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1.
Proanthocyanidins with a Low Degree of Polymerization are Good Inhibitors of Digestive Enzymes Because of their Ability to form Specific Interactions: A Hypothesis.
Vazquez-Flores, AA, Martinez-Gonzalez, AI, Alvarez-Parrilla, E, Díaz-Sánchez, ÁG, de la Rosa, LA, González-Aguilar, GA, Aguilar, CN
Journal of food science. 2018;(12):2895-2902
Abstract
Inhibition of target digestive enzymes is an accepted strategy to prevent diseases such as obesity and diabetes. Proanthocyanidins (PACs) are known for their ability to bind, inhibit, and precipitate enzymes, which makes them potential bioDrugs with an impact on the digestive process. PAC degree of polymerization (DP) is one of the structural features responsible for their differential inhibitory potency but the explanation for this phenomenon is still unclear. Pecan nut (Carya illinoinensis L.) kernels and nutshells are rich in oligomeric and polymeric PACs. We have used thiolysis and HPLC analyses to propose four theoretical model structures of PACs representative of four semipurified fractions obtained from pecan kernel and shell, which showed different inhibitory activity against intestinal lipases, amylases, and proteases. The noncovalent interactions between PACs and digestive enzymes were predicted by in silico methods through computational software. These observations are discussed in view of current literature on the biological effects of PACs with different DPs and allowed us to propose the hypothesis that "small oligomeric PACs could be digestive enzyme inhibitors due to their capacity to enter and bind the enzymes' specific cavities better than polymers and oligomers of medium and high molecular weight."
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2.
Punicalagin, an active pomegranate component, is a new inhibitor of PDIA3 reductase activity.
Giamogante, F, Marrocco, I, Cervoni, L, Eufemi, M, Chichiarelli, S, Altieri, F
Biochimie. 2018;:122-129
Abstract
BACKGROUND Polyphenolic compounds isolated from pomegranate fruit possess several pharmacological activities including anti-inflammatory, hepatoprotective, antigenotoxic and anticoagulant activities. The present work focuses the attention on PDIA3 interaction with punicalagin and ellagic acid, the most predominant components of pomegranate extracts. PDIA3, a member of the protein disulfide isomerase family involved in several cellular functions, is associated with different human diseases and it has the potential to be a pharmacological target. METHODS The interaction of polyphenols with PDIA3 purified protein was explored by fluorescence quenching and calorimetric techniques and their effect on PDIA3 activity was investigated. RESULTS A higher affinity was observed for punicalagin which also strongly affects PDIA3 reductase activity in vitro as a non-competitive inhibitor. Isothermal titration calorimetry confirmed the high affinity of punicalagin for PDIA3. Considering the PDIA3 involvement in oxidative cellular stress response observed in neuroblastoma cells after treatment with hydrogen peroxide, a comparative study was conducted to evaluate the effect of punicalagin on wild type and PDIA3-silenced cells. Punicalagin increases the cell sensitivity to hydrogen peroxide in neuroblastoma cells, but this effect is drastically reduced in PDIA3-silenced cells treated in the same experimental conditions. CONCLUSIONS Punicalagin binds PDIA3 and inhibits its redox activity. Comparative experiments conducted on unsilenced and PDIA3-silenced neuroblastoma cells suggest the potential of punicalagin to modulate PDIA3 reductase activity also in a biological model. GENERAL SIGNIFICANCE Punicalagin can be used as a new PDIA3 inhibitor and this can provide information on the molecular mechanisms underlying the biological activities of PDIA3 and punicalagin.
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3.
Comparing the Effects of Atorvastatin With Sodium Valproate (Divalproex) on Frequency and Intensity of Frequent Migraine Headaches: A Double-blind Randomized Controlled Study.
