Thiamine Research Articles

Protein responses in kenaf plants exposed to drought conditions determined using iTRAQ technology.

The molecular mechanisms that underlie drought stress responses in kenaf, an important crop for the production of natural fibers, are poorly understood. To address this issue, we describe here the first iTRAQ‐based comparative proteomic analysis of kenaf seedlings. Plants were divided into the following three treatment groups: Group A, watered normally (control); Group B, not watered for 6 days (drought treatment); and Group C, not watered for 5 days and then rewatered for 1 day (recovery treatment). A total of 5014 proteins were detected, including 4932 (i.e., 98.36%) that were matched to known proteins in a BLAST search. We detected 218, 107, and 348 proteins that were upregulated in Group B compared with Group A, Group C compared with Group A, and Group B compared with Group C, respectively. Additionally, 306, 145, and 231 downregulated proteins were detected during the same comparisons. Seventy differentially expressed proteins were analyzed and classified into 10 categories: photosynthesis, sulfur metabolism, amino sugar and nucleotide sugar metabolism, oxidative phosphorylation, ribosome, fatty acid elongation, thiamine metabolism, tryptophan metabolism, plant–pathogen interaction, and propanoate. Kenaf adapted to stress mainly by improving the metabolism of ATP, regulating photosynthesis according to light intensity, promoting the synthesis of osmoregulators, strengthening ion transport signal transmission, and promoting metabolism and cell stability. This is the first study to examine changes in protein expression in kenaf plants exposed to drought stress. Our results identified key drought‐responsive genes and proteins and may provide useful genetic information for improving kenaf stress resistance.

Thiaminase I Provides a Growth Advantage by Salvaging Precursors from Environmental Thiamine and Its Analogs in Burkholderia thailandensis.

Thiamine is essential to life, as it serves as a cofactor for enzymes involved in critical carbon transformations. Many bacteria can synthesize thiamine, while thiamine auxotrophs must obtain it or its precursors from the environment. Thiaminases degrade thiamine by catalyzing the base-exchange substitution of thiazole with a nucleophile, and thiaminase I specifically has been implicated in thiamine deficiency syndromes in animals. The biological role of this secreted enzyme has been a long-standing mystery. We used the thiaminase I-producing soil bacterium Burkholderia thailandensis as a model to ascertain its function. First, we generated thiamine auxotrophs, which are still able to use exogenous precursors (thiazole and hydroxymethyl pyrimidine), to synthesize thiamine. We found that thiaminase I extended the survival of these strains, when grown in defined media where thiamine was serially diluted out, compared to isogenic strains that could not produce thiaminase I. Thiamine auxotrophs grew better on thiamine precursors than thiamine itself, suggesting thiaminase I functions to convert thiamine to useful precursors. Furthermore, our findings demonstrate that thiaminase I cleaves phosphorylated thiamine and toxic analogs, which releases precursors that can then be used for thiamine synthesis. This study establishes a biological role for this perplexing enzyme and provides additional insight into the complicated nature of thiamine metabolism and how individual bacteria may manipulate the availability of a vital nutrient in the environment.IMPORTANCE The function of thiaminase I has remained a long-standing, unsolved mystery. The enzyme is only known to be produced by a small subset of microorganisms, although thiaminase I activity has been associated with numerous plants and animals, and is implicated in thiamine deficiencies brought on by consumption of organisms containing this enzyme. Genomic and biochemical analyses have shed light on potential roles for the enzyme. Using the genetically amenable thiaminase I-producing soil bacterium Burkholderia thailandensis, we were able to demonstrate that thiaminase I helps salvage precursors from thiamine derivatives in the environment and degrades thiamine to its precursors, which are preferentially used by B. thailandensis auxotrophs. Our study establishes a biological role for this perplexing enzyme and provides insight into the complicated nature of thiamine metabolism. It also establishes B. thailandensis as a robust model system for studying thiamine metabolism.

