Regulatory Effects of Black Rice Extract on Helicobacter pylori Infection-Induced Apoptosis

Scope: Black rice extract (BRE) contains cyanidin 3-O-glucoside (C3G), an anthocyanin, as the major component. In this study, we found that BRE inhibits the mRNA and protein expression of genes encoding cytotoxin-associated protein A (cagA) and vacuolating protein A (vacA) in Helicobacter pylori 60190 strain. Methods and results: We performed RT-PCR and western blotting to show that BRE inhibits the mRNA and protein expression of SecA. Because SecA is involved in VacA export in bacteria, our result suggests a positive correlation between BRE-induced inhibition of secA expression and VacA secretion. Further, we perform MTT assay and flow cytometry to show that BRE decreases the apoptosis of H. pylori-infected KATO III cells. Finally, we perform western blotting to show that the cell-protective effect of BRE is associated with decreased levels of active proapoptotic proteins caspases and PARP and increased levels of antiapoptotic proteins survivin and XIAP in H. pylori-infected cells. Conclusion: Thus, our results indicate that BRE acts as a potent inhibitor of the biogenesis of H. pylori virulence proteins and decreases the apoptosis of H. pylori-infected cells. Moreover, our results suggest that BRE can be used to exert beneficial effects in patients with gastroduodenal diseases caused by H. pylori.