Metallodrugs provide important first-line treatment against various forms of human cancer. To overcome chemotherapeutic resistance and widen treatment possibilities, new agents with improved or alternative modes of action are highly sought after. Here, we present a click chemistry strategy for developing DNA damaging metallodrugs. The approach involves the development of a series of polyamine ligands where three primary, secondary or tertiary alkyne-amines were selected and ‘clicked’ using the copper-catalysed azide-alkyne cycloaddition reaction to a 1,3,5-azide mesitylene core to produce a family of compounds we call the ‘Tri-Click’ (TC) series. From the isolated library, one dominant ligand (TC1) emerged as a high-affinity copper(II) binding agent with potent DNA recognition and damaging properties. Using a range of in vitro biophysical and molecular techniques—including free radical scavengers, spin trapping antioxidants and base excision repair (BER) enzymes—the oxidative DNA damaging mechanism of copper-bound TC1 was elucidated. This activity was then compared to intracellular results obtained from peripheral blood mononuclear cells exposed to Cu(II)–TC1 where use of BER enzymes and fluorescently modified dNTPs enabled the characterisation and quantification of genomic DNA lesions produced by the complex. The approach can serve as a new avenue for the design of DNA damaging agents with unique activity profiles.

Artificial metallo‐nucleases (AMNs) are promising DNA damaging drug candidates. Here, we demonstrate how the 1,2,3‐triazole linker produced by the Cu‐catalysed azide‐alkyne cycloaddition (CuAAC) reaction can be directed to build Cu‐binding AMN scaffolds. We selected biologically inert reaction partners tris(azidomethyl)mesitylene and ethynyl‐thiophene to develop TC‐Thio, a bioactive C3‐symmetric ligand in which three thiophene‐triazole moieties are positioned around a central mesitylene core. The ligand was characterised by X‐ray crystallography and forms multinuclear CuII and CuI complexes identified by mass spectrometry and rationalised by density functional theory (DFT). Upon Cu coordination, CuII‐TC‐Thio becomes a potent DNA binding and cleaving agent. Mechanistic studies reveal DNA recognition occurs exclusively at the minor groove with subsequent oxidative damage promoted through a superoxide‐ and peroxide‐dependent pathway. Single molecule imaging of DNA isolated from peripheral blood mononuclear cells shows that the complex has comparable activity to the clinical drug temozolomide, causing DNA damage that is recognised by a combination of base excision repair (BER) enzymes.

Artificial metallo‐nucleases (AMNs) are promising DNA damaging drug candidates. Here, we demonstrate how the 1,2,3‐triazole linker produced by the Cu‐catalysed azide‐alkyne cycloaddition (CuAAC) reaction can be directed to build Cu‐binding AMN scaffolds. We selected biologically inert reaction partners tris(azidomethyl)mesitylene and ethynyl‐thiophene to develop TC‐Thio, a bioactive C3‐symmetric ligand in which three thiophene‐triazole moieties are positioned around a central mesitylene core. The ligand was characterised by X‐ray crystallography and forms multinuclear CuII and CuI complexes identified by mass spectrometry and rationalised by density functional theory (DFT). Upon Cu coordination, CuII‐TC‐Thio becomes a potent DNA binding and cleaving agent. Mechanistic studies reveal DNA recognition occurs exclusively at the minor groove with subsequent oxidative damage promoted through a superoxide‐ and peroxide‐dependent pathway. Single molecule imaging of DNA isolated from peripheral blood mononuclear cells shows that the complex has comparable activity to the clinical drug temozolomide, causing DNA damage that is recognised by a combination of base excision repair (BER) enzymes.

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An ew chemistry ……g enerated artificial metallonuclease is reported in the Research Article by Andrew Kellett et al. (e202305759). Theo xidative DNAd amaging properties of ap olynuclear copper binding ligand called TC-Thio is demonstrated. Copper-TC-Thio binds in the minor groove of genomic DNAa nd promotes damage via as uperoxide linked mechanism. Theinset picture shows copper ions,bound to the TC-Thio ligand, melting into the DNAd uplex and filling the reaction chamber with molten liquid DNA.

An ew click chemistry ……g enerated artificial metallonuclease is reported in the Research Article by Andrew Kellett et al. (e202305759). Theo xidative DNAd amaging properties of ap olynuclear copper binding ligand called TC-Thio is demonstrated. Copper-TC-Thio binds in the minor groove of genomic DNAa nd promotes damage via as uperoxide linked mechanism. Theinset picture shows copper ions,bound to the TC-Thio ligand, melting into the DNAd uplex and filling the reaction chamber with molten liquid DNA.