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1.
Int J Mol Sci ; 25(8)2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38673944

RESUMO

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 (GI50 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 (ΔG -8.2 kcal/mol) demonstrates a better affinity with thiamine pyrophosphokinase than thiamine (ΔG -7.5 kcal/mol ) and oxythiamine (ΔG -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.


Assuntos
Simulação de Acoplamento Molecular , Oxitiamina , Humanos , Células HeLa , Oxitiamina/farmacologia , Oxitiamina/química , Oxitiamina/metabolismo , Tiamina/farmacologia , Tiamina/análogos & derivados , Tiamina/química , Antineoplásicos/farmacologia , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Simulação por Computador
2.
Int J Mol Sci ; 25(2)2024 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-38255994

RESUMO

Transketolase (TKT) is an essential thiamine diphosphate (ThDP)-dependent enzyme of the non-oxidative branch of the pentose phosphate pathway, with the glucose-6P flux through the pathway regulated in various medically important conditions. Here, we characterize the brain TKT regulation by acylation in rats with perturbed thiamine-dependent metabolism, known to occur in neurodegenerative diseases. The perturbations are modeled by the administration of oxythiamine inhibiting ThDP-dependent enzymes in vivo or by reduced thiamine availability in the presence of metformin and amprolium, inhibiting intracellular thiamine transporters. Compared to control rats, chronic administration of oxythiamine does not significantly change the modification level of the two detected TKT acetylation sites (K6 and K102) but doubles malonylation of TKT K499, concomitantly decreasing 1.7-fold the level of demalonylase sirtuin 5. The inhibitors of thiamine transporters do not change average levels of TKT acylation or sirtuin 5. TKT structures indicate that the acylated residues are distant from the active sites. The acylations-perturbed electrostatic interactions may be involved in conformational shifts and/or the formation of TKT complexes with other proteins or nucleic acids. Acetylation of K102 may affect the active site entrance/exit and subunit interactions. Correlation analysis reveals that the action of oxythiamine is characterized by significant negative correlations of K499 malonylation or K6 acetylation with TKT activity, not observed upon the action of the inhibitors of thiamine transport. However, the transport inhibitors induce significant negative correlations between the TKT activity and K102 acetylation or TKT expression, absent in the oxythiamine group. Thus, perturbations in the ThDP-dependent catalysis or thiamine transport manifest in the insult-specific patterns of the brain TKT malonylation and acetylations.


Assuntos
Sirtuínas , Tiamina Pirofosfato , Transcetolase , Animais , Ratos , Acilação , Encéfalo , Proteínas de Membrana Transportadoras , Oxitiamina , Tiamina/farmacologia , Transcetolase/metabolismo
3.
Cell Chem Biol ; 29(8): 1317-1324.e5, 2022 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-35901793

RESUMO

New therapeutic concepts are critically needed for carbapenem-resistant Pseudomonas aeruginosa, an opportunistic pathogen particularly recalcitrant to antibiotics. The screening of around 230,000 small molecules yielded a very low hit rate of 0.002% after triaging for known antibiotics. The only novel hit that stood out was the antimetabolite oxythiamine. Oxythiamine is a known transketolase inhibitor in eukaryotic cells, but its antibacterial potency has not been reported. Metabolic and transcriptomic analyses indicated that oxythiamine is intracellularly converted to oxythiamine pyrophosphate and subsequently inhibits several vitamin-B1-dependent enzymes, sensitizing the bacteria to several antibiotic and non-antibiotic drugs such as tetracyclines, 5-fluorouracil, and auranofin. The positive interaction between 5-fluorouracil and oxythiamine was confirmed in a murine ocular infection model, indicating relevance during infection. Together, this study revealed a system-level significance of thiamine metabolism perturbation that sensitizes P. aeruginosa to multiple small molecules, a property that could inform on the development of a rational drug combination.