Hesami, O, Sistanizad, M, Asadollahzade, E, Johari, MS, Beladi-Moghadam, N, Mazhabdar-Ghashghai, H
Clinical neuropharmacology. 2018;(3):94-97
Abstract
OBJECTIVES To evaluate the prophylactic effects of atorvastatin on frequency, intensity, and duration of migraine attacks compared with sodium valproate. METHODS In this randomized, double-blind, single-center controlled trial, patients with 6 to 15 migraine attacks per month, which were candidates of preventive treatment, were recruited. The patients were randomly allocated into 2 groups. The first group (A) received atorvastatin 40 mg daily, and the second group (B) received sodium valproate 500 mg daily. All patients were visited each month and followed up for 3 months. The characteristics of migraine headaches including frequency, intensity, and duration of attacks were recorded, as well as the number of analgesics taken per each attack and probable adverse effects. RESULTS From 100 patients enrolled in the study, 18 cases were excluded owing to adverse effects (2 cases) or lost to follow-up (16 cases). From 82 patients who completed the trial, 46 and 36 were in group A (atorvastatin) and group B (sodium valproate), respectively. Mean age of the patients was not significantly different in the 2 arms of the study (33.56 ± 8.51 in group A and 33.25 ± 9.91 years in group B, P = 0.877). Number, duration, and intensity of attacks and number of analgesics taken during attacks decreased significantly in both groups in monthly follow-ups. However, there was no statistically significant difference between 2 arms of the study in terms of attenuation in the characteristics of migraine attacks. On the other hand, patients in group A suffered fewer adverse effects compared with group B. CONCLUSIONS This study indicates that atorvastatin could be an alternative for sodium valproate in migraine prophylaxis with comparable efficacy and fewer adverse effects. Multicenter studies with larger sample size are recommended.
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4.
Identification of putative drug targets and annotation of unknown proteins in Tropheryma whipplei.
Palanisamy, N
Computational biology and chemistry. 2018;:130-138
Abstract
Tropheryma whipplei (T. whipplei) is the causative agent of Whipple's disease and blood culture-negative endocarditis. Due to the variability of symptoms, the disease is often poorly diagnosed. Treatment for this bacterial infection is often lengthy, and improper uptake of antibiotics has resulted in relapses in many patients. In the present study, using available bioinformatic tools and databases such as the Cluster Database at High Identity with Tolerance (CD-HIT), the Basic Local Alignment Search Tool for proteins (BLASTp), the Database of Essential Genes (DEG), and the DrugBank database, 13 putative drug targets were identified in T. whipplei by subtractive genome analysis that could be targeted with currently available drugs (experimental or approved). Further, a 3D model was generated for one of these putative drug targets, the T. whipplei DNA ligase, and in silico docking was performed with pyridochromanone and adenosine-derived inhibitors using the AutoDock Vina. Additionally, many of the T. whipplei protein sequences in the National Center for Biotechnology Information (NCBI) protein database were unknown/uncurated. Using available web servers e.g. the KEGG Automatic Annotation Server (KAAS), the BLASTp, the Conserved Domain Architecture Retrieval Tool (CDAT) and the Protein families (Pfam), the function/remote/domain homology for nearly 80% of these uncurated protein sequences were annotated. The data obtained in the present study will aid physicians and researchers alike in curbing this bacterial infection.
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5.
Inhibition of protein disulfide isomerase induces differentiation of acute myeloid leukemia cells.
Chlebowska-Tuz, J, Sokolowska, O, Gaj, P, Lazniewski, M, Firczuk, M, Borowiec, K, Sas-Nowosielska, H, Bajor, M, Malinowska, A, Muchowicz, A, et al
Haematologica. 2018;(11):1843-1852
Abstract
A cute myeloid leukemia is a malignant disease of immature myeloid cells. Despite significant therapeutic effects of differentiation-inducing agents in some acute myeloid leukemia subtypes, the disease remains incurable in a large fraction of patients. Here we show that SK053, a thioredoxin inhibitor, induces differentiation and cell death of acute myeloid leukemia cells. Considering that thioredoxin knock-down with short hairpin RNA failed to exert antiproliferative effects in one of the acute myeloid leukemia cell lines, we used a biotin affinity probe-labeling approach to identify potential molecular targets for the effects of SK053. Mass spectrometry of proteins precipitated from acute myeloid leukemia cells incubated with biotinylated SK053 used as a bait revealed protein disulfide isomerase as a potential binding partner for the compound. Biochemical, enzymatic and functional assays using fluorescence lifetime imaging confirmed that SK053 binds to and inhibits the activity of protein disulfide isomerase. Protein disulfide isomerase knockdown with short hairpin RNA was associated with inhibition of cell growth, increased CCAAT enhancer-binding protein α levels, and induction of differentiation of HL-60 cells. Molecular dynamics simulation followed by the covalent docking indicated that SK053 binds to the fourth thioredoxin-like domain of protein disulfide isomerase. Differentiation of myeloid precursor cells requires the activity of CCAAT enhancer-binding protein α, the function of which is impaired in acute myeloid leukemia cells through various mechanisms, including translational block by protein disulfide isomerase. SK053 increased the levels of CCAAT enhancer-binding protein α and upregulated mRNA levels for differentiation-associated genes. Finally, SK053 decreased the survival of blasts and increased the percentage of cells expressing the maturation-associated CD11b marker in primary cells isolated from bone marrow or peripheral blood of patients with acute myeloid leukemia. Collectively, these results provide a proof-of-concept that protein disulfide isomerase inhibition has potential as a therapeutic strategy for the treatment of acute myeloid leukemia and for the development of small-molecule inhibitors of protein disulfide isomerase.
