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1.
Biomolecules ; 14(3)2024 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-38540746

RESUMO

Amino acid restriction induces cellular stress and cells often respond via the induction of autophagy. Autophagy or 'self-eating' enables the recycling of proteins and provides the essential amino acids needed for cell survival. Of the naturally occurring amino acids, methionine restriction has pleiotropic effects on cells because methionine also contributes to the intracellular methyl pools required for epigenetic controls as well as polyamine biosynthesis. In this report, we describe the chemical synthesis of four diastereomers of a methionine depletion agent and demonstrate how controlled methionine efflux from cells significantly reduces intracellular methionine, S-adenosylmethionine (SAM), S-adenosyl homocysteine (SAH), and polyamine levels. We also demonstrate that human pancreatic cancer cells respond via a lipid signaling pathway to induce autophagy. The methionine depletion agent causes the large amino acid transporter 1 (LAT1) to preferentially work in reverse and export the cell's methionine (and leucine) stores. The four diastereomers of the lead methionine/leucine depletion agent were synthesized and evaluated for their ability to (a) efflux 3H-leucine from cells, (b) dock to LAT1 in silico, (c) modulate intracellular SAM, SAH, and phosphatidylethanolamine (PE) pools, and (d) induce the formation of the autophagy-associated LC3-II marker. The ability to modulate the intracellular concentration of methionine regardless of exogenous methionine supply provides new molecular tools to better understand cancer response pathways. This information can then be used to design improved therapeutics that target downstream methionine-dependent processes like polyamines.


Assuntos
Aminoácidos , Metionina , Humanos , Leucina/metabolismo , Metionina/metabolismo , S-Adenosilmetionina/metabolismo , Poliaminas/metabolismo , Racemetionina
2.
Macromol Rapid Commun ; : e2300665, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38444218

RESUMO

Glycidyl ethers are prepared from a series of furan-based diols and cured with a diamine to form thermosets. The furan diols demonstrate lower toxicity than bisphenol-A in a prior study. The diglycidyl ethers show improved thermal stability compared to the parent diols. Cured thermosets are prepared at elevated temperature using isophorone diamine (IPDA). Glass transition temperatures are in the range of 30-54 °C and depend on the structure of the furan diol. Coatings are prepared on steel substrates and show very high hardness, good adhesion, and a range of flexibility. Properties compare favorably with a control based on a bisphenol-A epoxy resin. The study demonstrates that epoxy resins based on furan diols, which have been shown to have lower toxicity than bisphenol-A, can form thermosets having properties comparable to a standard epoxy resin system; and thus, are viable as replacements for bisphenol-A epoxy resins.

3.
Alcohol Clin Exp Res (Hoboken) ; 48(4): 596-611, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38339830

RESUMO

BACKGROUND: Chronic alcohol consumption/misuse is a significant risk factor for pneumonia and lung infection leading to the development of chronic pulmonary disorders such as chronic obstructive pulmonary disease (COPD) and lung fibrosis. In this study, we sought to delineate the mechanism of alcohol-associated lung disease. We did so by measuring in vitro mitochondrial, endoplasmic reticulum (ER) oxidative stress in human bronchial epithelial cells (hBECs) treated with ethanol and its oxidative (acetaldehyde) and nonoxidative (fatty acid ethyl esters or FAEEs) metabolites. METHODS: Primary hBECs from a normal subject were treated with relevant concentrations of ethanol and its metabolites and incubated at 37°C for 24 h. Viability and cytotoxicity were determined using cell viability and lactate dehydrogenase (LDH) assay kits, respectively. Oxidized glutathione (GSSG) and reduced glutathione (GSH) were measured by colorimetric reaction, and 4-hydroxynenonal (4HNE) by immunohistochemistry. Endoplasmic reticulum stress and dysregulated cellular bioenergetics were determined by western blot analysis. Mitochondrial stress and real-time ATP production rates were determined using a Seahorse Extracellular Flux analyzer. Amelioration of ethanol-induced oxidative/ER stress and mitochondrial energetics was determined using an AMPKα agonist. RESULTS: Human bronchial epithelial cells treated with ethanol, acetaldehyde, and FAEEs showed a concentration-dependent increase in the secretion of LDH, oxidative/ER stress, deactivation of AMPKα phosphorylation and mitochondrial stress (decreased spare respiratory capacity) with concomitant decreases in mitochondrial and glycolytic ATP production rates. FAEEs caused greater cytotoxicity, ER stress, and dysregulated cellular bioenergetics than those ethanol and its oxidative metabolite. AMPKα agonist-pretreated cells significantly ameliorated ethanol-induced oxidative/ER stress, deactivation of AMPKα, and dysregulated cellular bioenergetics. CONCLUSIONS: Findings of this study suggest that ethanol and its metabolites contribute to cytotoxicity, oxidative/ER stress, and dysregulation of cellular bioenergetics in hBECs. The attenuation of ethanol-induced ER/oxidative stress and mitochondrial respiration by an AMPKα agonist may reflect a potential for it to be developed as a therapeutic agent for chronic alcohol-associated lung disease.

