Discovery of human Glutaminyl Cyclase inhibitors for the treatment of Alzheimer's disease

2017 Fiscal Year Annual Research Report

• Project/Area Number: 16F16385
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: ZHANG KAM 国立研究開発法人理化学研究所, 生命機能科学研究センター, チームリーダー (60558906)
• Co-Investigator(Kenkyū-buntansha): VIJAYAN DILEEP 国立研究開発法人理化学研究所, ライフサイエンス技術基盤研究センター, 外国人特別研究員
• Project Period (FY): 2016-11-07 – 2019-03-31
• Keywords: Alzheimer's disease / Glutaminyl cyclase / Drug design / Virtual screening

Outline of Annual Research Achievements

Alzheimer's disease (AD) is one of the major and chronic neurodegenerative disorders affecting the aged populations. Among various causative agents associated with the AD, Aβ aggregation and accumulation into plaques is one of the hallmark events. Human Glutaminyl cyclase (hQC) is found to be critically involved in the AD progression by mediating the formation of pGlu-Aβ peptides. Hence, inhibitors of hQC are useful for limiting the production of pGlu-Aβ peptides and thereby controlling the AD progression. In the current study, we are trying to identify potential hQC inhibitors using computational and experimental approaches. In our previous studies, using high throughput virtual screening, potential hQC inhibitors have been identified. The co-crystal structures of these inhibitors were determined along with their cytotoxicity profiles. The co-crystal structures explained novel binding modes to the ligands, which is highly promising for the future drug discovery studies.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The cytotoxicity profiles of 10 promising compounds has been determined with human neuroblastoma cell lines. The experiments were performed using two different methods such as MTT assay and using incucyte. Out of three concentrations tested, one was at the IC50 and the other two concentrations were higher and lower than IC50 values. A majority of the compounds except top active compounds (whose IC50 values were in nano-molar range) were exhibited cytotoxicity even at lower concentrations. The most active compounds were not exhibited any sort of cytotoxicity even at higher concentrations. Further, the most active compounds were then taken for MST analysis to determine the dissociation constants (Kd). The Kd value obtained from the experiment was comparable with their IC50 values. Molecular docking of histamine 3 receptor antagonists have been performed against hQC to design multi-target directed ligands. The promising ligand were subjected to enzymatic assay and crystallographic analysis.

Strategy for Future Research Activity

1. Since two of the H3R receptor antagonist exhibited promising activities in the computational studies, these molecules were taken for the in vitro IC50 calculations. The enzymatic assay is being carried out currently. Also, the co-crystal structure of these compounds with hQC is under investigation.
2. Since two of the compounds (obtained from high throughput virtual screening) exhibited promising results, they were subjected to structure based design. Several molecules were designed and their in silico binding studies were performed against hQC. Promising compounds are planned for custom synthesis and to be tested for their in vitro activities.