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  1. Article ; Online: Hybrid Classification/Regression Approach to QSAR Modeling of Stoichiometric Antiradical Capacity Assays’ Endpoints

    Petko Alov / Ivanka Tsakovska / Ilza Pajeva

    Molecules, Vol 27, Iss 2084, p

    2022  Volume 2084

    Abstract: Quantitative structure–activity relationships (QSAR) are a widely used methodology allowing not only a better understanding of the mechanisms of chemical reactions, including radical scavenging, but also to predict the relevant properties of chemical ... ...

    Abstract Quantitative structure–activity relationships (QSAR) are a widely used methodology allowing not only a better understanding of the mechanisms of chemical reactions, including radical scavenging, but also to predict the relevant properties of chemical compounds without their synthesis, isolation and experimental testing. Unlike the QSAR modeling of the kinetic antioxidant assays, modeling of the assays with stoichiometric endpoints depends strongly on the number of hydroxyl groups in the antioxidant molecule, as well as on some integral molecular descriptors characterizing the proportion of OH-groups able to enter and complete the radical scavenging reaction. In this work, we tested the feasibility of a “hybrid” classification/regression approach, consisting of explicit classification of individual OH-groups as involved in radical scavenging reactions, and using further the number of these OH-groups as a descriptor in simple-regression QSAR models of antiradical capacity assays with stoichiometric endpoints. A simple threshold classification based on the sum of trolox-equivalent antiradical capacity values was used, selecting OH-groups with specific radical stability- and reactivity-related electronic parameters or their combination as “active” or “inactive”. We showed that this classification/regression modeling approach provides a substantial improvement of the simple-regression QSAR models over those built on the number of total phenolic OH-groups only, and yields a statistical performance similar to that of the best reported multiple-regression QSARs for antiradical capacity assays with stoichiometric endpoints.
    Keywords antiradical capacity assays ; ABTS ●+ ; DPPH ● ; TEAC ; stoichiometric endpoint ; QSAR ; Organic chemistry ; QD241-441
    Subject code 540
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: An Application of InterCriteria Analysis Approach to Assess the AMMOS Software Platform Outcomes

    Dessislava Jereva / Maria Angelova / Ivanka Tsakovska / Petko Alov / Ilza Pajeva / Maria Miteva / Tania Pencheva

    Biomath, Vol 11, Iss

    2022  Volume 1

    Abstract: The experimental procedures of drug design, proven to be time-consuming and costly, are successfully complemented with computer-aided (in silico) approaches nowadays. Virtual ligand screening (VLS) is one of the most promising approaches when searching ... ...

    Abstract The experimental procedures of drug design, proven to be time-consuming and costly, are successfully complemented with computer-aided (in silico) approaches nowadays. Virtual ligand screening (VLS) is one of the most promising approaches when searching for new hit compounds. The efficiency of VLS procedures might be improved via post-docking optimization. In the focus of this investigation is AMMOS (Automatic Molecular Mechanics Optimization for in silico Screening) developed as multi-step structure-based procedure for efficient computational refinement of protein-ligand complexes at different levels of protein flexibility. Their performance has been assessed by the recently developed InterCriteria Analysis (ICrA), elaborated as multi-criterion decision-making approach to reveal possible relations in the behavior of pairs of criteria when multiple objects are considered. The capacity of ICrA as a supporting tool to assess the effect of applying different levels of protein flexibility in the post-docking optimization via AMMOS has been investigated and analyzed.
    Keywords decision making ; intercriteria analysis ; post-docking optimization ; Biology (General) ; QH301-705.5 ; Mathematics ; QA1-939
    Subject code 006
    Language English
    Publishing date 2022-05-01T00:00:00Z
    Publisher Biomath Forum
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: In Silico Identification of Multi-Target Ligands as Promising Hit Compounds for Neurodegenerative Diseases Drug Development

    Petko Alov / Hristo Stoimenov / Iglika Lessigiarska / Tania Pencheva / Nikolay T. Tzvetkov / Ilza Pajeva / Ivanka Tsakovska

    International Journal of Molecular Sciences, Vol 23, Iss 13650, p

    2022  Volume 13650

    Abstract: The conventional treatment of neurodegenerative diseases (NDDs) is based on the “one molecule—one target” paradigm. To combat the multifactorial nature of NDDs, the focus is now shifted toward the development of small-molecule-based compounds that can ... ...

