Event Title

Synthesis and Evaluation of (Dihydroxyphenyl)pyridones as Aggregation Inhibitors for Alzheimer’s Amyloid-β Peptide

Poster Number

007

Faculty Mentor

Robin K. Lammi, Ph.D., and James M. Hanna Jr., Ph.D.

College

College of Arts and Sciences

Department

Department of Chemistry, Physics, and Geology

Location

Rutledge Building

Start Date

12-4-2019 12:00 PM

End Date

April 2019

Description

Amyloid-β peptide (Aβ) self-assembles into neurotoxic, β-structured aggregates, which are the primary component of the extracellular senile plaques characteristic of Alzheimer’s disease. A variety of small molecules have been shown to inhibit the aggregation process; typically, these contain aromatic groups and one or more hydrogen-bond donors. Previous studies in our group have demonstrated that biphenyltetrols exhibit varying degrees of efficacy as Aβ aggregation inhibitors. 3,3′,4,4′-biphenyltetrol (3,4-BPT) effectively abrogates Aβ aggregation at stoichiometric concentrations (IC50 ~ 1X); other biphenyltetrol isomers were found to be less effective (IC50 ~ 2X to >10X), perhaps due to differing abilities to bind to Aβ through hydrogen bonding. Recent modeling studies suggest that binding of small molecules to Aβ may occur via several types of intermolecular interactions, including both hydrogen bonding and π-π interactions (i.e., π-stacking). In addition, other studies indicate that π-interactions between benzene and electron-deficient heterocyclic aromatic rings are stronger than similar benzene-benzene interactions. Based on these observations, we hypothesized that incorporation of a pyridone unit into the above-described hydroxybiaryl scaffold may lead to increased inhibition of Aβ aggregation. We therefore synthesized 5-(3′,4′-dihydroxyphenyl)-2-pyridone (1) and 4-(3′,4′-dihydroxyphenyl)-2-pyridone (2) via Suzuki coupling of 3,4-dimethoxybenzeneboronic acid with an appropriate bromomethoxypyridine, followed by demethylation in aqueous HBr. Evaluation of these compounds using a Congo red spectral shift assay gave preliminary IC50 values of 3.3 ± 0.3X for 1 and 2.9 ± 0.5X for 2.

Previously Presented/Performed?

Southeast Regional Meeting of the American Chemical Society (SERMACS), Augusta, Georgia, November, 2018

Grant Support?

Supported by an SC INBRE grant from the National Institute for General Medical Sciences (NIH-NIGMS)

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Apr 12th, 12:00 PM Apr 18th, 2:00 PM

Synthesis and Evaluation of (Dihydroxyphenyl)pyridones as Aggregation Inhibitors for Alzheimer’s Amyloid-β Peptide

Rutledge Building

Amyloid-β peptide (Aβ) self-assembles into neurotoxic, β-structured aggregates, which are the primary component of the extracellular senile plaques characteristic of Alzheimer’s disease. A variety of small molecules have been shown to inhibit the aggregation process; typically, these contain aromatic groups and one or more hydrogen-bond donors. Previous studies in our group have demonstrated that biphenyltetrols exhibit varying degrees of efficacy as Aβ aggregation inhibitors. 3,3′,4,4′-biphenyltetrol (3,4-BPT) effectively abrogates Aβ aggregation at stoichiometric concentrations (IC50 ~ 1X); other biphenyltetrol isomers were found to be less effective (IC50 ~ 2X to >10X), perhaps due to differing abilities to bind to Aβ through hydrogen bonding. Recent modeling studies suggest that binding of small molecules to Aβ may occur via several types of intermolecular interactions, including both hydrogen bonding and π-π interactions (i.e., π-stacking). In addition, other studies indicate that π-interactions between benzene and electron-deficient heterocyclic aromatic rings are stronger than similar benzene-benzene interactions. Based on these observations, we hypothesized that incorporation of a pyridone unit into the above-described hydroxybiaryl scaffold may lead to increased inhibition of Aβ aggregation. We therefore synthesized 5-(3′,4′-dihydroxyphenyl)-2-pyridone (1) and 4-(3′,4′-dihydroxyphenyl)-2-pyridone (2) via Suzuki coupling of 3,4-dimethoxybenzeneboronic acid with an appropriate bromomethoxypyridine, followed by demethylation in aqueous HBr. Evaluation of these compounds using a Congo red spectral shift assay gave preliminary IC50 values of 3.3 ± 0.3X for 1 and 2.9 ± 0.5X for 2.