJenny Aasa; Daniel Vare; Hitesh V. Motwani; Dag Jenssen; Margareta Törnqvist. 2016. "Quantification of the mutagenic potency and repair of glycidol-induced DNA lesions." Mutation Research/Genetic Toxicology and Environmental Mutagenesis 805, no. : 38-45.
Electrophiles have the ability to form adducts to nucleophilic sites in proteins and DNA. Internal exposure to such compounds thus constitutes a risk for toxic effects. Screening of adducts using mass spectrometric methods by adductomic approaches offers possibilities to detect unknown electrophiles present in tissues. Previously, we employed untargeted adductomics to detect 19 unknown adducts to N-terminal valine in hemoglobin (Hb) in human blood. This article describes the characterization of one of these adducts, which was identified as the adduct from ethyl vinyl ketone (EVK). The mean adduct level was 40 ± 12 pmol/g Hb in 12 human blood samples; adduct levels from acrylamide (AA) and methyl vinyl ketone (MVK) were quantified for comparison. Using l-valine p-nitroanilide (Val-pNA), introduced as a model of the N-terminal valine, the rate of formation of the EVK adduct was studied, and the rate constant determined to 200 M–1h–1 at 37 °C. In blood, the reaction rate was too fast to be feasibly measured, EVK showing a half-life <1 min. Parallel experiments with AA and MVK showed that the two vinyl ketones react approximately 2 × 103 times faster than AA. The EVK-Hb adduct was found to be unstable, with a half-life of 7.6 h. From the mean adduct level measured in human blood, a daily dose (area under the concentration–time-curve, AUC) of 7 nMh EVK was estimated. The AUC of AA from intake via food is about 20 times higher. EVK is naturally present in a wide range of foods and is also used as a food additive. Most probably, naturally formed EVK is a major source to observed adducts. Evaluation of available toxicological data and information on occurrence of EVK indicate that further studies of EVK are motivated. This study illustrates a quantitative strategy in the initial evaluation of the significance of an adduct detected through adduct screening.
Henrik Carlsson; Hitesh V. Motwani; Siv Osterman Golkar; Margareta Törnqvist. Characterization of a Hemoglobin Adduct from Ethyl Vinyl Ketone Detected in Human Blood Samples. Chemical Research in Toxicology 2015, 28, 2120 -2129.
AMA StyleHenrik Carlsson, Hitesh V. Motwani, Siv Osterman Golkar, Margareta Törnqvist. Characterization of a Hemoglobin Adduct from Ethyl Vinyl Ketone Detected in Human Blood Samples. Chemical Research in Toxicology. 2015; 28 (11):2120-2129.
Chicago/Turabian StyleHenrik Carlsson; Hitesh V. Motwani; Siv Osterman Golkar; Margareta Törnqvist. 2015. "Characterization of a Hemoglobin Adduct from Ethyl Vinyl Ketone Detected in Human Blood Samples." Chemical Research in Toxicology 28, no. 11: 2120-2129.
Hitesh V. Motwani; Maria De Rosa; Luke R. Odell; Anders Hallberg; Mats Larhed. ChemInform Abstract: Aspartic Protease Inhibitors Containing Tertiary Alcohol Transition-State Mimics. ChemInform 2015, 46, 1 .
AMA StyleHitesh V. Motwani, Maria De Rosa, Luke R. Odell, Anders Hallberg, Mats Larhed. ChemInform Abstract: Aspartic Protease Inhibitors Containing Tertiary Alcohol Transition-State Mimics. ChemInform. 2015; 46 (8):1.
Chicago/Turabian StyleHitesh V. Motwani; Maria De Rosa; Luke R. Odell; Anders Hallberg; Mats Larhed. 2015. "ChemInform Abstract: Aspartic Protease Inhibitors Containing Tertiary Alcohol Transition-State Mimics." ChemInform 46, no. 8: 1.