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6.
The effect of sodium nitrite infusion on renal function, brachial and central blood pressure during enzyme inhibition by allopurinol, enalapril or acetazolamide in healthy subjects: a randomized, double-blinded, placebo-controlled, crossover study.
Rosenbaek, JB, Pedersen, EB, Bech, JN
BMC nephrology. 2018;(1):244
Abstract
BACKGROUND Sodium nitrite (NaNO2) causes vasodilation, presumably by enzymatic conversion to nitric oxide (NO). Several enzymes with nitrite reducing capabilities have been discovered in vitro, but their relative importance in vivo has not been investigated. We aimed to examine the effects of NaNO2 on blood pressure, fractional sodium excretion (FENa), free water clearance (CH2O) and GFR, after pre-inhibition of xanthine oxidase, carbonic anhydrase, and angiotensin-converting enzyme. The latter as an approach to upregulate endothelial NO synthase activity. METHODS In a double-blinded, placebo-controlled, crossover study, 16 healthy subjects were treated, in a randomized order, with placebo, allopurinol 150 mg twice daily (TD), enalapril 5 mg TD, or acetazolamide 250 mg TD. After 4 days of treatment and standardized diet, the subjects were examined at our lab. During intravenous infusion of 240 μg NaNO2/kg/hour for 2 h, we measured changes in brachial and central blood pressure (BP), plasma cyclic guanosine monophosphate (P-cGMP), plasma and urine osmolality, GFR by 51Cr-EDTA clearance, FENa and urinary excretion rate of cGMP (U-cGMP) and nitrite and nitrate (U-NOx). Subjects were supine and orally water-loaded throughout the examination day. RESULTS Irrespective of pretreatment, we observed an increase in FENa, heart rate, U-NOx, and a decrease in CH2O and brachial systolic BP during NaNO2 infusion. P-cGMP and U-cGMP did not change during infusion. We observed a consistent trend towards a reduction in central systolic BP, which was only significant after allopurinol. CONCLUSION This study showed a robust BP lowering, natriuretic and anti-aquaretic effect of intravenous NaNO2 regardless of preceding enzyme inhibition. None of the three enzyme inhibitors used convincingly modified the pharmacological effects of NaNO2. The steady cGMP indicates little or no conversion of nitrite to NO. Thus the effect of NaNO2 may not be mediated by NO generation. TRIAL REGISTRATION EU Clinical Trials Register, 2013-003404-39 . Registered December 3 2013.
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7.
Epigenetic drug discovery: a success story for cofactor interference.
Ganesan, A
Philosophical transactions of the Royal Society of London. Series B, Biological sciences. 2018;(1748)
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Abstract
Within the past two decades, seven epigenetic drugs have received regulatory approval and numerous other candidates are currently in clinical trials. Among the epigenetic targets are the writer and eraser enzymes that are, respectively, responsible for the reversible introduction and removal of structural modifications in the nucleosome. This review discusses the progress achieved in the design and development of inhibitors against the key writer and eraser pairs: DNA methyltransferases and Tet demethylases; lysine/arginine methyltransferases and lysine demethylases; and histone acetyltransferases and histone deacetylases. A common theme for the successful inhibition of these enzymes in a potent and selective manner is the targeting of the cofactors present in the active site, namely zinc and iron cations, S-adenosylmethione, nicotinamide adenine dinucleotide, flavin adenine dinucleotide and acetyl Coenzyme A.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.
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8.
Protein methyltransferase inhibitors as precision cancer therapeutics: a decade of discovery.
Copeland, RA
Philosophical transactions of the Royal Society of London. Series B, Biological sciences. 2018;(1748)
Abstract
The protein methyltransferases (PMTs) represent a large class of enzymes that catalyse the methylation of side chain nitrogen atoms of the amino acids lysine or arginine at specific locations along the primary sequence of target proteins. These enzymes play a key role in the spatio-temporal control of gene transcription by performing site-specific methylation of lysine or arginine residues within the histone proteins of chromatin, thus effecting chromatin conformational changes that activate or repress gene transcription. Over the past decade, it has become clear that the dysregulated activity of some PMTs plays an oncogenic role in a number of human cancers. Here we review research of the past decade that has identified specific PMTs as oncogenic drivers of cancers and progress toward the discovery and development of selective, small molecule inhibitors of these enzymes as precision cancer therapeutics.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.