Spectrochromatographic determination of dorzolamide hydrochloride and timolol maleate in an ophthalmic solution using three-way analysis methods

In this study, the simultaneous spectrochromatographic determination of dorzolamide hydrochloride (DOR) and timolol maleate (TMM) in an ophthalmic formulation was performed by applying multiway resolution methods, parallel factor analysis (PARAFAC) and three way partial least squares (3W-PLS) models. In similar manner, unfolded partial least squares (U-PLS) approach was applied to the UPLC analysis of the related drugs. For the three-way resolutions, the ultra-performance liquid chromatography–photodiode array (UPLC-PDA) data array of the calibration samples and others (validation and commercial samples) containing the analyzed drugs (DOR and TMM) and thiamine hydrochloride as an internal standard (IS) was decomposed into triads or trilinear components. These three different calibration models were employed for the spectrochromatographic resolution of a commercial ophthalmic formulation of DOR and TMM and then successful quantitation results were obtained. Analysis results provided by applying three-way and two-way resolutions were statistically compared to those obtained by the newly developed standard UPLC approach. It was observed that the proposed methods gave comparable determination results for analysis of the DOR-TMM ophthalmic formulation.

H-point standard addition for simultaneous reagent-free spectrophotometric determination of B1 and B6 vitamins.

Vitamin deficiency is a main cause of many disorders and diseases that cannot be treated without using dietary supplements and multivitamin medications. We present here a UV-spectrophotometric method for simultaneous assay of two of the widely used vitamins, thiamine hydrochloride (vitamin B1) and pyridoxine hydrochloride (vitamin B6). The method is based on H-point standard addition to estimate the vitamins under study in their pure solutions and multivitamin ampoules by measuring the absorption of the mixture at 283 and 298 nm allowing its application in quality control laboratories. The work summarizes the theoretical basis of the H-point standard addition method. Moreover, a guide for the selection of the two wavelengths at which the calibration curves are constructed is given in this investigation. The linear ranges of the calibration graphs are 6.75-67.5 and 2.06-20.56 μg/mL for thiamine and pyridoxine, respectively. Correlation coefficients (r2) were found to be 0.9990 and 0.9899 at 283 nm and 0.9855 and 0.9995 at 298 nm for vitamin B1 and vitamin B6, respectively. Oscillator strength (f), transition dipole moment (μ) and resonance energy (RN) were calculated. The method was successfully applied for dual determination of the vitamins in their pure solutions and multivitamin ampoules with recovery values ranging from 98.41 to 102.6 and from 95.39 to 104.9% for thiamine and pyridoxine, respectively. The accuracy and precision of the proposed method is obvious from the low relative standard deviation values which are not more than 1.19%.

Thiamine for Septic Shock

The metabolic demands of septic shock commonly lead to thiamine deficiency, and thiamine has therefore received attention as an adjunctive therapy for

Probing the binding ability of vitamin B1 with bovine serum albumin: Calorimetric, light scattering, spectroscopic and volumetric studies

Abstract Various techniques like spectroscopy (UV-visible absorption, fluorescence, 1H-NMR), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and volumetry (density and sound velocity) have been used to throw light on the interactional behaviour of vitamin B1 i.e. thiamine hydrochloride (TH) with bovine serum albumin (BSA). The spectroscopic results revealed the preservation of tertiary structure of BSA after TH binding. The affinity value of the order of 104 M−1 has been deduced from both absorption and fluorescence titrations. Metal ion (Ca2+, Mg2+, K+, Mn2+, Na+, and Ni2+) effect on the interactional behaviour has also been monitored. The increase in the hydrodynamic size and decrease in the emission intensity through static quenching mechanism of BSA along with its non-specific nature of interactions with TH have been observed. The ionic interactions at lower TH concentrations and hydrophobic interactions at higher concentrations along with hydrational shell structural changes have been visualized from initial increase of both V and Ks values at lower while decrease at higher concentrations of TH. Calorimetric binding enthalpograms also show the initial exothermic binding process followed by endothermic. The involvement of ethylthiazolium part of TH in hydrophobic interactions whereas substituted pyrimidine ring part in hydrophilic interactions has been depicted from 1H-NMR measurements.

Construction of a novel turn-on-off fluorescence sensor used for highly selective detection of thiamine via its quenching effect on o-phen-Zn2+ complex.