4.
Life Sci ; 322: 121670, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-37030615

RESUMO

AIMS: Dysregulation of pancreatic fat and lipotoxic inflammation are common clinical findings in alcoholic chronic pancreatitis (ACP). In this study, we investigated a relationship between dysregulated pancreatic lipid metabolism and the development of injury in a chronic ethanol (EtOH) feeding model of hepatic alcohol dehydrogenase 1- deficient (ADH-) deer mice. METHODS: ADH- and hepatic ADH normal (ADH+) deer mice were fed a liquid diet containing 3 % EtOH for three months and received a single gavage of binge EtOH with/without fatty acid ethyl esters (FAEEs) one week before the euthanasia. Plasma and pancreatic tissue were analyzed for lipids including FAEEs, inflammatory markers and adipokines using GC-MS, bioassays/kits, and immunostaining, respectively. Pancreatic morphology and proteins involved in lipogenesis were determined by the H & E staining, electron microscopy and Western blot analysis. KEY FINDINGS: Chronic EtOH feeding in ADH- vs. ADH+ deer mice resulted in a significant increase in the levels of pancreatic lipids including FAEEs, adipokines (leptin and resistin), fat infiltration with inflammatory cells and lipid droplet deposition along with the proteins involved in lipogenesis. The changes exacerbated by an administration of binge EtOH with/without FAEEs in the pancreas of ADH- vs. ADH+ deer mice fed chronic EtOH suggest a metabolic basis for ACP. SIGNIFICANCE: These findings suggest that the liver-pancreatic axis plays a crucial role in etiopathogenesis of ACP, as the increased body burden of EtOH due to hepatic ADH deficiency exacerbates pancreatic injury.


Assuntos
Álcool Desidrogenase , Etanol , Animais , Etanol/toxicidade , Etanol/metabolismo , Álcool Desidrogenase/genética , Álcool Desidrogenase/metabolismo , Peromyscus/metabolismo , Fígado/metabolismo , Pâncreas/metabolismo , Ácidos Graxos/metabolismo , Inflamação/patologia , Hormônios Pancreáticos/metabolismo , Fenótipo , Ésteres , Adipocinas/metabolismo
5.
J Med Chem ; 65(22): 15391-15415, 2022 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-36382923

RESUMO

Polyamine biosynthesis is regulated by ornithine decarboxylase (ODC), which is transcriptionally activated by c-Myc. A large library was screened to find molecules that potentiate the ODC inhibitor, difluoromethylornithine (DFMO). Anthranilic acid derivatives were identified as DFMO adjunct agents. Further studies identified the far upstream binding protein 1 (FUBP1) as the target of lead compound 9. FUBP1 is a single-stranded DNA/RNA binding protein and a master controller of specific genes including c-Myc and p21. We showed that 9 does not inhibit 3H-spermidine uptake yet works synergistically with DFMO to limit cell growth in the presence of exogenous spermidine. Compound 9 was also shown to inhibit the KH4 FUBP1-FUSE interaction in a gel shift assay, bind to FUBP1 in a ChIP assay, reduce both c-Myc mRNA and protein expression, increase p21 mRNA and protein expression, and deplete intracellular polyamines. This promising hit opens the door to new FUBP1 inhibitors with increased potency.


