The ability of sulfur compounds to scavenge ROS has been investigated as a possible antioxidant mechanism for these compounds. Allium compounds are known antioxidants, and Kim et al. have examined the radical scavenging activity of five allium compounds (S-allyl-l-cysteine (ALI), S-allyl-l-cysteine sulfoxide (SAC) [98], diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS) [148]. They determined that only SAC and ALI effectively protect ischemic neuronal cells from damage at 1–100 μM and 10–100 μM concentrations, respectively. These two compounds also effectively scavenge hydroxyl radical in vitro, but have no effect on hydrogen peroxide or superoxide levels. In contrast, DATS and DADS were efficient superoxide scavengers; however, they did not scavenge hydrogen peroxide or prevent neuronal damage. Surprisingly, DATS did not scavenge any radical species. From these results, the authors suggest that certain allium compounds could provide neuroprotective from ROS implicated in neurodegeneration [148].