Tunable Cysteine-Targeting Electrophilic Heteroaromatic Warheads Induce Ferroptosis

Once considered potential liabilities, the modern era
witnesses
a renaissance of interest in covalent inhibitors in drug discovery.
The available toolbox of electrophilic warheads is limited by constraints
on tuning reactivity and selectivity. Following our work on a class
of ferroptotic agents termed CETZOLEs, we discovered new tunable heterocyclic
electrophiles which are capable of inducing ferroptosis. The biological
evaluation demonstrated that thiazoles with an alkyne electrophile
at the 2-position selectively induce ferroptosis with high potency.
Density functional theory calculations and NMR kinetic studies demonstrated
the ability of our heterocycles to undergo thiol addition, an apparent
prerequisite for cytotoxicity. Chemoproteomic analysis indicated several
potential targets, the most prominent among them being GPX4 protein.
These results were further validated by western blot analysis and
the cellular thermal shift assay. Incorporation of these heterocycles
into appropriate pharmacophores generated highly cytotoxic agents
such as the analogue BCP-T.A, with low nM IC50 values in ferroptosis-sensitive cell lines.