, 1999). An in vivo study showed that 6 weeks after the administration of a garlic extract, H. pylori-induced GSK458 cost gastritis in Mongolian gerbils was decreased in a dose-dependent manner compared with the control group, even though the number of viable H. pylori was not changed (Iimuro et al., 2002). Several epidemiological studies suggested that a decreased risk of gastric cancer is associated with an increasing consumption of allium vegetables (You et al., 1989), possibly due to an effect on H. pylori, as this organism is associated

with gastric cancer. Thus, it is very important to study the antibacterial mode of action of garlic constituents because of the high incidences of H. pylori-related diseases throughout the world. Although previous studies have revealed that the antimicrobial effect of garlic is mainly due to its chemical reaction with thiol groups of various enzymes, such as alcohol dehydrogenase

and thioredoxin reductase (Ankri & Mirelman, 1999), a detailed analysis is lacking of the global molecular responses induced by garlic and its derivatives, and a proteomic strategy is required to globally profile the cellular Smoothened Agonist concentration responses at the protein level under defined conditions. Allitridi, whose chemical constituent is diallyl trisulfide (DATS), is a proprietary garlic derivative and has been successfully used to treat both systemic fungal and bacterial infections in China (Shen et al., 1996). In the present investigation, to obtain a comprehensive picture of the antibacterial mode of action of allitridi in H. pylori, proteomic analysis was used to study the global protein alterations induced by allitridi treatment. In addition, the effects of allitridi on virulence factor production by H. pylori were also investigated at subinhibitory concentrations. Helicobacter pylori

26695 was kindly provided by Dr Zhang Jianzhong from the Chinese Disease Control and Prevention Center. Allitridi was obtained from Jinan Limin Pharmaceutical Co., Ltd (Shandong, China). The bacteria were cultured to the early exponential phase in Brucella broth containing 10% fetal bovine serum with 120 r.p.m. shaking in a microaerobic environment (5% O2, 10% CO2 and 85% N2) at 37 °C. Aliquots of 10 mL of the cell cultures were supplemented with a series of concentrations of allitridi TCL to examine its inhibitory effect. To assay viability at each time point (0, 6, 12 and 24 h), the number of CFU was determined by plating serial dilutions of cultures in duplicate on Skirrow agar plates with 5% (v/v) sheep blood. Each assay was replicated at least three times. Exponentially growing H. pylori supplemented with or without 1 μg mL−1 allitridi for 6 h were harvested by centrifugation and resuspended in lysis buffer containing 8 M urea, 2 M thiourea, 4% CHAPS, 1% dithiothreitol, 1% pharmalyte (pH range 3–10), 1% protease inhibitor and 1% nuclease mix (Amersham Biosciences).