Antimicrobial activity of hydralazine against methicillin-resistant and methicillin-susceptible Staphylococcus aureus.

Background: Staphylococcus aureus is a human pathogen responsible for high mortality rates. The development of new antimicrobials is urgent. Materials & methods: The authors evaluated the activity of hydralazine along with its synergism with other drugs and action on biofilms. With regard to action mechanisms, the authors evaluated cell viability, DNA damage and molecular docking. Results: MIC and minimum bactericidal concentration values ranged from 128 to 2048 µg/ml. There was synergism with oxacillin (50%) and vancomycin (25%). Hydralazine reduced the viability of biofilms by 50%. After exposure to hydralazine 2× MIC, 58.78% of the cells were unviable, 62.07% were TUNEL positive and 27.03% presented damage in the comet assay (p < 0.05). Hydralazine showed affinity for DNA gyrase and TyrRS. Conclusion: Hydralazine is a potential antibacterial.

Staphylococcus aureus is a bacterium that can cause infection. Infections of S. aureus are becoming difficult to treat, but developing new drugs is a challenge. Repurposing them may be easier. This study looks at the possibility of using hydralazine, a type of medicine used to treat high blood pressure, against S. aureus. The authors found that hydralazine can kill S. aureus and can be used with other antibiotics, including oxacillin and vancomycin. Hydralazine interferes with important processes for the multiplication and survival of this bacterium. These results are preliminary but encouraging. Further studies are needed to confirm the use of hydralazine as a new treatment for S. aureus infections.

Antibacterial Potency of an Active Compound from Sansevieria trifasciata Prain: An Integrated In Vitro and In Silico Study.

Sansevieria trifasciata Prain holds great potential as a valuable asset in pharmaceutical development. In this study, our focus is to explore and assess the antibacterial activity of various components derived from this plant, including extracts, fractions, subfractions, and isolates, explicitly targeting two common bacteria: Escherichia coli and Streptococcus aureus. The isolated compound, identified as a derivative pyridone alkaloid (5-methyl-11-(2-oxopyridin-1(2H)-yl)undecaneperoxoicacid), demonstrates notable antibacterial effects. The extracts, fractions, subfractions, and isolates reveal significant bacterial growth reductions (p < 0.05). The minimum inhibitory concentration (MIC) values for Escherichia coli were 1.95 ppm, 3.9 ppm, 15.62 ppm, and 7.81 ppm, respectively, while the MIC values for Streptococcus aureus were 1.95 ppm, 1.95 ppm, 15.62 ppm, and 7.81 ppm, respectively. Computational analysis showed the isolates' interaction with key residues on the active site of ß-ketoacyl-ACP synthase from Escherichia coli and TyrRS from Streptococcus aureus. The findings indicate that the isolates exhibit a strong affinity for specific residues, including His333, Cys163, and Phe392 in ß-ketoacyl-ACP synthase, as well as Arg88, His117, Glu160, and Gln213 in TyrRS. Comparative energy calculations using MMPBSA demonstrate the isolates' favorable binding energy (-104,101 kJ/mol for ß-ketoacyl-ACP synthase and -81,060 kJ/mol for TyrRS) compared to ciprofloxacin. The elucidated antibacterial activity and molecular interactions of the isolates present valuable knowledge for future in vitro studies, facilitating the development of novel antibacterial agents targeting diverse bacterial strains.

Tackling Microbial Resistance with Isatin-Decorated Thiazole Derivatives: Design, Synthesis, and in vitro Evaluation of Antimicrobial and Antibiofilm Activity.

