{
  "abstract": "Background: DNase I inhibitors may be useful as biochemical tools and as potential leads for investigating pathological processes associated with excessive DNA degradation. Squaramides represent attractive scaffolds for drug discovery owing to their rigid, highly polarized structure and versatile hydrogen-bonding properties. Methods: Four novel pyridine-containing squaramides (5a–5d), comprising two symmetric and two asymmetric derivatives, were synthesized and structurally characterized by spectroscopic methods and, for 5a and 5b, single-crystal X-ray diffraction. Their DNase I inhibitory activity and cytotoxicity were evaluated experimentally. Comparative structure–activity analysis, molecular docking, molecular descriptor calculations, and in silico ADME profiling were additionally performed. Results: All compounds inhibited bovine pancreatic DNase I, with IC50 values ranging from 34.42 ± 5.86 to 61.95 ± 9.61 μM. Compound 5a showed the highest inhibitory activity within the present series (IC50 = 34.42 ± 5.86 μM). Comparison with five previously reported structurally related derivatives identified preliminary structure–activity trends, with 5a exhibiting the highest activity among the nine compounds considered. Molecular docking predicted a common preferred binding region within the major DNA-contact/catalytic region of DNase I and suggested possible noncovalent ligand–enzyme interactions. Molecular descriptor calculations revealed differences in the electronic properties of selected compounds, while in silico ADME analysis predicted generally favorable physicochemical and absorption-related properties together with potential pharmacokinetic liabilities. No measurable cytotoxicity was observed against the investigated cancer cell lines at the tested concentrations. Conclusions: Pyridine-containing squaramides represent a promising scaffold for further investigation as DNase I inhibitors, with 5a providing a useful starting point for subsequent structural optimization and mechanistic studies.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000 Sofia, Bulgaria",
    "Centre of Excellence in Informatics and Information and Communication Technologies, Bulgarian Academy of Sciences, Akad. Georgi Bonchev Str., Block 2 and 25A, 1113 Sofia, Bulgaria",
    "Department of General and Inorganic Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria",
    "Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str., Bl. 9, 1113 Sofia, Bulgaria",
    "Department of Pharmacology, Pharmacotherapy and Toxicology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000 Sofia, Bulgaria",
    "Department of Pharmacy, Faculty of Medicine, University of Niš, Blvd. Dr Zorana Đinđića 81, 18000 Niš, Serbia",
    "Department of Chemistry, Faculty of Medicine, University of Niš, Blvd. Dr Zorana Đinđića 81, 18000 Niš, Serbia",
    "Institute of Mineralogy and Crystallography, “Akad. Ivan Kostov”, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Bl. 107, 1113 Sofia, Bulgaria",
    "Center of Competence “Personalized Innovative Medicine”—2 PERIMED—2, Vasil Aprilov Blvd. 15A, 4002 Plovdiv, Bulgaria"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 11,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Mariyana Atanasova",
      "orcid": "0000-0001-9761-0355"
    },
    {
      "affs": [
        2
      ],
      "name": "Nina Ruseva"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "Georgi Tirolski"
    },
    {
      "affs": [
        3
      ],
      "name": "Simeon Stoyanov"
    },
    {
      "affs": [
        5
      ],
      "name": "Ana Marković"
    },
    {
      "affs": [
        6
      ],
      "name": "Andrija Šmelcerović",
      "orcid": "0000-0001-7724-0967"
    },
    {
      "affs": [
        7
      ],
      "name": "Magdalena Angelova"
    },
    {
      "affs": [
        7,
        8
      ],
      "name": "Hristina Sbirkova-Dimitrova"
    },
    {
      "affs": [
        0
      ],
      "name": "Adriana Bakalova",
      "orcid": "0000-0002-3017-3258"
    },
    {
      "affs": [
        1,
        4
      ],
      "name": "Rositsa Mihaylova",
      "orcid": "0000-0001-5763-0730"
    },
    {
      "affs": [
        0,
        1,
        3
      ],
      "name": "Emiliya Cherneva",
      "orcid": "0000-0002-1097-1850"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4g001f0zzw172.bib",
  "cited_by": 0,
  "doi": "10.3390/molecules31193548",
  "fulltext_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13667282/?tool=EBI",
  "id": "4g001f0zzw172",
  "issns": [
    "1420-3049"
  ],
  "landing_url": "https://europepmc.org/article/PMC/PMC13667282",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1605|Synthesis and biological activity"
    ]
  ],
  "openalex": "W7220441576",
  "pdf_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13667282/pdf/?tool=EBI",
  "pmcid": "PMC13667282",
  "pmid": null,
  "published": "2026-10-01",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/4g001f0zzw172.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:31Z",
      "native_id": "PMC:PMC13667282",
      "source": "europepmc",
      "url": "https://europepmc.org/article/PMC/PMC13667282"
    },
    {
      "first_seen": "2026-10-30T12:18:42Z",
      "native_id": "10.3390/molecules31193548",
      "source": "crossref",
      "url": "https://www.mdpi.com/1420-3049/31/19/3548"
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  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1605|Synthesis and biological activity",
      "subfield": "organic"
    }
  ],
  "title": "Synthesis, Biological Evaluation, and Molecular Docking of Pyridine-Containing Squaramides as DNase I Inhibitors",
  "title_text": "Synthesis, Biological Evaluation, and Molecular Docking of Pyridine-Containing Squaramides as DNase I Inhibitors",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:42Z",
  "url": "https://research.draconitic.com/paper/4g001f0zzw172",
  "venue": "Molecules (Basel, Switzerland)",
  "versions": []
}