Biological Evaluation of 8-Hydroxyquinolines as Multi-Target Directed Ligands for Treating Alzheimer's Disease

Repurposing of 8-Hydroxyquinoline-based Butyrylcholinesterase and Cathepsin B Ligands as Potent Non-peptidic Deoxyribonuclease I Inhibitors

A library of 31 butyrylcholinesterase (BChE) and cathepsin B (CatB) inhibitors, was screened in vitro for inhibition of deoxyribonuclease I (DNase I). Compounds 22, 8 and 7 are among the most potent synthetic non-peptide DNase I inhibitors reported up to date. Three 8-hydroxyquinoline analogues inhibited both DNase I and BChE with IC50 values below 35 µM and 50 nM, respectively, while 2 nitroxoline derivatives inhibited DNase I and Cat B endopeptidase activity with IC50 values below 60 µM and 20 µM, respectively. Selected derivatives were screened for various co-target binding affinities at dopamine D2 and D3, histamine H3 and H4 receptors and inhibition of 5-lipoxygenase. Compound 8 bound to the H3 receptor and is highlighted as the most promising multifunctional ligand with a favorable pharmacokinetic profile and one of the most potent non-peptide DNase I inhibitors. The present study demonstrates that 8-hydroxyquinoline is a structural fragment critical for DNase I inhibition in the presented series of compounds.

An oxidation responsive nano-radiosensitizer increases radiotherapy efficacy by remolding tumor vasculature

As an excellent candidate material for nano-sensitizers, gold nanostructures have shown great potential in radiotherapy. Nevertheless, severe hypoxia and low accumulation of nanomedicine caused by poor perfusion at the tumor site have significantly reduced radiotherapy efficacy. Vascular normalization has gained attention owing to its ability to relieve hypoxia and increase perfusion. The synergistic therapy of tumor vascular normalization and radiotherapy has become a new option to increase anti-cancer efficacy. However, the commonly used strategy of suppressing a single growth factor to induce vascular normalization is limited by tumor compensatory effects. In this work, we developed a strategy to inhibit oxidative stress in tumors by generating chelating agents in response to hydrogen peroxide, thereby inhibiting multi-angiogenic factors simultaneously to normalize blood vessels. Concretely, sodium alginate (SA) reacted with 8-quinoline boric acid (QBA) to form SA-QBA. Then gold nanoparticles (Au NPs) were modified with SA-QBA to obtain Au@SA-QBA. The system was simple in structure and could generate 8HQ in response to H₂O₂in vitro to inhibit oxidative stress and reduce the expression of VEGF, bFGF, and Ang-2. In vivo, the perfusion unit (PU) increased by 78% after Au@SA-QBA treatment, and the coverage of pericytes increased by 32%, which in turn induced vascular normalization. In addition, blood routine and blood biochemical tests confirmed its good biocompatibility and 8HQ was not detected in the supernatant after homogenization of major organs. More importantly, after the synergistic treatment of vascular normalization and radiotherapy (4 Gy), the tumor growth inhibition rate was increased by 38.6% compared to the Au@SA-treated group with negligible side effects to normal tissues.

Protein Formulations Containing Polysorbates: Are Metal Chelators Needed at All?

Proteins are prone to post-translational modifications at specific sites, which can affect their physicochemical properties, and consequently also their safety and efficacy. Sources of post-translational modifications include oxygen and reactive oxygen species. Additionally, catalytic amounts of Fe(II) or Cu(I) can promote increased activities of reactive oxygen species, and thus catalyse the production of particularly reactive hydroxyl radicals. When oxidative post-translational modifications are detected in the biopharmaceutical industry, it is common practice to add chelators to the formulation. However, the resultant complexes with metals can be even more damaging. Indeed, this is supported here using an ascorbate redox system assay and peptide mapping. Ethylenediaminetetraacetic acid (EDTA) addition strongly accelerated the formation of hydroxyl radicals in an iron-ascorbate system, while diethylenetriaminepentaacetic acid (DTPA) addition did not. When Fe(III) was substituted with Cu(II), EDTA addition almost stopped hydroxyl radical production, whereas DTPA addition showed continued production, but at a reduced rate. Further, EDTA accelerated metal-catalysed oxidation of proteins, and thus did not protect them from Fe-mediated oxidative damage. As every formulation is unique, justification for EDTA or DTPA addition should be based on experimental data and not common practice.