In addition, NP4P (300 μg/mL) did not affect the growth curves of S. aureus IFO12732 (Figure 2A) and E. coli JM109 (Figure 2B). These results indicate that NP4P was less toxic to microbes. Figure 2 Effect of NP4P on bacterial growth. Staphylococcus aureus IFO12732 (A) and Escherichia coli JM109 (B) in the logarithmic phase were suspended in 2 mL of IFO702 medium with or without 300 μg/mL of NP4P. Their optical densities were adjusted to 0.06-0.08 at 600 nm. The bacterial suspension was

incubated at 30°C. Bacterial growth was estimated by measuring the change in optical density. All experiments were performed in triplicate. Each data point represents the mean ± SEM. Enhancer activity for antimicrobial peptides selleck chemicals The parent peptide P4P inhibited the bactericidal activity of cecropin P4 and some other antimicrobial peptides ([22]; S. Ueno and Y. Kato, unpublished data), encouraging us to test whether NP4P affected the activities of other antimicrobial agents. We examined the effect of NP4P on the bactericidal activities of the nematode CSαβ-type cationic AMP ASABF-α [23–25] against S. aureus IFO12732 (Figure

3A) and polymyxin B against E. coli JM109 in 10 mM Tris-HCl, pH 7.4 (Figure 3B). Unexpectedly, NP4P enhanced these activities at ≥ 5 μg/mL in a dose-dependent manner. The dose-effect curves of ASABF-α and polymyxin B were shifted to almost 10 times Ilomastat concentration lower concentration in the presence of 100 μg/mL NP4P. buy PD173074 However, the enhancement was completely abolished in a high ionic strength condition (150 mM NaCl, 50 mM NaHCO3, 10 mM Tris-HCl, pH 7.4). Figure 3 NP4P enhancement of bactericidal

activities of AMPs. The dose-effect curves were determined in the presence of NP4P at various concentrations (0, 2.5, 5, 20, and 100 μg/mL). Bactericidal activities were measured against S. aureus IFO12732 for ASABF-α (A) and against E. coli JM109 to polymyxin B (B). Viability is defined as normalized number of viable cells to the number in the absence of ASABF-α or polymyxin B. Furthermore, we tested NP4P enhancement at 20 μg/mL for the activities of antimicrobial agents against buy Sorafenib various microbes (Table 1). The results can be summarized as: (1) The bactericidal activities of all tested membrane-disrupting AMPs (ASABF-α, polymyxin B, and nisin) were enhanced. (2) The enhancement was selective depending on the type of bacterial species. For instance, the activities of ASABF-α against S. aureus IFO12732 and E. coli JM109 were enhanced, whereas a lesser enhancement was observed against M. luteus IFO 12708, B. subtilis IFO3134, P. aeruginosa IFO3899, and S. marcescens IFO3736.