Assuntos
Eflornitina , Espermidina , Eflornitina/farmacologia , RNA Mensageiro/genética , Proteínas de Ligação a RNA , Espermidina/metabolismo
6.
Int J Mol Sci ; 23(17)2022 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-36077029

RESUMO

The design and development of analgesics with mixed-opioid receptor interactions has been reported to decrease side effects, minimizing respiratory depression and reinforcing properties to generate safer analgesic therapeutics. We synthesized bis-cyclic guanidine heterocyclic peptidomimetics from reduced tripeptides. In vitro screening with radioligand competition binding assays demonstrated variable affinity for the mu-opioid receptor (MOR), delta-opioid receptor (DOR), and kappa-opioid receptor (KOR) across the series, with compound 1968-22 displaying good affinity for all three receptors. Central intracerebroventricular (i.c.v.) administration of 1968-22 produced dose-dependent, opioid receptor-mediated antinociception in the mouse 55 °C warm-water tail-withdrawal assay, and 1968-22 also produced significant antinociception up to 80 min after oral administration (10 mg/kg, p.o.). Compound 1968-22 was detected in the brain 5 min after intravenous administration and was shown to be stable in the blood for at least 30 min. Central administration of 1968-22 did not produce significant respiratory depression, locomotor effects or conditioned place preference or aversion. The data suggest these bis-cyclic guanidine heterocyclic peptidomimetics with multifunctional opioid receptor activity may hold potential as new analgesics with fewer liabilities of use.


Assuntos
Peptidomiméticos , Insuficiência Respiratória , Analgésicos/química , Analgésicos/farmacologia , Analgésicos Opioides , Animais , Guanidina/farmacologia , Guanidinas/farmacologia , Ligantes , Camundongos , Peptidomiméticos/química , Peptidomiméticos/farmacologia , Receptores Opioides , Receptores Opioides delta/metabolismo , Receptores Opioides kappa/metabolismo , Receptores Opioides mu/metabolismo
7.
Angew Chem Int Ed Engl ; 61(31): e202203353, 2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-35545813

RESUMO

Photodegradable, recyclable, and renewable, crosslinked polymers from bioresources show promise towards developing a sustainable strategy to address the issue of plastics degradability and recyclability. Photo processes are not widely exploited for upcycling polymers in spite of the potential to have spatial and temporal control of the degradation in addition to being a green process. In this report we highlight a methodology in which biomass-derived crosslinked polymers can be programmed to degrade at ≈300 nm with ≈60 % recovery of the monomer. The recovered monomer was recycled back to the crosslinked polymer.


Assuntos
Plásticos , Polímeros , Biomassa
8.
Am J Physiol Gastrointest Liver Physiol ; 322(3): G327-G345, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34984929

RESUMO

Alcoholic chronic pancreatitis (ACP) is a fibroinflammatory disease of the pancreas. However, metabolic basis of ACP is not clearly understood. In this study, we evaluated differential pancreatic injury in hepatic alcohol dehydrogenase-deficient (ADH-) deer mice fed chronic ethanol (EtOH), chronic plus binge EtOH, and chronic plus binge EtOH and fatty acid ethyl esters (FAEEs, nonoxidative metabolites of EtOH) to understand the metabolic basis of ACP. Hepatic ADH- and ADH normal (ADH+) deer mice were fed Lieber-DeCarli liquid diet containing 3% (wt/vol) EtOH for 3 mo. One week before the euthanization, chronic EtOH-fed mice were further administered with an oral gavage of binge EtOH with/without FAEEs. Blood alcohol concentration (BAC), pancreatic injury, and inflammatory markers were measured. Pancreatic morphology, ultrastructural changes, and endoplasmic reticulum (ER)/oxidative stress were examined using H&E staining, electron microscopy, immunostaining, and/or Western blot, respectively. Overall, BAC was substantially increased in chronic EtOH-fed groups of ADH- versus ADH+ deer mice. A significant change in pancreatic acinar cell morphology, with mild to moderate fibrosis and ultrastructural changes evident by dilatations and disruption of ER cisternae, ER/oxidative stress along with increased levels of inflammatory markers were observed in the pancreas of chronic EtOH-fed groups of ADH- versus ADH+ deer mice. Furthermore, chronic plus binge EtOH and FAEEs exposure elevated BAC, enhanced ER/oxidative stress, and exacerbated chronic EtOH-induced pancreatic injury in ADH- deer mice suggesting a role of increased body burden of EtOH and its metabolism under reduced hepatic ADH in initiation and progression of ACP.NEW & NOTEWORTHY We established a chronic EtOH feeding model of hepatic alcohol dehydrogenase-deficient (ADH-) deer mice, which mimics several fibroinflammatory features of human alcoholic chronic pancreatitis (ACP). The fibroinflammatory and morphological features exacerbated by chronic plus binge EtOH and FAEEs exposure provide a strong case for metabolic basis of ACP. Most importantly, several pathological and molecular targets identified in this study provide a much broader understanding of the mechanism and avenues to develop therapeutics for ACP.


