Alzheimer's disease (AD) is a complex disease with an unknown etiology. Available treatments, limited to cholinesterase inhibitors and N-methyl-d-aspartate receptor (NMDAR) antagonists, provide symptomatic relief only. As single-target therapies have not proven effective, rational specific-targeted combination into a single molecule represents a more promising approach for treating AD, and is expected to yield greater benefits in alleviating symptoms and slowing disease progression. In the present study, we designed, synthesized, and biologically evaluated 24 novel N-methylpropargylamino-quinazoline derivatives. Initially, compounds were thoroughly inspected by in silico techniques determining their oral and CNS availabilities. We tested, in vitro, the compounds' effects on cholinesterases and monoamine oxidase A/B (MAO-A/B), as well as their impacts on NMDAR antagonism, dehydrogenase activity, and glutathione levels. In addition, we inspected selected compounds for their cytotoxicity on undifferentiated and differentiated neuroblastoma SH-SY5Y cells. We collectively highlighted II-6h as the best candidate endowed with a selective MAO-B inhibition profile, NMDAR antagonism, an acceptable cytotoxicity profile, and the potential to permeate through BBB. The structure-guided drug design strategy applied in this study imposed a novel concept for rational drug discovery and enhances our understanding on the development of novel therapeutic agents for treating AD.

• Keywords
• Alzheimer’s disease, N-methyl-d-aspartate receptor, acetylcholinesterase, enzyme inhibition, monoamine oxidase A/B, multi-target directed ligands,
• MeSH
• Acetylcholinesterase metabolism   MeSH
• Alzheimer Disease * drug therapy   MeSH
• Cholinesterase Inhibitors therapeutic use   MeSH
• Monoamine Oxidase Inhibitors therapeutic use   MeSH
• Humans MeSH
• Monoamine Oxidase metabolism   MeSH
• Neuroblastoma * drug therapy   MeSH
• Drug Design MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Cholinesterase Inhibitors MeSH
• Monoamine Oxidase Inhibitors MeSH
• Monoamine Oxidase MeSH

PURPOSE: Titanium dioxide nanoparticles, 25 nm in size of crystallites (TiO2 P25), are among the most produced nanomaterials worldwide. The broad use of TiO2 P25 in material science has implied a request to evaluate their biological effects, especially in the lungs. Hence, the pulmonary A549 cell line has been used to estimate the effects of TiO2 P25. However, the reports have provided dissimilar results on caused toxicity. Surprisingly, the physicochemical factors influencing TiO2 P25 action in biological models have not been evaluated in most reports. Thus, the objective of the present study is to characterize the preparation of TiO2 P25 for biological testing in A549 cells and to evaluate their biological effects. METHODS: We determined the size and crystallinity of TiO2 P25. We used four techniques for TiO2 P25 dispersion. We estimated the colloid stability of TiO2 P25 in distilled water, isotonic NaCl solution, and cell culture medium. We applied the optimal dispersion conditions for testing the biological effects of TiO2 P25 (0-100 µg.mL-1) in A549 cells using biochemical assays (dehydrogenase activity, glutathione levels) and microscopy. RESULTS: We found that the use of fetal bovine serum in culture medium is essential to maintain sufficient colloid stability of dispersed TiO2 P25. Under these conditions, TiO2 P25 were unable to induce a significant impairment of A549 cells according to the results of biochemical and microscopy evaluations. When the defined parameters for the use of TiO2 P25 in A549 cells were met, similar results on the biological effects of TiO2 P25 were obtained in two independent cell laboratories. CONCLUSION: We optimized the experimental conditions of TiO2 P25 preparation for toxicity testing in A549 cells. The results presented here on TiO2 P25-induced cellular effects are reproducible. Therefore, our results can be helpful for other researchers using TiO2 P25 as a reference material.

• Keywords
• A549 cells, P25, dispersion, nanoparticles, nanotoxicity, titanium dioxide,
• MeSH
• A549 Cells MeSH
• Sodium Chloride MeSH
• Glutathione MeSH
• Metal Nanoparticles MeSH
• Humans MeSH
• Nanoparticles * chemistry   MeSH
• Oxidoreductases MeSH
• Lung MeSH
• Serum Albumin, Bovine * MeSH
• Titanium MeSH
• Water MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Sodium Chloride MeSH
• Glutathione MeSH
• Oxidoreductases MeSH
• Serum Albumin, Bovine * MeSH
• Titanium MeSH
• titanium dioxide MeSH Browser
• Water MeSH