Introduction: Antibiotic resistance is a global threat that has been increasing recently, especially with antibiotic overuse and misuse. The search for new antibiotics is becoming more and more indispensable. Methods: Design and synthesis of isatin derivatives as surrogates of SB-239629, a bacterial tyrosine-tRNA synthetases (TyrRS) inhibitor. The newly synthesized compounds were screened for their antimicrobial and antibiofilm activities. Docking studies were used to investigate potential binding modes of these compounds with TyrRS. Results and Discussion: Newly synthesized isatin-decorated thiazole derivatives (7b, 7d, and 14b) have shown potent antimicrobial activities against E. coli, a representative of gram-negative bacteria. Also, 7f showed the best activity against Methicillin Resistant Staphylococcus aureus (MRSA). In addition, 7h and 11f were found to have antifungal activities against Candida albicans equivalent to that of the reference Nystatin. All the new isatin derivatives with antimicrobial activities were found to exhibit strong biofilm distortion effects at half their minimum inhibitory concentrations (MIC). Moreover, thiazole derivatives 11a-f showed promising biofilm formation inhibition. Finally, molecular docking studies were used to investigate possible binding modes of target compounds with S. aureus and E. coli TyrRS. Conclusion: The novel isatin-decorated thiazole derivatives show strong antimicrobial and antifungal activities with potential action on TyrRS.

Bioactivities and in silico study of Pergularia tomentosa L. phytochemicals as potent antimicrobial agents targeting type IIA topoisomerase, TyrRS, and Sap1 virulence proteins.

Pergularia tomentosa L. (P. tomentosa) has been largely used in Tunisian folk medicine as remedies against skin diseases, asthma, and bronchitis. The main objectives of this study were to identify phytochemical compounds that have antioxidant and antimicrobial properties from the stem, leaves, and fruit crude methanolic extracts of P. tomentosa, and to search for tyrosyl-tRNA synthetase (TyrRS), topoisomerase type IIA, and Candidapepsin-1 (SAP1) enzyme inhibitors through molecular docking study. Phytochemical quantification revealed that fruit and leaves extracts displayed the highest total flavonoids (582 mg QE/g Ex; 219 mg QE/g Ex) and tannins content (375 mg TAE/g Ex; 216 mg TAE/g Ex), also exhibiting significant scavenging activity to decrease free radicals for ABTS, DPPH, ß-carotene, and FRAP assay with IC50 values (> 1 mg/mL). Additionally, promising antimicrobial activities towards different organs have been observed against several bacteria and Candida strains. From the liquid chromatography-mass spectrometry (LC-MS) analysis, five polyphenolic compounds, namely digitoxigenin, digitonin glycoside and calactina in the leaves, kaempferol in the fruit, and calotropagenin in the stems, were identified. They were also analyzed for their drug likeliness, based on computational methods. Molecular docking study affirmed that the binding affinity of calactin and actodigin to the active site of TyrRS, topoisomerase type IIA, and SAP1 target virulence proteins was the highest among the examined dominant compounds. Therefore, this study indicated that P. tomentosa methanolic extracts displayed great potential to become a potent antimicrobial agent and might be a promising source for therapeutic and nutritional functions. These phytocompounds could be further promoted as a candidate for drug discovery and development.

Towards resolving the enigma of the dichotomy of resveratrol: cis- and trans-resveratrol have opposite effects on TyrRS-regulated PARP1 activation.

Unlike widely perceived, resveratrol (RSV) decreased the average lifespan and extended only the replicative lifespan in yeast. Similarly, although not widely discussed, RSV is also known to evoke neurite degeneration, kidney toxicity, atherosclerosis, premature senescence, and genotoxicity through yet unknown mechanisms. Nevertheless, in vivo animal models of diseases and human clinical trials demonstrate inconsistent protective and beneficial effects. Therefore, the mechanism of action of RSV that elicits beneficial effects remains an enigma. In a previously published work, we demonstrated structural similarities between RSV and tyrosine amino acid. RSV acts as a tyrosine antagonist and competes with it to bind to human tyrosyl-tRNA synthetase (TyrRS). Interestingly, although both isomers of RSV bind to TyrRS, only the cis-isomer evokes a unique structural change at the active site to promote its interaction with poly-ADP-ribose polymerase 1 (PARP1), a major determinant of cellular NAD+-dependent stress response. However, retention of trans-RSV in the active site of TyrRS mimics its tyrosine-bound conformation that inhibits the auto-poly-ADP-ribos(PAR)ylation of PARP1. Therefore, we proposed that cis-RSV-induced TyrRS-regulated auto-PARylation of PARP1 would contribute, at least in part, to the reported health benefits of RSV through the induction of protective stress response. This observation suggested that trans-RSV would inhibit TyrRS/PARP1-mediated protective stress response and would instead elicit an opposite effect compared to cis-RSV. Interestingly, most recent studies also confirmed the conversion of trans-RSV and its metabolites to cis-RSV in the physiological context. Therefore, the finding that cis-RSV and trans-RSV induce two distinct conformations of TyrRS with opposite effects on the auto-PARylation of PARP1 provides a potential molecular basis for the observed dichotomic effects of RSV under different experimental paradigms. However, the fact that natural RSV exists as a diastereomeric mixture of its cis and trans isomers and cis-RSV is also a physiologically relevant isoform has not yet gained much scientific attention.

