IC50: 170 nM (PDI).

3-Methyltoxoflavin is a potent Protein disulfide isomerase (PDI) inhibitor, with an IC ₅₀ of 170 nM. 3-Methyltoxoflavin is toxic in a panel of human glioblastoma cell lines. From the screen, 3-Methyltoxoflavin emerges as the most cytotoxic inhibitor of PDI. Bromouridine labeling and sequencing (Bru-seq) of nascent RNA reveals that 3-Methyltoxoflavin induces Nrf2 antioxidant response, ER stress response, and autophagy. Specifically, 3-Methyltoxoflavin upregulates heme oxygenase 1 and SLC7A11 transcription and protein expression and represses PDI target genes such as TXNIP and EGR1. Interestingly, 3-Methyltoxoflavin-induced cell death does not proceed via apoptosis or necrosis, but by a mixture of autophagy and ferroptosis.