Sodium sulfite causes gastric mucosal cell death by inducing oxidative stress

Sulfites are commonly used as a preservative and antioxidant additives in the food industry. Sulfites are absorbed by the gastrointestinal tract and distributed essentially to all body tissues. Although sulfites have been believed to be safe food additives, some studies have shown that they exhibit adverse effects in various tissues. In this study, we examined the cytotoxic effect of sodium sulfite (Na₂SO₃) against rat gastric mucosal cells (RGM1) and further investigated its underlying molecular mechanism. We demonstrated that exposure to Na₂SO₃ exerts significant cytotoxicity in RGM1 cells through induction of oxidative stress. Exposure of RGM1 cells to Na₂SO₃ caused a significant formation of protein carbonyls and 8-hydroxy-2'-deoxyguanosine, major oxidative stress markers, with a concomitant accumulation of carbonylated protein-related aggregates. Furthermore, we found that incubation of lysozyme with Na₂SO₃ evokes protein carbonylation and aggregation via the metal ion-catalyzed free radical formation derived from Na₂SO₃. Our results suggest that Na₂SO₃ might lead to gastric tissue injury via induction of oxidative stress by the formation of Na₂SO₃-related free radicals.