Assuntos
Oxitiamina , Tiamina Pirofosfato , Animais , Antibacterianos/farmacologia , Fluoruracila , Camundongos , Oxitiamina/metabolismo , Oxitiamina/farmacologia , Pseudomonas aeruginosa/metabolismo , Complexo Piruvato Desidrogenase/metabolismo , Tiamina/metabolismo , Tiamina/farmacologia , Tiamina Pirofosfato/análise , Tiamina Pirofosfato/metabolismo
4.
Artigo em Inglês | MEDLINE | ID: mdl-35409800

RESUMO

OBJECTIVES: To explore the potential application of B-OT in the aspiration tract. MATERIALS AND METHODS: We conceived and optimized an in vitro model simulating the mouth-washing process to assess tolerance to B-OT on primary human gingival fibroblasts. Cells derived from 4 unrelated donors were flushed with medium containing drugs of various concentration for one minute twice daily for 3 days. RESULTS: No effect was seen on the cells up to 1000 µM B-OT. In addition, we treated the cells with B-OT permanently in medium, corresponding to a systemic treatment. No effect was seen by 10 µM B-OT and only a slight reduction (approximately 10%) was seen by 100 µM B-OT. CONCLUSIONS: Our results suggest good tolerance of oral cells for B-OT, favoring the further development of this antiviral reagent as a mouth-washing solution and nasal spray.


Assuntos
Antivirais , Oxitiamina , Fibroblastos , Humanos , Oxitiamina/farmacologia , Oxitiamina/uso terapêutico
5.
Pediatr Nephrol ; 36(4): 987-993, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33067673

RESUMO

BACKGROUND: Oxythiamine is a uremic toxin that acts as an antimetabolite to thiamine and has been associated with cases of Shoshin beriberi syndrome in adults. We sought to identify whether surgical stress and ischemia/reperfusion injury may precipitate functional thiamine deficiency in children peritransplant. METHODS: We retrospectively analyzed a cohort of pediatric kidney transplant recipients. Oxythiamine levels were measured in pre-transplant serum samples by mass spectrometry and tested for association with severity of lactic acidosis in the first 24 h post-transplant. Secondary outcomes included association with hyperglycemia and indicators of dialysis adequacy (DA). RESULTS: Forty-seven patients were included in the analysis. Median oxythiamine levels differed by modality, measuring 0.67 nM (IQR 0.31, 0.74), 0.34 nM (IQR 0.28, 0.56), and 0.25 nM (IQR 0.17, 0.38) for peritoneal dialysis (PD), hemodialysis (HD), and no dialysis, respectively (p = 0.05). Oxythiamine was associated with 24-h lactate levels (r = 0.38, p = 0.02) and negatively associated with DA (r = - 0.44, p = 0.02). Median oxythiamine levels were higher in patients with poor DA (0.92 nM (IQR 0.51, 1.01) vs. 0.40 nM (IQR 0.24, 0.51), p < 0.01). Sensitivity analysis showed absence of residual association of oxythiamine with 24-h lactate or dialysis modality, but remained significant for DA (p = 0.03). One patient manifested Shoshin beriberi syndrome (oxythiamine 2.03 nM). CONCLUSIONS: Oxythiamine levels are associated with DA at transplant. Patients on PD with no residual kidney function and low DA manifest the highest oxythiamine levels and may be at an increased risk for developing acute Shoshin beriberi syndrome in the early post-transplant period.


Assuntos
Beriberi , Transplante de Rim , Oxitiamina/sangue , Criança , Progressão da Doença , Hemodinâmica , Humanos , Transplante de Rim/efeitos adversos , Lactatos/sangue , Diálise Renal , Estudos Retrospectivos
6.
Mol Cell Endocrinol ; 499: 110595, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31563469

RESUMO

The pentose phosphate pathway (PPP) plays an important role in the biosynthesis of ribonucleotide precursor and NADPH. Cancer cells frequently increase the flux of glucose into the PPP to support the anabolic demands and regulate oxidative stress. Consistently, metabolomic analyses indicate an upregulation of the PPP in thyroid cancer. In the present study, we found that the combination of glucose-6-phosphate dehydrogenase (G6PD) and transketolase inhibitors (6-aminonicotinamide and oxythiamine) exerted an additive or synergistic effect on cell growth inhibition in thyroid cancer cells. Targeting PPP significantly increased cellular reactive oxygen species (ROS) and induced endoplasmic reticulum (ER) stress and apoptosis. Suppressed cell viability could be partially rescued with treatment with the ROS scavenger or apoptosis inhibitor but not ER-stress inhibitor. Taken together, dual PPP blockade leads to pharmacologic additivity or synergism and causes ROS-mediated apoptosis in thyroid cancer cells.