    Abstract The conventional treatment of neurodegenerative diseases (NDDs) is based on the “one molecule—one target” paradigm. To combat the multifactorial nature of NDDs, the focus is now shifted toward the development of small-molecule-based compounds that can modulate more than one protein target, known as “multi-target-directed ligands” (MTDLs), while having low affinity for proteins that are irrelevant for the therapy. The in silico approaches have demonstrated a potential to be a suitable tool for the identification of MTDLs as promising drug candidates with reduction in cost and time for research and development. In this study more than 650,000 compounds were screened by a series of in silico approaches to identify drug-like compounds with predicted activity simultaneously towards three important proteins in the NDDs symptomatic treatment: acetylcholinesterase (AChE), histone deacetylase 2 (HDAC2), and monoamine oxidase B (MAO-B). The compounds with affinities below 5.0 µM for all studied targets were additionally filtered to remove known non-specifically binding or unstable compounds. The selected four hits underwent subsequent refinement through in silico blood-brain barrier penetration estimation, safety evaluation, and molecular dynamics simulations resulting in two hit compounds that constitute a rational basis for further development of multi-target active compounds against NDDs.
    Keywords neurodegenerative diseases ; acetylcholinesterase ; histone deacetylase 2 ; monoamine oxidase B ; multi-target-directed ligands ; virtual screening ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 540 ; 500
    Language English
    Publishing date 2022-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: New Potential Pharmacological Targets of Plant-Derived Hydroxyanthraquinones from Rubia spp.

    Petko Alov / Merilin Al Sharif / Hristo Najdenski / Tania Pencheva / Ivanka Tsakovska / Maya Margaritova Zaharieva / Ilza Pajeva

    Molecules, Vol 27, Iss 3274, p

    2022  Volume 3274

    Abstract: The increased use of polyphenols nowadays poses the need for identification of their new pharmacological targets. Recently, structure similarity-based virtual screening of DrugBank outlined pseudopurpurin, a hydroxyanthraquinone from Rubia cordifolia spp. ...

    Abstract The increased use of polyphenols nowadays poses the need for identification of their new pharmacological targets. Recently, structure similarity-based virtual screening of DrugBank outlined pseudopurpurin, a hydroxyanthraquinone from Rubia cordifolia spp., as similar to gatifloxacin, a synthetic antibacterial agent. This suggested the bacterial DNA gyrase and DNA topoisomerase IV as potential pharmacological targets of pseudopurpurin. In this study, estimation of structural similarity to referent antibacterial agents and molecular docking in the DNA gyrase and DNA topoisomerase IV complexes were performed for a homologous series of four hydroxyanthraquinones. Estimation of shape- and chemical feature-based similarity with (S)-gatifloxacin, a DNA gyrase inhibitor, and (S)-levofloxacin, a DNA topoisomerase IV inhibitor, outlined pseudopurpurin and munjistin as the most similar structures. The docking simulations supported the hypothesis for a plausible antibacterial activity of hydroxyanthraquinones. The predicted docking poses were grouped into 13 binding modes based on spatial similarities in the active site. The simultaneous presence of 1-OH and 3-COOH substituents in the anthraquinone scaffold were emphasized as relevant features for the binding modes’ variability and ability of the compounds to strongly bind in the DNA-enzyme complexes. The results reveal new potential pharmacological targets of the studied polyphenols and help in their prioritization as drug candidates and dietary supplements.
    Keywords pseudopurpurin ; DNA gyrase ; DNA topoisomerase IV ; antibacterial action ; similarity-based screening ; docking ; Organic chemistry ; QD241-441
    Subject code 540
    Language English
    Publishing date 2022-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Design, Synthesis, In Silico Studies and In Vitro Evaluation of New Indole- and/or Donepezil-like Hybrids as Multitarget-Directed Agents for Alzheimer’s Disease

    Violina T. Angelova / Borislav Georgiev / Tania Pencheva / Ilza Pajeva / Miroslav Rangelov / Nadezhda Todorova / Dimitrina Zheleva-Dimitrova / Elena Kalcheva-Yovkova / Iva V. Valkova / Nikolay Vassilev / Rositsa Mihaylova / Denitsa Stefanova / Boris Petrov / Yulian Voynikov / Virginia Tzankova

    Pharmaceuticals, Vol 16, Iss 1194, p

    2023  Volume 1194

    Abstract: Alzheimer’s disease (AD) is considered a complex neurodegenerative condition which warrants the development of multitargeted drugs to tackle the key pathogenetic mechanisms of the disease. In this study, two novel series of melatonin- and donepezil-based ...

