DNA, the biopolymer as a target material for metalloinsertors: From chemistry to preclinical implications

Characterization of Antimicrobial, Antioxidant, and Leishmanicidal Activities of Schiff Base Derivatives of 4-Aminoantipyrine

Our main interest is the characterization of compounds to support the development of alternatives to currently marketed drugs that are losing effectiveness due to the development of resistance. Schiff bases are promising biologically interesting compounds having a wide range of pharmaceutical properties, including anti-inflammatory, antipyretic, and antimicrobial activities, among others. In this work, we have synthesized 12 Schiff base derivatives of 4-aminoantipyrine. In vitro antimicrobial, antioxidant, and cytotoxicity properties are analyzed, as well as in silico predictive adsorption, distribution, metabolism, and excretion (ADME) and bioactivity scores. Results identify two potential Schiff bases: one effective against E. faecalis and the other with antioxidant activity. Both have reasonable ADME scores and provides a scaffold for developing more effective compounds in the future. Initial studies are usually limited to laboratory in vitro approaches, and following these initial studies, much research is needed before a drug can reach the clinic. Nevertheless, these laboratory approaches are mandatory and constitute a first filter to discriminate among potential drug candidates and chemical compounds that should be discarded.

Metal-mediated diradical tuning for DNA replication arrest via template strand scission

A series of M(PyED)·X (X = 2Cl-, SO42-) pyridine-metalloenediyne complexes [M = Cu(II), Fe(II), or Zn(II)] and their independently synthesized, cyclized analogs have been prepared to investigate their potential as radical-generating DNA-damaging agents. All complexes possess a 1:1 metal-to-ligand stoichiometry as determined by electronic absorption spectroscopy and X-ray diffraction. Solution structural analysis reveals a pπ Cl [Formula: see text] Cu(II) LMCT (22,026 cm-1) for Cu(PyED)·2Cl, indicating three nitrogens and a chloride in the psuedo-equatorial plane with the remaining pyridine nitrogen and solvent in axial positions. EPR spectra of the Cu(II) complexes exhibit an axially elongated octahedron. This spectroscopic evidence, together with density functional theory computed geometries, suggest six-coordinate structures for Cu(II) and Fe(II) complexes and a five-coordinate environment for Zn(II) analogs. Bergman cyclization via thermal activation of these constructs yields benzannulated product indicative of diradical generation in all complexes within 3 h at 37 °C. A significant metal dependence on the rate of the reaction is observed [Cu(II) > Fe(II) > Zn(II)], which is mirrored in in vitro DNA-damaging outcomes. Whereas in situ chelation of PyED leads to considerable degradation in the presence of all metals within 1 h under hyperthermia conditions, Cu(II) activation produces >50% compromised DNA within 5 min. Additionally, Cu(II) chelated PyED outcompetes DNA polymerase I to successfully inhibit template strand extension. Exposure of HeLa cells to Cu(PyBD)·SO4 (IC50 = 10 μM) results in a G2/M arrest compared with untreated samples, indicating significant DNA damage. These results demonstrate metal-controlled radical generation for degradation of biopolymers under physiologically relevant temperatures on short timescales.