Assuntos
Álcool Desidrogenase , Pancreatite Alcoólica , Álcool Desidrogenase/metabolismo , Animais , Concentração Alcoólica no Sangue , Ésteres , Etanol , Ácidos Graxos/metabolismo , Peromyscus/metabolismo
9.
Chem Rev ; 122(6): 5842-5976, 2022 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-35073048

RESUMO

Benefiting from the impressive increase in fundamental knowledge, the last 20 years have shown a continuous burst of new ideas and consequently a plethora of new catalytic methods for enantioselective radical reactions. This review aims to provide a complete survey of progress achieved over this latter period. The first part of this review focuses on the use of chiral organocatalysts, and these include catalysts covalently linked to the substrate and those that interact with the substrate by weaker interactions like hydrogen bonds. The second part of the review is devoted to transition-metal redox catalysis which is organized according to increasing atomic number for the first-row transition metals (Ti, Cr, Fe, Mn, Co, Ni, Cu). Bioinspired manganese- and iron-mediated hydroxylations and oxidations are also discussed. A specific section is dedicated to the reactivity of Ru, Rh, and Ir complexes as Lewis acids with a special focus on complexes chiral at metal. Absorption of photons result in different events such as energy transfer, single-electron transfer, and hydrogen-atom transfer facilitating the formation of radicals. Organocatalysis has been successfully combined with photocatalysts, a reactivity which has opened new pathways enlarging the number of radical precursors available. The merger of photocatalysis with organo- or metalla-photocatalysis has brought novelty and allowed for the discovery of a large number of original transformations. The use of enzyme-catalyzed reactions involving radical intermediates which also largely benefit from visible-light irradiation are included in the review. This review provides a comprehensive inventory of progress in enantioselective radical reactions with a goal of detailing the reaction mechanisms involved in these transformations such that any nonspecialist could find their own creativity to invent yet unknown applications.


Assuntos
Hidrogênio , Ácidos de Lewis , Catálise , Hidrogênio/química , Oxirredução , Estereoisomerismo
10.
J Med Chem ; 64(21): 15593-15607, 2021 11 11.
Artigo em Inglês | MEDLINE | ID: mdl-34695351

RESUMO

Snyder Robinson Syndrome (SRS) is a rare disease associated with a defective spermine synthase gene and low intracellular spermine levels. In this study, a spermine replacement therapy was developed using a spermine prodrug that enters cells via the polyamine transport system. The prodrug was comprised of three components: a redox-sensitive quinone "trigger", a "trimethyl lock (TML)" aryl "release mechanism", and spermine. The presence of spermine in the design facilitated uptake by the polyamine transport system. The quinone-TML motifs provided a redox-sensitive agent, which upon intracellular reduction generated a hydroquinone, which underwent intramolecular cyclization to release free spermine and a lactone byproduct. Rewardingly, most SRS fibroblasts treated with the prodrug revealed a significant increase in intracellular spermine. Administering the spermine prodrug through feeding in a Drosophila model of SRS showed significant beneficial effects. In summary, a spermine prodrug is developed and provides a lead compound for future spermine replacement therapy experiments.


Assuntos
Desenvolvimento de Medicamentos , Deficiência Intelectual Ligada ao Cromossomo X/tratamento farmacológico , Pró-Fármacos/uso terapêutico , Espermina/uso terapêutico , Animais , Relação Dose-Resposta a Droga , Drosophila , Feminino , Masculino , Estrutura Molecular , Oxirredução , Pró-Fármacos/química , Pró-Fármacos/metabolismo , Espermina/química , Espermina/metabolismo , Relação Estrutura-Atividade
11.
Indian Dermatol Online J ; 12(1): 90-96, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33768028

