Search

The study focuses on the green synthesis of Ag@Ag 2 O nanostructures using Padina algae extract and functionalizing them with L-tryptophan to enhance their properties as a colorimetric sensor for simultaneous detection of ultra-trace levels of thiamin and riboflavin. The nanostructures are characterized using techniques like XRD, FESEM, FTIR, TEM, AFM, and DLS to understand their morphology, structure, and interactions with target molecules. FESEM analysis revealed the hierarchical flower-like Ag@Ag 2 O nanostructures. The TEM image shows the formation of core-shell nanostructures. Also, DLS analysis and surface zeta potential spectra illustrated the aggregated nature of fabricated nanocomposites in the presence of vitamins. The study is the first to report simultaneous determination of thiamin and riboflavin using a colorimetric sensor based on Ag@Ag 2 O-L-Try nanocomposites using partial leas square (PLS). The dynamic range of thiamin and riboflavin was achieved in 0.1 mol L - 1 acetate buffer pH 4 and the ratio Ag@Ag 2 O: L-try 1:1. The Ag@Ag 2 O-L-Try sensor exhibited two linear ranges of 0.1- 1.0 and 3-350 µMol L - 1 for riboflavin and a linear range 3.0-60 µMol L - 1 for thiamin. Also, low detection limit of 1.92 µMol L - 1 and 0.048 µMol L - 1 was obtained for riboflavin and thiamin, respectively. The results indicated that the success of the method depends on the selective and sensitive colorimetric assay of the sensor along with the simultaneous determination by the PLS algorithm. Hence, the proposed technique can be used for the accurate and precise determination of vitamins in different pharmaceutical syrup and tablet samples., (© 2024. The Author(s).)

Thiamine (vitamin B 1 ) functions as an essential coenzyme in cells. Humans and other mammals cannot synthesise this vitamin de novo and thus have to take it up from their diet. Eventually, every cell needs to import thiamine across its plasma membrane, which is mainly mediated by the two specific thiamine transporters SLC19A2 and SLC19A3. Loss of function mutations in either of these transporters lead to detrimental, life-threatening metabolic disorders. SLC19A3 is furthermore a major site of drug interactions. Many medications, including antidepressants, antibiotics and chemotherapeutics are known to inhibit this transporter, with potentially fatal consequences for patients. Despite a thorough functional characterisation over the past two decades, the structural basis of its transport mechanism and drug interactions has remained elusive. Here, we report seven cryo-electron microscopy (cryo-EM) structures of the human thiamine transporter SLC19A3 in complex with various ligands. Conformation-specific nanobodies enable us to capture different states of SLC19A3's transport cycle, revealing the molecular details of thiamine recognition and transport. We identify seven previously unknown drug interactions of SLC19A3 and present structures of the transporter in complex with the inhibitors fedratinib, amprolium and hydroxychloroquine. These data allow us to develop an understanding of the transport mechanism and ligand recognition of SLC19A3., (© 2024. The Author(s).)

Vitamin Bs, a group of water-soluble compounds, are essential nutrients for almost all living organisms. However, due to their structural heterogeneity, rapid and simultaneous analysis of multiple vitamin Bs is still challenging. In this paper, it is discovered that a hetero-octameric Mycobacterium smegmatis porin A (MspA) nanopore containing a sole nickel ion-bound nitrilotriacetic acid (NTA-Ni) adapter at its pore constriction is suitable for the simultaneous sensing of different vitamin Bs, including vitamin B1 (thiamine), vitamin B3 (nicotinic acid and nicotinamide), vitamin B5 (pantothenic acid), and vitamin B6 (pyridoxine, pyridoxal, and pyridoxamine). Assisted by a custom machine learning algorithm, all seven vitamin Bs can be fully distinguished, reporting a general accuracy of 99.9%. This method was further validated in the rapid analysis of commercial cosmetics and natural food, suggesting its potential uses in food and drug administration.

In solution, analogues of the Breslow intermediate formed during catalysis by benzoylformate decarboxylase (BFDC) undergo rapid, irreversible fragmentation. The ability of BFDC to prevent this reaction and preserve its cofactor is a striking example of an enzyme 'steering' a reactive intermediate towards a productive pathway. To understand how BFDC suppresses the off-pathway reactivity of this Breslow intermediate, a clear mechanistic understanding of the fragmentation reaction is required. Here, DFT calculations reveal an unexpected mechanism for the solution-phase fragmentation that involves an intramolecular cyclization and a subsequent retro-ene reaction to release the final products. Free energy profiles demonstrate that this pathway is significantly more facile than the previously proposed mechanism that invoked Breslow intermediate enolates as intermediates. Additional computations have been performed to understand why related Breslow intermediates do not undergo analogous fragmentation reactions. Calculations performed with two closely related Breslow intermediates suggest that subtle differences in the relative values of ΔG ≠ for protonation and fragmentation dictate whether a given intermediate will fragment or not. These differences and the fragmentation mechanism unveiled in this work may have ramifications for the mechanism of BFDC and other thiamin-dependent enzymes and could provide general lessons related to the control of reactive intermediates by enzymes., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

Graphite carbon nitride (g-C 3 N 4 ) is a two-dimensional nano-sheet with electronic properties, which shows unique characteristics with high chemical and thermal stability in its structure. The functionalization of these compounds through covalent bonding is an important step towards significantly improving their properties and capabilities. To achieve this goal, a novel strategy for the covalent functionalization of Fe 3 O 4 @g-C 3 N 4 with thiamine hydrochloride (vitamin B1) via cyanuric chloride (TCT), which is a divalent covalent linker, was presented. The efficiency of Fe 3 O 4 @gC 3 N 4 @Thiamine as a heterogeneous organic catalyst in the synthesis of spirooxindole-pyran derivatives and 2-amino-4H-pyran under solvent-free conditions was evaluated and the yields of high-purity products were presented. In addition, easy recycling and reuse for seven consecutive cycles without significant reduction in catalytic activity are other features of this catalyst. Moreover, the performance of the prepared sorbent in the microextraction technique (herein, magnetic solid phase extraction) was studied. The tebuconazole was selected as the target analyte. The target analyte was extracted and determined by HPLC-UV. Under the optimum condition, the linear range of the method (LDR) was estimated in the range of 0.2-100 μg L -1 (the coefficient of determination of 0.9962 for tebuconazole). The detection limit (LOD) of the method for tebuconazole was calculated to be 0.05 µg L -1 . The limit of quantification (LOQ) of the method was also estimated to be 0.16 µg L -1 . In order to check the precision of the proposed method, the intra-day and inter-day relative standard deviations (RSD%) were calculated, which were in the range of 1.5- 2.8%. The method was used for the successful extraction and determination of tebuconazole in tomato, cucumber, and carrot samples., (© 2024. The Author(s).)

Using halloysite clay and vitamin B1 hydrochloride, a novel acidic halloysite-dendrimer catalytic composite has been developed for conversion of fructose to 5-hydroxymthylfurfural. To grow the dendritic moiety on halloysite, it was first functionalized and then reacted with melamine, epichlorohydrin and vitamin B1 hydrochloride respectively. Then, the resulting composite was treated with ZnCl 2 to furnish Lewis acid sites. Use of vitamin B1 as the cationic moiety of ionic liquid obviated use of toxic chemicals and resulted in more environmentally friendly composite. Similarly, dendritic moiety of generation 2 was also grafted on halloysite and the activity of both catalysts for conversion of fructose to 5-hydroxymthylfurfural was investigated to disclose the role of dendrimer generation. For the best catalytic composite, the reaction variables were optimized via RSM and it was revealed that use of 0.035 g catalyst per 0.1 g fructose at 95 °C furnished HMF in 96% yield in 105 min. Turnover numbers (TONs) and frequencies (TOFs) were estimated to be 10,130 and 5788 h -1 , respectively. Kinetic studies also underlined that Ea was 22.85 kJ/mol. The thermodynamic parameters of Δ H ≠ , Δ S ≠ and Δ G ≠ , were calculated to be 23 kJ/mol, - 129.2 J/mol and 72.14 kJ/mol, respectively. Notably, the catalyst exhibited good recyclability and hot filtration approved heterogeneous nature of catalysis., (© 2024. The Author(s).)