    Abstract Alzheimer’s disease (AD) is considered a complex neurodegenerative condition which warrants the development of multitargeted drugs to tackle the key pathogenetic mechanisms of the disease. In this study, two novel series of melatonin- and donepezil-based hybrid molecules with hydrazone ( 3a–r ) or sulfonyl hydrazone ( 5a–l ) fragments were designed, synthesized, and evaluated as multifunctional ligands against AD-related neurodegenerative mechanisms. Two lead compounds ( 3c and 3d ) exhibited a well-balanced multifunctional profile, demonstrating intriguing acetylcholinesterase (AChE) inhibition, promising antioxidant activity assessed by DPPH, ABTS, and FRAP methods, as well as the inhibition of lipid peroxidation in the linoleic acid system. Compound 3n , possessing two indole scaffolds, showed the highest activity against butyrylcholinesterase (BChE) and a high selectivity index (SI = 47.34), as well as a pronounced protective effect in H 2 O 2 -induced oxidative stress in SH-SY5Y cells. Moreover, compounds 3c , 3d , and 3n showed low neurotoxicity against malignant neuroblastoma cell lines of human (SH-SY5Y) and murine (Neuro-2a) origin, as well as normal murine fibroblast cells (CCL-1) that indicate the in vitro biocompatibility of the experimental compounds. Furthermore, compounds 3c , 3d , and 3n were capable of penetrating the blood–brain barrier (BBB) in the experimental PAMPA-BBB study. The molecular docking showed that compound 3c could act as a ligand to both MT1 and MT2 receptors, as well as to AchE and BchE enzymes. Taken together, those results outline compounds 3c , 3d , and 3n as promising prototypes in the search of innovative compounds for the treatment of AD-associated neurodegeneration with oxidative stress. This study demonstrates that hydrazone derivatives with melatonin and donepezil are appropriate for further development of new AChE/BChE inhibitory agents.
    Keywords AChE/BChE ; Alzheimer’s disease ; neurodegenerative disorders ; antioxidants ; donepezil ; melatonin ; Medicine ; R ; Pharmacy and materia medica ; RS1-441
    Subject code 540
    Language English
    Publishing date 2023-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Optimized Structure-based Methodology for Studying PPARγ Partial Agonists

    Merilin Al Sharif / Antonia Diukendjieva / Petko Alov / Ivanka Tsakovska / Ilza Pajeva

    International Journal Bioautomation, Vol 22, Iss 1, Pp 65-

    2018  Volume 72

    Abstract: The peroxisome proliferator-activated receptor (PPAR) γ is a master regulator of the lipid and glucose metabolism, and thus is a valuable drug target. Since its full activation is accompanied by a number of adverse effects, researchers focus on discovery ...

    Abstract The peroxisome proliferator-activated receptor (PPAR) γ is a master regulator of the lipid and glucose metabolism, and thus is a valuable drug target. Since its full activation is accompanied by a number of adverse effects, researchers focus on discovery of novel compounds with ligand-receptor interaction patterns of PPARγ partial agonists. Molecular modelling is an appropriate way to achieve this goal. In this study we aimed at optimization of the docking algorithm for structure-based investigation of PPARγ partial agonists. A dataset with structures and activities of PPARγ partial agonists was constructed. A comparative study of different scoring functions’ performance was conducted by redocking the partial agonists’ structures selected from experimentally resolved 3D structures of PPARγ protein-ligand complexes. The docking protocols’ performance regarding pose scoring, reproducibility and interpretability in the context of the collected activity data was estimated. An optimized docking protocol was developed to successfully correlate the docking scores of the studied compounds with their experimentally derived activity values and to provide the best matching degree with their experimental binding modes. Overall, these results could be useful for further molecular modelling studies of novel PPARγ partial agonists by selection of reliable docking poses to predict their binding mode and for ranking them in respect to their agonistic activity using the calculated docking scores.
    Keywords PPARγ ; Partial agonists ; Docking ; Optimization ; Biology (General) ; QH301-705.5
    Subject code 540
    Language English
    Publishing date 2018-03-01T00:00:00Z
    Publisher Bulgarian Academy of Sciences
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Novel Heat Shock Protein 90 Inhibitors Suppress P-Glycoprotein Activity and Overcome Multidrug Resistance in Cancer Cells

    Jelena Dinić / Ana Podolski-Renić / Mirna Jovanović / Loana Musso / Ivanka Tsakovska / Ilza Pajeva / Sabrina Dallavalle / Milica Pešić

    International Journal of Molecular Sciences, Vol 20, Iss 18, p

    2019  Volume 4575

    Abstract: Heat Shock Protein 90 (Hsp90) chaperone interacts with a broad range of client proteins involved in cancerogenesis and cancer progression. However, Hsp90 inhibitors were unsuccessful as anticancer agents due to their high toxicity, lack of selectivity ... ...