1,3-Butadiene (BD) is a rodent and human carcinogen. In the cancer tests, mice have been much more susceptible than rats with regard to BD-induced carcinogenicity. The species-differences are dependent on metabolic formation/disappearance of the genotoxic BD epoxy-metabolites that lead to variations in the respective in vivo doses, i.e. "area under the concentration-time curve" (AUC). Differences in AUC of the most gentoxic BD epoxy-metabolite, diepoxybutane (DEB), are considered important with regard to cancer susceptibility. The present work describes: the application of cob(I)alamin for accurate measurements of in vitro enzyme kinetic parameters associated with BD epoxy-metabolites in human, mouse and rat; the use of published data on hemoglobin (Hb) adduct levels of BD epoxides from BD exposure studies on the three species to calculate the corresponding AUCs in blood; and a parallelogram approach for extrapolation of AUC of DEB based on the in vitro metabolism studies and adduct data from in vivo measurements. The predicted value of AUC of DEB for humans from the parallelogram approach was 0.078 nM · h for 1 ppm · h of BD exposure compared to 0.023 nM · h/ppm · h as calculated from Hb adduct levels observed in occupational exposure. The corresponding values in nM · h/ppm · h were for mice 41 vs. 38 and for rats 1.26 vs. 1.37 from the parallelogram approach vs. experimental exposures, respectively, showing a good agreement. This quantitative inter-species extrapolation approach will be further explored for the clarification of metabolic rates/pharmacokinetics and the AUC of other genotoxic electrophilic compounds/metabolites, and has a potential to reduce and refine animal experiments.
Hitesh V. Motwani; Margareta Törnqvist. In vivo doses of butadiene epoxides as estimated from in vitro enzyme kinetics by using cob(I)alamin and measured hemoglobin adducts: An inter-species extrapolation approach. Toxicology and Applied Pharmacology 2014, 281, 276 -284.
AMA StyleHitesh V. Motwani, Margareta Törnqvist. In vivo doses of butadiene epoxides as estimated from in vitro enzyme kinetics by using cob(I)alamin and measured hemoglobin adducts: An inter-species extrapolation approach. Toxicology and Applied Pharmacology. 2014; 281 (3):276-284.
Chicago/Turabian StyleHitesh V. Motwani; Margareta Törnqvist. 2014. "In vivo doses of butadiene epoxides as estimated from in vitro enzyme kinetics by using cob(I)alamin and measured hemoglobin adducts: An inter-species extrapolation approach." Toxicology and Applied Pharmacology 281, no. 3: 276-284.
Aspartic proteases (APs) are a class of enzymes engaged in the proteolytic digestion of peptide substrates. APs play important roles in physiological and infectious pathways, making them plausible drug targets. For instance in the treatment of HIV infections, access to an efficient combination of protease and reverse transcriptase inhibitors have changed a terminal illness to a chronic but manageable disease. However, the benefits have been limited due to the emergence of drug resistant viral strains, poor pharmacokinetic properties of peptidomimetic inhibitors and adverse effects associated with the treatment. In the 1980s, D. Rich and co-workers proposed a novel strategy for the development of AP inhibitors by replacing the secondary hydroxyl group with a tertiary alcohol as part of the transition state (TS) mimicking moiety. This strategy has been extensively explored over the last decade with a common belief that masking of the polar group, e.g. by intramolecular hydrogen bonding, has the potential to enhance transcellular transport. This is the first review presenting the advances of AP inhibitors comprising a tertiary hydroxyl group. The inhibitors have been classified into different tert-hydroxy TS mimics and their design strategies, synthesis, biological activities, structure–activity-relationships and X-ray structures are discussed.
Hitesh V. Motwani; Maria De Rosa; Luke R. Odell; Anders Hallberg; Mats Larhed. Aspartic protease inhibitors containing tertiary alcohol transition-state mimics. European Journal of Medicinal Chemistry 2014, 90, 462 -490.
AMA StyleHitesh V. Motwani, Maria De Rosa, Luke R. Odell, Anders Hallberg, Mats Larhed. Aspartic protease inhibitors containing tertiary alcohol transition-state mimics. European Journal of Medicinal Chemistry. 2014; 90 ():462-490.
Chicago/Turabian StyleHitesh V. Motwani; Maria De Rosa; Luke R. Odell; Anders Hallberg; Mats Larhed. 2014. "Aspartic protease inhibitors containing tertiary alcohol transition-state mimics." European Journal of Medicinal Chemistry 90, no. : 462-490.