As a natural renewable biomacromolecule, lignin has some inherently interesting properties such as fluorescence, antioxidation, and antibacterial performance. However, the unsatisfactory fluorescence and biological activities have greatly limited their value-added and large-scale applications. In this work, lignin nanoparticles (LNPs) grafted with vitamin B 1 hybrid nanoparticles (LEVs) were obtained by using ethylenediamine and different contents of vitamin B 1 through a simple hydrothermal method. The chemical structure, fluorescence properties, and bioactivity were characterized to assess the effects of ethylenediamine and vitamin B 1 on the properties of LEVs. It was found that the fluorescence performance of synthesized LEV particles was improved with the increase in the amount of vitamin B 1 . The free radical scavenging rate (RSA, %) increased to 97.8%, while the antibacterial rates reached up to 99.9%. The antibacterial activity of LEV involved multiple combined mechanisms. The introduction of imine, amide groups, and positively charged VB 1 of LEV will make it easier to interact with the negatively charged bacterial phospholipid membranes and cause bacterial lysis and death. Then, the PVA/LEV hydrogel composites were prepared by the freezing-thawing method, and the results showed that PVA/LEV hydrogels had more comprehensive performance such as improved mechanical properties and antioxidant and antibacterial activities, resulting in its great potential to be used as an efficient biomedical material.

Vitamin B1 is an essential cofactor for enzymes involved in the metabolism of carbohydrates, particularly Transketolases. These enzymes are amenable to therapeutic interventions because of their specificity. In the final step of the Vitamin B1 biosynthesis pathway, Thiamine Pyrophosphokinase (TPK) converts thiamin into its active form, Thiamin Pyrophosphate (TPP), allowing researchers to investigate the functional importance of this enzyme and the pathway's dispensability in Leishmania donovani , a protozoan parasite that causes visceral leishmaniasis. In this study, various in silico , biochemical, biophysical, and cellular assays-based experiments have been conducted to identify and characterize Ld TPK, and to provide a sound platform for the discovery of potential Ld TPK inhibitors. Ld TPK structural modelling ensured high protein quality. Oxythiamine and pyrithiamine were found to bind well with Ld TPK with considerable binding energies, and MD simulation-based experiments indicated the stability of the complexation. Additionally, Ld TPK1 was found to activate ROS defense in amastigotes, and its inhibition using oxythiamine and pyrithiamine led to the growth inhibition of L. donovani promastigotes and intracellular amastigotes. These findings highlight Ld TPK as a promising target for the development of new anti-leishmanial agents. An in-depth analysis of the enzymes involved in TPP biosynthesis in L. donovani has the potential to yield novel therapeutic strategies for Leishmaniasis.Communicated by Ramaswamy H. Sarma.

Thiamine (vitamin B1) is an essential vitamin serving in its diphosphate form as a cofactor for enzymes in the citric acid cycle and pentose-phosphate pathways. Its concentration reported in the pM and nM range in environmental and clinical analyses prompted our consideration of the components used in pre-analytical processing, including the selection of filters, filter apparatuses, and sample vials. The seemingly innocuous use of glass fiber filters, glass filter flasks, and glass vials, ubiquitous in laboratory analysis of clinical and environmental samples, led to marked thiamine losses. 19.3 nM thiamine was recovered from a 100 nM standard following storage in glass autosampler vials and only 1 nM of thiamine was obtained in the filtrate of a 100 nM thiamine stock passed through a borosilicate glass fiber filter. We further observed a significant shift towards phosphorylated derivatives of thiamine when an equimolar mixture of thiamine, thiamine monophosphate, and thiamine diphosphate was stored in glass (most notably non-silanized glass, where a reduction of 54% of the thiamine peak area was observed) versus polypropylene autosampler vials. The selective losses of thiamine could lead to errors in interpreting the distribution of phosphorylated species in samples. Further, some loss of phosphorylated thiamine derivatives selectively to amber glass vials was observed relative to other glass vials. Our results suggest the use of polymeric filters (including nylon and cellulose acetate) and storage container materials (including polycarbonate and polypropylene) for thiamine handling. Losses to cellulose nitrate and polyethersulfone filters were far less substantial than to glass fiber filters, but were still notable given the low concentrations expected in samples. Thiamine losses were negated when thiamine was stored diluted in trichloroacetic acid or as thiochrome formed in situ, both of which are common practices, but not ubiquitous, in thiamine sample preparation., (© 2024. The Author(s).)

It is important to search for cytostatic compounds in order to fight cancer. One of them could be 2'-methylthiamine, which is a thiamine antimetabolite with an additional methyl group at the C-2 carbon of thiazole. So far, the cytostatic potential of 2'-methylthiamine has not been studied. We have come forward with a simplified method of synthesis using commercially available substrates and presented a comparison of its effects, as boosted by oxythiamine, on normal skin fibroblasts and HeLa cancer cells, having adopted in vitro culture techniques. Oxythiamine has been found to inhibit the growth and metabolism of cancer cells significantly better than 2'-methylthiamine (GI 50 36 and 107 µM, respectively), while 2'-methylthiamine is more selective for cancer cells than oxythiamine (SI = 180 and 153, respectively). Docking analyses have revealed that 2'-methylthiamine (Δ G -8.2 kcal/mol) demonstrates a better affinity with thiamine pyrophosphokinase than thiamine (Δ G -7.5 kcal/mol ) and oxythiamine (Δ G -7.0 kcal/mol), which includes 2'-methylthiamine as a potential cytostatic. Our results suggest that the limited effect of 2'-methylthiamine on HeLa arises from the related arduous transport as compared to oxythiamine. Given that 2'-methylthiamine may possibly inhibit thiamine pyrophosphokinase, it could once again be considered a potential cytostatic. Thus, research should be carried out in order to find the best way to improve the transport of 2'-methylthiamine into cells, which may trigger its cytostatic properties.

Thiamine diphosphate (ThDP), the bioactive form of vitamin B 1 , is an essential coenzyme needed for processes of cellular metabolism in all organisms. ThDP-dependent enzymes all require ThDP as a coenzyme for catalytic activity, although individual enzymes vary significantly in substrate preferences and biochemical reactions. A popular way to study the role of these enzymes through chemical inhibition is to use thiamine/ThDP analogues, which typically feature a neutral aromatic ring in place of the positively charged thiazolium ring of ThDP. While ThDP analogues have aided work in understanding the structural and mechanistic aspects of the enzyme family, at least two key questions regarding the ligand design strategy remain unresolved: 1) which is the best aromatic ring? and 2) how can we achieve selectivity towards a given ThDP-dependent enzyme? In this work, we synthesise derivatives of these analogues covering all central aromatic rings used in the past decade and make a head-to-head comparison of all the compounds as inhibitors of several ThDP-dependent enzymes. Thus, we establish the relationship between the nature of the central ring and the inhibitory profile of these ThDP-competitive enzyme inhibitors. We also demonstrate that introducing a C2-substituent onto the central ring to explore the unique substrate-binding pocket can further improve both potency and selectivity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

The yeast thiamin pyrimidine synthase THI5p catalyzes one of the most complex organic rearrangements found in primary metabolism. In this reaction, the active site His66 and PLP are converted to thiamin pyrimidine in the presence of Fe(II) and oxygen. The enzyme is a single-turnover enzyme. Here, we report the identification of an oxidatively dearomatized PLP intermediate. We utilize oxygen labeling studies, chemical-rescue-based partial reconstitution experiments, and chemical model studies to support this identification. In addition, we also identify and characterize three shunt products derived from the oxidatively dearomatized PLP.