In this work, a simple and selective fluorescence sensor approach called 'turn-on-off' for the determination of thiamine (TM) has been developed. As known, the o-phenanthroline (o-phen) has inner fluorescence, though when reacted with zinc ions to form the o-phen-Zn2+ complex the fluorescence intensity was enhanced effectively, while upon addition of TM into the o-phen-Zn2+ complex solution, the intensity of the system was gently quenched, which was termed the 'turn-on-off' probe. Notably, the method possessed highly selective, sensitive determination for TM with a detection limit of 0.25μmolL-1 and the reduced fluorescence intensity was proportional to the concentration of TM in the range 0.84-80.0μmolL-1 . Besides, the proposed mechanism was also investigated through exploring the Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy. Furthermore, this manner was successfully applied into practical samples for TM detection with satisfactory results.

Thiamine status, metabolism and application in dairy cows: a review.

As the co-enzyme of pyruvate dehydrogenase and α-ketoglutarate dehydrogenase, thiamine plays a critical role in carbohydrate metabolism in dairy cows. Apart from feedstuff, microbial thiamine synthesis in the rumen is the main source for dairy cows. However, the amount of ruminal thiamine synthesis, which is influenced by dietary N levels and forage to concentrate ratio, varies greatly. Notably, when dairy cows are overfed high-grain diets, subacute ruminal acidosis (SARA) occurs and results in thiamine deficiency. Thiamine deficiency is characterised by decreased ruminal and blood thiamine concentrations and an increased blood thiamine pyrophosphate effect to >45 %. Thiamine deficiency caused by SARA is mainly related to the increased thiamine requirement during high grain feeding, decreased bacterial thiamine synthesis in the rumen, increased thiamine degradation by thiaminase, and decreased thiamine absorption by transporters. Interestingly, thiamine deficiency can be reversed by exogenous thiamine supplementation in the diet. Besides, thiamine supplementation has beneficial effects in dairy cows, such as increased milk and component production and attenuated SARA by improving rumen fermentation, balancing bacterial community and alleviating inflammatory response in the ruminal epithelium. However, there is no conclusive dietary thiamine recommendation for dairy cows, and the impacts of thiamine supplementation on protozoa, solid-attached bacteria, rumen wall-adherent bacteria and nutrient metabolism in dairy cows are still unclear. This knowledge is critical to understand thiamine status and function in dairy cows. Overall, the present review described the current state of knowledge on thiamine nutrition in dairy cows and the major problems that must be addressed in future research.

Fluorometric determination of sulfide ions via its inhibitory effect on the oxidation of thiamine by Cu(II) ions.

A fluorometric assay is described for sulfide ions determination. It is based on the finding that the oxidation of the non-fluorescent substrate thiamine (TH) by Cu(II) in basic solution to form fluorescent thiochrome is inhibited by sulfide ions. This results in a decrease in fluorescence intensity which is proportional to the concentration of sulfide ions. Under the optimized conditions, the decrease in fluorescence, best measured at excitation/emission wavelengths of 370/440nm, decreases linearly in the 0.03 to 2.5μM sulfide ions concentration range. The detection limit is 20nM. The method shows excellent selectivity over many potentially interfering ions and has been successfullyapplied to the determination of sulfide ions in spiked tap water, lake water and thesynthetic wastewatersamples. The method is time-saving and environmentally friendly, and in our perception shows a great potential in water quality inspection and environmental monitoring. Graphical abstract A fluorescent assay for sulfide ions detection is proposed based on its inhibitory effect on the oxidation of thiamine by Cu(II) ions.

