Diacylfuroxans Are Masked Nitrile Oxides That Inhibit GPX4 Covalently

GPX4 represents a promising yet difficult-to-drug therapeutic target for the treatment of, among others, drug-resistant cancers. While most GPX4 inhibitors rely on a chloroacetamide moiety to modify covalently the protein’s catalytic selenocysteine residue, the discovery and mechanistic elucidation of structurally diverse GPX4-inhibiting molecules has uncovered novel electrophilic warheads that bind and inhibit GPX4. Here we report our discovery that diacylfuroxans can act as masked nitrile oxides that inhibit GPX4 covalently. These observations illuminate a novel molecular mechanism of action for biologically active furoxans and also suggest that nitrile oxides may be uniquely suited to targeting GPX4.