# (±)-2-Cyclohexyl-5-methoxy-2H-chromene, a Synthetic 5‑Methoxyflavone Derivative, Is a Selective DNA Polymerase‑β Inhibitor with Neuroprotective Activity against β‑Amyloid Toxicity

## TL;DR

A new compound inhibits DNA polymerase-β selectively and protects neurons from β-amyloid toxicity.

## Contribution

A selective DNA polymerase-β inhibitor with neuroprotective activity is developed and validated.

## Key findings

- Chromene selectively inhibits DNA polymerase-β without affecting primase/DNA pol-α complex activity.
- Chromene prevents β-amyloid-induced DNA replication and apoptosis in cultured neurons.
- The compound amplifies methylmethanesulfonate toxicity in wild-type but not DNA pol-β-null fibroblasts.

## Abstract

DNA polymerase-β (DNA pol-β) plays a critical
role
in β-amyloid-induced neurodegeneration by mediating aberrant
DNA replication in postmitotic neurons. In previous work, we demonstrated
that 5-methoxyflavone inhibits DNA pol-β, though computational
analyses suggested potential binding to the primase p58 subunit. Through
molecular modeling, here, we designed (S)-2-cyclohexyl-5-methoxy-2H-chromene (S-chromene), a novel flavone-derived
inhibitor exhibiting strong electrostatic complementarity with DNA
pol-β but weak interaction with primase p58, suggesting enhanced
selectivity. (R)-2-cyclohexyl-5-methoxy-2H-chromene (R-chromene) exhibited indistinguishable
binding properties from S-chromene. The compound
was obtained as a racemic mixture (chromene). Since the separated
enantiomers were unstable, all biological assays used the racemate.
DNA polymerase activity assay confirmed that chromene inhibited selectively
DNA pol-β without affecting the primase/DNA pol-α complex
activity. Also, the compound amplified methylmethanesulfonate toxicity
in wild-type but not DNA pol-β-null fibroblasts, validating
target-engagement. In cultured neurons, chromene effectively prevented
β-amyloid-induced DNA replication and apoptosis. Ours is the
first demonstration of a chromene acting as a selective DNA pol-β
inhibitor endowed with a unique mechanism of neuroprotection.