RESUMO

BACKGROUND: Confluent and reticulate papillomatosis (CRP) is an uncommon benign, acquired keratinization disorder. Studies on this disorder are lacking except for a few case reports and there is a paucity of Indian literature on the condition. OBJECTIVES/METHODS: To study and describe the various morphological patterns and histopathological findings, as well as assess the response to treatment of 30 patients diagnosed with CRP. RESULTS: Thirtypatients with a diagnosis of confluent and reticulate papillomatosis were included in the study. The male to female ratio was 1:1.5. Mean age at onset of skin eruptions was 27.3 years and mean duration of skin eruptions was 8.2 months. Most of the patients (60%) were asymptomatic. The majority (66.7%) had lesions distributed over upper trunk. Two-thirds of patients had typical brown macules in confluent and reticulate pattern. KOH mount was done in 24 cases and was positive in three cases (12.5%) for yeast-like hyphae. Biopsy demonstrated variable degrees of hyperkeratosis, papillomatosis, and moderate acanthosis. Thirteen out of eighteenpatients on minocycline showed complete clearance within 3 weeks andthreepatients had more than 50% improvement at the end of 3 weeks. Doxycycline showed satisfactory response but results were less satisfactory with azithromycin. CONCLUSION: CRP is an uncommon condition. There is a paucity of large studies in Indian literature. The present study highlightssuch a large cohort of cases. Prevalence of CRP was more in female in contrast to western studies. Association of CRP with hyperthyroidism was described in many studies but the present study highlights the association with hypothyroidism. Morphological variants like shiny atrophic lesions, verrucous lesions, and involvement of atypical sites like forearm have been described. Role of minocycline in the management of chronic and recurrent cases has been reinforced.

12.
Alcohol Clin Exp Res ; 45(5): 961-978, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33690904

RESUMO

BACKGROUND: Alcoholic chronic pancreatitis (ACP) is a serious inflammatory disorder of the exocrine pancreatic gland. A previous study from this laboratory showed that ethanol (EtOH) causes cytotoxicity, dysregulates AMPKα and ER/oxidative stress signaling, and induces inflammatory responses in primary human pancreatic acinar cells (hPACs). Here we examined the differential cytotoxicity of EtOH and its oxidative (acetaldehyde) and nonoxidative (fatty acid ethyl esters; FAEEs) metabolites in hPACs was examined to understand the metabolic basis and mechanism of ACP. METHODS: We evaluated concentration-dependent cytotoxicity, AMPKα inactivation, ER/oxidative stress, and inflammatory responses in hPACs by incubating them for 6 h with EtOH, acetaldehyde, or FAEEs at clinically relevant concentrations reported in alcoholic subjects using conventional methods. Cellular bioenergetics (mitochondrial stress and a real-time ATP production rate) were determined using Seahorse XFp Extracellular Flux Analyzer in AR42J cells treated with acetaldehyde or FAEEs. RESULTS: We observed concentration-dependent increases in LDH release, inactivation of AMPKα along with upregulation of ACC1 and FAS (key lipogenic proteins), downregulation of p-LKB1 (an oxidative stress-sensitive upstream kinase regulating AMPKα) and CPT1A (involved in ß-oxidation of fatty acids) in hPACs treated with EtOH, acetaldehyde, or FAEEs. Concentration-dependent increases in oxidative stress and ER stress as measured by GRP78, unspliced XBP1, p-eIF2α, and CHOP along with activation of p-JNK1/2, p-ERK1/2, and p-P38MAPK were present in cells treated with EtOH, acetaldehyde, or FAEEs, respectively. Furthermore, a significant decrease was observed in the total ATP production rate with subsequent mitochondrial stress in AR42J cells treated with acetaldehyde and FAEEs. CONCLUSIONS: EtOH and its metabolites, acetaldehyde and FAEEs, caused cytotoxicity, ER/oxidative and mitochondrial stress, and dysregulated AMPKα signaling, suggesting a key role of EtOH metabolism in the etiopathogenesis of ACP. Because oxidative EtOH metabolism is negligible in the exocrine pancreas, the pathogenesis of ACP could be attributable to the formation of FAEEs and related pancreatic acinar cell injury.


Assuntos
Células Acinares/efeitos dos fármacos , Depressores do Sistema Nervoso Central/farmacologia , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Etanol/farmacologia , Mitocôndrias/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Pâncreas/citologia , Quinases Proteína-Quinases Ativadas por AMP/efeitos dos fármacos , Quinases Proteína-Quinases Ativadas por AMP/metabolismo , Proteínas Quinases Ativadas por AMP/efeitos dos fármacos , Proteínas Quinases Ativadas por AMP/metabolismo , Acetaldeído/farmacologia , Acetil-CoA Carboxilase/efeitos dos fármacos , Acetil-CoA Carboxilase/metabolismo , Células Acinares/metabolismo , Carnitina O-Palmitoiltransferase/efeitos dos fármacos , Carnitina O-Palmitoiltransferase/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Ésteres/farmacologia , Humanos , Mitocôndrias/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/efeitos dos fármacos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/efeitos dos fármacos , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Proteína Quinase 8 Ativada por Mitógeno/efeitos dos fármacos , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , Proteína Quinase 9 Ativada por Mitógeno/efeitos dos fármacos , Proteína Quinase 9 Ativada por Mitógeno/metabolismo
13.
Bioorg Med Chem Lett ; 37: 127842, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33556575