Assuntos
6-Aminonicotinamida/farmacologia , Oxitiamina/farmacologia , Via de Pentose Fosfato/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Neoplasias da Glândula Tireoide/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Glucosefosfato Desidrogenase , Humanos , NADP/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Neoplasias da Glândula Tireoide/tratamento farmacológico
7.
Vet Dermatol ; 29(6): 476-e160, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30251451

RESUMO

BACKGROUND: Malassezia pachydermatis is an opportunistic yeast involved in skin and ear canal infections of dogs and cats. Reports suggest that strains of M. pachydermatis resistant to commonly used antifungal agents may be emerging. Therefore, new therapeutic strategies should be explored. OBJECTIVES: The synergistic effect of oxythiamine (OT) and ketoconazole (KTC) was analysed using a reference strain and field isolates (n = 66) of M. pachydermatis. Hydrogel formulations containing these components also were evaluated. METHODS AND MATERIALS: The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of OT, KTC and their mixtures were determined by a broth macrodilution method. The antifungal effects of hydrogel formulations were determined by a plate diffusion method. RESULTS: The MIC and MFC values of OT were in the range 0.08 × 103 to 10 × 103  mg/L. All M. pachydermatis strains showed higher susceptibility to KTC (MICs and MFCs in the range 0.04-0.32 mg/L). Formulations that combined OT and KTC showed a synergistic effect for all tested isolates (n = 66). Hydrogels that contained OT at a concentration of 10 × 103 or 20 × 103  mg/L and KTC at the concentration of 0.1 × 103  mg/L showed a stronger effect than a commercially available product with KTC alone (20 × 103  mg/L). CONCLUSIONS AND CLINICAL IMPORTANCE: Synergy of these drugs may allow for successful topical treatment which utilizes lower doses of KTC without changing its therapeutic effectiveness. Hydrogel formulations proved to be attractive drug carriers for potential topical use.


Assuntos
Antifúngicos/uso terapêutico , Dermatomicoses/veterinária , Doenças do Cão/microbiologia , Cetoconazol/uso terapêutico , Malassezia , Otite Externa/veterinária , Oxitiamina/uso terapêutico , Animais , Antifúngicos/administração & dosagem , Dermatomicoses/tratamento farmacológico , Doenças do Cão/tratamento farmacológico , Cães , Sinergismo Farmacológico , Quimioterapia Combinada , Hidrogel de Polietilenoglicol-Dimetacrilato/administração & dosagem , Cetoconazol/administração & dosagem , Malassezia/efeitos dos fármacos , Testes de Sensibilidade Microbiana/veterinária , Otite Externa/tratamento farmacológico , Otite Externa/microbiologia , Oxitiamina/administração & dosagem
8.
J Investig Med ; 66(5): 1-9, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29502067

RESUMO

This study tested the hypothesis that the effects of lovastatin on anaplastic thyroid cancer cell growth are mediated by upregulation of transketolase (TKT) expression. The effects of lovastatin on TKT protein levels in ARO cells were determined using western blot and proteomic analyses. After treatment with lovastatin and oxythiamine, the in vitro and in vivo growth of ARO cells was determined using 3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assays and tumor xenografts in nude mice. TKT protein expression in the ARO tumors was assessed using immunohistochemistry analysis. Proteomic analysis revealed that 25 µM lovastatin upregulated TKT expression. Co-treatment of ARO cells with 1 µM lovastatin + 1 µM oxythiamine increased TKT protein expression compared with control levels; however, no differences were observed with 10 µM lovastatin + 1 µM oxythiamine. Furthermore, treatment with either oxythiamine or lovastatin alone reduced ARO tumor expression of TKT, as well as decreased ARO cell proliferation in vitro and tumor growth in vivo. However, mice treated with both lovastatin and oxythiamine at the same time had tumor volumes similar to that of the untreated control group. We conclude that either lovastatin or oxythiamine reduced ARO cell growth; however, the combination of these drugs resulted in antagonism of ARO tumor growth.


