Development and Application of a Chemical Probe Based on a Neuroprotective Flavonoid Hybrid for Target Identification Using Activity-Based Protein Profiling

Alzheimer’s disease (AD) is
the most common form of dementia,
and up to now, there are no disease-modifying drugs available. Natural
product hybrids based on the flavonoid taxifolin and phenolic acids
have shown a promising pleiotropic neuroprotective profile in cell
culture assays and even disease-modifying effects in vivo. However, the detailed mechanisms of action remain unclear. To elucidate
the distinct intracellular targets of 7-O-esters
of taxifolin, we present in this work the development and application
of a chemical probe, 7-O-cinnamoyltaxifolin-alkyne,
for target identification using activity-based protein profiling.
7-O-Cinnamoyltaxifolin-alkyne remained neuroprotective
in all cell culture assays. Western blot analysis showed a comparable
influence on the same intracellular pathways as that of the lead compound
7-O-cinnamoyltaxifolin, thereby confirming its suitability
as a probe for target identification experiments. Affinity pulldown
and MS analysis revealed adenine nucleotide translocase 1 (ANT-1)
and sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) as
intracellular interaction partners of 7-O-cinnamoyltaxifolin-alkyne
and thus of 7-O-esters of taxifolin.