Determination of nitrate by the IE-HPLC-UV method in the brain tissues ofWistar rats poisoned with paraquat

This work was a part of an initial study regarding the involvement of reactive nitrogen species (RNS) in paraquat (PQ) neurotoxicity. The nitrate concentration in the vulnerable regions of the brain (cortex, striatum and hippocampus) of Wistar rats was used as a measure of nitric oxide (NO) production or catabolism of the formed RNS. The tissue homogenates were deproteinized with acetonitrile and then centrifuged. Nitrate was measured in filtrated supernatants by simple and rapid isocratic ion-exchange high performance liquid chromatography with UV detection (IE-HPLC-UV) at 214 nm. The mobile phase (pH 8.5) consisted of borate buffer/gluconate concentrate, methanol, acetonitrile and deionized water (2:12:12:74, v/v/v/v), and the flow rate was 1.3 mL/min. Physiological nitrate levels (18.8 ± 6.1 nmol/mg of proteins), as well as a diverse range of nitrate concentrations could be determined with good precision (CV = 2.2 %) and accuracy (recovery of spiked samples was 99 ± 4%) in the brain tissue homogenates. Linearity was achieved in the range of nitrate from 0‑80 mM. The retention time of nitrate anion was 5.3 ± 0.3 min

An Integrative in Silico Drug Repurposing Approach for Identification of Potential Inhibitors of SARS-CoV-2 Main Protease

Aims: An infectious disease (COVID-19) caused by the coronavirus SARS-CoV-2 emerged in Wuhan, China in December 2019. Currently, SARS-CoV-2 infected more than 9 million people and caused more than 450 000 deaths. Considering the urgent need for novel therapeutics, drug repurposing approach might offer rapid solutions comparing to de novo drug design. In this study, we investigated an integrative in silico drug repurposing approach as a valuable tool for rapid selection of potential candidates against SARS-CoV-2 Main Protease (Mpro).Main methods: To screen FDA-approved drugs, we designed an integrative in silico drug repurposing approach implementing structure-based molecular modelling techniques, physiologically-based pharmacokinetic (PBPK) modelling of drugs disposition and data-mining analysis of drug-gene-COVID-19 association.Key findings: Through the presented approach, 43 candidates with potential inhibitory effect on Mpro were selected and further evaluated according to the predictions of tissue disposition, drug-gene-COVID-19 associations and potential pleiotropic effects. We singled out 9 FDA approved drugs as the most promising for their profiling in COVID-19 drug discovery campaigns. Our results were in agreement with current experimental findings, which validate the applied integrative approach and may support clinical decisions for a novel epidemic wave of COVID-19.Significance: To the best of our knowledge, this is the first integrative in silico repurposing study for COVID-19 with a clear advantage in linking structure-based molecular modeling of Mpro inhibitors with predictions of tissue disposition, drug-gene-COVID-19 associations and prediction of pleiotropic effects of selected candidates.</div

Short-Term Administration of Lemon Balm Extract Ameliorates Myocardial Ischemia/Reperfusion Injury: Focus on Oxidative Stress

We aimed to investigate the cardioprotective effects of ethanolic Melissa officinalis L. extract (ME) in the rat model of myocardial ischemia/reperfusion (I/R) injury. Thirty-two Wistar rats were randomly divided into a CTRL non-treated control group with myocardial I/R injury and three experimental groups of rats treated with 50, 100, or 200 mg/kg of ME for 7 days per os. Afterward, hearts were isolated, and cardiodynamic function was assessed via the Langendorff model of global 20 min ischemia and 30 min reperfusion. Oxidative stress parameters were determined spectrophotometrically from the samples of coronary venous effluent (O2−, H2O2, TBARS, and NO2−,) and heart tissue homogenate (TBARS, NO2−, SOD, and CAT). H/E and Picrosirius red staining were used to examine cardiac architecture and cardiac collagen content. ME improved cardiodynamic parameters and achieved to preserve cardiac architecture after I/R injury and to decrease fibrosis, especially in the ME200 group compared to CTRL. ME200 and ME100 markedly decreased prooxidants TBARS, O2−, and H2O2 while increasing NO2−. Hereby, we confirmed the ME`s ability to save the heart from I/R induced damage, even after short-term preconditioning in terms of preserving cardiodynamic alterations, cardiac architecture, fibrosis, and suppressing oxidative stress, especially in dose of 200 mg/kg