Assuntos
Lovastatina/uso terapêutico , Carcinoma Anaplásico da Tireoide/tratamento farmacológico , Carcinoma Anaplásico da Tireoide/patologia , Transcetolase/metabolismo , Animais , Apoptose/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Lovastatina/farmacologia , Masculino , Camundongos Nus , Oxitiamina/farmacologia , Proteômica , Carcinoma Anaplásico da Tireoide/enzimologia , Carga Tumoral/efeitos dos fármacos
9.
Biosci Rep ; 38(1)2018 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-29208764

RESUMO

Thiamine plays a very important coenzymatic and non-coenzymatic role in the regulation of basic metabolism. Thiamine diphosphate is a coenzyme of many enzymes, most of which occur in prokaryotes. Pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes as well as transketolase are the examples of thiamine-dependent enzymes present in eukaryotes, including human. Therefore, thiamine is considered as drug or diet supplement which can support the treatment of many pathologies including neurodegenerative and vascular system diseases. On the other hand, thiamine antivitamins, which can interact with thiamine-dependent enzymes impeding their native functions, thiamine transport into the cells or a thiamine diphosphate synthesis, are good propose to drug design. The development of organic chemistry in the last century allowed the synthesis of various thiamine antimetabolites such as amprolium, pyrithiamine, oxythiamine, or 3-deazathiamine. Results of biochemical and theoretical chemistry research show that affinity to thiamine diphosphate-dependent enzymes of these synthetic molecules exceeds the affinity of native coenzyme. Therefore, some of them have already been used in the treatment of coccidiosis (amprolium), other are extensively studied as cytostatics in the treatment of cancer or fungal infections (oxythiamine and pyrithiamine). This review summarizes the current knowledge concerning the synthesis and mechanisms of action of selected thiamine antivitamins and indicates the potential of their practical use.


Assuntos
Desenho de Fármacos , Tiamina Pirofosfato/metabolismo , Tiamina/metabolismo , Amprólio/química , Amprólio/metabolismo , Antimetabólitos/uso terapêutico , Transporte Biológico , Humanos , Oxitiamina/antagonistas & inibidores , Oxitiamina/metabolismo , Piritiamina/antagonistas & inibidores , Piritiamina/metabolismo , Tiamina/antagonistas & inibidores , Tiamina/síntese química , Tiamina Pirofosfato/química
10.
Int J Mol Sci ; 18(4)2017 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-28425973

RESUMO

Epitope detection in monocytes (EDIM) represents a liquid biopsy exploiting the innate immune system. Activated monocytes (macrophages) phagocytose unwanted cells/cell fragments from the whole body including solid tissues. As they return to the blood, macrophages can be used for a non-invasive detection of biomarkers, thereby providing high sensitivity and specificity, because the intracellular presence of biomarkers is due to an innate immune response. Flow cytometry analysis of blood enables the detection of macrophages and phagocytosed intracellular biomarkers. In order to establish a pan-cancer test, biomarkers for two fundamental biophysical mechanisms have been exploited. The DNaseX/Apo10 protein epitope is a characteristic of tumor cells with abnormal apoptosis and proliferation. Transketolase-like 1 (TKTL1) is a marker for an anaerobic glucose metabolism (Warburg effect), which is concomitant with invasive growth/metastasis and resistant to radical and apoptosis inducing therapies. The detection of Apo10 and TKTL1 in blood macrophages allowed a sensitive (95.8%) and specific (97.3%) detection of prostate, breast and oral squamous cell carcinomas. Since TKTL1 represents a drugable target, the EDIM based detection of TKTL1 enables a targeted cancer therapy using the vitamin derivatives oxythiamine or benfo-oxythiamine.


