Functionalized Allopurinols Targeting Amyloid-Binding Alcohol Dehydrogenase Rescue Aβ-Induced Mitochondrial Dysfunction

Abstract

Alzheimer’s disease (AD) is the most common dementia affecting one in nine people over 65. Only a handful of small-molecule drugs and the anti-β amyloid (Aβ) antibody aducanumab are approved to treat AD. However, they only serve to reduce symptoms of advanced disease. Novel treatments administered early in disease progression before the accumulation of Aβ and tau reaches the threshold where neuroinflammation is triggered and irreversible neuronal damage occurs are more likely to provide effective therapy. There is a growing body of evidence implying that mitochondrial dysfunction occurs at an early stage of AD pathology. The mitochondrial enzyme amyloid-binding alcohol dehydrogenase (ABAD) binds to Aβ potentiating toxicity. Moreover, ABAD has been shown to be overexpressed in the same areas of the brain most affected by AD. Inhibiting the Aβ–ABAD protein–protein interaction without adversely affecting normal enzyme turnover is hypothesized to be a potential treatment strategy for AD. Herein, we conduct structure–activity relationship studies across a series of functionalized allopurinol derivatives to determine their ability to inhibit Aβ-mediated reduction of estradiol production from ABAD. The lead compound resulting from these studies possesses potent activity with no toxicity up to 100 μM, and demonstrates an ability to rescue defective mitochondrial metabolism in human SH-SY5Y cells and rescue both defective mitochondrial metabolism and morphology ex vivo in primary 5XFAD AD mouse model neurons.

Physiologically relevant fluorescent assay for identification of 17β‐hydroxysteroid dehydrogenase type 10 inhibitors

“…E2 as an enzyme substrate has been used several times to measure the HSD10 enzymatic activity with different method readouts, including absorbance (Aitken et al, 2017; Powell et al, 2000; Schmidt et al, 2020; Shafqat et al, 2003; Yan et al, 1999), thin‐layer chromatography (TLC) method (He et al, 1999), TLC in combination with radioactive‐labelled E2 (Ayan et al, 2012; Boutin et al, 2018, 2021; Boutin & Poirier, 2018) or ELISA‐based E2 determination (Morsy et al, 2022). TLC detection method was also used for the determination of HSD10 activity using ALLOP as the substrate (Boutin et al, 2018; He, Wegiel, & Yang, 2005; Yang et al, 2009).…”

Protein Interactome of Amyloid-β as a Therapeutic Target

“…Secondly, Huperzine A, an alkaloid isolated from lycopodium, was found to reduce the deposition of Aβ and the ABAD level, as well to weaken Aβ–ABAD interaction and finally to ameliorate cerebral mitochondrial function in APP/PS1 mice [ 127 ]. Evidence of the neuroprotective effect of ABAD blocking comes also from the recent data obtained in experiments on human SH-SY5Y cells and the culture of primary neurons of 5xFAD transgenic mice; ABAD inhibition was performed with allopurinol derivatives and resulted in a reduction in Aβ-induced mitochondrial dysfunction [ 128 ].…”

C-3 Steroidal Hemiesters as Inhibitors of 17β-Hydroxysteroid Dehydrogenase Type 10

“…To date, several groups of 17β-HSD10 inhibitors have been described in the literature. For details, see the review of Vinklarova et al They can be divided into several groups based on their structure, namely, benzothiazole-based ureas, − pyrazole-pyrimidine compounds, , steroidal inhibitors, − and risperidone or its analogs . Based on the mechanism of action, inhibitors of 17β-HSD10 are designed to either block the catalytic activity of the enzyme or modulate the interaction of 17β-HSD10 with amyloid-β (Aβ) that is contributing to Aβ-induced toxicity by promoting mitochondrial dysfunction.…”