Seven novel tertiary alcohol containing linear HIV-1 protease inhibitors (PIs), decorated at the para position of the benzyl group in the P1' side with (hetero)aromatic moieties, were synthesized and biologically evaluated. To study the inhibition and antiviral activity effect of P1-P3 macrocyclization, 14- and 15-membered macrocyclic PIs were prepared by ring-closing metathesis of the corresponding linear PIs. The macrocycles were more active than the linear precursors and compound 10f, with a 2-thiazolyl group in the P1' position, was the most potent PI of this new series (Ki 2.2 nM, EC50 0.2 μM). Co-crystallized complexes of both linear and macrocyclic PIs with the HIV-1 protease enzyme were prepared and analyzed.
Maria De Rosa; Johan Unge; Hitesh V. Motwani; Åsa Rosenquist; Lotta Vrang; Hans Wallberg; Mats Larhed. Synthesis of P1′-Functionalized Macrocyclic Transition-State Mimicking HIV-1 Protease Inhibitors Encompassing a Tertiary Alcohol. Journal of Medicinal Chemistry 2014, 57, 6444 -6457.
AMA StyleMaria De Rosa, Johan Unge, Hitesh V. Motwani, Åsa Rosenquist, Lotta Vrang, Hans Wallberg, Mats Larhed. Synthesis of P1′-Functionalized Macrocyclic Transition-State Mimicking HIV-1 Protease Inhibitors Encompassing a Tertiary Alcohol. Journal of Medicinal Chemistry. 2014; 57 (15):6444-6457.
Chicago/Turabian StyleMaria De Rosa; Johan Unge; Hitesh V. Motwani; Åsa Rosenquist; Lotta Vrang; Hans Wallberg; Mats Larhed. 2014. "Synthesis of P1′-Functionalized Macrocyclic Transition-State Mimicking HIV-1 Protease Inhibitors Encompassing a Tertiary Alcohol." Journal of Medicinal Chemistry 57, no. 15: 6444-6457.
Hitesh V. Motwani; Hisashi Shimakoshi; Bernard T. Golding; Margareta Törnqvist; Yoshio Hisaeda. Alkylcobyrinate from sucralose and mechanistic aspects of its CoC bond cleavage. Tetrahedron Letters 2014, 55, 2667 -2670.
AMA StyleHitesh V. Motwani, Hisashi Shimakoshi, Bernard T. Golding, Margareta Törnqvist, Yoshio Hisaeda. Alkylcobyrinate from sucralose and mechanistic aspects of its CoC bond cleavage. Tetrahedron Letters. 2014; 55 (16):2667-2670.
Chicago/Turabian StyleHitesh V. Motwani; Hisashi Shimakoshi; Bernard T. Golding; Margareta Törnqvist; Yoshio Hisaeda. 2014. "Alkylcobyrinate from sucralose and mechanistic aspects of its CoC bond cleavage." Tetrahedron Letters 55, no. 16: 2667-2670.
The operationally simple, rapid, and mild three‐component title reaction uses aryl iodides and aryl bromides.
Hitesh V. Motwani; Mats Larhed. ChemInform Abstract: Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalyzed Carbonylative Negishi Cross-Couplings. ChemInform 2013, 45, 1 .
AMA StyleHitesh V. Motwani, Mats Larhed. ChemInform Abstract: Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalyzed Carbonylative Negishi Cross-Couplings. ChemInform. 2013; 45 (1):1.
Chicago/Turabian StyleHitesh V. Motwani; Mats Larhed. 2013. "ChemInform Abstract: Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalyzed Carbonylative Negishi Cross-Couplings." ChemInform 45, no. 1: 1.
The cover picture shows the advancement of the current strategy from the past ones for the preparation of diarylated ethanones by palladium‐catalysed carbonylative Negishi cross‐couplings. The left part represents a classical carbonylation set‐up in which a CO gas tube is coupled to a reaction chamber on a conventional heating block. In the current work, Mo(CO)6 (white powder) was used as a solid source of CO that made the reaction safer by avoiding the use of the toxic CO gas, and, with the aid of microwave radiation for heating, the speed of the reaction was enhanced. Combining these two factors in an easy‐to‐use microwave vial, two novel protocols were developed and applied to synthesize a series of diarylated ethanones. Details are discussed in the Short Communication by H. V. Motwani and M. Larhed on page 4729 ff.
