Polypyridyl‐Based Copper Phenanthrene Complexes: Combining Stability with Enhanced DNA Recognition

다국어 초록 (Multilingual Abstract)

We report a series of copper(II) artificial metallo‐nucleases (AMNs) and demonstrate their DNA damaging properties and in‐vitro cytotoxicity against human‐derived pancreatic cancer cells. The compounds combine a tris‐chelating polypyridyl ligand, di‐(2‐pycolyl)amine (DPA), and a DNA intercalating phenanthrene unit. Their general formula is Cu‐DPA‐N,N' (where N,N'=1,10‐phenanthroline (Phen), dipyridoquinoxaline (DPQ) or dipyridophenazine (DPPZ)). Characterisation was achieved by X‐ray crystallography and continuous‐wave EPR (cw‐EPR), hyperfine sublevel correlation (HYSCORE) and Davies electron‐nuclear double resonance (ENDOR) spectroscopies. The presence of the DPA ligand enhances solution stability and facilitates enhanced DNA recognition with apparent binding constants (Kapp) rising from 105 to 107 m−1 with increasing extent of planar phenanthrene. Cu‐DPA‐DPPZ, the complex with greatest DNA binding and intercalation effects, recognises the minor groove of guanine–cytosine (G‐C) rich sequences. Oxidative DNA damage also occurs in the minor groove and can be inhibited by superoxide and hydroxyl radical trapping agents. The complexes, particularly Cu‐DPA‐DPPZ, display promising anticancer activity against human pancreatic tumour cells with in‐vitro results surpassing the clinical platinum(II) drug oxaliplatin.
A new class of stabilised artificial metallo‐nuclease (AMN) combining a di‐(2‐pycolyl)amine (DPA) scaffold with the copper(II) N,N’‐phenanthrene chemical nuclease core is reported. Three compounds of general formula [Cu(DPA)(N,N’)]2+ were structurally determined by single X‐ray crystallography and their solution properties characterised by cw‐EPR, HYSCORE, and ENDOR spectroscopies. The compounds demonstrate excellent DNA binding properties—particularly Cu‐DPA‐DPPZ—with excellent in‐vitro cytotoxicity toward human pancreatic tumour cells.