In Vitro Inhibitory Effect of Flavonoids on Growth, Infection and Vacuolation of Helicobacter pylori

Abstract

Flavonoids, which are main constituents of herbal medicines, have been reported to inhibit the growth of Helicobacter pylori (HP). Therefore, to evaluate the anti-HP activity of some flavonoids (flavanols, flavones, flavonols and isoflavonoids), their effects on the growth and vacuolation of HP as well as the infective properties of HP against HeLa cells were investigated. Catechins, quercetin and naringenin weakly inhibited the growth of HP, but all tested compounds did not inhibit HP infection into KATO III cells and HP urease activity. Quercetin and naringenin inhibited HP VacA vacuolation in HeLa cells with IC₅₀ values of 0.046 and 0.36 mM, respectively. Quercetin also inhibited procaspase-3 activation to caspase-3 in HeLa cells induced by HP VacA toxin, which may induce cell death via the proteolytic activation of a cascade of caspases. However, quercetin did not affect Bax and Bcl-2 protein levels. Based on these findings, quercetin may improve gastric cell death by inhibiting apoptotic signaling by HP VacA toxin.

Abbreviations

HP:Helicobacter pylori

BSA:bovine serum albumin

ESL:enhanced chemiluminescence

MIC:minimum inhibitory concentration

MTT:methylthiazolyldiphenyl-tetrazolium bromide

PBS:phosphate-buffered saline

VacA:Vacuolating cytotoxin

Key words

Helicobacter pylori - VacA toxin - procaspase-3 - flavonols - flavones - flavanols - isoflavonoids

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