Hitesh V. Motwani; Mats Larhed. Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalysed Carbonylative Negishi Cross-Couplings (Eur. J. Org. Chem. 22/2013). European Journal of Organic Chemistry 2013, 2013, 1 .
AMA StyleHitesh V. Motwani, Mats Larhed. Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalysed Carbonylative Negishi Cross-Couplings (Eur. J. Org. Chem. 22/2013). European Journal of Organic Chemistry. 2013; 2013 (22):1.
Chicago/Turabian StyleHitesh V. Motwani; Mats Larhed. 2013. "Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalysed Carbonylative Negishi Cross-Couplings (Eur. J. Org. Chem. 22/2013)." European Journal of Organic Chemistry 2013, no. 22: 1.
Two protocols for palladium‐catalysed carbonylative Negishi cross‐couplings were developed for aryl iodides and aryl bromides. The two main breakthroughs were that molybdenum hexacarbonyl [Mo(CO)6] could be used as a solid in situ source of CO, and that controlled microwave irraditaion could be used for heating. Consequently, the reactions were safe (in contrast to when CO gas was used) and fast (in comparison to when conventional heating was used). The carbonylative cross‐coupling reactions were carried out using commercially available benzylzinc bromide in closed vials (90–120 °C for 0.5–1 h) to give a set of diarylated ethanones, a common pharmacophore found in several pharmaceuticals, in moderate to high isolated yields (47–84 %). The mild three‐component carbonylation protocol presented here is operationally simple, safe, and rapid, and the formation of the carbonylative Negishi cross‐coupling product is favoured over the product of Negishi cross‐coupling.
Hitesh V. Motwani; Mats Larhed. Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalysed Carbonylative Negishi Cross-Couplings. European Journal of Organic Chemistry 2013, 2013, 4729 -4733.
AMA StyleHitesh V. Motwani, Mats Larhed. Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalysed Carbonylative Negishi Cross-Couplings. European Journal of Organic Chemistry. 2013; 2013 (22):4729-4733.
Chicago/Turabian StyleHitesh V. Motwani; Mats Larhed. 2013. "Diarylated Ethanones from Mo(CO) 6 -Mediated and Microwave-Assisted Palladium-Catalysed Carbonylative Negishi Cross-Couplings." European Journal of Organic Chemistry 2013, no. 22: 4729-4733.
Glycidamide (GA) is the epoxy metabolite of acrylamide (AA). A sensitive analytical method for quantitative measurement of GA from in vitro metabolism studies is useful in several contexts, e.g. in studies of enzyme kinetics in different species and factors influencing the metabolism of AA to GA. It is however difficult to analyse compounds like GA, mainly due to their inherent reactivity. In the present study cob(I)alamin {Cbl(I)}, a reduced form of vitamin B(12), was used for trapping of GA. Cbl(I) can react with electrophilic species, such as an epoxide, 10(5) times faster than standard nucleophiles. The trapping of GA by Cbl(I) results in the formation of an alkylcobalamin (GA-Cbl) that was used for quantitative analysis of the epoxide. The alkylcobalamin was analysed by LC-MS/MS using an electrospray ionization source in the positive ion mode. The Cbl(I) method was validated for measurement of GA in liver S9 fractions from human and rat. GA levels down to 0.01 μM were measured in the S9 fractions, providing a sensitivity that was ca. 100 times higher than that earlier estimated by the Cbl(I) method for measurement of other (e.g. butadiene) epoxides. Compared to current analytical methods for measurement of GA, the Cbl(I) method was 10-100 times more sensitive. The method was applied to quantify GA formed from the metabolism of AA in liver S9 from human and rat.
Hitesh V. Motwani; Margareta Törnqvist. Quantitative analysis by liquid chromatography–tandem mass spectrometry of glycidamide using the cob(I)alamin trapping method: Validation and application to in vitro metabolism of acrylamide. Journal of Chromatography A 2011, 1218, 4389 -4394.
