Structural fingerprinting of pleiotropic flavonoids for multifaceted Alzheimer's disease

Roles of Apigenin and Nepetin in the Assembly Behavior and Cytotoxicity of Prion Neuropeptide PrP106-126

Development of potential inhibitors to prevent prion protein (PrP) fibrillation is a therapeutic strategy for prion diseases. The prion neuropeptide PrP106-126, a research model of abnormal PrP (PrPSc), presents similar physicochemical and biochemical characters to PrPSc, which is also a target of potential inhibitors against prion deposition. Many flavones have antioxidant, anti-inflammatory, and antibacterial properties, and they are applied in treating prion disorder and other amyloidosis as well. However, the inhibition mechanism of flavones on PrP106-126 fibrillation is still unclear. In the current work, apigenin and nepetin were used to suppress the aggregation of PrP106-126 and to alleviate the peptide-induced cytotoxicity. The results showed that apigenin and nepetin impeded the fibril formation of PrP106-126 and depolymerized the preformed fibrils. They were bound to PrP106-126 predominantly by hydrophobic and hydrogen bonding interactions. In addition, both flavones upregulated cell viability and decreased membrane leakage through reducing peptide oligomerization. The differences in inhibition and cell protection between the two small molecules were presumably attributed to the substitution of hydroxyl and methoxy groups in nepetin, which demonstrated the significant structure-function relationship of flavones with prion neuropeptide and the prospect of flavonoids as drug candidates against prion diseases.

Novel alkyl-substituted 4-methoxy benzaldehyde thiosemicarbazones: Multi-target directed ligands for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder affecting mental ability and interrupts neurocognitive functions. Treating multifactorial conditions of AD with a single-target-directed drug is highly difficult. Thus, a multi-target-directed ligand (MTDL) development strategy has been developed as a promising approach for the treatment of AD. Herein, we have synthesized two novel thiosemicarbazones as MTDLs and reported their bioactivities against diverse neuropathological events involved in AD. In vitro studies revealed that both compounds exhibited promising anticholinesterase activity (AChE, IC50 = 15.98 μM, MZET and IC50 = 30.23 μM, MZMT), well supported by a detailed computational study. Both analogs have shown good thermodynamic behaviour and stability through interactions with characteristic amino acid residues throughout simulation of 100 ns against acetylcholinesterase enzyme. In an electrophysiology assay, these analogs have shown a characteristic inhibitory response against the GluN1-1a + GluN2B subunit of N-methyl-D-aspartate receptors. Pre-treatment of BV-2 microglial cells with MZET effectively decreased nitrite production compared to nitrite produced by lipopolysaccharide-treated cells alone. Further, the effect of MZMT and MZET on autophagy regulation was determined using stably transfected SH-SY5Y neuroblastoma cells. MZET significantly enhanced the autophagy flux in neuroblastoma cells. A significant decrease in copper-catalysed oxidation of amyloid-β in presence of synthesized thiosemicarbazones was also observed. Collectively, our findings indicated that these analogs have potential as effective anti-AD candidates and can be used as a prototype to develop more safer multi-targeted anti-AD drugs.