Transketolase catalyzes the interconversion of keto and aldo sugars. Its coenzyme is thiamine diphosphate. The binding of keto sugar with thiamine diphosphate is possible only after C2 deprotonation of its thiazole ring. It is believed that deprotonation occurs due to the direct transfer of a proton to the amino group of its aminopyrimidine ring. Using mass spectrometry, it is shown that a water molecule is directly involved in the deprotonation process. After the binding of thiamine diphosphate with transketolase and its subsequent cleavage, a thiamine diphosphate molecule is formed with a mass increased by one oxygen molecule. After fragmentation, a thiamine diphosphate molecule is formed with a mass reduced by one and two hydrogen atoms, that is, HO and H 2 O are split off. Based on these data, it is assumed that after the formation of holotransketolase, water is covalently bound to thiamine diphosphate, and carbanion is formed as a result of its elimination. This may be a common mechanism for other thiamine enzymes. The participation of a water molecule in the catalysis of the one-substrate transketolase reaction and a possible reason for the effect of the acceptor substrate on the affinity of the donor substrate for active sites are also shown.

Thiamine pyrophosphate (TPP), an essential co-factor for all species, is biosynthesised through a metabolically expensive pathway regulated by TPP riboswitches in bacteria, fungi, plants and green algae. Diatoms are microalgae responsible for c. 20% of global primary production. They have been predicted to contain TPP aptamers in the 3'UTR of some thiamine metabolism-related genes, but little information is known about their function and regulation. We used bioinformatics, antimetabolite growth assays, RT-qPCR, targeted mutagenesis and reporter constructs to test whether the predicted TPP riboswitches respond to thiamine supplementation in diatoms. Gene editing was used to investigate the functions of the genes with associated TPP riboswitches in Phaeodactylum tricornutum. We found that thiamine-related genes with putative TPP aptamers are not responsive to supplementation with thiamine or its precursor 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP), and targeted mutation of the TPP aptamer in the THIC gene encoding HMP-P synthase does not deregulate thiamine biosynthesis in P. tricornutum. Through genome editing we established that PtTHIC is essential for thiamine biosynthesis and another gene, PtSSSP, is necessary for thiamine uptake. Our results highlight the importance of experimentally testing bioinformatic aptamer predictions and provide new insights into the thiamine metabolism shaping the structure of marine microbial communities with global biogeochemical importance., (© 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.)

The eukaryotic thiamin pyrimidine synthase, THI5p, has been identified as a suicidal/single-turnover enzyme that catalyzes the conversion of its active site histidine and lysine-bound pyridoxal phosphate (PLP) to the thiamin pyrimidine (HMP-P). Here we identify the histidine and PLP fragments using bottom-up proteomics and LC-MS analysis. We also identify the active form of the iron cofactor and quantitate the oxygen requirement of the THI5p reaction. This information is integrated into a mechanistic proposal for this remarkable reaction.

Recently, a yellow Maillard pigment named pyrizepine was identified from a heated solution containing thiamine and glucose. Here, we examined the formation scheme of this pigment and some biological properties. The mass spectrometry and nuclear magnetic resonance data of pyrizepine prepared from [6-13C] glucose showed that the carbon at 6-position of glucose was inserted at 2 different positions of pyrizepine. 5-(Aminomethyl)-2-methylpyridin-4-amine (AMPA), a degradation product of thiamine, was detected in the reaction solution. The pigment also formed in the solution containing AMPA in place of thiamine. These results showed that pyrizepine formed from AMPA and C4 fragments derived from glucose. Pyrizepine showed antioxidative activities in the superoxide dismutase, 2,2-diphenyl-1-picrylhydrazyl, and H-ORAC assays. The pigment did not show mutagenicity with the Ames test. A trace amount of the pigment was detected in a pan-fried ground pork sample added glucose using liquid chromatography-tandem mass spectrometry., (© The Author(s) 2022. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Thiamin (or thiamine), known as vitamin B1, represents an indispensable component of human diets, being pivotal in energy metabolism. Thiamin research depends on adequate vitamin quantification in plant tissues. A recently developed quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is able to assess the level of thiamin, its phosphorylated entities and its biosynthetic intermediates in the model plant Arabidopsis thaliana, as well as in rice. However, their implementation requires expensive equipment and substantial technical expertise. Microbiological assays can be useful in deter-mining metabolite levels in plant material and provide an affordable alternative to MS-based analysis. Here, we evaluate, by comparison to the LC-MS/MS reference method, the potential of a carefully chosen panel of yeast assays to estimate levels of total vitamin B1, as well as its biosynthetic intermediates pyrimidine and thiazole in Arabidopsis samples. The examined panel of Saccharomyces cerevisiae mutants was, when implemented in microbiological assays, capable of correctly assigning a series of wild-type and thiamin biofortified Arabidopsis plant samples. The assays provide a readily applicable method allowing rapid screening of vitamin B1 (and its biosynthetic intermediates) content in plant material, which is particularly useful in metabolic engineering approaches and in germplasm screening across or within species., (© 2022 The Authors New Phytologist © 2022 New Phytologist Foundation.)

The present study evaluated the effect of chitosan thiamine nanoparticles (TCNP) on the activation of defence responses in chickpea against stress caused by wilt pathogen, Fusarium oxysporum f. sp. ciceri (FOC), under greenhouse condition. A significant increase in enzymatic and non-enzymatic antioxidants was observed in the TCNP treated chickpea plants challenged with FOC compared to the untreated control. Histochemical staining showed high deposition of lignin in the vascular bundles of chickpea stem tissues in TCNP treated plants challenged with FOC. More than 90% protection against wilt pathogen was observed in TCNP treated chickpea plants challenged with FOC, under greenhouse condition. Higher accumulation of antioxidants and phenylpropanoids in TCNP treated challenged chickpea plants well correlates with resistance against wilt pathogen. These results suggest that the elicitation of stress response in TCNP treated chickpea during FOC interaction play a vital role in suppressing the wilt disease in chickpea., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Dry cured loins containing nitrogen (proline and ornithine) and sulfur (thiamine) compounds as precursors of aroma compounds at two concentration levels were manufactured. The effect of precursor addition on the microbiology and chemical parameters of loins was studied together with the aroma study performed by olfactometry and Free Choice Profile sensory analyses. Addition of precursors did not affect the microbial and chemical parameters, while aroma was affected when precursors were added at the highest level. The dry loin aroma profile was mainly composed by compounds 3-methylbutanal, methional, ethyl 3-methylbutanoate, 3-methylbutanoic acid, 1-octen-3-ol, 2-acetyl-1-pyrroline and 2-acetylpyrrole that contribute to musty, cooked potatoes, fruity, cheesy, mushroom, roasted and meaty odor notes. Proline and ornithine supplementation modified the loins aroma profile producing toasted odors, while the effect of thiamine supplementation on the aroma was revealed by the presence of sulfur derived compounds (methional and 2-methyl-3-(methylthio)furan) that contribute to the "cured meat odor"., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Thiamine (vitamin B1) is crucial for life and plays a central role in metabolism. It contains thiazole and pyrimidine moieties that are constructed independently and then assembled together to generate thiamine phosphate. The study of the thiazole moiety is relatively clear, but deciphering the mechanistic enzymology of thiamine pyrimidine is more difficult. This review aims to summarize the recent research progress on ThiC rearrangement, mainly including the mechanism, related enzymes, and genes involved in the rearrangement., (© 2021 Wiley-VCH GmbH.)

