We have probed small molecule compound CID 9998128 as a potential multitarget drug for the Alzheimer's disease (AD) using in silico and in vitro experiments. By all-atom simulation and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method, we have demonstrated that this compound strongly binds to both amyloid β42 (Aβ) fibrils and β-secretase, and the van der Waals interaction dominates over the electrostatic interaction in binding affinity. A detailed analysis at the atomic level revealed that indazole in CID 99998128 structure made a major contribution to instability of all studied complexes. In vitro experiments have shown that CID 9998128 inhibits the Aβ amyloid fibrillization and is capable to clear Aβ fibrils. Moreover, the compound dose-dependently decreases β-site amyloid precursor protein cleaving enzyme (BACE-1) activity with EC value in micromolar range. Thus, our study has revealed that CID 9998128 is a good candidate for AD treatment through preventing production of Aβ peptides and degrading their aggregates. For drug design, we predict that the chemical structure of potent AD multitarget inhibitors should not contain indazole.

Exogenous insulin, used as a therapeutic agent for diabetes, forms insoluble deposits containing amyloid fibrillar structures near the administration site. We have analyzed the in vitro anti-amyloid activity of four green tea constituents: (-)-epigallocatechin gallate (EGCG), (-)-epicatechin (EC), gallic acid (GA), caffeine (CF), and their equimolar mixtures. Regarding individually tested compounds, only EGCG inhibited the fibrillization process. The individual EC, GA, and CF molecules were ineffective. The presence of EGCG in equimolar combinations with GA, EC, or CF was required for the inhibitory activity of most mixtures. Molecular docking revealed that EGCG interacts with an essential amyloidogenic region of insulin chain B. Individually inactive GA had a potentiating effect on the activity of EGCG. In contrast, EC and CF had a negative impact on the activity of the mixtures. We have observed diverse morphology and the amount of insulin amyloid aggregates formed in the presence of studied compounds. The distinct types of amyloid aggregates created in vitro in the presence of EGCG and other green tea constituents were characterized. Results indicate that the biological activity of individual molecules is not directly applicable to the pooled samples effects prediction.

The formation and accumulation of amyloid aggregates are the phenomena that accompany amyloidoses, which are currently untreatable and include Alzheimer’s and Parkinson’s diseases, diabetes mellitus, non-neuropathic lysozyme systemic amyloidosis, and others. One of the very promising therapeutic approaches seems to be an inhibition of amyloid formation and/or clearance of amyloid aggregates. Small molecules have a great potential to interfere with amyloid fibrillation of peptides and polypeptides, which can be improved by connection of cyclic structures into single multicyclic molecules and their dimerization. In our study, we focused on heterodimers consisting of 7-methoxytacrine (7-MEOTA) and 2-amino­benzo­thiazole (BTZ) parent molecules connected by an aliphatic linker. Using in vitro and in silico methods, we investigated the ability of studied compounds to inhibit the amyloid aggregation of hen egg white lysozyme. Heterodimerization led to significant improvement of inhibitory activity compared to that of the parent molecules. The efficiency of the heterodimers varied; the most effective inhibitor contained the longest linker, eight carbons long. We suggest that binding of a heterodimer to a lysozyme blocks the interaction between the β-domain and C-helix region essential for the formation of amyloid cross-β structure. Elongation of the linker ultimately enhances the compound’s ability to prevent this interaction by allowing the BTZ part of the heterodimer to bind more effectively, increasing the compound’s binding affinity, and also by greater steric obstruction. This study represents an important contribution to the recent rational design of potential lead small molecules with anti-amyloid properties, and the heterodimers studied are prospective candidates for the treatment of systemic lysozyme amyloidosis and other amyloid-related diseases.