APPROPRIATE UTILIZATION AND STOCKING OF ANTIDOTES IN QATAR PUBLIC HOSPITALS: A PROSPECTIVE STUDY

BackgroundFew studies evaluating preparedness and availability of antidotes in the emergency setting exist and none have been conducted in Qatar. To address this; we conducted a study to evaluate antidote stocking and utilization in Qatar hospital pharmacies and emergency departments. MethodsOur aim was: 1) evaluate the appropriate use and timely administration of antidotes, and; 2) evaluate stocking of the 31 most important antidotes our main public hospitals. For the evaluation of the first aim; research assistants prospectively collected data on ED patients who received any key antidote over the 6-month study period using both ED and pharmacy records. For the second aim; survey assessing stocking of these key antidotes was sent to the four general hospitals in Qatar to determine their availability and whether they are stocked in the ED or only in the main pharmacy.ResultsPoison exposure in 471 cases were evaluated. Antidotes were given within 30 minutes in 73% of cases, which included atropine, calcium, dextrose, flumazenil, naloxone, pralidoxime, sodium bicarbonate, thiamine, vitamin K and scorpion and snake antivenoms. Administration occurred later than 60 minutes in 2% of cases, exclusively with N-acetylecysteine and activated charcoal. Atropine,dextrose, naloxone, pralidoxime (2-PAM), sodium bicarbonate, and anti-venoms were clinically indicated 92% of the time they were ordered. N-acetylcysteine was indicated in only 51.5% of administrations. ConclusionOver 90% of antidotes were administered in less than 30 minutes. N-acetylcysteine administration was frequently delayed due to preparation outside of the ED. This delay of administration did not have any adverse effect on clinical management. Antidote stocking varied significantly between hospitals and antidotes necessary for cyanide and toxic alcohol poisoning were deficient in all public hospitals. The implication indicates the need for the development of national guidelines to standardize the stocking and administration of the antidotes among the country public hospitals.

16S rRNA Long-Read Sequencing of the Granulation Tissue from Nonsmokers and Smokers-Severe Chronic Periodontitis Patients.

Smoking has been associated with increased risk of periodontitis. The aim of the present study was to compare the periodontal disease severity among smokers and nonsmokers which may help in better understanding of predisposition to this chronic inflammation mediated diseases. We selected deep-seated infected granulation tissue removed during periodontal flap surgery procedures for identification and differential abundance of residential bacterial species among smokers and nonsmokers through long-read sequencing technology targeting full-length 16S rRNA gene. A total of 8 phyla were identified among which Firmicutes and Bacteroidetes were most dominating. Differential abundance analysis of OTUs through PICRUST showed significant (p>0.05) abundance of Phyla-Fusobacteria (Streptobacillus moniliformis); Phyla-Firmicutes (Streptococcus equi), and Phyla Proteobacteria (Enhydrobacter aerosaccus) in nonsmokers compared to smokers. The differential abundance of oral metagenomes in smokers showed significant enrichment of host genes modulating pathways involving primary immunodeficiency, citrate cycle, streptomycin biosynthesis, vitamin B6 metabolism, butanoate metabolism, glycine, serine, and threonine metabolism pathways. While thiamine metabolism, amino acid metabolism, homologous recombination, epithelial cell signaling, aminoacyl-tRNA biosynthesis, phosphonate/phosphinate metabolism, polycyclic aromatic hydrocarbon degradation, synthesis and degradation of ketone bodies, translation factors, Ascorbate and aldarate metabolism, and DNA replication pathways were significantly enriched in nonsmokers, modulation of these pathways in oral cavities due to differential enrichment of metagenomes in smokers may lead to an increased susceptibility to infections and/or higher formation of DNA adducts, which may increase the risk of carcinogenesis.

REGULATION OF THIAMINE BIOSYNTHESIS UPON EXOGENOUS APPLICATION OF THE VITAMIN IN OIL PALM (Elaeis guineensis)

Thiamine (vitamin B1) is an essential microelement that is synthesised de novo by plants and microorganisms. The active form of thiamine is thiamine pyrophosphate (TPP), which plays a prominent role in plant's metabolic activity particularly as an enzymatic cofactor. In vivo analysis of thiamine in oil palm was performed where four months old oil palm seedlings were treated with 125 ml of 50 mM thiamine hydrochloride and tissue samples were collected at Day 0, 1, 2 and 3. The expression of ThiC gene fragment was analysed via quantitative real time polymerase chain reaction (qPCR) which showed an approximately five-fold decrease post-thiamine treatment. Analysis of thiamine and its derivatives via high performance liquid chromatography (HPLC) showed that the concentration of thiamine decreased, while TPP increased post-thiamine treatment. It is suggested that thiamine biosynthesis in oil palm can be effectively regulated at the physiological concentrations of the vitamin.