Three forms of pseudo-crystalline polymorph of thiamine chloride hydrochloride are dependent on hydration states. We investigated how the measurement environment affects the transition of the pseudo-crystalline polymorph, and aimed to establish a reliable method of identifying the forms clearly by IR spectrophotometry. We prepared three pseudo-crystalline forms and compared their IR spectra. In the IR spectra obtained by the potassium chloride (KCl) disk method, Form II was identified based on its characteristic absorption, but Forms I and III could not be distinguished clearly. Form I transformed to Form III after mixing with undried KCl powder, and Form III transformed to Form I by simply being left in the laboratory environment. These results suggested that the reversible transformation between Forms I and III occurred depending on the hydration status during the process of measurement, as measured by the shift in the absorption wavenumber of the primary alcohol stretching vibration. In addition, Forms I and III could not be distinguished clearly by the X-ray powder diffraction and their crystalline forms were similar plate crystals. However, in the IR spectra by the attenuated total reflection (ATR) method, the three forms could be identified based on each characteristic absorption. In summary, the ATR method does not require pretreatment for sample analysis, can be performed quickly, and is thus suitable to identify crystalline polymorph forms such as pseudo-crystalline polymorphs of thiamine chloride hydrochloride, which transform easily depending on the hydration status in a measurement environment.

A novel capillary-based fluorescence microsensor for artemisinin was developed with functional polyoxometalates (POMs) as nanozyme by a layer-by-layer self-assembly strategy. Vanadomolybdophosphoric heteropoly acid (H 5 PMo 10 V 2 O 40 , PMoV 2 ) and tungstophosphoric heteropoly acid (Na 5 PW 11 O 39 Cu, PW 11 Cu) with high peroxidase-like activity were synthesized and immobilized on capillary to catalyze artemisinin/thiamine reaction and generate the amplified fluorescence signal. The wide linear range up to 13.0 μM with the low limit of detection of 0.03 μM (S/N = 3) was achieved for the determination of artemisinin by using the proposed POMs-microsensor. The method has been successfully used to detect artemisinin in human plasma and antimalarial drugs with satisfactory accuracy. This work developed a novel capillary fluorescence microsensor with functional POMs as nanozyme, which can serve as a promising candidate in fluorescence microanalysis., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Oxythiamine (OT) and 3-deazathiamine (DAT) are the antimetabolites of thiamine. The aim of study was to compare the effects of OT and DAT pyrophosphates (-PP) on the kinetics of mammalian pyruvate dehydrogenase complex (PDHC) and the in vitro culture of HeLa cells. The kinetic study showed that 3-deazathiamine pyrophosphate (DATPP) was a much stronger competitive inhibitor ( K i = 0.0026 μM) of PDHC than OTPP ( K i = 0.025 μM). Both K i values were much lower versus K m for thiamine pyrophosphate (0.06 μM). However, DATPP added to the culture medium for the HeLa cells culture did not hamper the rate of cell growth and showed not significant impact on the viability of the cells, whereas OTPP and OT showed a significant cytostatic effect. The differences between the thiamine antivitamins in their effect on cell growth in vitro may be due to differences in physicochemical properties and difficulty in DAT transport across the cell membrane.

Rice, consumed by most people across the world, serves as a great mode for carrying nutrients. The processed, starch-rich white rice is mostly devoid of nutrients. High-pressure processing (HPP) is a technology known to produce cold gelatinizing effects in starch. This work shows the application of HPP in fortification of two types of white rice through high pressure gelatinization. The rice grains were impregnated with vitamin B 1 , calcium, and zinc. HPP treatment was carried out at the temperatures of 50 °C and 70 °C for up to 20 min. The samples were analysed for thiamine using the fluorometric method and minerals using ICP-MS. Results showed that the transfer of nutrients increases with treatment temperature and time, producing high level of nutrient uptake. HPP-fortified rice also showed stability after storage of two months. The moderate-temperature HPP has a great potential to be used as a method to produce a ready-to-eat variety of rice., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Reviewed herein are key research accomplishments of Professor Ronald Charles D. Breslow (1931-2017) throughout his more than 60 year research career. These accomplishments span a wide range of topics, most notably physical organic chemistry, medicinal chemistry, and bioorganic chemistry. These topics are reviewed, as are topics of molecular electronics and origin of chirality, which combine to make up the bulk of this review. Also reviewed briefly are Breslow's contributions to the broader chemistry profession, including his work for the American Chemical Society and his work promoting gender equity. Throughout the article, efforts are made to put Breslow's accomplishments in the context of other work being done at the time, as well as to include subsequent iterations and elaborations of the research., (Copyright © 2021 Elsevier Inc. All rights reserved.)

A simple and rapid ratiometric fluorescent sensing system for D-penicillamine (D-PA) determination is developed based on yellow carbon dots (Y-CDs) combined with thiochrome (oxVB 1 ) for the first time. The oxidization of thiamine (VB 1 ) can be catalyzed by Alkaline-hydrolyzed artemisinin (a-ART) to form oxVB 1 , which leads to the occurrence of fluorescence emission peak at 466 nm. Furthermore, the oxidation reaction between a-ART and VB 1 could be inhibited by D-PA, and accompanied with the decrease of fluorescence at 466 nm. However, the fluorescence peak of Y-CDs as an internal reference at 566 nm was almost unchanged. The ratiometric signal changes contributed to a robust and sensitive D-PA sensing. Under the optimal condition, a good linear response for the D-PA detection was obtained in the ranges of 0.5-50 μM with a detection limit of 0.33 μM. In addition, Y-CDs and thiochrome-based sensing system was applied to D-PA determination in real samples and obtained acceptable results. We developed a new carbon dots/thiochrome fluorescent nanoprobe for ratiometric fluorescence sensing of D-penicillamine., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

Here, we demonstrate that the two distinct formulations of our anti-sepsis drug candidate Rejuveinix (RJX), have a very favorable safety profile in Wistar Albino rats at dose levels comparable to the projected clinical dose levels. 14-day treatment with RJX-P (RJX PPP.18.1051) or RJX-B (RJX-B200702-CLN) similarly elevated the day 15 tissue levels of the antioxidant enzyme superoxide dismutase (SOD) as well as ascorbic acid in both the lungs and liver in a dose-dependent fashion. The activity of SOD and ascorbic acid levels were significantly higher in tissues of RJX-P or RJX-B treated rats than vehicle-treated control rats (p < 0.0001). There was no statistically significant difference between tissue SOD activity or ascorbic acid levels of rats treated with RJX-P vs. rats treated with RJX-B (p > 0.05). The observed elevations of the SOD and ascorbic acid levels were transient and were no longer detectable on day 28 following a 14-day recovery period. These results demonstrate that RJX-P and RJX-B are bioequivalent relative to their pharmacodynamic effects on tissue SOD and ascorbic acid levels. Furthermore, both formulations showed profound protective activity in a mouse model of sepsis. In agreement with the PD evaluations in rats and their proposed mechanism of action, both RJX-P and RJX-B exhibited near-identical potent and dose-dependent anti-oxidant and anti-inflammatory activity in the LPS-GalN model of ARDS and multi-organ failure in mice., (Copyright © 2021 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Phenolic compounds and thiamine may serve as therapies against oxidative stress-related neurodegenerative diseases. However, it is important to note that these components show high instability under changing conditions. The study's aim was to determine the impact of the thiamine concentration (hydrochloride-TH and pyrophosphate-TP; in the range 0.02 to 20 mg/100 g on the indices of the chelating properties and reducing power, and free radicals scavenging indices of EGCG, EGC, ECG and caffeine added from 0.04 to 6.0 mg/100 g. Our research confirmed that higher concentrations of TH and TP can exhibit significant activity against the test antioxidant indices of all components. When above 5.0 mg/100 g of thiamine was used, the radical scavenging abilities of the compound decreased in the following order: EGCG > ECG > EGC > caffeine. The highest correlation was found for the concentration of thiamine pyrophosphate to 20.0 mg/100 g and EGCG. Knowledge of the impact of factors associated with the concentration of both EGCG, EGC, ECG or caffeine and thiamine on their activity could carry weight in regulating the quality supplemented foods, especially of nutrition support for people of all ages were oral, enteral tube feeding and parenteral nutrition).

