Designing dichlorobinaphthoquinone as a prooxidative anticancer agent based on hydrogen peroxide-responsive in situ production of hydroxyl radicals

First Direct and Unequivocal Electron Spin Resonance Spin-Trapping Evidence for pH-Dependent Production of Hydroxyl Radicals from Sulfate Radicals

“…Identical DMPO adducts were also observed when • OH was produced by three other typical • OH-generating systems in the absence and presence of • OH scavengers (Figures S8–S10). These typical • OH-generating systems include the classic • OH-generating Fenton system, − a well-known • OH source via irradiation of N -hydroxypyridine-2­(1 H )-thione (NHPT), , and the new metal-independent • OH-generating tetrachloro-1,4-benzoquinone (TCBQ)/H 2 O 2 system we have developed recently. ,− Especially, for the TCBQ/H 2 O 2 system, at pH = 7.4 and 11.0, the formation of DMPO/ • OH, DMPO/ • CH 3 , and DMPO/ • CH­(CH 3 )­OH in the absence and presence of DMSO and EtOH was very obvious, which further confirmed that • OH is indeed produced by the UV-PDS system.…”

“…In order to compare the similarities and differences to other typical • OH-generating systems, parallel studies were also conducted with the classic metal-dependent inorganic Fenton system Fe­(II)/H 2 O 2 , − the well-known photochemical • OH source N -hydroxypyridine-2­(1 H )-thione (NHPT), , and the new metal-independent organic Fenton-like system tetrachloro-1,4-benzoquinone (TCBQ)/H 2 O 2 recently developed by our research group. ,− …”