AMA StyleHitesh V. Motwani, Margareta Törnqvist. Quantitative analysis by liquid chromatography–tandem mass spectrometry of glycidamide using the cob(I)alamin trapping method: Validation and application to in vitro metabolism of acrylamide. Journal of Chromatography A. 2011; 1218 (28):4389-4394.
Chicago/Turabian StyleHitesh V. Motwani; Margareta Törnqvist. 2011. "Quantitative analysis by liquid chromatography–tandem mass spectrometry of glycidamide using the cob(I)alamin trapping method: Validation and application to in vitro metabolism of acrylamide." Journal of Chromatography A 1218, no. 28: 4389-4394.
Vitamin B12, viz., cyano- or hydroxo-cobalamin, can be chemically or enzymatically converted into the derivatives methyl- and adenosyl-cobalamin, which are complex organometallic cofactors associated with several cobalamin-dependent enzymes. The reduced form of vitamin B12, cob(I)alamin {Cbl(I)}, obtained by reduction of hydroxocobalamin (OH-Cbl) with e.g. sodium borohydride, is one of the most powerful nucleophiles known. Cbl(I) was shown to react readily with the synthetic sweetener sucralose (1,6-dichloro-1,6-dideoxy-β-d-fructofuranosyl-4-chloro-4-deoxy-α-d-galactopyranoside) in an aqueous system to form an alkylcobalamin (Suc-Cbl). This occurred by replacement of one of the three chlorine atoms of sucralose with a cobalamin moiety. The efficiency of trapping sucralose in presence of excess Cbl(I) was estimated to be >90%. Furthermore, in an in vitro study using human liver S9 with NADPH regeneration, in presence of OH-Cbl and sucralose, Suc-Cbl was shown to be formed. The Suc-Cbl was characterized primarily by LC-ESI+-MS/MS. Given the human consumption of sucralose from food and beverages, such a reaction between the sweetener and reduced vitamin B12 could occur in vivo
Hitesh V. Motwani; Shiran Qiu; Bernard T. Golding; Henrik Kylin; Margareta Törnqvist. Cob(I)alamin reacts with sucralose to afford an alkylcobalamin: Relevance to in vivo cobalamin and sucralose interaction. Food and Chemical Toxicology 2011, 49, 750 -757.
AMA StyleHitesh V. Motwani, Shiran Qiu, Bernard T. Golding, Henrik Kylin, Margareta Törnqvist. Cob(I)alamin reacts with sucralose to afford an alkylcobalamin: Relevance to in vivo cobalamin and sucralose interaction. Food and Chemical Toxicology. 2011; 49 (4):750-757.
Chicago/Turabian StyleHitesh V. Motwani; Shiran Qiu; Bernard T. Golding; Henrik Kylin; Margareta Törnqvist. 2011. "Cob(I)alamin reacts with sucralose to afford an alkylcobalamin: Relevance to in vivo cobalamin and sucralose interaction." Food and Chemical Toxicology 49, no. 4: 750-757.
Adducts to Hb could be used as biomarkers to monitor exposure to isocyanates. Particularly useful is the measurement of carbamoylation of N-terminal valines in Hb, after detachment as hydantoins. The synthesis of references from the reactive isocyanates, especially diisocyanates, has been problematic due to side reactions and polymerization of the isocyanate starting material. A simpler, safer, and more general method for the synthesis of valine adducts of isocyanates has been developed using N-[(4-nitrophenyl)carbamate]valine methylamide (NPCVMA) as the key precursor to adducts of various mono- and diisocyanates of interest. By reacting NPCVMA with a range of isocyanate-related amines, carbamoylated valines are formed without the use of the reactive isocyanates. The carbamoylated products synthesized here were cyclized with good yields of the formed hydantoins. The carbamoylated derivative from phenyl isocyanate also showed quantitative yield in a test with cyclization under the conditions used in blood. This new pathway for the preparation of N-carbamoylated model compounds overcomes the above-mentioned problems in the synthesis and is a general and simplified approach, which could make such reference compounds of adducts to N-terminal valine from isocyanates accessible for biomonitoring purposes. The synthesized hydantoins corresponding to adducts from isocyanic acid, methyl isocyanate, phenyl isocyanate, and 2,6-toluene diisocyanate were characterized by LC-MS analysis. The background level of the hydantoin from isocyanic acid in human blood was analyzed with the LC-MS conditions developed.