Background: Infantile beriberi-related mortality is still common in South and Southeast Asia. Interventions to increase maternal thiamine intakes, and thus human milk thiamine, are warranted; however, the required dose remains unknown., Objectives: We sought to estimate the dose at which additional maternal intake of oral thiamine no longer meaningfully increased milk thiamine concentrations in infants at 24 wk postpartum, and to investigate the impact of 4 thiamine supplementation doses on milk and blood thiamine status biomarkers., Methods: In this double-blind, 4-parallel arm randomized controlled dose-response trial, healthy mothers were recruited in Kampong Thom, Cambodia. At 2 wk postpartum, women were randomly assigned to consume 1 capsule, containing 0, 1.2 (estimated average requirement), 2.4, or 10 mg of thiamine daily from 2 through 24 weeks postpartum. Human milk total thiamine concentrations were measured using HPLC. An Emax curve was plotted, which was estimated using a nonlinear least squares model in an intention-to-treat analysis. Linear mixed-effects models were used to test for differences between treatment groups. Maternal and infant blood thiamine biomarkers were also assessed., Results: In total, each of 335 women was randomly assigned to1 of the following thiamine-dose groups: placebo (n = 83), 1.2 mg (n = 86), 2.4 mg (n = 81), and 10 mg (n = 85). The estimated dose required to reach 90% of the maximum average total thiamine concentration in human milk (191 µg/L) is 2.35 (95% CI: 0.58, 7.01) mg/d. The mean ± SD milk thiamine concentrations were significantly higher in all intervention groups (183 ± 91, 190 ± 105, and 206 ± 89 µg/L for 1.2, 2.4, and 10 mg, respectively) compared with the placebo group (153 ± 85 µg/L; P < 0.0001) and did not significantly differ from each other., Conclusions: A supplemental thiamine dose of 2.35 mg/d was required to achieve a milk total thiamine concentration of 191 µg/L. However, 1.2 mg/d for 22 wk was sufficient to increase milk thiamine concentrations to similar levels achieved by higher supplementation doses (2.4 and 10 mg/d), and comparable to those of healthy mothers in regions without beriberi. This trial was registered at clinicaltrials.gov as NCT03616288., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)

The oxidation reaction of thiamine (vitamin B1) to thiochrome was investigated by DFT calculations. Three reaction systems, [A] thiamine + methyl peroxy radical + (H2O)8, [B] thiamine + cyanogen bromide + HO-(H2O)8 and [C] thiamine + mercury(ii) chloride + HO-(H2O)8, were investigated. wB97X-D/6-311+G** for [A] and [B] and wB97X-D/SDD&6-311(+)G** for [C] geometry optimizations were carried out with the solvent effect (water). The effect is of the self-consistent reaction field (SCRF) with the polarizable continuum model (PCM). In [A], the H3C-O2˙ adduct of thiamine undergoes simultaneous cleavage of the C-H and O-O bonds, leading to a very stable 2(3H)-thiazolone intermediate. The same intermediate was obtained after the cleavage of the C-H and O-H bonds of the HO adduct of thiamine in [B] and [C]. After the formation of the key intermediate, the N-protonated thiochrome was afforded via three steps. In reflection of the water-soluble character of vitamin B1, proton transfers along hydrogen bonds of the water cluster enhance those steps.

In times of widespread multiple antibiotic resistance, the bacterial colonization of crucial medical surfaces should be detected as fast as possible. In this work, we present the non-destructive SERS method for the detection of bacterial colonization. SERS is an excellent tool for the monitoring of suitable substances in low concentrations. The SERS substrate was prepared by the aggregation of citrate-stabilized gold nanoparticles and the adsorption of the reporters (crystal violet, thiamine, and adenine). We have tested the substrate for the detection of clinically relevant S. aureus and P. aeruginosa bacteria. The SERS spectra before and after the substrate incubation revealed the degradation of the reporter by the growing bacteria. The growth of P. aeruginosa was detected using the substrates with preadsorbed crystal violet or adenine. The suitable reporter for the detection of S. aureus remains to be discovered. The selection of the reporters resistant to exposure but easily degraded by bacteria will open the way for the in situ monitoring of bacterial colonization, thus complementing the arsenal of methods in the battle against hospital infections., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: The current approach to reducing bacterial contamination in blood transfusion products is through detection or pathogen reduction methods, some of which utilize ultraviolet (UV) light photosensitizers. A small number of photosensitizers are being used as single agents in combination with UV light, but their efficacy can be limited against some pathogens. Benzophenone (BP) and vitamins B1, B6, and K3 have been identified as effective UVA photosensitizers for inactivation of bacteria. We evaluated whether combining pairs of photosensitizers in this group would have synergistic bactericidal effects on Gram-negative and Gram-positive bacteria., Study Design and Methods: Bacteria species of Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Klebsiella pneumoniae were mixed with 0 to 100 mM concentrations of photosensitizers and exposed to UVA irradiation at 18 J/cm 2 to assess their bactericidal effects., Results: Single photosensitizers irradiated with UVA produced a range of bactericidal activity. When combined in pairs, all demonstrated some synergistic bactericidal effects with up to 4-log reduction above the sum of activities of individual molecules in the pair against bacteria in plasma. Photosensitizer pairs with BP had the highest synergism across all bacteria. With vitamin K3 in the pair, synergism was evident for Gram-positive but not for Gram-negative bacteria. Vitamin B1 and vitamin B6 had the least synergism. These results indicate that a combination approach with multiple photosensitizers may extend effectiveness of pathogen reduction in plasma., Conclusions: Combining photosensitizers in pathogen reduction methods could improve bactericidal efficacy and lead to use of lower concentrations of photosensitizers to reduce toxicities and unwanted side effects., (© 2020 AABB.)

Thiamine (vitamin B1), which is synthesized only in bacteria, fungi and plants and which humans should take with diet, participates in basic biochemical and physiological processes in a versatile way and its deficiency is associated with neurological problems accompanied by cognitive dysfunctions. The rat glioblastoma (C6) model was used, which was exposed to a limited environment and toxicity with glutamate. The cells were stressed by exposure to glutamate in the presence and absence of thiamine. The difference in cell proliferation was evaluated in the XTT assay. Oxidative stress (OS) markers malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels, as well as endoplasmic reticulum (ER) stress markers 78-kDa glucose-regulated protein (GRP78), activating transcription factor-4 (ATF-4), and C/EBP homologous protein (CHOP) levels, were measured with commercial kits. Apoptosis determined by flow cytometry was confirmed by 4',6-diamidino-2-phenylindole (DAPI) staining. At all concentrations, thiamine protects the cells and increased the viability against glutamate-induced toxicity. Thiamine also significantly decreased the levels of MDA, while increasing SOD and CAT levels. Moreover, thiamine reduced ER stress proteins' levels. Moreover, it lessened the apoptotic cell amount and enhanced the live-cell percentage in the flow cytometry and DAPI staining. As a result, thiamine may be beneficial nutritional support for individuals with a predisposition to neurodegenerative disorders due to its protective effect on glutamate cytotoxicity in glioblastoma cells by suppressing OS and ER stress.

