👤 Sara Waheed

Alzheimer's disease (AD) is characterized by the gradual deterioration of cognitive functions, speech impairment, and memory loss. It can potentially be treated by targeting the beta-site amyloid precursor protein cleavage enzyme 1 (BACE1), which plays a key role in amyloid plaque formation, neurofibrillary tangles, and hyperphosphorylated tau protein. Current drugs have limitations in terms of safety, efficacy, and blood-brain barrier permeability. In view of this, this study was designed to determine the potential inhibitors of the BACE1 enzyme by virtual screening using a curated library of 415 natural products including terpenoids, phenolic compounds, and alkaloids from different medicinal plants. Based on the docking score and interaction analysis, 50 compounds were selected for the downstream analysis, such as ligand binding interactions, pharmacokinetics, druglikness and physicochemical parameters. Among the lead compounds, Palmatine (compound 45) and Berberine (compound 49), demonstrated optimal drug-likeness and blood-brain barrier permeability among the top compounds. 2-[(9Z,12Z)-heptadeca-9,12-dienyl]-6-hydroxybenzoic acid (compound 4) was inactive in most toxicity parameters. Pharmacophore analysis revealed that Palmatine and Berberine share similar features with the standard, highlighting their potential as effective compounds. Furthermore, structural chemistry analysis provided insights on their shared isoquinoline alkaloid framework, illustrating their structural similarities. Molecular dynamics simulations confirmed the stability of the Palmatine-BACE1 and Berberine-BACE1 complexes during a 50 ns production run. Overall, these findings highlighted the potential of Palmatine and Berberine as promising candidates for the experimental validation and the development of the drugs for the treatment of AD. Show less

The relationship between observed clinical phenotypes and underlying genotypes is blended or skewed in multiple molecular diagnoses, complicating a comprehensive molecular genetic diagnosis. We report two families with dual diagnoses, using the deafness-associated gene, COL4A6, to exemplify its contribution to blended, complex clinical presentations. This is an observational study within a large, ethnically diverse rare disease cohort, focusing on families with hearing loss and suspected dual diagnoses, followed by functional and structural studies of novel variants. Families were identified through a large rare disease sequencing initiative. Exome or genome sequencing was performed, with follow-up RNA studies for a synonymous COL4A6 variant. Spatial and temporal expression analysis in zebrafish traced col4a6 expression in the otic vesicle and ear from 1 to 5 days post-fertilization. Structural modeling was used to estimate variant impact on protein structure. We identified two families affected by multiple genetic disorders. The first family presented a missense COL4A6 variant (NM₀₃₃₆₄₁.4: c.1480G>A p.(Gly494Arg)), accounting for hearing loss, while a likely pathogenic HEXA variant (NM₀₀₀₅₂₀.6: c.902T>G p.(Met301Arg)) explained Tay-Sachs disease features. The second family exhibited a synonymous COL4A6 variant (NM₀₃₃₆₄₁.4: c.1767G>A p.(Pro589=)), leading to partial exon skipping and hearing loss, along with a pathogenic splice-site variant in DYM (NM₀₀₁₃₅₃₂₁₄.3: c.1125 + 1G>T p.?), causing the Dyggve-Melchior-Clausen disease. Our findings highlight the importance of recognizing dual molecular diagnoses to untangle blended phenotypes, as well as the diagnostic relevance of synonymous variants with predicted splicing effects. Show less