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

    Alov, Petko / Tsakovska, Ivanka / Pajeva, Ilza

    Molecules (Basel, Switzerland)

    2022  Volume 27, Issue 7

    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.
    MeSH term(s) Antioxidants/chemistry ; Phenols ; Quantitative Structure-Activity Relationship
    Chemical Substances Antioxidants ; Phenols
    Language English
    Publishing date 2022-03-24
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 1413402-0
    ISSN 1420-3049 ; 1431-5165 ; 1420-3049
    ISSN (online) 1420-3049
    ISSN 1431-5165 ; 1420-3049
    DOI 10.3390/molecules27072084
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Synthesis and Biological Study of 4-Aminopyridine-Peptide Derivatives Designed for the Treatment of Neurodegenerative Disorders.

    Vezenkov, Lyubomir T / Tsekova, Daniela S / Kostadinova, Ivanka / Mihaylova, Rositsa / Lozanov, Valentin / Vassilev, Nikolay G / Danchev, Nikolai / Tsakovska, Ivanka / Pajeva, Ilza

    Current Alzheimer research

    2023  Volume 20, Issue 2, Page(s) 120–129

    Abstract: Background: Alzheimer's disease (AD) and Multiple sclerosis (MS) lead to neurodegenerative processes negatively affecting millions of people worldwide. Their treatment is still difficult and practically incomplete. One of the most commonly used drugs ... ...

    Abstract Background: Alzheimer's disease (AD) and Multiple sclerosis (MS) lead to neurodegenerative processes negatively affecting millions of people worldwide. Their treatment is still difficult and practically incomplete. One of the most commonly used drugs against these neurodegenerative diseases is 4-aminopyridine. However, its use is confined by the high toxicity.
    Objectives: The aim of this work is to obtain new peptide derivatives of 4-aminopyridine with decreased toxicity compared to 4-aminopyridine.
    Methods: Synthesis was conducted in solution using a consecutive condensation approach. The new derivatives were characterized by melting points, NMR, and Mass spectra. Important ADME (absorption, distribution, metabolism, and excretion) properties have been studied in silico using ACD/Percepta v.2020.2.0 software. Acute toxicity was determined in mice according to a Standard protocol. All new derivatives were tested in vitro for cytotoxic activity in a panel of human (HEP-G2, BV-173) and murine (NEURO 2A) tumor cell lines via a standard MTT-based colorimetric method. β-secretase inhibitory activity was determined by applying the fluorescent method.
    Results: New derivatives of 4-aminopyridine containing analogues of the β-secretase inhibitory peptide (Boc-Val-Asn-Leu-Ala-OH) were obtained. The in vivo toxicity of the tested compounds was found to be as high as 1500 mg/kg. Cell toxicity screening against tumor cell lines of different origins showed negligible growth-inhibitory effects of all investigated 4-aminopyridine analogues.
    Conclusion: Synthesis of new peptide derivatives of 4-aminopyridine is reported. Acute toxicity studies revealed a ca. 150 times lower toxicity of the new compounds as compared to 4-aminopyridine that may be ascribed to their peptide fragment.
    MeSH term(s) Mice ; Humans ; Animals ; 4-Aminopyridine/toxicity ; 4-Aminopyridine/therapeutic use ; Amyloid Precursor Protein Secretases/metabolism ; Alzheimer Disease/drug therapy ; Peptides/pharmacology ; Cell Line, Tumor
    Chemical Substances 4-Aminopyridine (BH3B64OKL9) ; Amyloid Precursor Protein Secretases (EC 3.4.-) ; Peptides
    Language English
    Publishing date 2023-06-06
    Publishing country United Arab Emirates
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2205170-3
    ISSN 1875-5828 ; 1567-2050
    ISSN (online) 1875-5828
    ISSN 1567-2050
    DOI 10.2174/1567205020666230602142012
    Database MEDical Literature Analysis and Retrieval System OnLINE

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

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

    International journal of molecular sciences

    2022  Volume 23, Issue 21

    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.
    MeSH term(s) Humans ; Acetylcholinesterase/metabolism ; Neurodegenerative Diseases/drug therapy ; Ligands ; Monoamine Oxidase/metabolism ; Drug Development ; Molecular Docking Simulation ; Cholinesterase Inhibitors/pharmacology ; Cholinesterase Inhibitors/therapeutic use ; Cholinesterase Inhibitors/chemistry ; Structure-Activity Relationship
    Chemical Substances Acetylcholinesterase (EC 3.1.1.7) ; Ligands ; Monoamine Oxidase (EC 1.4.3.4) ; Cholinesterase Inhibitors
    Language English
    Publishing date 2022-11-07
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms232113650
    Database MEDical Literature Analysis and Retrieval System OnLINE

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

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

    Molecules (Basel, Switzerland)

    2022  Volume 27, Issue 10

    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 ... ...