Role of disordered regions in transferring tyrosine to its cognate tRNA.

Aminoacyl tRNA synthetase (AARS) plays an important role in transferring each amino acid to its cognate tRNA. Specifically, tyrosyl tRNA synthetase (TyrRS) is involved in various functions including protection from DNA damage due to oxidative stress, protein synthesis and cell signaling and can be an attractive target for controlling the pathogens by early inhibition of translation. TyrRS has two disordered regions, which lack a stable 3D structure in solution, and are involved in tRNA synthetase catalysis and stability. One of the disordered regions undergoes disorder-to-order transition (DOT) upon complex formation with tRNA whereas the other remains disordered (DR). In this work, we have explored the importance of these disordered regions using molecular dynamics simulations of both free and RNA-complexed states. We observed that the DOT and DR regions of the first subunit acts as a flap and interact with the acceptor arm of the tRNA. The DOT-DR flap closes when tyrosine (TyrRSTyr) is present at the active site of the complex and opens in the presence of tyrosine monophosphate (TyrRSYMP). The DOT and DR regions of the second subunit interact with the anticodon stem as well as D-loop of the tRNA, which might be involved in stabilizing the complex. The anticodon loop of the tRNA binds to the structured region present in the C-terminal of the protein, which is observed to be flexible during simulations. Detailed energy calculations also show that TyrRSTyr complex has stronger binding energy between tRNA and protein compared to TyrRSYMP; on the contrary, the anticodon is strongly bound in TyrRSYMP. The results obtained in the present study provide additional insights for understanding catalysis and the involvement of disordered regions in Tyr transfer to cognate tRNA.

Resveratrol attenuates oxidative injury in human umbilical vein endothelial cells through regulating mitochondrial fusion via TyrRS-PARP1 pathway.

BACKGROUND/AIMS: Oxidative stress-induced damage in endothelial cells is a crucial initiator of atherosclerosis (AS), which is highly related to excessive reactive oxygen species (ROS) and mitochondrial dynamics. Resveratrol (RSV) exerts beneficial effects against endothelial oxidative injury, while the underlying mechanisms have not been fully elucidated. Thus, we aimed to explore the role of mitochondria dynamics during the anti-oxidative activities of RSV in palmitic acid (PA)-stimulated human umbilical vein endothelial cells (HUVECs) and to verify whether tyrosyl transfer- RNA synthetase (TyrRS) and poly (ADP-ribose) polymerase 1 (PARP1) are targeted during this process. METHODS: HUVECs were exposed to 200 µM of PA for 16 h before treated with 10 µM of RSV for 8 h. Cell viability was detected using Cell counting kit-8 (CCK-8) assay. The intracellular ROS level and mitochondria membrane potential (MMP) were measured using microplate reader and flow cytometry. The malondialdehyde and superoxide dismutase were measured using the microplate reader. The mitochondrial morphology and fusion process was observed under transmission electron microscopy and confocal microscopy. TyrRS and PARP1 were knocked down with the specific small interference RNAs (siRNA), and the protein expressions of TyrRS, PARP1, and mitochondrial fusion proteins (MFN1, MFN2, and OPA1) were measured by western blot. RESULTS: RSV treatment suppressed the PA-induced injuries in HUVECs, including the damage to cell viability, oxidative stress, and loss of MMP. Additionally, RSV improved the protein levels of MFN1, MFN2, and OPA1 as well as inhibited the PA-induced fragmentation of mitochondria. However, the effects of RSV on oxidative stress and mitochondrial fusion were abolished by the pretreatment of siRNAs of TyrRS and PARP1, indicating that these effects of RSV were dependent on the TyrRS-PARP1 pathway. CONCLUSIONS: RSV attenuated endothelial oxidative injury by regulating mitochondrial fusion via TyrRS-PARP1 signaling pathway.