Ronnie Davies; Per Rydberg; Emelie Westberg; Hitesh V. Motwani; Erik Johnstone; Margareta Törnqvist. A New General Pathway for Synthesis of Reference Compounds of N-Terminal Valine−Isocyanate Adducts. Chemical Research in Toxicology 2010, 23, 540 -546.
AMA StyleRonnie Davies, Per Rydberg, Emelie Westberg, Hitesh V. Motwani, Erik Johnstone, Margareta Törnqvist. A New General Pathway for Synthesis of Reference Compounds of N-Terminal Valine−Isocyanate Adducts. Chemical Research in Toxicology. 2010; 23 (3):540-546.
Chicago/Turabian StyleRonnie Davies; Per Rydberg; Emelie Westberg; Hitesh V. Motwani; Erik Johnstone; Margareta Törnqvist. 2010. "A New General Pathway for Synthesis of Reference Compounds of N-Terminal Valine−Isocyanate Adducts." Chemical Research in Toxicology 23, no. 3: 540-546.
The reduced state of vitamin B(12), cob(I)alamin, acts as a supernucleophile that reacts ca. 10(5) times faster than standard nucleophiles, for example, thiols. Methods have been developed for trapping electrophilically reactive compounds by exploiting this property of cob(I)alamin. 1,3-Butadiene (BD) has recently been classified as a group 1 human carcinogen by the International Agency for Research on Cancer (IARC). The carcinogenicity of BD is considered to be dependent on the activation or deactivation of the reactive metabolites of BD, that is, the epoxides (oxiranes) 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 1,2-epoxy-3,4-butanediol (EBdiol). Cytochrome P450 (P450) isozymes are involved in oxidation of BD to EB and further activation to DEB. EB and DEB are hydrolyzed by epoxide hydrolases (EH) to 3,4-dihydroxy-1-butene (BDdiol) and EBdiol, respectively. EBdiol can also be formed by oxidation of BDdiol. In the present study, cob(I)alamin was used for instant trapping of the BD epoxide metabolites generated in in vitro metabolism to study enzyme kinetics. The substrates EB, DEB, and BDdiol were incubated with rat S9 liver fraction, and apparent K(m) and apparent V(max), were determined. The ratio of conversion of EB to DEB (by P450) to the rate of deactivation of DEB by EH was 1.09. Formation of EBdiol from hydrolysis of DEB was ca. 10 times faster than that from oxidation of BDdiol. It was also found that the oxidation of EB to DEB was much faster than that of BDdiol to EBdiol. The study offers comparative enzyme kinetic data of different BD metabolic steps, which is useful for quantitative interspecies comparison. Furthermore, a new application of cob(I)alamin was demonstrated for the measurement of enzyme kinetics of compounds that form electophilically reactive metabolites.
Hitesh V. Motwani; Charlotta Fred; Johanna Haglund; Bernard T. Golding; Margareta Törnqvist. Cob(I)alamin for Trapping Butadiene Epoxides in Metabolism with Rat S9 and for Determining Associated Kinetic Parameters. Chemical Research in Toxicology 2009, 22, 1509 -1516.
AMA StyleHitesh V. Motwani, Charlotta Fred, Johanna Haglund, Bernard T. Golding, Margareta Törnqvist. Cob(I)alamin for Trapping Butadiene Epoxides in Metabolism with Rat S9 and for Determining Associated Kinetic Parameters. Chemical Research in Toxicology. 2009; 22 (9):1509-1516.
Chicago/Turabian StyleHitesh V. Motwani; Charlotta Fred; Johanna Haglund; Bernard T. Golding; Margareta Törnqvist. 2009. "Cob(I)alamin for Trapping Butadiene Epoxides in Metabolism with Rat S9 and for Determining Associated Kinetic Parameters." Chemical Research in Toxicology 22, no. 9: 1509-1516.