    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
    MeSH term(s) Anti-Bacterial Agents/chemistry ; Anti-Bacterial Agents/pharmacology ; DNA Gyrase/chemistry ; DNA Topoisomerase IV ; Gatifloxacin ; Molecular Docking Simulation ; Polyphenols ; Rubia
    Chemical Substances Anti-Bacterial Agents ; Polyphenols ; DNA Topoisomerase IV (EC 5.99.1.-) ; DNA Gyrase (EC 5.99.1.3) ; Gatifloxacin (L4618BD7KJ)
    Language English
    Publishing date 2022-05-19
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 1413402-0
    ISSN 1420-3049 ; 1431-5165 ; 1420-3049
    ISSN (online) 1420-3049
    ISSN 1431-5165 ; 1420-3049
    DOI 10.3390/molecules27103274
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: HAGE, the helicase antigen as a biomarker for breast cancer prognosis (WO2013144616).

    Wiese, Michael / Pajeva, Ilza K

    Expert opinion on therapeutic patents

    2014  Volume 24, Issue 6, Page(s) 723–725

    Abstract: Introduction: Breast cancer (BC) is the most common cancer in women and it ranks second as a cause of cancer death in women (after lung cancer). The receptor-based diagnosis of BC tumors allows application of more individual therapies. Depending on the ... ...

    Abstract Introduction: Breast cancer (BC) is the most common cancer in women and it ranks second as a cause of cancer death in women (after lung cancer). The receptor-based diagnosis of BC tumors allows application of more individual therapies. Depending on the status of the receptors and other risk markers, like tumor size and lymph node status, patients are assigned to risk classes. Invention of new biomarkers that could improve diagnosis and prognosis of BC patients is thus of an increased need.
    Areas covered: The invention estimates the possibility of using the amount of expression of helicase antigen (HAGE) in samples of BC tissue as a biomarker for screening and prognosis. A total of 1650 BC patients were tested for HAGE expression and analyzed for well-characterized prognostic and predictive factors. HAGE expression was found to correlate significantly with aggressive clinicopathological features. A total of 443 triple negative patients were analyzed for therapeutic treatment received and survival. The HAGE expression was identified as a predictor of response to anthracycline treatment. The result was confirmed by comparison with an independent validation group.
    Expert opinion: Тo identify patients who could be treated, a more detailed analysis taking into account, the full distribution spectrum of HAGE expression is desirable.
    MeSH term(s) Biomarkers, Tumor/analysis ; Breast Neoplasms/mortality ; Breast Neoplasms/pathology ; Breast Neoplasms/therapy ; DEAD-box RNA Helicases/analysis ; Female ; Humans ; Neoplasm Proteins/analysis ; Prognosis
    Chemical Substances Biomarkers, Tumor ; Neoplasm Proteins ; DDX43 protein, human (EC 3.6.1.-) ; DEAD-box RNA Helicases (EC 3.6.4.13)
    Language English
    Publishing date 2014-06
    Publishing country England
    Document type Journal Article
    ZDB-ID 1186201-4
    ISSN 1744-7674 ; 0962-2594 ; 1354-3776
    ISSN (online) 1744-7674
    ISSN 0962-2594 ; 1354-3776
    DOI 10.1517/13543776.2014.913025
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: In Memoriam: Prof. Dr. Joachim K. Seydel.

    Pajeva, Ilza / Wiese, Michael

    Molecular informatics

    2014  Volume 33, Issue 5, Page(s) 321

    Language English
    Publishing date 2014-05
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2537668-8
    ISSN 1868-1751 ; 1868-1743
    ISSN (online) 1868-1751
    ISSN 1868-1743
    DOI 10.1002/minf.201480571
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Book review of Structural Bioinformatics

    Pajeva Ilza K

    BioMedical Engineering OnLine, Vol 8, Iss 1, p

    An Algorithmic Approach by Forbes J. Burkowski

    2009  Volume 14

    Keywords Medicine (General) ; R5-920 ; Medicine ; R ; DOAJ:Medicine (General) ; DOAJ:Health Sciences
    Language English
    Publishing date 2009-07-01T00:00:00Z
    Publisher BioMed Central
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article: New Therapeutic Strategy for Overcoming Multidrug Resistance in Cancer Cells with Pyrazolo[3,4-

    Podolski-Renić, Ana / Dinić, Jelena / Stanković, Tijana / Tsakovska, Ivanka / Pajeva, Ilza / Tuccinardi, Tiziano / Botta, Lorenzo / Schenone, Silvia / Pešić, Milica

    Cancers

    2021  Volume 13, Issue 21

    Abstract: Tyrosine kinase inhibitors (TKIs) often interact with the multidrug resistant (MDR) phenotype of cancer cells. In some cases, TKIs increase the susceptibility of MDR cancer cells to chemotherapy. As the overexpression of membrane transporter P- ... ...

