In a 24-h time-course examination, the MIC of allitridi we obtained was about 1 μg mL−1, and doses higher than 1 μg mL−1 exerted an apparent bactericidal effect. Certainly, subinhibitory

concentrations of allitridi (25% and 50% of MIC) can still inhibit the growth of H. pylori in a concentration-dependent manner (Fig. 1). For the purpose of elucidating the bacteriostatic mechanism of allitridi in H. pylori, the following proteomic analysis was carried out with 1 μg mL−1 allitridi for 6 h to ensure that the H. pylori was completely inhibited, but still viable. To investigate global protein expression changes PR-171 purchase induced by allitridi, 2-DE analysis of H. pylori cultured with or without allitridi was performed. Figure 2 shows that a total of 21 protein spots were identified to be differentially expressed on the 2-DE maps of the two groups. According to their known or postulated functions,

all these proteins were classified in Y27632 Table 1, with functions involving energy metabolism, biosynthesis, bacterial virulence, redox reaction, protein fate and some unknown function. They will be discussed in detail in the following. The process of energy metabolism and biosynthesis is very important to bacterial growth and viability. In our experiment, two proteins (Aconitase B and F0F1 ATP synthase subunit α) responsible for energy metabolism were downregulated by allitridi. Simultaneously, many proteins involved in biosynthesis were also suppressed by allitridi. The 2-DE maps identified three enzymes (aspartate-semialdehyde dehydrogenase, phosphoserine

aminotransferase and phosphoglycerate dehydrogenase) related to amino acid biosynthesis, two proteins (translation elongation factor EF-G and ribosomal protein S1) involved in protein synthesis, transcription termination factor ρ participating in mRNA synthesis, and β-ketoacyl-acyl carrier protein synthase II (FabF) responsible for fatty acid biosynthesis. The above findings revealed that allitridi has multiple inhibitory effects targeting proteins involved in energy metabolism and biosynthesis, leading to the inhibition of H. pylori growth. Our data showed that two important virulence proteins of H. pylori, cytotoxin-associated gene A (CagA) and neutrophil-activating protein (NapA), were downregulated Adenosine by allitridi. Previous studies have revealed that infection with the cagA-positive H. pylori is associated with higher grades of gastric mucosal inflammation, atrophic gastritis and gastric carcinoma (Hatakeyama & Higashi, 2005). Our results indicated that allitridi at MIC can effectively suppress the production of CagA, which would considerably alleviate the pathogenicity of H. pylori. It has been well documented that NapA plays a major role in neutrophil and monocyte recruitment and activation, resulting in the production of reactive oxygen species by these cells (Evans et al., 1995; Satin et al., 2000). Our data indicated that the virulence of H.