Synthesis and characterization of high affinity fluorogenic α-synuclein probes

Fluorescent small molecules are powerful tools for imaging alpha-synuclein pathology in vitro and in vivo. In this work, we explore benzofuranone as a potential scaffold for the design of fluorescent alpha-synuclein probes. These compounds have high affinity for alpha-synuclein, show fluorescent turn-on upon binding to fibrils, and display different binding to Lewy bodies, Lewy neurites and glial cytoplasmic inclusion pathologies in post-mortem brain tissue. These studies not only reveal the potential of benzofuranone compounds as alpha-synuclein specific fluorescent probes, but also have implications for the ways in which alpha-synucleinopathies are conformationally different and display distinct small molecule binding sites.