    Abstract Heat Shock Protein 90 (Hsp90) chaperone interacts with a broad range of client proteins involved in cancerogenesis and cancer progression. However, Hsp90 inhibitors were unsuccessful as anticancer agents due to their high toxicity, lack of selectivity against cancer cells and extrusion by membrane transporters responsible for multidrug resistance (MDR) such as P-glycoprotein (P-gp). Recognizing the potential of new compounds to inhibit P-gp function and/or expression is essential in the search for effective anticancer drugs. Eleven Hsp90 inhibitors containing an isoxazolonaphtoquinone core were synthesized and evaluated in two MDR models comprised of sensitive and corresponding resistant cancer cells with P-gp overexpression (human non-small cell lung carcinoma and colorectal adenocarcinoma). We investigated the effect of Hsp90 inhibitors on cell growth inhibition, P-gp activity and P-gp expression. Structure−activity relationship analysis was performed in respect to cell growth and P-gp inhibition. Compounds 5, 7, and 9 directly interacted with P-gp and inhibited its ATPase activity. Their potential P-gp binding site was identified by molecular docking studies. In addition, these compounds downregulated P-gp expression in MDR colorectal carcinoma cells, showed good relative selectivity towards cancer cells, while compound 5 reversed resistance to doxorubicin and paclitaxel in concentration-dependent manner. Therefore, compounds 5, 7 and 9 could be promising candidates for treating cancers with P-gp overexpression.
    Keywords isoxazolonaphthoquinones ; Hsp90 inhibitors ; P-glycoprotein inhibitors ; cancer ; multidrug resistance ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Language English
    Publishing date 2019-09-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: A Free Web-Based Protocol to Assist Structure-Based Virtual Screening Experiments

    Nathalie Lagarde / Elodie Goldwaser / Tania Pencheva / Dessislava Jereva / Ilza Pajeva / Julien Rey / Pierre Tuffery / Bruno O. Villoutreix / Maria A. Miteva

    International Journal of Molecular Sciences, Vol 20, Iss 18, p

    2019  Volume 4648

    Abstract: Chemical biology and drug discovery are complex and costly processes. In silico screening approaches play a key role in the identification and optimization of original bioactive molecules and increase the performance of modern chemical biology and drug ... ...

    Abstract Chemical biology and drug discovery are complex and costly processes. In silico screening approaches play a key role in the identification and optimization of original bioactive molecules and increase the performance of modern chemical biology and drug discovery endeavors. Here, we describe a free web-based protocol dedicated to small-molecule virtual screening that includes three major steps: ADME-Tox filtering (via the web service FAF-Drugs4), docking-based virtual screening (via the web service MTiOpenScreen), and molecular mechanics optimization (via the web service AMMOS2 [Automatic Molecular Mechanics Optimization for in silico Screening]). The online tools FAF-Drugs4, MTiOpenScreen, and AMMOS2 are implemented in the freely accessible RPBS (Ressource Parisienne en Bioinformatique Structurale) platform. The proposed protocol allows users to screen thousands of small molecules and to download the top 1500 docked molecules that can be further processed online. Users can then decide to purchase a small list of compounds for in vitro validation. To demonstrate the potential of this online-based protocol, we performed virtual screening experiments of 4574 approved drugs against three cancer targets. The results were analyzed in the light of published drugs that have already been repositioned on these targets. We show that our protocol is able to identify active drugs within the top-ranked compounds. The web-based protocol is user-friendly and can successfully guide the identification of new promising molecules for chemical biology and drug discovery purposes.
    Keywords web server ; virtual screening ; docking ; molecular mechanics ; structure refinement ; ADME-Tox ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 540
    Language English
    Publishing date 2019-09-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Computational Analysis of Chemical Space of Natural Compounds Interacting with Sulfotransferases

    Iglika Lessigiarska / Yunhui Peng / Ivanka Tsakovska / Petko Alov / Nathalie Lagarde / Dessislava Jereva / Bruno O. Villoutreix / Arnaud B. Nicot / Ilza Pajeva / Tania Pencheva / Maria A. Miteva

    Molecules, Vol 26, Iss 6360, p

    2021  Volume 6360

    Abstract: The aim of this study was to investigate the chemical space and interactions of natural compounds with sulfotransferases (SULTs) using ligand- and structure-based in silico methods. An in-house library of natural ligands (hormones, neurotransmitters, ... ...