This study investigated thiamine degradation in thiamine mononitrate (TMN):polymer solid dispersions, accounting for the physical state of the vitamin and the recrystallization tendency of TMN in these dispersions. Results were compared with those from solid dispersions containing a different salt form of thiamine (thiamine chloride hydrochloride (TClHCl)). TMN:polymer dispersions were prepared by lyophilizing solutions containing TMN and amorphous polymers (pectin and PVP (polyvinylpyrrolidone)). Samples were stored in controlled temperature and relative humidity (RH) environments for eight weeks and monitored periodically by X-ray diffraction and high performance liquid chromatography (HPLC). Moisture sorption, glass transition temperature (T g ), intermolecular interactions, and pH were also determined. Similar to the TClHCl:polymer dispersions, thiamine was more chemically labile in the amorphous state than the crystalline state, when present in lower proportions in amorphous TMN:polymer dispersions despite increasing T g values, when environmental storage conditions exceeded the T g of the dispersion, and when co-formulated with PVP compared to pectin. When thiamine remained as an amorphous solid, chemical stability of thiamine did not differ as a function of counterion present (TMN vs. TClHCl). However, storage at 75% RH led to hydration of thiamine:PVP dispersions, and the resulting pH of the solutions as a function of thiamine salt form led to a higher chemical stability in the acidic TClHCl samples than in the neutral TMN samples.

The antiviral activity of nucleoside reverse transcriptase inhibitors is often hampered by insufficient phosphorylation. Nucleoside triphosphate analogues are presented, in which the γ-phosphate was covalently modified by a non-bioreversible, lipophilic 4-alkylketobenzyl moiety. Interestingly, primer extension assays using human immunodeficiency virus reverse transcriptase (HIV-RT) and three DNA-polymerases showed a high selectivity of these γ-modified nucleoside triphosphates to act as substrates for HIV-RT, while they proved to be nonsubstrates for DNA-polymerases α, β, and γ. In contrast to d4TTP, the γ-modified d4TTPs showed a high resistance toward dephosphorylation in cell extracts. A series of acyloxybenzyl-prodrugs of these γ-ketobenzyl nucleoside triphosphates was prepared. The aim was the intracellular delivery of a stable γ-modified nucleoside triphosphate to increase the selectivity of such compounds to act in infected versus noninfected cells. Delivery of γ-ketobenzyl-d4TTPs was proven in T-lymphocyte cell extracts. The prodrugs were potent inhibitors of HIV-1/2 in cultures of infected CEM/0 cells and more importantly in thymidine kinase-deficient CD4 + T-cells.

RNA 5'-modifications are known to extend the functional spectrum of ribonucleotides. In recent years, numerous non-canonical 5'-modifications, including adenosine-containing cofactors from the group of B vitamins, have been confirmed in all kingdoms of life. The structural component of thiamine adenosine triphosphate (thiamine-ATP), a vitamin B1 derivative found to accumulate in Escherichia coli and other organisms in response to metabolic stress conditions, suggests an analogous function as a 5'-modification of RNA. Here, we report the synthesis of thiamine adenosine dinucleotides and the preparation of pure 5'-thiamine-capped RNAs based on phosphorimidazolide chemistry. Furthermore, we present the incorporation of thiamine-ATP and thiamine adenosine diphosphate (thiamine-ADP) as 5'-caps of RNA by T7 RNA polymerase. Transcripts containing the thiamine modification were modified specifically with biotin via a combination of thiazole ring opening, nucleophilic substitution and copper-catalyzed azide-alkyne cycloaddition. The highlighted methods provide easy access to 5'-thiamine RNA, which may be applied in the development of thiamine-specific RNA capture protocols as well as the discovery and confirmation of 5'-thiamine-capped RNAs in various organisms.

Background & Aims: Wernicke's encephalopathy is associated mainly with malnourishment in alcohol-dependent patients but can be caused also by cancer, Crohn's disease, gastrointestinal surgery or prolonged parenteral nutrition (PN) without adequate supplementation of vitamins. The disorder, with a significant mortality rate of up to 20%, is often associated with the underlying disease and intensifies after administration of non-supplemented PN. Thus, it seems justified to add thiamine to PN admixtures prepared for parenterally fed patients. Due to the lack of data on the stability of thiamine in PN admixtures at concentrations exceeding 60 mg/L, we decided to determine the possibility of adding a high dose of thiamine (800 mg per bag, 320 mg/L) to PN admixtures in order to treat Wernicke's encephalopathy in malnourished patients., Methods: The study aimed to assess the stability of the physical properties of PN admixtures (pH, zeta potential, particle size) and to determine thiamine content using an HPLC method., Results: Thiamine was found to degrade regardless of the PN admixture composition and storage conditions. The highest decrease in thiamine content was observed at room temperature without light protection whereas the lowest at a temperature of 4 ± 1 °C with light protection., Conclusions: The treatment of Wernicke's encephalopathy in parenterally fed patients is possible with the use of high thiamine doses (800 mg) added to PN admixtures without a decrease in the drug content above 10% within the first 24 h. It should be emphasized that thiamine as a photosensitive drug must be stored and administered under conditions ensuring light protection., Competing Interests: Conflict of interest All the authors declare no conflict of interest in relation to this work., (Copyright © 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Thiamine is an essential micronutrient, but delivery of the vitamin in supplements or foods is challenging because it is unstable under heat, alkaline pH, and processing/storage conditions. Although distributed as a crystalline ingredient, thiamine chloride hydrochloride (TClHCl) likely exists in the amorphous state, specifically in supplements. Amorphous solids are generally less chemically stable than their crystalline counterparts, which is an unexplored area related to thiamine delivery. The objective of this study was to document thiamine degradation in the amorphous state. TClHCl:polymer dispersions were prepared by lyophilizing solutions containing TClHCl and amorphous polymers (pectin and PVP (poly[vinylpyrrolidone])). Samples were stored in controlled temperature (30-60 °C) and relative humidity (11%) environments for 8 weeks and monitored periodically by X-ray diffraction (to document physical state) and HPLC (to quantify degradation). Moisture sorption, glass transition temperature (T g ), intermolecular interactions, and pH were also determined. Thiamine was more labile in the amorphous state than the crystalline state and when present in lower proportions in amorphous polymer dispersions, despite increasing T g values. Thiamine was more stable in pectin dispersions than PVP dispersions, attributed to differences in presence and extent of intermolecular interactions between TClHCl and pectin. The results of this study can be used to control thiamine degradation in food products and supplements to improve thiamine delivery and decrease rate of deficiency.

Objective: To optimize radiolabeling with 99m Tc and 67 Ga of albumin nanoparticles coated with 4 differents synthetic polymers and to evaluate their stability in vivo and in vitro, as well as their biodistribution in vivo after intravenous administration., Material and Methods: The nanoparticles were prepared using albumin and NOTA-modified albumin by the desolvation method and coated with 4 different polymers; HPMC, GMN2, GPM2 and GTM2. They were purified, lyophilized and characterized. Radiolabelling with 99m Tc was perfomed with 74 MBq of 99m Tc sodium pertechnetate, previously reduced with and acid solution of tin chloride at different concentrations (0.003, 0.005, 0.007, 0.01, 0.05 and 0.1mg/ml) and at different times (5, 10, 15, 30 and 60minutes) and temperatures (room temperature, 40°C and 60°C). Radiolabelling with 67 Ga was perfomed by incubation of the nanoparticles with 37 MBq of 67 Gallium chloride (obtained from commercial gallium- 67 citrate) at different times (10 and 30minutes) and temperatures (room temperature, 30°C and 60°C), and posterior purification with microconcentrators. The radiochemical purity was evaluated by TLC. Stability studies of radiolabeled nanoparticles in physiological serum and blood plasma were perfomed. Biodistribution studies of nanoparticles coated with GPM2 polymer were carried out in Wistar rats after intravenous administration of the nanoparticles. Control animals were carried out with 99m Tc sodium pertechnetate and 67 Ga chloride. To do so, the animals were killed and activity in organs was measured in a gamma counter., Results: 99m Tc labeling was carried out optimally with a tin concentration of 0.007mg/ ml for the GPM2 nanoparticles and 0.005mg / ml for the rest of the formulations, with a radiolabelling time of 10minutes at room temperature. In the case of 67 Ga the label was optimized at 30° C temperature and 30minutes of incubation. In both cases the radiochemical purity obtained was greater than 97%. The nanoparticles showed high stability in vitro after 48hours of labeling (70% nanoparticles labeled with 99m Tc and 90% those labeled with 67 Ga). Biodistribution studies of nanoparticles 99m Tc -GPM2 and 67 Ga -NOTA-GPM2 showed a high accumulation of activity in the liver at 2 and 24hours after intravenous administration., Conclusion: The labeling procedure with 99m Tc and 67 Ga of albumin and albumin modified with NOTA nanoparticles allows obtaining nanoparticles with high labeling yields and adequate in vitro stability, allowing their use for in vivo studies., (Copyright © 2020 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.)