RESUMO

A series of novel indolyl-α-keto-1,3,4-oxadiazole derivatives have been synthesized by employing molecular iodine-mediated oxidative cyclization of acylhydrazones. In vitro anti cell proliferation activity of these derivatives against various cancer cells lines such as human lymphoblast (U937), leukemia (Jurkat & SB) and human breast (BT474) was investigated. Among the synthesized indolyl-α-keto-1,3,4-oxadiazoles 19a-p, only one compound (19e) exhibited significant antiproliferative activity against a panel of cell lines. The compound 19e with 3,4,5-trimethoxyphenyl motif, endowed strong cytotoxicity against U937, Jurkat, BT474 and SB cancer cells with IC50 values of 7.1, 3.1, 4.1, and 0.8 µM, respectively. Molecular docking studies suggested a potential binding mode for 19e in the colchicine binding site of tubulin. When tested for in vitro tubulin polymerizaton, 19e inhibited tubulin polymezations (IC50 = 10.66 µM) and induced apoptosis through caspase 3/7 activation. Further, the derivative 19e did not cause necrosis when measured using lactate dehydrogenase assay.


Assuntos
Antineoplásicos/farmacologia , Oxidiazóis/farmacologia , Moduladores de Tubulina/farmacologia , Tubulina (Proteína)/metabolismo , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Estrutura Molecular , Oxidiazóis/síntese química , Oxidiazóis/química , Polimerização/efeitos dos fármacos , Relação Estrutura-Atividade , Moduladores de Tubulina/síntese química , Moduladores de Tubulina/química
14.
Angew Chem Int Ed Engl ; 60(2): 774-778, 2021 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-33090615

RESUMO

The factors responsible for the kinetic resolution of alcohols by chiral pyridine derivatives have been elucidated by measurements of relative rates for a set of substrates with systematically growing aromatic side chains using accurate competitive linear regression analysis. Increasing the side chain size from phenyl to pyrenyl results in a rate acceleration of more than 40 for the major enantiomer. Based on this observation a new catalyst with increased steric bulk has been designed that gives enantioselectivity values of up to s=250. Extensive conformational analysis of the relevant transition states indicates that alcohol attack to the more crowded side of the acyl-catalyst intermediate is favoured due to stabilizing CH-π-stacking interactions. Experimental and theoretical results imply that enantioselectivity enhancements result from accelerating the transformation of the major enantiomer through attractive non-covalent interactions (NCIs) rather than retarding the transformation of the minor isomer through repulsive steric forces.

15.
Nat Commun ; 11(1): 6017, 2020 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-33243991

RESUMO

The lower Brahmaputra River in Bangladesh and Northeast India often floods during the monsoon season, with catastrophic consequences for people throughout the region. While most climate models predict an intensified monsoon and increase in flood risk with warming, robust baseline estimates of natural climate variability in the basin are limited by the short observational record. Here we use a new seven-century (1309-2004 C.E) tree-ring reconstruction of monsoon season Brahmaputra discharge to demonstrate that the early instrumental period (1956-1986 C.E.) ranks amongst the driest of the past seven centuries (13th percentile). Further, flood hazard inferred from the recurrence frequency of high discharge years is severely underestimated by 24-38% in the instrumental record compared to previous centuries and climate model projections. A focus on only recent observations will therefore be insufficient to accurately characterise flood hazard risk in the region, both in the context of natural variability and climate change.

