2. Academic Validation
  3. Cytotoxic pyrrole-based gold(III) chelates target human topoisomerase II as dual-mode inhibitors and interact with human serum albumin

Cytotoxic pyrrole-based gold(III) chelates target human topoisomerase II as dual-mode inhibitors and interact with human serum albumin

  • Eur J Med Chem. 2025 Apr 5:287:117330. doi: 10.1016/j.ejmech.2025.117330.
Sheldon Sookai 1,  Matthew Akerman 2,  Mia Færch 3,  Yasien Sayed 3,  Orde Q Munro 4
Affiliations

Affiliations

  • 1 Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO WITS 2050, Johannesburg, South Africa. Electronic address: Sheldon.Sookai@wits.ac.za.
  • 2 School of Chemistry, University of KwaZulu-Natal, Pietermaritzburg, 3201, South Africa.
  • 3 Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2050, South Africa.
  • 4 Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO WITS 2050, Johannesburg, South Africa; School of Chemistry, University of Leeds, Woodhouse Lane, LS2 9JT, UK.
PMID: 39904146 DOI: 10.1016/j.ejmech.2025.117330
Abstract

Topoisomerase IIα (Top II) is a critical Enzyme that resolves DNA topology during transcription and replication. Inhibitors of Top II are used as Anticancer agents and are classified as interfacial poisons (IFPs) or catalytic inhibitors (CICs). Here, we report a novel class of cytotoxic, stable cationic gold(III) Schiff base chelates (AuL1, AuL2, and AuL3) with DNA-intercalating properties. In the NCI-60 screen, AuL1 and AuL3 exhibited potent cytotoxicity (mean GI50 values of 11 (7) μM and 14 (9) μM, respectively), whereas AuL2 showed minimal cytotoxicity. Cluster analysis aligned AuL1 and AuL3 with the Top II poison etoposide. Mechanistic studies revealed that AuL1 acts as an IFP at concentrations between 0.5 and 50 μM and as a CIC at concentrations between 50 and 500 μM. Further investigations demonstrated that all three gold(III) chelates bind to and intercalate DNA, the main substrate for Top II. Finally, binding studies with human serum albumin (HSA) indicated that the chelates have moderate affinity for the protein. Thermodynamic analysis indicates entropically driven binding, with minimal structural disruption observed via UV-CD spectroscopy. These findings highlight the dual mode Top II inhibition mechanism delineated for the gold(III) chelates and their favourable pharmacodynamic interactions with HSA, underscoring their potential as promising Anticancer agents.

Keywords

Albumin; DNA; NCI-60; Therapeutic; Topoisomerase.

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