Assuntos
Apoptose/imunologia , Biomarcadores Tumorais , Análise Química do Sangue/métodos , Epitopos/imunologia , Monócitos/imunologia , Monócitos/metabolismo , Animais , Apoptose/genética , Evolução Biológica , Biópsia , Detecção Precoce de Câncer , Epitopos/genética , Fluordesoxiglucose F18 , Humanos , Imunidade Inata , Ácido Láctico/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Terapia de Alvo Molecular , Neoplasias/sangue , Neoplasias/diagnóstico , Neoplasias/genética , Neoplasias/imunologia , Oxitiamina/farmacologia , Tomografia por Emissão de Pósitrons/métodos , Recidiva , Ativação Transcricional , Transcetolase/genética , Transcetolase/metabolismo
11.
Bioorg Chem ; 69: 153-158, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27816798

RESUMO

It has previously been established that the deprotonated amino substituent of the pyrimidine of thiamin diphosphate (ThDP) acts as an internal base to accept the C2H of the thiazolium in ThDP-dependent enzymes. The amino group has also been implicated in assisting the departure of the aldehydic product formed after loss of CO2 from ketoacid substrates. However, the potential role for the pyrimidine amino group in the key decarboxylation step has not been assessed. Oxythiamin contains a hydroxyl group in place of the pyrimidine amino group in thiamin, providing a basis for comparison of reactivity. Lactyl-oxythiamin (LOTh), the conjugate of pyruvic acid and oxythiamin was prepared by condensation of ethyl pyruvate and hydroxyl-protected oxythiamin followed by deprotection and acidic hydrolysis of the ethyl ester. The rate constants observed for the decarboxylation of LOTh in neutral and acidic solutions are about four times smaller than those for the corresponding compound that contains the amino group, lactylthiamin. The difference in reactivity is consistent with the amino group's participation in facilitating the decarboxylation step by allowing a competitive addition pathway that produces bicarbonate and has implications for the corresponding enzymic reaction.


Assuntos
Oxitiamina/química , Pirimidinas/química , Ácido Pirúvico/química , Tiamina/química , Catálise , Descarboxilação , Estrutura Molecular
12.
Kidney Int ; 90(2): 252-254, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27418090

RESUMO

Zhang et al. found that plasma concentrations of the thiamine antimetabolite oxythiamine are significantly increased in patients with end-stage renal disease. These investigators discuss the potential sources of oxythiamine and the consequences of its plasma elevation. This commentary addresses the significance of these findings and expands on the potential role of gut microbiome in the generation of this antithiamine metabolite.


Assuntos
Falência Renal Crônica , Deficiência de Tiamina , Humanos , Oxitiamina , Insuficiência Renal Crônica , Tiamina
13.
Kidney Int ; 90(2): 396-403, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27198804

RESUMO

Decreased transketolase activity is an unexplained characteristic of patients with end-stage renal disease and is linked to impaired metabolic and immune function. Here we describe the discovery of a link to impaired functional activity of thiamine pyrophosphate cofactor through the presence, accumulation, and pyrophosphorylation of the thiamine antimetabolite oxythiamine in renal failure. Plasma oxythiamine was significantly increased by 4-fold in patients receiving continuous ambulatory peritoneal dialysis and 15-fold in patients receiving hemodialysis immediately before the dialysis session (healthy individuals, 0.18 [0.11-0.22] nM); continuous ambulatory peritoneal dialysis patients, 0.64 [0.48-0.94] nM; and hemodialysis patients (2.73 [1.52-5.76] nM). Oxythiamine was converted to the transketolase inhibitor oxythiamine pyrophosphate. The red blood cell oxythiamine pyrophosphate concentration was significantly increased by 4-fold in hemodialysis (healthy individuals, 15.9 nM and hemodialysis patients, 66.1 nM). This accounted for the significant concomitant 41% loss of transketolase activity (mU/mg hemoglobin) from 0.410 in healthy individuals to 0.240 in hemodialysis patients. This may be corrected by displacement with excess thiamine pyrophosphate and explain lifting of decreased transketolase activity by high-dose thiamine supplementation in previous studies. Oxythiamine is likely of dietary origin through cooking of acidic thiamine-containing foods. Experimentally, trace levels of oxythiamine were not formed from thiamine degradation under physiologic conditions but rather under acidic conditions at 100(°)C. Thus, monitoring of the plasma oxythiamine concentration in renal failure and implementation of high-dose thiamine supplements to counter it may help improve the clinical outcome of patients with renal failure.


