In Silico and Chromatographic Methods for Analysis of Biotransformation of Prospective Neuroprotective Pyrrole-Based Hydrazone in Isolated Rat Hepatocytes.

In the current study, chromatographic and in silico techniques were applied to investigate the biotransformation of ethyl 5-(4-bromophenyl)-1-(2-(2-(2-hydroxybenzylidene) hydrazinyl)-2-oxoethyl)-2-methyl-1H-pyrrole-3-carboxylate (11b) in hepatocytic media. The initial chromatographic procedure was based on the employment of the conventional octadecyl stationary phase method for estimation of the chemical stability. Subsequently, a novel and rapid chromatographic approach based on a phenyl-hexyl column was developed, aiming to separate the possible metabolites. Both methods were performed on a Dionex 3000 ThermoScientific (ACM 2, Sofia, Bulgaria) device equipped with a diode array detector set up at 272 and 279 nm for analytes detection. An acetonitrile: phosphate buffer of pH 3.5: methanol (17:30:53 v/v/v) was eluted isocratically as a mobile phase with a 1 mL/min flow rate. A preliminary purification from the biological media was achieved by protein precipitation with methanol. A validation procedure was carried out, where the method was found to correspond to all ICH (Q2) and M10 set criteria. Additionally, an in silico-based approach with the online server BioTransformer 3.0 was applied in an attempt to predict the possible metabolites of the title compound 11b. It was hypothesized that four CYP450 isoforms (1A2, 2C9, 3A4, and 2C8) were involved in the phase I metabolism, resulting in the formation of 12 metabolites. Moreover, docking studies were conducted to evaluate the formation of stable complexes between 11b and the aforementioned isoforms. The obtained data indicated three metabolites as the most probable products, two of which (M9_11b and M10_11b) were synthesized by a classical approach for verification. Finally, liquid chromatography with a mass detector was implemented for comprehensive and summarized analysis, and the obtained results revealed that the metabolism of the 11b proceeds possibly with the formation of glucuronide and glycine conjugate of M11_11b.

Synthesis, DFT Study, and In Vitro Evaluation of Antioxidant Properties and Cytotoxic and Cytoprotective Effects of New Hydrazones on SH-SY5Y Neuroblastoma Cell Lines.

A series of ten new hydrazide-hydrazone derivatives bearing a pyrrole ring were synthesized and structurally elucidated through appropriate spectral characteristics. The target hydrazones were assessed for radical scavenging activity through 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) tests, with ethyl 5-(4-bromophenyl)-1-(2-(2-(4-hydroxy-3,5-dimethoxybenzylidene)hydrazine-yl)-2-oxoethyl)-2-methyl-1H-pyrrole-3-carboxylate (7d) and ethyl 5-(4-bromophenyl)-1-(3-(2-(4-hydroxy-3,5-dimethoxybenzylidene) hydra zine-yl)-3-oxopropyl)-2-methyl-1H-pyrrole-3-carboxylate (8d) highlighted as the best radical scavengers from the series. Additional density functional theory (DFT) studies have indicated that the best radical scavenging ligands in the newly synthesized molecules are stable, do not decompose into elements, are less polarizable, and with a hard nature. The energy of the highest occupied molecular orbital (HOMO) revealed that both compounds possess good electron donation capacities. Overall, 7d and 8d can readily scavenge free radicals in biological systems via the donation of hydrogen atoms and single electron transfer. The performed in vitro assessment of the compound's protective activity on the H2O2-induced oxidative stress model on human neuroblastoma cell line SH-SY5Y determined 7d as the most perspective representative with the lowest cellular toxicity and the highest protection.

Structure-Based Design of Novel MAO-B Inhibitors: A Review.

