To test the effect of DMS on the concentration of extracellular oxidants, the MPP model was used to identify the cytoprotection of DMS. SH‐SY5Y cells were treated with or without 2 mm MPP for 48 h; then, the cell viability was evaluated by MTT test. Compared with MPP‐treated group (66 ± 4% of control, P < 0.01 vs. control), the cell viability in DMS‐treated groups increased to 76 ± 2% (6.2 μm), 79 ± 3% (12.5 μm), 82 ± 3% (25 μm), 84 ± 3% (50 μm), and 84 ± 5% (100 μm, Fig. 4D). Meanwhile, the cell viability of Met‐treated group raised from 52 ± 1% to 61 ± 4% (100 μm), 62 ± 5% (500 μm), and 70 ± 6% (1000 μm) of control (Fig. 4E).