Assuntos
Antimetabólitos/toxicidade , Falência Renal Crônica/metabolismo , Oxitiamina/toxicidade , Deficiência de Tiamina/induzido quimicamente , Tiamina Pirofosfato/metabolismo , Transcetolase/antagonistas & inibidores , Adulto , Dieta/efeitos adversos , Feminino , Humanos , Falência Renal Crônica/sangue , Falência Renal Crônica/terapia , Masculino , Pessoa de Meia-Idade , Oxitiamina/sangue , Oxitiamina/metabolismo , Processamento de Proteína Pós-Traducional , Diálise Renal , Eliminação Renal , Tiamina Pirofosfoquinase/metabolismo , Tiamina/uso terapêutico , Deficiência de Tiamina/tratamento farmacológico , Complexo Vitamínico B/uso terapêutico
14.
J Recept Signal Transduct Res ; 36(3): 233-42, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26481897

RESUMO

Transketolase is a connecting link between glycolytic and pentose phosphate pathway, which is considered as the rate-limiting step due to synthesis of large number of ATP molecule and it can be proposed as a plausible target facilitating the growth of cancerous cells suggesting its potential role in cancer. Oxythiamine, an antimetabolite has been proved to be an efficient anticancerous compound in vitro, but its structural elucidation of the inhibitory mechanism has not yet been done against the human transketolase-like 1 protein (TKTL1). The three-dimensional (3D) structure of TKTL1 protein was modeled and subjected for refinement, stability and validation. Based on the reported homologs of transketolase (TKT), the active site residues His46, Ser49, Ser52, Ser53, Ile56, Leu82, Lys84, Leu123, Ser125, Glu128, Asp154, His160, Thr216 and Lys218 were identified and considered for molecular-modeling studies. Docking studies reveal the H-bond interactions with residues Ser49 and Lys218 that could play a major role in the activity of TKTL1. Molecular dynamics (MD) simulation study was performed to reveal the comparative stability of both native and complex forms of TKTL1. MD trajectory at 30 ns, confirm the role of active site residues Ser49, Lys84, Glu128, His160 and Lys218 in suppressing the activity of TKTL1. Glu128 is observed to be the most important residue for deprotonation state of the aminopyrimidine moiety and preferred to be the site of inhibitory action. Thus, the proposed mechanism of inhibition through in silico studies would pave the way for structure-oriented drug designing against cancer.


Assuntos
Inibidores Enzimáticos/farmacologia , Oxitiamina/farmacologia , Transcetolase/antagonistas & inibidores , Sequência de Aminoácidos , Domínio Catalítico , Inibidores Enzimáticos/química , Humanos , Ligação de Hidrogênio , Ligantes , Simulação de Dinâmica Molecular , Dados de Sequência Molecular , Oxitiamina/química , Alinhamento de Sequência , Termodinâmica , Transcetolase/química , Transcetolase/metabolismo
15.
Mycoses ; 59(2): 108-16, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26691773

RESUMO

Severe skin diseases and systemic fungaemia are caused by Malassezia pachydermatis and Candida albicans respectively. Antifungal therapies are less effective because of chronic character of infections and high percentage of relapses. Therefore, there is a great need to develop new strategies of antifungal therapies. We previously found that oxythiamine decreases proliferation of yeast (Saccharomyces cerevisiae), therefore we suggest that thiamine antivitamins can be considered as antifungal agents. The aim of this study was the comparison of thiamine antivitamins (oxythiamine, amprolium, thiochrome, tetrahydrothiamine and tetrahydrooxythiamine) inhibitory effect on the growth rate and energetic metabolism efficiency in non-pathogenic S. cerevisiae and two potentially pathogenic species M. pachydermatis and C. albicans. Investigated species were cultured on a Sabouraud medium supplemented with trace elements in the presence (40 mg l(-1)) or absence of each tested antivitamins to estimate their influence on growth rate, enzyme activity and kinetic parameters of pyruvate decarboxylase and malate dehydrogenase of each tested species. Oxythiamine was the only antivitamin with antifungal potential. M. pachydermatis and S. cerevisiae were the most sensitive, whereas C. albicans was the least sensitive to oxythiamine action. Oxythiamine can be considered as supportive agent in superficial mycoses treatment, especially those caused by species from the genus Malassezia.