With the significant growth of patients suffering from neurodegenerative diseases (NDs), novel classes of compounds targeting monoamine oxidase type B (MAO-B) are promptly emerging as distinguished structures for the treatment of the latter. As a promising function of computer-aided drug design (CADD), structure-based virtual screening (SBVS) is being heavily applied in processes of drug discovery and development. The utilization of molecular docking, as a helping tool for SBVS, is providing essential data about the poses and the occurring interactions between ligands and target molecules. The current work presents a brief discussion of the role of MAOs in the treatment of NDs, insight into the advantages and drawbacks of docking simulations and docking software, and a look into the active sites of MAO-A and MAO-B and their main characteristics. Thereafter, we report new chemical classes of MAO-B inhibitors and the essential fragments required for stable interactions focusing mainly on papers published in the last five years. The reviewed cases are separated into several chemically distinct groups. Moreover, a modest table for rapid revision of the revised works including the structures of the reported inhibitors together with the utilized docking software and the PDB codes of the crystal targets applied in each study is provided. Our work could be beneficial for further investigations in the search for novel, effective, and selective MAO-B inhibitors.

Repurposing of FDA-approved drugs as dual-acting MAO-B and AChE inhibitors against Alzheimer's disease: An in silico and in vitro study.

An in silico consensus molecular docking approach and in vitro evaluations were adopted in the present study to explore a dataset of FDA-approved drugs as novel multitarget MAO-B/AChE agents in the treatment of Alzheimer's disease (AD). GOLD 5.3 and Glide were employed in the virtual assessments and consensus superimpositions of the obtained poses were applied to increase the reliability of the docking protocols. Furthermore, the top ranked molecules were subjected to binding free energy calculations using MM/GBSA, Induced fit docking (IFD) simulations, and a literature review. Consequently, the top four multitarget drugs were examined for their in vitro MAO-B and AChE inhibition effects. The consensus molecular docking identified Dolutegravir, Rebamipide, Loracarbef and Diflunisal as potential multitarget drugs. The biological data demonstrated that most of the docking scores were in good correlation with the in vitro experiments, however the theoretical simulations in the active site of MAO-B identified two false-positives - Rebamipide and Diflunisal. Dolutegravir and Loracarbef were accessed as active MAO-B inhibitors, while Dolutegravir, Rebamapide and Diflunisal as potential AChE inhibitors. The antiretroviral agent Dolutegravir exhibited the most potent multitarget activity - 41% inhibition of MAO-B (1 µM) and 68% inhibition of AChE (10 µM). Visualizations of the intermolecular interactions of Dolutegravir in the active sites of MAO-B and AChE revealed the formation of several stable hydrogen bonds. Overall, Dolutegravir was identified as a potential anti-AD drug, however further in vivo evaluations should be considered.

In silico and In vitro Determination of Antiproliferative Activity of Series N-Pyrrolyl Hydrazide-Hydrazones and Evaluation of their Effects on Isolated Rat Mycrosomes and Hepatocytes.

BACKGROUND: The significant increase in patients suffering from different types of cancer, guides scientists to take prompt measures in the development of novel and effective antiproliferative agents, where the intercalation of heterocyclic fragments in the designed molecules has proven to be a useful practice. OBJECTIVE: The newly synthesized compounds were obtained from the corresponding 1,4-dicarbonyl derivative through multicomponent reactions to produce biologically active target molecules and assessed by in silico and in vitro assays for their possible antitumor activity. METHODS: The pharmacological bioassay was conducted in the panel of human tumor cell lines (i) SKW-3 (ACC 53) - human T-cell leukemia and (ii) HL-60 (ACC 3) - human acute myeloid leukemia (AML). The statistical processing of MTT data included the paired Student's t-test with p ≤ 0.05 set as significance level. RESULTS: All evaluated structures displayed a higher cytotoxic effect against the acute myeloid leukemia HL-60 with 11o and 11p as the most active compared to the activity against SKW-3 cell line. Throughout the cytotoxicity screening two molecules, 11l and 12o, displayed comparable chemosensitivity on both cell lines. The corresponding hepatotoxicity on isolated rat hepatocytes and microsomes was also established, identifying 11, 12 and 12a as the least toxic and 11x, 11d, 12x and 12d as the most toxic derivatives. CONCLUSION: As the most promising compound is underlined ethyl 1-(2-(2-((1-acetyl-1H-indol-3-yl)methylene)hydrazinyl)-2- oxoethyl)-5-(4-bromophenyl)-2-methyl-1H-pyrrole-3-carboxylate (11l) demonstrating highest activity on both evaluated tumor cell lines, decreased hepatotoxicity on all evaluated parameters and docking score of -7.517 kcal/mol.

In silico Identification of Novel SARS-CoV-2 Main Protease and Nonstructural Protein 13 (nsp13) Inhibitors through Consensus Docking and Free Binding Energy Calculations.