To obtain high-kokumi-active building blocks, which can be used to produce savory process flavors, it is essential to obtain a better understanding on the formation rate of kokumi-active compounds, such as 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one or 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine. The present work showed quantitative studies in several model reaction systems on the recently discovered kokumi-active thiamine derivates. It was possible to show that the thiamine conversion in aqueous model reactions could be directed toward the taste-modulating compounds by adjusting the pH value (6.5), the heating time (120 min), and the heating temperature (120 °C). With the development of a new natural deep eutectic solvents (NADES) system consisting of thiamine, cysteine, ribose, and sodium hydroxide, it was possible to obtain high yields of the targeted taste-modulating analytes, such as 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine. Furthermore, the current study showed that kokumi-active thiamine derivates, such as S -((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteine, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one, 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine, and 5-(((furan-2-ylmethyl)thio)methyl)-2-methylpyrimidin-4-amine, can be classified as natural "food-borne" taste enhancers and occur in thiamine-rich, thermally treated foodstuff.

A novel cyclometalated gold(iii) complex supported by chlorambucil coupled with phenylpyridine (CHL-N^C) and a hybrid of vitamin B1 with dithiocarbamate (B1-DTC) with the formula [(CHL-N^C)AuIII(B1-DTC)](Cl2), 1, was synthesized and fully characterized using different techniques, including multinuclear NMR, mass spectrometry, and elemental analysis. This complex is water-soluble and stable in a biological environment. This new complex offers a new scaffold to explore the biological properties of gold(iii) complexes as an anticancer drug. The antiproliferative activities of complex 1 and free ligands against breast and colon cancer cells showed auspicious results with IC50 values in the micromolar range for complex 1 and more active than cisplatin and free ligands with selectivity over non-tumorigenic cells human lung fibroblasts, MRC-5. The DNA binding and inhibition of thioredoxin reductase of complex 1 were studied and compared with molecular docking results. Moreover, the Au cellular uptake and apoptosis of this new complex were investigated.

Expanding the catalytic repertoire of ribozymes to include vitamin synthesis requires efficient labelling of RNA with the substrate of interest, prior to in vitro selection. For this purpose, we rationally designed and synthesized six GMP-conjugates carrying a synthetic pre-thiamine or biotin precursor and investigated their transcription incorporation properties by T7 RNA polymerase.

Neurodegenerative diseases are accompanied by changes in the activity of thiamine mono- and diphosphate phosphatases, but molecular identification of these mammalian enzymes is incomplete. In this work, the protein fraction of bovine brain synaptosomes displaying phosphatase activity toward thiamine derivatives was subjected to affinity chromatography on thiamine-Sepharose. Protein fractions eluted with thiamine (pH 7.4 or 5.6), NaCl, and urea were assayed for the phosphatase activity against thiamine monophosphate (ThMP), thiamine diphosphate (ThDP), and structurally similar purine nucleotides. Proteins in each fraction were identified by mass spectrometry using the SwissProt database for all organisms because of insufficient annotation of the bovine genome. Peptides of two annotated bacterial phosphatases, alkaline phosphatase L from the DING protein family and exopolyphosphatase, were identified in the acidic thiamine eluate. The abundance of peptides of alkaline phosphatase L and exopolyphosphatase in the eluted fractions correlated with ThMPase and ThDPase activities, respectively. The elution profiles of the ThMPase and ThDPase activities differed from the elution profiles of nucleotide phosphatases, thus indicating the specificity of these enzymes toward thiamine derivatives. The search for mammalian DING phosphatases in the eluates from thiamine-Sepharose revealed X-DING-CD4, mostly eluted by the acidic thiamine solution (pH 5.6). The identified exopolyphosphatase demonstrated structural similarity with apyrases possessing the ThDPase activity. The obtained results demonstrate that mammalian DING proteins and apyrases exhibit ThMPase and ThDPase activity, respectively.

Our research groups have been involved for many years in studies aimed at identifying new active organic compounds endowed with pharmacological properties. In this work, we focused our attention on the evaluation of cardiovascular and molecular drug resistance (MDR) reverting activities of some nitrosubstituted sulphur-containing heterocycles. Firstly, we have examined the effects of 4-nitro-3-(4-methylphenyl)-3,6-dihydro-2 H -thiopyran S,S -dioxide 5 , and have observed no activity. Then we have extended our investigation to the 3-aryl-4-nitrobenzothiochromans S,S -dioxide 6 and 7 , and have observed an interesting biological profile. Cardiovascular activities were assessed for all compounds using ex vivo studies, while the MDR reverting effect was evaluated only for selected compounds using tumor cell lines. All compounds were shown to affect cardiovascular parameters. Compound 7i exerted the most effect on negative inotropic activity, while 6d and 6f could be interesting molecules for the development of more active ABCB1 inhibitors. Both 6 and 7 represent structures of large possible biological interest, providing a scaffold for the identification of new ABCB1 inhibitors., Competing Interests: The authors declare no conflict of interest.

A fluorometric assay for histidine (His) is described. It is based on the inhibitory effect of His on nanocubes consisting of cobalt-containing Prussian Blue analog (CoFe NCbs), which have a strong oxidation effect on thiamine (THI) in the presence of NaOH. THI is nonfluorescent but the oxidized form (thiochrome; ThC) has a strong blue fluorescence, with excitation/emission maxima at 370/445 nm. His inhibits the oxidation effect of the CoFe NCbs due to the strong interaction between its imidazole side chain and the amino groups of the CoFe NCbs. This method is fast and has good sensitivity and selectivity. The lower detection limit is 14.3 nM of His, the linear range extends from 0.05 to 2.5 μM, and the relative standard deviation is calculated to be 1.5%. The method was successfully employed to quantify His in spiked serum samples. Graphical abstractSchematic representation of cobalt-containing Prussian Blue nanocubes (CoFe NCbs)-thiamine (THI)-based fluorometric assay for Histine (His). His inhibits the generation of thiochrome (ThC; the oxidized form of THI). The detection limit is 14.3 nM with the linear range of 0.05-2.5 μM.