Assuntos
Antifúngicos/farmacologia , Antimetabólitos/farmacologia , Candida albicans/efeitos dos fármacos , Candidíase Cutânea/tratamento farmacológico , Dermatomicoses/tratamento farmacológico , Malassezia/efeitos dos fármacos , Tiamina/antagonistas & inibidores , Antifúngicos/uso terapêutico , Antimetabólitos/uso terapêutico , Candida albicans/crescimento & desenvolvimento , Candidíase Cutânea/microbiologia , Dermatomicoses/microbiologia , Fungemia/tratamento farmacológico , Fungemia/microbiologia , Humanos , Malassezia/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Oxitiamina/farmacologia , Oxitiamina/uso terapêutico , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/crescimento & desenvolvimento
16.
Genet Mol Res ; 14(3): 11043-51, 2015 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-26400334

RESUMO

Oxythiamine (OT) has been proven to be a potential anticancer drug. With the help of NMR-based metabonomics, we studied the metabolic changes within tumor-bearing mice with different levels of OT administration using a C57BL/6 mouse Lewis lung carcinoma tumor transplantation model. We administered different concentrations of OT (75, 150, 300, and 600 mg∙kg(-1)∙day(-1)) to the mice orally for 2 weeks, recorded animal weights and tumor volumes, sacrificed the animals, and collected blood and tumor mass samples for nuclear magnetic resonance determination. Compared with the findings for the control (untreated) group, the tumor weights and volumes of the 150, 300, and 600 mg∙kg-1∙day-1 groups decreased with no difference among these OT groups. A large metabolite difference was observed in plasma metabolites between the blank and control groups, which indicated the success of the tumor-bearing model. The metabolites in tumor associated with thiamine-dependent enzymes (TDEs) underwent considerable change between the OT and control groups, exhibiting concentration dependence and enzyme specificity. The restriction of TDEs by OT may be a major mechanism underlying its anticancer effect. The role of OT as a potential anticancer drug and a dehydrogenase inhibitor should therefore be taken into consideration in future tumor research.


Assuntos
Antineoplásicos/farmacologia , Biomarcadores Tumorais/sangue , Carcinoma Pulmonar de Lewis/sangue , Oxitiamina/farmacologia , Animais , Carcinoma Pulmonar de Lewis/tratamento farmacológico , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Masculino , Redes e Vias Metabólicas , Camundongos Endogâmicos C57BL , Transplante de Neoplasias , Espectroscopia de Prótons por Ressonância Magnética
17.
Mol Cell Biochem ; 403(1-2): 51-60, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25626895

RESUMO

The oxythiamine (OXY) is antivitamin of thiamine. The finding that OXY increases the cytoplasmic concentration of pyruvate, known to enhance collagen biosynthesis, led us to investigate the mechanism of this antivitamin action on collagen biosynthesis in cultured human skin fibroblasts. Confluent fibroblasts were treated with micromolar concentrations (30-1,000 µM) of OXY for 24 and 48 h. It was found that OXY-dependent increase in collagen biosynthesis was accompanied by parallel increase in prolidase activity and level, compared to untreated cells. Since phosphoenolpyruvate (PEP) is known as an inhibitor of prolidase-the enzyme that plays important role in collagen biosynthesis, the mechanism of pyruvate interconversion was considered as a regulatory switch in collagen biosynthesis. In fact, 3-MPA, specific inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), contributed to up-regulation of prolidase activity, suggesting that down-regulation of PEP formation is an underlying mechanism. Since collagen biosynthesis and prolidase activity are regulated by signal induced by activated α2ß1 integrin receptor as well as insulin-like growth factor-I receptor (IGF-IR), the expression of these receptors was measured by Western immunoblot analysis. The exposure of the cells to OXY contributed to decrease in IGF-IR, α2ß1 integrin receptor, pERK1/2, and NF-κB p65 expressions. It was accompanied by increase in total ERK1/2 expression and induction of phosphorylation of Akt protein. The data suggest that OXY-dependent increase of collagen biosynthesis in cultured human skin fibroblasts results from activation of prolidase activity and level, induction in pAkt expression and down-regulation of pERK1/2 and NF-κB p65, the known inhibitor of collagen gene expression.