Re-emergence of thiamine deficiency disease in the Pacific islands (2014-15): A case-control study.

BackgroundFrom late 2014 multiple atolls in Kiribati reported an unusual and sometimes fatal illness. We conducted an investigation to identify the etiology of the outbreak on the most severely affected atoll, Kuria, and identified thiamine deficiency disease as the cause. Thiamine deficiency disease has not been reported in the Pacific islands for >5 decades. We present the epidemiological, clinical, and laboratory findings of the investigation.Methodology/Principal findingsWe initially conducted detailed interviews and examinations on previously identified cases to characterize the unknown illness and develop a case definition. Active and passive surveillance was then conducted to identify additional cases. A questionnaire to identify potential risk factors and blood samples to assay biochemical indices were collected from cases and asymptomatic controls. Thiamine hydrochloride treatment was implemented and the response to treatment was systematically monitored using a five-point visual analogue scale and by assessing resolution of previously abnormal neurological examination findings. Risk factors and biochemical results were assessed by univariate and multivariate analyses. 69 cases were identified on Kuria (7% attack rate) including 34 confirmed and 35 unconfirmed. Most were adults (median age 28 years [range 0–62]) and 83% were male. Seven adult males and two infants died (13% case fatality rate). Resolution of objective clinical signs (78%) or symptoms (94%) were identified within one week of starting treatment. Risk factors included having a friend with thiamine deficiency disease and drinking kava; drinking yeast alcohol reduced the risk of disease. Higher chromium (p<0·001) but not thiamine deficiency (p = 0·66) or other biochemical indices were associated with disease by univariate analyses. Chromium (p<0·001) and thiamine deficiency (p = 0·02) were associated with disease by multivariate analysis.Conclusions/SignificanceAn outbreak of thiamine deficiency disease (beriberi) in Kiribati signals the re-emergence of a classic nutritional disease in the Pacific islands after five decades. Although treatment is safe and effective, the underlying reason for the re-emergence remains unknown. Chromium was highly and positively correlated with disease in this study raising questions about the potential role of factors other than thiamine in the biochemistry and pathophysiology of clinical disease.

MicroRNA Profiling in Glaucoma Eyes With Varying Degrees of Optic Neuropathy by Using Next-Generation Sequencing.

To explore the microRNA (miRNA) profile and its putative role in glaucomatous optic neuropathy by using next-generation sequencing. Aqueous humor (AH) samples were collected from 19 primary open-angle glaucoma (POAG) eyes and 17 cataract eyes before surgery. Next-generation sequencing was performed for RNA samples extracted from 18 AH samples, and the bioinformatics approach was applied for samples with adequate clean data output. The other 18 samples were used for quantitative PCR validation of sequencing results. In total, 12 (six POAG and six cataract controls) samples with sufficient clean data output after sequencing were used for further data analysis. Four hundred sixty-six and 480 mature miRNAs were detected in the POAG and cataract control groups, respectively. Among them, 164 miRNAs were detected in all POAG samples, and 96 miRNAs were detected in all cataract control samples. Furthermore, 88 miRNAs were identified as differently expressed between POAG and cataract control eyes. In addition, 16 miRNAs were differently expressed between POAG eyes with severe visual field damage and eyes with moderate visual field damage. This differential expression was predicted to regulate thiamine metabolism, purine metabolism, and transcriptional misregulation. Relative expression patterns of hsa-miR-184, hsa-miR-486-5p, and hsa-miR-93-5p were confirmed by quantitative PCR. This study comprehensively demonstrated the miRNA expression profile in the AH of POAG eyes, especially the differential expression of miRNA in eyes with varying degrees of visual field damage, which, together with the underlying miRNA-related pathways, indicate new targets for the pathogenesis and progression of POAG.