    Abstract Tyrosine kinase inhibitors (TKIs) often interact with the multidrug resistant (MDR) phenotype of cancer cells. In some cases, TKIs increase the susceptibility of MDR cancer cells to chemotherapy. As the overexpression of membrane transporter P-glycoprotein (P-gp) is the most common alteration in MDR cancer cells, we investigated the effects of TKI pyrazolo[3,4-
    Language English
    Publishing date 2021-10-22
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2527080-1
    ISSN 2072-6694
    ISSN 2072-6694
    DOI 10.3390/cancers13215308
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Molecular Modeling Approach to Study the PPARγ-Ligand Interactions.

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

    Methods in molecular biology (Clifton, N.J.)

    2019  Volume 1966, Page(s) 261–289

    Abstract: The chapter is focused on methods relevant for predictive toxicology and computer-aided drug design (adverse outcome pathway development, pharmacophore modeling, docking, and 3D QSAR analysis) and applied to study interactions between peroxisome ... ...

    Abstract The chapter is focused on methods relevant for predictive toxicology and computer-aided drug design (adverse outcome pathway development, pharmacophore modeling, docking, and 3D QSAR analysis) and applied to study interactions between peroxisome proliferator-activated receptor γ (PPARγ) and its ligands. The methods have been combined to develop an integrated in silico approach allowing both to predict potential PPARγ-mediated hepatotoxicity of receptor's full agonists, thus supporting hazard characterization, and to identify naturally derived antidiabetic triterpenoids potentially acting through PPARγ partial agonism.
    MeSH term(s) Humans ; Hypoglycemic Agents/pharmacology ; Ligands ; Molecular Docking Simulation/methods ; Oxazoles/pharmacology ; PPAR gamma/agonists ; PPAR gamma/chemistry ; PPAR gamma/metabolism ; Protein Conformation ; Quantitative Structure-Activity Relationship ; Rosiglitazone/pharmacology ; Tyrosine/analogs & derivatives ; Tyrosine/pharmacology
    Chemical Substances GW 409544 ; Hypoglycemic Agents ; Ligands ; Oxazoles ; PPAR gamma ; Rosiglitazone (05V02F2KDG) ; Tyrosine (42HK56048U)
    Language English
    Publishing date 2019-04-30
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-4939-9195-2_22
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Xanthates As Useful Probes for Testing the Active Sites of Cytochromes P450 4A11 and 2E1.

    Stoyanova, Tsveta / Lessigiarska, Iglika / Mikov, Momir / Pajeva, Ilza / Yanev, Stanislav

    Frontiers in pharmacology

    2017  Volume 8, Page(s) 672

    Abstract: Xanthates (alkyl or aryl derivatives of dithiocarbonic acid) have been shown to be selective mechanism-based inactivators of cytochromes P450 2B1/2B6 and 2E1 due to covalent binding of a reactive intermediate to apoprotein after double hydrogen ... ...

    Abstract Xanthates (alkyl or aryl derivatives of dithiocarbonic acid) have been shown to be selective mechanism-based inactivators of cytochromes P450 2B1/2B6 and 2E1 due to covalent binding of a reactive intermediate to apoprotein after double hydrogen abstraction at α-carbon atom, suggesting interaction of the xanthate dithiocarbonic head with the enzyme heme. The structures of xanthates with a long alkyl chain are similar to the fatty acids. Saturated fatty acids (FA) such as lauric acid (LA), are metabolized by different cytochrome P450 isoforms to ω- and (ω-1)-hydroxy products, in humans done by CYP4A11 and CYP2E1, respectively. In the present study we aimed at elucidating the possible interactions of xanthates with two cytochrome P450 isoforms CYP4A11 and CYP2E1 involved in the metabolism of the FA. Our experiments showed that LA-ω-hydroxylation by CYP4A11 is inhibited in a competitive manner by xanthates with long alkyl chain (C12-xanthate being the most potent inhibitor). On the other hand LA-(ω-1)-hydroxylation reaction by purified CYP2E1 is inactivated by a mechanism-based type. The suggested differences in the interactions of C12-xanthate with the two cytochrome P450 isoforms were investigated by molecular modeling using docking approach. The results suggested that in CYP2E1 active site C12-xanthate coordinates to the heme with its most vulnerable dithiocarbonic head leading to a mechanism-based inactivation. In CYP4A11 xanthate alkyl chain is exposed to the heme, thus, a potenial ω-hydroxylated xanthate product could be formed, which could inhibit in a competitive manner the hydroxylation of LA. The observed differences of xanthates interactions with the active sites of the two similar cytochrome P450 isoforms (CYP4A11 and CYP2E1) involved in the metabolism of FA, which lead to different changes in the enzyme activity, suggest that xanthates can be used as probing tools for analyzing enzyme active sites when exploring useful and selective compounds influencing FA homeostasis.
    Language English
    Publishing date 2017-09-22
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2587355-6
    ISSN 1663-9812
    ISSN 1663-9812
    DOI 10.3389/fphar.2017.00672
    Database MEDical Literature Analysis and Retrieval System OnLINE

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