Assuntos
Colágeno/biossíntese , Fibroblastos/metabolismo , Oxitiamina/farmacologia , Western Blotting , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Dipeptidases/metabolismo , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/enzimologia , Humanos , Pele/citologia
18.
Biomed Res Int ; 2014: 572915, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25028661

RESUMO

In animal experiments, hippocampal neurogenesis and the activity of thiamine-dependent transketolase decrease markedly under conditions of thiamine deficiency. To further investigate the effect of thiamine deficiency on the proliferation of hippocampal progenitor cells (HPCs) and the potential mechanisms involved in this effect, we cultured HPCs in vitro in the absence of thiamine and found that proliferation and transketolase activity were both significantly repressed. Furthermore, specific inhibition of transketolase activity by oxythiamine strongly inhibited HPC proliferation in a dose-dependent manner. However, thiamine deficiency itself inhibited the proliferation to a greater degree than did oxythiamine. Taken together, our results suggest that modulation of transketolase activity might be one of the mechanisms by which thiamine regulates the proliferation of hippocampal progenitor cells.


Assuntos
Proliferação de Células , Regulação para Baixo , Regulação Enzimológica da Expressão Gênica , Hipocampo/enzimologia , Células-Tronco Neurais/enzimologia , Deficiência de Tiamina/enzimologia , Transcetolase/biossíntese , Animais , Antimetabólitos/farmacologia , Células Cultivadas , Relação Dose-Resposta a Droga , Hipocampo/patologia , Células-Tronco Neurais/patologia , Oxitiamina/farmacologia , Ratos , Ratos Sprague-Dawley , Deficiência de Tiamina/patologia
19.
Georgian Med News ; (229): 73-80, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24850610

RESUMO

Presented article suggests the novel hypothesis of carcinogenesis, where the key moment for all types (biological, physical, chemical) of carcinogenesis has been discussed. For confirmation of the hypothesis thorough theoretical analysis of the mechanisms of malignant transformation of cells after influence of any type of carcinogens and results of experiments have been presented. Hypothesis highlights are formulated as follows: 1) Covalent bond disorders between S+-methionine and Fe3+ atoms in cytochrome; 2) Electron transport chain blockade with certain ligand after its penetration in cytochrome pocket with further formation of 6th coordination bond between ligand and Fe atom (in one case increase in mitochondrial pH precede-, and in other, it follows electron transport chain blockade in cytochromes); 3) Fe3+ reduction up to Fe2+ leading to blockade of aerobic glycolysis; 4) Decrease in enzyme (Е1-TDP, oxidases etc.) activity due to mitochondrial pH alterations; 5) Production of S-adenosylmethionine owing to lipoic acid amide leading to accumulation of homocysteine in cytoplasm with further penetration in cell nucleus producing DNA mutations; 6) Fe2+ wash-out from cytochrome and its deposition in ferritin.


Assuntos
Apoptose/efeitos dos fármacos , Carcinogênese/efeitos dos fármacos , Neoplasias Experimentais/tratamento farmacológico , Oxitiamina/análogos & derivados , Animais , Masculino
20.
Exp Oncol ; 36(1): 48-9, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24691285

RESUMO

AIM: The aim of the presented article was investigation of anticancer efficacy of hydroxyethylthiamine diphosphate (HTD) in vivo. MATERIALS AND METHODS: The study was carried out on 30 C57BL/6J mice subcutaneously transplanted with Ehrlich carcinoma. Animals were treated with intraperitoneal injections of the solution composed from pyruvic acid and thiamine bromide every other day during 10 days and thereafter, every day during 2 weeks. Treatment efficacy was evaluated by tumor growth inhibition. RESULTS: In experimental animals treated with HTD, significant tumor growth inhibition has been registered: 73% at day 45(th) compared to the control group (p < 0.001). CONCLUSION: Treatment with HTD demonstrated high anticancer efficacy in vivo.


Assuntos
Carcinoma de Ehrlich/tratamento farmacológico , Oxitiamina/análogos & derivados , Animais , Carcinoma de Ehrlich/patologia , Injeções Intraperitoneais , Camundongos , Oxitiamina/administração & dosagem
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