GC\u2013MS analysis of the ruminal metabolome response to thiamine supplementation during high grain feeding in dairy cows

IntroductionThiamine is known to attenuate high-concentrate diet induced subacute ruminal acidosis (SARA) in dairy cows, however, the underlying mechanisms remain unclear.ObjectivesThe major objective of this study was to investigate the metabolic mechanisms of thiamine supplementation on high-concentrate diet induced SARA.MethodsSix multiparous, rumen-fistulated Holstein cows were used in a replicated 3 × 3 Latin square design. The treatments included a control diet (CON; 20% starch, dry matter basis), a SARA-inducing diet (SAID; 33.2% starch, dry matter basis) and SARA-inducing diet supplemented with 180 mg of thiamine/kg of dry matter intake (SAID + T). On d21 of each period, ruminal fluid samples were collected at 3 h post feeding, and GC/MS was used to analyze rumen fluid samples.ResultsPCA and OPLS-DA analysis demonstrated that the ruminal metabolite profile were different in three treatments. Compared with CON treatment, SAID feeding significantly decreased rumen pH, acetate, succinic acid, increased propionate, pyruvate, lactate, glycine and biogenic amines including spermidine and putrescine. Thiamine supplementation significantly decreased rumen content of propionate, pyruvate, lactate, glycine and spermidine; increase rumen pH, acetate and some medium-chain fatty acids. The enrichment analysis of different metabolites indicated that thiamine supplementation mainly affected carbohydrates, amino acids, pyruvate and thiamine metabolism compared with SAID treatment.ConclusionsThese findings revealed that thiamine supplementation could attenuate high-concentrate diet induced SARA by increasing pyruvate formate-lyase activity to promote pyruvate to generate acetyl-CoA and inhibit lactate generation. Besides, thiamine reduced biogenic amines to alleviate ruminal epithelial inflammatory response.

Metabolomics and pathway analyses to characterize metabolic alterations in pregnant dairy cows on D 17 and D 45 after AI

Nutrient flow to the embryo and placenta is crucial for proper development and growth during pregnancy. In this study, a metabonomic analysis was undertaken to better understand global changes in pregnant dairy cows on D 17 and D 45 after timed artificial insemination (AI). Metabolic changes in the blood plasma of pregnant dairy cows were investigated using HPLC-MS and a multivariate statistical analysis. Changes in metabolic networks were established using the MetPA method. Alterations in six metabolic pathways were found on D 17 and D 45, including variations in the level of alpha-linolenic acid metabolism, glycerophospholipid metabolism, pentose and glucuronate interconversions, glycerolipid metabolism, folate biosynthesis, and tyrosine metabolism. In addition to these pathways, 9 metabolic pathways were markedly altered on D 45. These pathways included changes in the one-carbon pool caused by folate; phenylalanine, tyrosine and tryptophan biosynthesis; thiamine metabolism; pantothenate and CoA biosynthesis; purine metabolism; inositol phosphate metabolism; amino sugar and nucleotide sugar metabolism; pentose phosphate; and the TCA pathway. The combination of metabonomics and network methods used in this study generated rich biochemical insight into possible biological modules related to early pregnancy in dairy cows.

Simultaneous spectrophotometric determination of thiamine and pyridoxine in multivitamin dosage forms using H-point standard addition and Vierodt᾿s methods

Two simple, reliable and accurate spectrophotometric methods were described for the simultaneous determination of thiamine hydrochloride (THC) and pyridoxine hydrochloride (PYH) in pharmaceutical formulation without any pre-separation procedures. These methods are based on the difference in the color observed from diazotization coupling methods of THC and PYH. When the diazonium salts formed from the reaction of HNO2 with p-nitroaniline (PNA), they were coupled with THC and PYH in sodium hydroxide medium and the formed dyes had maximum absorption bands at 452 nm for THC and 482 nm for PYH. All experimental parameters were optimized to reduce experimental error. The first method was based on the Vierodt᾿s method, in which the two wavelengths 452 and 482 nm λmax of THC and PYH, respectively, were selected for the formation of simultaneous equation. In the second method the H-point standard addition method (HPSAM) was applied, when absorbances at wavelengths pair, 452 and 500 nm, were monitored with the addition of a standard solution of THC to a solution containing a fixed concentration of THC and PYH. The results from applying Vierodt᾿s and HPSA methods showed that THC and PYH can be determined simultaneously in the concentration range 1.5–11.0 μg mL−1 (LOD = 0.48 μg mL−1) and 0.4–5.0 μg mL−1 (LOD = 0.23 μg mL−1), respectively. The methods were successfully applied for simultaneous determination of THC and PYH in different synthetic and pharmaceutical products. To assess the obtained vitamins (THC and PYH) analysis by both methods (Vierodt᾿s and HPSAM) in the several pharmaceutical formulations, the results are compared with that obtained by HPLC method as a reference, and good agreements between the results indicate the reliability of the proposed methods.