Tyrosyl-tRNA synthetase inhibitors: a patent review.

INTRODUCTION: Bacterial infection has been a consistent and relentless threat to human health because of emerging resistance to existing antibiotics. Therefore, much of the research has been focused on the design of new potent antibacterial agents. Tyrosyl-tRNA synthetase (TyrRS), as a member of aminoacyl-tRNA synthetase family, could recognize the information including the coincident tRNA molecules and the amino acids' structures, which are essential in translating the coded information into protein structures in nucleic acids. Therefore, the discovery and application of tyrosyl-tRNA synthetase inhibitors might be a potential strategy to control these diseases in humans. Areas covered: This review covers 1999 to 2016 wherein several new analogues were claimed as TyrRS inhibitors based on their chemical structures. Xiao, Z.P. et al patented two Chinese patents related to TyrRS inhibitors which are included. Expert opinion: Due to the pivotal role in translation, tyrosyl-tRNA synthetase has been recognized as a promising target for a new generation of antibiotics with selectivity and specificity. However, while some of the TyrRS inhibitors showed encouraging results, there is an urgent need to develop novel TyrRS inhibitors with higher activity and selectivity. Based on the published SAR results, selective tyrosyl-tRNA synthetase inhibitors could be designed and developed as the next generation of antibacterial agents.

Resveratrol Attenuates Aß25-35 Caused Neurotoxicity by Inducing Autophagy Through the TyrRS-PARP1-SIRT1 Signaling Pathway.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of ß-amyloid peptide (Aß) and loss of neurons. Resveratrol (RSV) is a natural polyphenol that has been found to be beneficial for AD through attenuation of Aß-induced toxicity in neurons both in vivo and in vitro. However, the specific underlying mechanisms remain unknown. Recently, autophagy was found to protect neurons from toxicity injuries via degradation of impaired proteins and organelles. Therefore, the aim of this study was to determine the role of autophagy in the anti-neurotoxicity effect of RSV in PC12 cells. We found that RSV pretreatment suppressed ß-amyloid protein fragment 25-35 (Aß25-35)-induced decrease in cell viability. Expression of light chain 3-II, degradation of sequestosome 1, and formation of autophagosomes were also upregulated by RSV. Suppression of autophagy by 3-methyladenine abolished the favorable effects of RSV on Aß25-35-induced neurotoxicity. Furthermore, RSV promoted the expression of sirtuin 1 (SIRT1), auto-poly-ADP-ribosylation of poly (ADP-ribose) polymerase 1 (PARP1), as well as tyrosyl transfer-RNA (tRNA) synthetase (TyrRS). Nevertheless, RSV-mediated autophagy was markedly abolished with the addition of inhibitors of SIRT1 (EX527), nicotinamide phosphoribosyltransferase (STF-118804), PARP1 (AG-14361), as well as SIRT1 and TyrRS small interfering RNA transfection, indicating that the action of RSV on autophagy induction was dependent on TyrRS, PARP1 and SIRT1. In conclusion, RSV attenuated neurotoxicity caused by Aß25-35 through inducing autophagy in PC12 cells, and the autophagy was partially mediated via activation of the TyrRS-PARP1-SIRT1 signaling pathway.

Effect of Mini-Tyrosyl-tRNA Synthetase/Mini-Tryptophanyl-tRNA Synthetase on Angiogenesis in Rhesus Monkeys after Acute Myocardial Infarction.