    Abstract The aim of this study was to investigate the chemical space and interactions of natural compounds with sulfotransferases (SULTs) using ligand- and structure-based in silico methods. An in-house library of natural ligands (hormones, neurotransmitters, plant-derived compounds and their metabolites) reported to interact with SULTs was created. Their chemical structures and properties were compared to those of compounds of non-natural (synthetic) origin, known to interact with SULTs. The natural ligands interacting with SULTs were further compared to other natural products for which interactions with SULTs were not known. Various descriptors of the molecular structures were calculated and analyzed. Statistical methods (ANOVA, PCA, and clustering) were used to explore the chemical space of the studied compounds. Similarity search between the compounds in the different groups was performed with the ROCS software. The interactions with SULTs were additionally analyzed by docking into different experimental and modeled conformations of SULT1A1. Natural products with potentially strong interactions with SULTs were outlined. Our results contribute to a better understanding of chemical space and interactions of natural compounds with SULT enzymes and help to outline new potential ligands of these enzymes.
    Keywords sulfotransferase ; SULT1A1 ; natural compounds ; ANOVA ; PCA ; cluster analysis ; Organic chemistry ; QD241-441
    Subject code 540
    Language English
    Publishing date 2021-10-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article: In vitro and in silico studies of the membrane permeability of natural flavonoids from Silybum marianum (L.) Gaertn. and their derivatives

    Diukendjieva, Antonia / Andrea Richarz / Ilza Pajeva / Ivanka Tsakovska / Mark T.D. Cronin / Petko Alov / Tania Pencheva / Vladimir Kren

    Phytomedicine. 2019 Feb., v. 53

    2019  

    Abstract: In recent years the number of natural products used as pharmaceuticals, components of dietary supplements and cosmetics has increased tremendously requiring more extensive evaluation of their pharmacokinetic properties.This study aims at combining in ... ...

    Abstract In recent years the number of natural products used as pharmaceuticals, components of dietary supplements and cosmetics has increased tremendously requiring more extensive evaluation of their pharmacokinetic properties.This study aims at combining in vitro and in silico methods to evaluate the gastrointestinal absorption (GIA) of natural flavonolignans from milk thistle (Silybum marianum (L.) Gaertn.) and their derivatives.A parallel artificial membrane permeability assay (PAMPA) was used to evaluate the transcellular permeability of the plant main components. A dataset of 269 compounds with measured PAMPA values and specialized software tools for calculating molecular descriptors were utilized to develop a quantitative structure-activity relationship (QSAR) model to predict PAMPA permeability.The PAMPA permeabilities of 7 compounds constituting the main components of the milk thistle were measured and their GIA was evaluated. A freely-available and easy to use QSAR model predicting PAMPA permeability from calculated physico-chemical molecular descriptors was derived and validated on an external dataset of 783 compounds with known GIA. The predicted permeability values correlated well with obtained in vitro results. The QSAR model was further applied to predict the GIA of 31 experimentally untested flavonolignans.According to both in vitro and in silico results most flavonolignans are highly permeable in the gastrointestinal tract, which is a prerequisite for sufficient bioavailability and use as lead structures in drug development. The combined in vitro/in silico approach can be used for the preliminary evaluation of GIA and to guide further laboratory experiments on pharmacokinetic characterization of bioactive compounds, including natural products.
    Keywords bioactive compounds ; bioavailability ; computer software ; cosmetics ; data collection ; drugs ; flavonoids ; gastrointestinal system ; intestinal absorption ; laboratory experimentation ; membrane permeability ; models ; pharmacokinetics ; prediction ; quantitative structure-activity relationships ; Silybum marianum
    Language English
    Dates of publication 2019-02
    Size p. 79-85.
    Publishing place Elsevier GmbH
    Document type Article
    ZDB-ID 1205240-1
    ISSN 1618-095X ; 0944-7113
    ISSN (online) 1618-095X
    ISSN 0944-7113
    DOI 10.1016/j.phymed.2018.09.001
    Database NAL-Catalogue (AGRICOLA)

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