16.
Biochem Pharmacol ; 180: 114174, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32717227

RESUMO

Primary toxicity targets of alcohol and its metabolites in the pancreas are cellular energetics and endoplasmic reticulum (ER). Therefore, the role of AMP-Activated Protein Kinase (AMPKα) in amelioration of ethanol (EtOH)-induced pancreatic acinar cell injury including ER/oxidative stress, inflammatory responses, the formation of fatty acid ethyl esters (FAEEs) and mitochondrial bioenergetics were determined in human pancreatic acinar cells (hPACs) and AR42J cells incubated with/without AMPKα activator [5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)]. EtOH treated hPACs showed concentration and time-dependent increases for FAEEs and inactivation of AMPKα, along with the upregulation of ACC1 and FAS (key lipogenic proteins) and downregulation of CPT1A (involved ß-oxidation of fatty acids). These cells also showed significant ER stress as evidenced by the increased expression for GRP78, IRE1α, and PERK/CHOP arm of unfolded protein response promoting apoptosis and activating p-JNK1/2 and p-ERK1/2 with increased secretion of cytokines. AR42J cells treated with EtOH showed increased oxidative stress, impaired mitochondrial biogenesis, and decreased ATP production rate. However, AMPKα activation by AICAR attenuated EtOH-induced ER/oxidative stress, lipogenesis, and inflammatory responses as well as the formation of FAEEs and restored mitochondrial function in hPACs as well as AR42J cells. Therefore, it is likely that EtOH-induced inactivation of AMPKα plays a crucial role in acinar cell injury leading to pancreatitis. Findings from this study also suggest that EtOH-induced inactivation of AMPKα is closely related to ER/oxidative stress and synthesis of FAEEs, as activation of AMPKα by AICAR attenuates formation of FAEEs, ER/oxidative stress and lipogenesis, and improves inflammatory responses and mitochondrial bioenergetics.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Células Acinares/enzimologia , Retículo Endoplasmático/enzimologia , Etanol/farmacologia , Estresse Oxidativo/fisiologia , Pâncreas/enzimologia , Células Acinares/efeitos dos fármacos , Aciltransferases/metabolismo , Adulto , Células Cultivadas , Relação Dose-Resposta a Droga , Retículo Endoplasmático/efeitos dos fármacos , Chaperona BiP do Retículo Endoplasmático , Ácidos Graxos não Esterificados/metabolismo , Feminino , Humanos , Lipídeos , Masculino , Pessoa de Meia-Idade , Estresse Oxidativo/efeitos dos fármacos , Pâncreas/citologia , Pâncreas/efeitos dos fármacos , Fenótipo
17.
Biochim Biophys Acta Mol Cell Res ; 1867(10): 118762, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32502617

RESUMO

BACKGROUND: Microtubules, the key components of the eukaryotic cytoskeleton and mitotic spindle, are one of the most sought-after targets for cancer chemotherapy, especially due to their indispensible role in mitosis. Cervical cancer is a prevalent malignancy among women of developing countries including India. In spite of the remarkable therapeutic advancement, the non-specificity of chemotherapeutic drugs adversely affect the patients' survival and well-being, thus, necessitating the quest for novel indole-based anti-microtubule agent against cervical cancer, with high degree of potency and selectivity. METHODS: For in vitro studies, we used MTT assay, confocal microscopy, fluorescence microscopy, flow cytometry and Western blot analysis. Study in cell free system was accomplished by spectrophotometry, fluorescence spectroscopy and TEM and computational analysis was done by AutodockTools 1.5.6. RESULTS: NMK-BH2 exhibited significant and selective anti-proliferative activity against cervical cancer HeLa cells (IC50 = 1.5 µM) over normal cells. It perturbed the cytoskeletal and spindle microtubules of HeLa cells leading to mitotic block and cell death by apoptosis and autophagy. Furthermore, NMK-BH2 targeted the tubulin-microtubule system through fast and strong binding to the αß-tubulin heterodimers at colchicine-site. CONCLUSION: This study identifies and characterises NMK-BH2 as a novel anti-microtubule agent and provides insights into its key anti-cancer mechanism through two different cell death pathways: apoptosis and autophagy, which are mutually independent. GENERAL SIGNIFICANCE: It navigates the potential of the novel bis (indolyl)-hydrazide-hydrazone, NMK-BH2, to serve as lead for development of new generation microtubule-disrupting chemotherapeutic with improved efficacy and remarkable selectivity towards better cure of cervical cancer.


Assuntos
Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Colchicina/metabolismo , Hidrazonas/farmacologia , Microtúbulos/metabolismo , Polimerização , Tubulina (Proteína)/metabolismo , Neoplasias do Colo do Útero/patologia , Animais , Sítios de Ligação , Biomarcadores Tumorais/metabolismo , Proliferação de Células/efeitos dos fármacos , Sistema Livre de Células , Simulação por Computador , Feminino , Cabras , Células HeLa , Humanos , Hidrazonas/química , Cinética , Ligantes , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Microtúbulos/efeitos dos fármacos , Microtúbulos/ultraestrutura , Mitose/efeitos dos fármacos , Espectrometria de Fluorescência , Fuso Acromático/efeitos dos fármacos , Fuso Acromático/metabolismo , Tubulina (Proteína)/química
18.
Molecules ; 25(12)2020 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-32560446