Deoxyribonucleoside triphosphates (dNTPs) are building blocks for the biosynthesis of DNA. Various modified dNTPs' analogs have synthesized by structural changes of nucleoside's susgar and nucleobases and employed for synthesis of modified DNA. A very few modified dNTPs have prepared from non-sugar nucleoside analogs. This report describes the synthesis of acyclic nucleoside triphosphate (NTP) analog from amino acid L-Serine as aminopropanolyl-thymine triphosphate ( ap- TTP) and demonstrate its biochemical evaluation as enzymatic incorporation of ap- TTP into DNA with DNA polymerases with primer extension methods. Alanyl peptide nucleicacids (Ala-PNA) are the analogs of DNA which contains alanyl backbone. Aminopropanolyl - analogs are derivatives of alanyl back bone. Ap-TTP analog is nucleoside triphosphate analog derived from Ala-PNA. Importantly, this report also sheds light on the crystal packing arrangement of alaninyl thymine ester derivative in solid-state and reveals the formation of self-duplex assembly in anti -parallel fashion via reverse Watson-Crick hydrogen bonding and π-π interactions. Hence, ap- TTP is a useful analog which also generates the free amine functional group at the terminal of DNA oligonucleotide after incorporation.

Malignant cells frequently demonstrate an oncogenic-driven reliance on glycolytic metabolism to support their highly proliferative nature. Overexpression of pyruvate dehydrogenase kinase (PDK) may promote this unique metabolic signature of tumor cells by inhibiting mitochondrial function. PDKs function to phosphorylate and inhibit pyruvate dehydrogenase (PDH) activity. Silencing of PDK expression has previously been shown to restore mitochondrial function and reduce tumor cell proliferation. High dose Vitamin B1, or thiamine, possesses antitumor properties related to its capacity to reduce PDH phosphorylation and promote its enzymatic activity, presumably through PDK inhibition. Though a promising nutraceutical approach for cancer therapy, thiamine's low bioavailability may limit clinical effectiveness. Here, we have demonstrated exploiting the commercially available lipophilic thiamine analogs sulbutiamine and benfotiamine increases thiamine's anti-cancer effect in vitro. Determined by crystal violet proliferation assays, both sulbutiamine and benfotiamine reduced thiamine's millimolar IC50 value to micromolar equivalents. HPLC analysis revealed that sulbutiamine and benfotiamine significantly increased intracellular thiamine and TPP concentrations in vitro, corresponding with reduced levels of PDH phosphorylation. Through an ex vitro kinase screen, thiamine's activated cofactor form thiamine pyrophosphate (TPP) was found to inhibit the function of multiple PDK isoforms. Attempts to maximize intracellular TPP by exploiting thiamine homeostasis gene expression resulted in enhanced apoptosis in tumor cells. Based on our in vitro evaluations, we conclude that TPP serves as the active species mediating thiamine's inhibitory effect on tumor cell proliferation. Pharmacologic administration of benfotiamine, but not sulbutiamine, reduced tumor growth in a subcutaneous xenograft mouse model. It remains unclear if benfotiamine's effects in vivo are associated with PDK inhibition or through an alternative mechanism of action. Future work will aim to define the action of lipophilic thiamine mimetics in vivo in order to translate their clinical usefulness as anticancer strategies., (Copyright © 2019 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

The photolysis of thiochrome (THC), an oxidation product of thiamine (vitamin B 1 ) (THE), used for its fluorimetric assay, has been studied in the pH range 7.0-12.0. THC undergoes photooxidation to oxodihydrothiochrome (ODTHC) which is oxidized to a non-fluorescent compound (OP1) on UV irradiation. The kinetics of the consecutive first-order reactions: THC→k 1 ODTHC→k 2 OP1, has been evaluated and the values of first-order rate constants, k 1 (0.58-4.20 × 10 -5 , s -1 ) and k 2 (0.05-2.03 × 10 -5 , s -1 ), at pH 7.0-12.0 have been determined. The rates of degradation of THC and ODTHC are enhanced with pH and the second-order rate constants k 1 ' and k 2 ' for the OH - ion-catalyzed reaction are in the range of 0.002-58.3 M -1  s -1 . The quantum yields of the photolysis of THC and ODTHC in the pH range 7.0-12.0 have been determined. THC, ODTHC and OP1 have been identified by chromatographic, spectrometric and fluorimetric methods. THC and ODTHC have similar fluorescence characteristics and emit at 450 and 445 nm, respectively. THC, ODTHC and OP1 with distinct absorption maxima (370, 344 and 290 nm, respectively) have been determined by a newly developed and validated multicomponent spectrometric method during the photolysis reactions. The on-line formation of THC by the photooxidation of THE may lead to the degradation of THC and give erroneous results in the fluorimetric assay of THE. A scheme for the photolysis reactions of THC in aqueous solution is presented., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Increasing the thiamine concentration in a respective process flavor yields a product with a significant higher kokumi activity. S-plot analysis of the mass spectrometric data revealed beside thiamine itself, 4-methyl-5-thiazoleethanol, ( S )-((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteine, N -((4-amino-2-methylpyrimidin-5-yl)methyl)formamide, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one, and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine as marker molecules for a process flavor with higher thiamine concentration. Sensory-based targeted isolation revealed that ( S )-((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteine, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one, and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine showed an influence on the kokumi taste activity with taste threshold concentrations between 35 and 120 μmol/L. An adapted mass spectrometric-based carbon module labeling experiment as well as quantitative studies clearly demonstrated thiamine as the only precursor and an intermolecular formation pathway for the compounds ( S )-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine. On the basis of the knowledge that several thiamine derivatives showed taste-modulating activity, selected thiamine-based binary model reactions and synthesis were carried out. This resulted in the isolation of further thiamine-derived taste modulators like ( S )-((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteinylglycine, ( S )-3-((((4-amino-2-methylpyrimidin-5-yl)methyl)thio)methyl)piperazine-2,5-dione, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)pentan-2-one, 5-(((furan-2-ylmethyl)thio)methyl)-2-methylpyrimidin-4-amine, and (4-amino-2-methylpyrimidin-5-yl)methanethiol, 2-methyl-5-((methylthio)methyl)pyrimidin-4-amine with taste thresholds ranging from 35 to 880 μmol/L.

Harmful cyanobacteria bloom (HCB) has occurred frequently in recent years and it is urgent to develop novel algicides to deal with this problem. In this paper, a series of novel thiamin diphosphate (ThDP) analogs 5a-5g were designed and synthesized targeting cyanobacterial pyruvate dehydrogenase complex E1 (Cy-PDHc E1). Our results showed that compounds 5a-5g have higher inhibitory activities against Cy-PDHc E1 (IC 50 9.56-3.48 µM) and higher inhibitory activities against two model cyanobacteria strains Synechocystis sp PCC6803 (EC 50 2.03-1.58 µM) and Microcystis aeruginosa FACHB905 (EC 50 1.86-0.95 µM). Especially, compound 5b displayed highest inhibitory activities (IC 50  = 3.48 µM) against Cy-PDHc E1 and powerful inhibitory activities against cyanobacteria Synechocystis sp PCC6803 (EC 50  = 1.58 µM) and Microcystis aeruginosa FACHB905 (EC 50  = 1.04 µM). Moreover, the inhibitory activities of compound 5b were even higher than those of copper sulfate (EC 50  = 2.02 and 1.71 µM separately) which has been widely used as algicide against cyanobacteria PCC6803 and FACHB905. The more important was that compound 5b display much higher inhibitory selectivity between Cy-PDHc E1 (Inhibitory rate 97.4%) and porcine PDHc E1 (Inhibitory rate 11.8%) under the same concentration (100 μM). The inhibition kinetic experiment and molecular docking research showed that compound 5b can inhibit Cy-PDHc E1 by occupying the ThDP-binding pocket and then blocking Cy-PDHc E1 bound to ThDP as competitive inhibitor. The imagines of SEM and TEM showed that cellular microstructures were heavily destroyed under compound 5b stress. Our results demonstrated compound 5b could be taken as a potential lead compound targeting Cy-PDHc E1 to obtain environment-friendly algicide for harmful cyanobacterial blooms control., (Copyright © 2019 Elsevier Ltd. All rights reserved.)