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Efficacy of a novel inhibitor of vascular adhesion protein-1 in reducing albuminuria in patients with diabetic kidney disease (ALBUM): a randomised, placebo-controlled, phase 2 trial.
de Zeeuw, D, Renfurm, RW, Bakris, G, Rossing, P, Perkovic, V, Hou, FF, Nangaku, M, Sharma, K, Heerspink, HJL, Garcia-Hernandez, A, et al
The lancet. Diabetes & endocrinology. 2018;(12):925-933
Abstract
BACKGROUND Many patients with diabetic kidney disease have residual albuminuria and are at risk of disease progression. The ALBUM trial investigated the efficacy of a novel, orally active inhibitor of vascular adhesion protein-1, ASP8232, compared with placebo for reducing albuminuria in individuals with type 2 diabetes and chronic kidney disease. METHODS In this randomised, double-blind, placebo-controlled phase 2 trial, we randomly assigned individuals (aged 18-85 years) from 64 clinical sites in nine European countries to receive ASP8232 40 mg or placebo orally once daily for 12 weeks using a web-based randomisation schedule (block size 4), stratified by country. Eligible patients had a urinary albumin-to-creatinine ratio (UACR) of 200-3000 mg/g, an estimated glomerular filtration rate of at least 25 mL/min per 1·73 m2 but lower than 75 mL/min per 1·73 m2, HbA1c less than 11·0% (97 mmol/mol), and stable treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers and antidiabetic medication for 3 months or more. The primary endpoint was mean change from baseline to week 12 in log-transformed first morning void UACR, which was assessed in all patients who received at least one dose of study drug and had at least one post-baseline UACR measurement (full analysis set). Safety was assessed in all patients who received at least one dose of study drug. Participants and investigators were masked to treatment allocation. This trial is registered with ClinicalTrials.gov, number NCT02358096. FINDINGS 125 participants were randomly assigned to receive ASP8232 (n=64) or placebo (n=61), of whom 120 (60 in each group) were included in the full analysis set; all participants were assessed for safety endpoints. At 12 weeks, UACR decreased by 17·7% (95% CI 5·0 to 28·6) in the ASP8232 group and increased by 2·3% (-11·4 to 18·1) in the placebo group; the placebo-adjusted difference between groups was -19·5% (95% CI -34·0 to -1·8; p=0·033). 39 (61%) patients in the ASP8232 group and 34 (56%) patients in the placebo group had a treatment-emergent adverse event, of which 16 in the ASP8232 group and four in the placebo group were drug-related. The most frequently reported adverse events that were possibly drug-related in the ASP8232 group were renal impairment (five patients) and decreased eGFR (three patients); in the placebo group, no single drug-related treatment-emergent adverse event was reported by more than one participant. INTERPRETATION ASP8232 is effective in reducing albuminuria in patients with diabetic kidney disease and is safe and well tolerated. These findings warrant further research to ascertain the effect of ASP8232 on delaying progression of diabetic kidney disease. FUNDING Astellas.
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10.
Insight into the molecular mechanism of yeast acetyl-coenzyme A carboxylase mutants F510I, N485G, I69E, E477R, and K73R resistant to soraphen A.
Gao, J, Liang, L, Chen, Q, Zhang, L, Huang, T
Journal of computer-aided molecular design. 2018;(4):547-557
Abstract
Acetyl-coenzyme A carboxylases (ACCs) is the first committed enzyme of fatty acid synthesis pathway. The inhibition of ACC is thought to be beneficial not only for diseases related to metabolism, such as type-2 diabetes, but also for infectious disease like bacterial infection disease. Soraphen A, a potent allosteric inhibitor of BC domain of yeast ACC, exhibit lower binding affinities to several yeast ACC mutants and the corresponding drug resistance mechanisms are still unknown. We report here a theoretical study of binding of soraphen A to wild type and yeast ACC mutants (including F510I, N485G, I69E, E477R, and K73R) via molecular dynamic simulation and molecular mechanics/generalized Born surface area free energy calculations methods. The calculated binding free energies of soraphen A to yeast ACC mutants are weaker than to wild type, which is highly consistent with the experimental results. The mutant F510I weakens the binding affinity of soraphen A to yeast ACC mainly by decreasing the van der Waals contributions, while the weaker binding affinities of Soraphen A to other yeast ACC mutants including N485G, I69E, E477R, and K73R are largely attributed to the decreased net electrostatic (ΔEele + ΔGGB) interactions. Our simulation results could provide important insights for the development of more potent ACC inhibitors.