BACKGROUND: A new strain of a novel disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been recently declared a pandemic by the World Health Organization (WHO). The virus results in significant mortality and morbidity across the planet; therefore, novel treatments are urgently required. Recently deposited crystallographic structures of SARS-CoV-2 proteins have ignited the interest in virtual screenings of large databases. OBJECTIVE: In the current study, we evaluated the inhibitory capacity of the IMPPAT phytochemical database (8500 compounds) and the SuperDRUG2 dataset (4000 compounds) in SARS-CoV-2 main protease and helicase Nsp13 through consensus-based docking simulations. METHODS: Glide and GOLD 5.3 were implemented in the in silico process. Further MM/GBSA calculations of the top 10 inhibitors in each protein were carried out to investigate the binding free energy of the complexes. An analysis of the major ligand-protein interactions was also conducted. RESULTS: After the docking simulations, we acquired 10 prominent phytochemicals and 10 FDAapproved drugs capable of inhibiting Nsp5 and Nsp13. Delphinidin 3,5,3'-triglucoside and hirsutidin 3-O-(6-O-p-coumaroyl)glucoside demonstrated the most favorable binding free energies against Nsp5 and Nsp13, respectively. CONCLUSION: In conclusion, the analysis of the results identified that the phytochemicals demonstrated enhanced binding capacities compared to the FDA-approved database.

In Silico Evaluation and In Vitro Determination of Neuroprotective and MAO-B Inhibitory Effects of Pyrrole-Based Hydrazones: A Therapeutic Approach to Parkinson's Disease.

Parkinson's disease is a huge burden in modern medicinal practice. A serious drawback of current antiparkinsonian therapy is its symptomatic nature. This directed our investigations in the search for new more potent derivatives, affecting not only the loss of dopaminergic neurons but also the oxidative damage of neuronal cells. Thus in vitro neurotoxicity and neuroprotective analysis on a group of N-pyrrolyl hydrazide-hydrazones were performed. The neurotoxicity of the target derivatives was determined on a subcellular level in isolated rat synaptosomes, mitochondria and microsomes determining their effect on cellular vitality, GSH depletion and MDA production. The neuroprotective effects of the evaluated hydrazones were measured in three models of induced oxidative stress: 6-OHDA, t-BuOOH and Fe2+/AA-induced lipid peroxidation. Molecular docking simulations along with in vitro evaluation of MAO-B inhibitory potential of the target molecules were also performed. The results identified the ethyl 5-(4-bromophenyl)-1-(3-hydrazinyl-3-oxopropyl)-2-methyl-1H-pyrrole-3-carboxylate (12) as the most promising compound with the lowest neurotoxicity and highest neuroprotection on all evaluated parameters and inhibiting the hMAOB enzyme by 50%, comparable with the activity of the reference, Selegiline. The compatibility of the in silico and in vitro evaluations is a good prerequisite for these methods to be applied in future assessment of pyrrole-based compounds as anti-Parkinson agents.

Pyrrole as an Important Scaffold of Anticancer Drugs: Recent Advances.

With the significant increase of patients suffering from different types of cancer, it is evident that prompt measures in the development of novel and effective agents need to be taken. Pyrrole moiety has been found in various active compounds with anti-inflammatory, antiseptic, antibacterial, lipid-lowering and anticancer properties. Recent advances in the exploration of highly active and selective cytotoxic structures containing pyrrole motifs have shown promising data for future investigations. Accordingly, this review presents an overview of recent developments in the pyrrole derivatives as anticancer agents, with a main focus towards the key moieties required for the anti-tumor activities. Pyrrole molecules comprising prominent targeting capacities against microtubule polymerization, tyrosine kinases, cytochrome p450 family 1, histone deacetylase and bcl-2 proteins were reported. In addition, several mechanisms of action, such as apoptosis, cell cycle arrest, inhibiting kinases, angiogenesis, disruption of cell migration, modulation of nuclear receptor responsiveness and others were analyzed. Furthermore, in most of the discussed cases we provided synthesis schemes of the mentioned molecules. Overall, the utilization of pyrrole scaffold for the design and synthesis of novel anticancer drugs could be a promising approach for future investigations.