AIMS: The purpose of this study was to clarify the effect of mini-tyrosyl-tRNA synthetase/mini-tryptophanyl-tRNA synthetase (mini-TyrRS/mini-TrpRS) in ischemic angiogenesis in rhesus monkeys with acute myocardial infarction (AMI). METHODS: A 27-gauge needle was incorporated percutaneously into the left ventricular myocardium of rhesus monkeys with AMI. All monkeys were randomized to receive adenoviral vector mini-TyrRS/mini-TrpRS, which was administered as five injections into the infarcted myocardium, or saline or ad-null (control groups). The injections were guided by EnSite NavX left ventricular electroanatomical mapping. Mini-TyrRS/mini-TrpRS proteins were detected by Western blot and immunoprecipitation analyses. Microvessel density (MVD) per section was measured using immunostaining with a CD34 monoclonal antibody. Proliferating cardiomyocytes were identified through histological and immunohistochemical analyses. Myocardial perfusion and cardiac function were estimated by G-SPECT. Infarction size was also measured. RESULTS: Western blot analyses showed that compared to the normal zone, the expression level of mini-TyrRS/mini-TrpRS was significantly different in the infarction zone. G-SPECT analysis indicated that the mini-TyrRS group had better cardiac function and myocardial perfusion after the injection of ad-mini-TyrRS than before, while mini-TrpRS injection had a totally opposite effect. After mini-TyrRS was administered, there was less of an infarction zone and more proliferating cardiomyocytes and capillaries in the mini-TyrRS group compared to both of the control groups, and the ad-mini-TrpRS group had a totally opposite effect. CONCLUSION: These results indicated that angiogenesis could be either stimulated by mini-TyrRS or inhibited by mini-TrpRS.

Synthesis and evaluation of new tyrosyl-tRNA synthetase inhibitors as antibacterial agents based on a N2-(arylacetyl)glycinanilide scaffold.

Tyrosyl-tRNA synthetase (TyrRS), an essential enzyme in bacterial protein biosynthesis, is an attractive therapeutic target for finding novel antibacterial agents, and a series of N2-(arylacetyl)glycinanilides has been herein synthesized and identified as TyrRS inhibitors. These efforts yielded several compounds, with IC50 in the low micromolar range against TyrRS from Staphylococcus aureus. Out of the obtained compounds, 3ap is the most active and exhibits excellent activity against both Gram-positive (S. aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. In comparison with the parent scaffold 3-arylfuran-2(5H)-one, N2-(arylacetyl)glycinanilide significantly improved the potency against Gram-negative bacterial strains, indicating that this scaffold offers a significant potential for developing new antibacterial drugs.

Design, synthesis and molecular docking of salicylic acid derivatives containing metronidazole as a new class of antimicrobial agents.

A series of novel salicylic acid derivatives containing metronidazole as Staphylococcus aureus Tyrosyl-tRNA synthetase (TyrRS) inhibitors have been synthesized and evaluated their biology activities as potential antibacterial agents. Among these compounds, compound 5r exhibited the most potent antibacterial activity against Gram-positive (S. aureus ATCC 6538 and Bacillus subtilis ATCC 6633) and Gram-negative (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 13525) with MICs of 0.39-1.57 µg/mL and showed the most potent S. aureus Tyrosyl-tRNA synthetase inhibitory with 2.3 µM. Docking simulation was performed to insert compound 5r into the crystal structure of S. aureus Tyrosyl-tRNA synthetase active site to determine the probable binding model. These results suggested that compound 5r may be a promising antibacterial agent.

Synthesis, molecular docking and biological evaluation of 3-arylfuran-2(5H)-ones as anti-gastric ulcer agent.