RESUMO

Biocomposites can be both environmentally and economically beneficial: during their life cycle they generally use and generate less petroleum-based carbon, and when produced from the byproduct of another industry or recycled back to the manufacturing process, they will bring additional economic benefits through contributing to a circular economy. Here we investigate and compare the environmental performance of a biocomposite composed of a soybean oil-based resin (epoxidized sucrose soyate) and flax-based reinforcement using life cycle assessment (LCA) methodology. We evaluate the main environmental impacts that are generated during the production of the bio-based resin used in the biocomposite, as well as the biocomposite itself. We compare the life cycle impacts of the proposed biocomposite to a functionally similar petroleum-based resin and flax fiber reinforced composite, to identify tradeoffs between the environmental performance of the two products. We demonstrate that the bio-based resin (epoxidized sucrose soyate) compared to a conventional (bisphenol A-based) resin shows lower negative environmental impacts in most studied categories. When comparing the biocomposite to the fossil fuel derived composite, it is demonstrated that using epoxidized sucrose soyate versus a bisphenol A (BPA)-based epoxy resin can improve the environmental performance of the composite in most categories except eutrophication and ozone layer depletion. For future designs, considering an alternative cross-linker to facilitate the bond between the bio-based resin and the flax fiber, may help improve the overall environmental performance of the biocomposite. An uncertainty analysis was also performed to evaluate the effect of variation in LCA model inputs on the environmental results for both the biocomposite and composite. The findings show a better overall carbon footprint for the biocomposite compared to the BPA-based composite at almost all times, demonstrating a good potential for marketability especially in the presence of incentives or regulations that address reducing the carbon intensity of products. This analysis allowed us to pinpoint hotspots in the biocomposite's supply chain and recommend future modifications to improve the product's sustainability.


Assuntos
Resinas Epóxi/química , Resinas Epóxi/síntese química , Sacarose/química , Meio Ambiente
19.
Biomolecules ; 10(5)2020 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-32349207

RESUMO

Chronic excessive alcohol use is a well-recognized risk factor for pancreatic dysfunction and pancreatitis development. Evidence from in vivo and in vitro studies indicates that the detrimental effects of alcohol on the pancreas are from the direct toxic effects of metabolites and byproducts of ethanol metabolism such as reactive oxygen species. Pancreatic dysfunction and pancreatitis development are now increasingly thought to be multifactorial conditions, where alcohol, genetics, lifestyle, and infectious agents may determine the initiation and course of the disease. In this review, we first highlight the role of nonoxidative ethanol metabolism in the generation and accumulation of fatty acid ethyl esters (FAEEs) that cause multi-organellar dysfunction in the pancreas which ultimately leads to pancreatitis development. Further, we discuss how alcohol-mediated altered autophagy leads to the development of pancreatitis. We also provide insights into how alcohol interactions with other co-morbidities such as smoking or viral infections may negatively affect exocrine and endocrine pancreatic function. Finally, we present potential strategies to ameliorate organellar dysfunction which could attenuate pancreatic dysfunction and pancreatitis severity.


Assuntos
Alcoolismo/complicações , Pancreatite/metabolismo , Animais , Autofagia , Humanos , Secreção de Insulina , Pancreatite/etiologia , Resposta a Proteínas não Dobradas
20.
Pharmacol Res Perspect ; 8(2): e00586, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32342655

RESUMO

The prognosis for metastatic castration-resistant prostate cancer is unfavorable, and although Poly(ADP)-ribose polymerase-1 (PARP-1) inhibitors have shown efficacy in the treatment of androgen-receptor dependent malignancies, the limited number of options present obstacles for patients that are not responsive to these treatments. Here we utilize an integrated screening strategy that combines cellular screening assays, informatics, in silico computational approaches, and dose-response testing for reducing a compound library of confirmed PARP-1 inhibitors. Six hundred and sixty-four validated PARP-1 inhibitors were reduced to 9 small molecules with favorable physicochemical/ADME properties, unique chemical fingerprints, high dissimilarity to existing drugs, few off-target effects, and dose-responsivity in the 1 µmol/L - 20 µmol/L range. The top 9 unique molecules identified by our integrated screening strategy will be selected for further preclinical development including cytotoxicity testing, effects on mitosis, structure-activity relationship, physicochemical/ADME studies, and in vivo testing.


Assuntos
Poli(ADP-Ribose) Polimerase-1/antagonistas & inibidores , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Simulação por Computador , Humanos , Masculino , Células PC-3
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