Preparation and Spectroscopic Studies of Charge-Transfer Complexes of Thiamine Hydrochloride with Different Electron Acceptor

Abstract—Electronic interactions associated with charge transfer complexes formation of iodine, chloranilic acid (H2CA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with vitamin B1 have been studied spectrophotometrically. The accumulated data indicated formation of CT-complexes of the general formula [(VB1)(acceptor) n ], (n = 1 or 2). The 1 : 2 and 1 : 1 donor: acceptor molar ratios were calculated on the basis of elemental analysis and photometric titrations. The solid complexes were prepared and characterized by their conductivity, UV-Vis, IR, and 1H NMR spectra, and thermogravimetric analyses (TGA, DTG). The characteristic physical constants (KCT, eCT, μ, ΔG, Ip, f, ECT) of the formed CT-complexes were determined to be strongly dependent on nature of the electron acceptors.

Palladium N-Heterocyclic Carbene Complex of Vitamin B1 Supported on Silica-Coated Fe3O4 Nanoparticles: A Green and Efficient Catalyst for C–C Coupling

Fe3O4@SiO2 nanoparticles were prepared by hydrolysis of TEOS in the presence of Fe3O4 nanoparticles that were synthesized through co-precipitation procedure. Then, thiamine hydrochloride (VB1) was covalently connected with silica to provide a biodegradable, nontoxic and inexpensive NHC ligand for the formation of complex with palladium. This magnetic bionanocatalyst was characterized using FT-IR, XPS, FE-SEM, TEM, EDX, XRD, VSM, TGA and ICP-AES analysis. The Fe3O4@SiO2@VB1-Pd was found as a magnetically separable and highly active catalyst for the Suzuki coupling reactions of various aryl halides with substituted phenylboronic acids. Under appropriate conditions, all reactions afforded the desired products in excellent yields at short reaction times. Moreover, this catalyst can be easily recovered by using a magnetic field and directly reused for five times in this cross coupling with good yield and suitable time.

PET Imaging Analysis of Vitamin B1 Kinetics with [11C]Thiamine and its Derivative [11C]Thiamine Tetrahydrofurfuryl Disulfide in Rats.

Thiamine is an essential component of glucose metabolism and energy production. The disulfide derivative, thiamine tetrahydrofurfuryl disulfide (TTFD), is better absorbed than readily-available water-soluble thiamine salts because it does not require the rate-limiting transport system required for thiamine absorption. However, the detailed pharmacokinetics of thiamine and TTFD under normal and pathological conditions have not yet been clarified. C-11-labeled thiamine and TTFD were recently synthesized by our group. In this study, to clarify the differences in pharmacokinetics and metabolism of these probes, a quantitative PET imaging study and radiometabolite analysis of C-11-labeled thiamine and TTFD were performed in the rat heart. Positron emission tomography (PET) imaging with [11C]thiamine and [11C]TTFD was performed in normal rats to determine the pharmacokinetics of these probes, and the radiometabolites of both probes from the blood and heart tissue were analyzed by thin-layer chromatography. Accumulation of [11C]TTFD was significantly higher than that of [11C]thiamine in the rat heart. Moreover, as a result of the radiometabolite analysis of heart tissue at 15min after the injection of [11C]TTFD, thiamine pyrophosphate, which serves as a cofactor for the enzymes involved in glucose metabolism, was found as the major radiometabolite and at a significantly higher level than in the [11C]thiamine-injected group. PET imaging techniques for visualizing the kinetics and metabolism of thiamine using [11C]thiamine and [11C]TTFD were developed in this study. Consequently, noninvasive PET imaging for the pathophysiology of thiamine-related cardiac function may provide novel information about heart failure and related disorders.