3-Arylfuran-2(5H)-one derivatives show good antibacterial activity and were determined as tyrosyl-tRNA synthetase (TyrRS) inhibitors. In a systematic medicinal chemistry exploration, we demonstrated chemical opportunities to treat infections caused by Helicobacter pylori. Twenty 3-arylfuran-2(5H)-ones were synthesized and evaluated for anti-H. pylori, antioxidant and anti-urease activities which are closely interconnected with H. pylori infection. The results displayed that some of the compounds show excellent antioxidant activity, and good anti-H. pylori and urease inhibitory activities. Out of these compounds, 3-(3-methylphenyl)furan-2(5H)-one (b9) showed the most potent antioxidant activity (IC50=8.2 µM) and good anti-H. pylori activity (MIC50=2.6 µg/mL), and it can be used as a good candidate for discovering novel anti-gastric ulcer agent.

Novel 3-arylfuran-2(5H)-one-fluoroquinolone hybrid: design, synthesis and evaluation as antibacterial agent.

3-Arylfuran-2(5H)-one, a novel antibacterial pharmacophore targeting tyrosyl-tRNA synthetase (TyrRS), was hybridized with the clinically used fluoroquinolones to give a series of novel multi-target antimicrobial agents. Thus, twenty seven 3-arylfuran-2(5H)-one-fluoroquinolone hybrids were synthesized and evaluated for their antimicrobial activities. Some of the hybrids exhibited merits from both parents, displaying a broad spectrum of activity against resistant strains including both Gram-negative and Gram-positive bacteria. The most potent compound (11) in antibacterial assay shows MIC50 of 0.11µg/mL against Multiple drug resistant Escherichia coli, being about 51-fold more potent than ciprofloxacin. The enzyme assays reveal that 11 is a potent multi-target inhibitor with IC50 of 1.15±0.07µM against DNA gyrase and 0.12±0.04µM against TyrRS, respectively. Its excellent inhibitory activities against isolated enzymes and intact cells strongly suggest that 11 deserves to further research as a novel antibiotic.

Synthesis, molecular docking and biological evaluation of metronidazole derivatives containing piperazine skeleton as potential antibacterial agents.

Metronidazole has a broad-spectrum antibacterial activity. Hereby a series of novel metronidazole derivatives were designed and synthesized based on nitroimidazole scaffold in order to find some more potent antibacterial drugs. For these compounds which were reported for the first time, their antibacterial activities against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus were tested. These compounds showed good antibacterial activities against Gram-positive strains. Compound 4m represented the most potent antibacterial activity against S. aureus ATCC 25923 with MIC of 0.003 µg/mL and it showed the most potent activity against S. aureus TyrRS with IC50 of 0.0024 µM. Molecular docking of 4m into S. aureus tyrosyl-tRNA synthetase active site were also performed to determine the probable binding mode.

Proteomics-based identification of tumor relevant proteins in lung adenocarcinoma.

BACKGROUND: Lung cancer has the highest mortality rate among malignant tumors. Proteomics is a powerful tool to identify protein biomarkers. The identification of protein biomarkers associated with lung adenocarcinoma would have significance for making prognoses and designing targeted therapies. METHODS: In our study, we applied a two-dimensional difference gel electrophoresis approach coupled to a matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis for the identification of proteins differentially expressed between lung adenocarcinoma and the paired normal bronchial epithelial tissues derived from seven patients (four of them developed distant metastasis after operation). In addition, we chose two candidate proteins and examine their expression levels in lung adenocarcinoma and adjacent normal tissues using immunohistochemistry methods, and their expression levels in serum of patients and healthy donors by ELISA. RESULT: In this study, 173 proteins were found to be differentially expressed (ratio>1.5 or<-1.5, P≤0.05), and 22 of them were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Thirteen proteins were at lower levels in the lung adenocarcinoma group, while nine proteins were at higher abundance. Immunohistochemistry analysis confirmed the expression levels of the two candidate proteins. The differential expression of the candidate secreted protein in serum from lung adenocarcinoma samples and healthy controls was showed by ELISA. CONCLUSION: Our results demonstrated a differential protein expression pattern for lung adenocarcinoma compared with the paired normal bronchial epithelial tissues. Further functional validation of candidate proteins is ongoing and might provide new insights in lung adenocarcinoma.