Non-competitive, cell-permeable inhibitor of protein tyrosine phosphatases (PTPs) (IC50 = 0.09 - 1.7 μM); displays irreversible inhibition through catalysis of the hydrogen peroxide-dependent oxidation of PTP. Enhances insulin signaling in vitro and insulin tolerance in ob/ob mice in vivo. Also inhibits several cytochrome P450 isoforms (IC50 <10 μM). Purity 98%. MW (observed): 241.25