ABSTRACT
In the present study, the antimicrobial activity of glycyrrhetinic acid (GA) against Staphylococcus aureus, and its influence on the production of S. aureus alpha-haemolysin (Hla) were investigated, along with the in vivo activity of GA against S. aureus-induced pneumonia. GA could not inhibit the growth of S. aureus, but the secretion of Hla by S. aureus was significantly inhibited by low concentrations of GA in a dose-dependent manner. Furthermore, in vivo data show that GA provides protection against staphylococcal pneumonia in a murine model system.
Subject(s)
Anti-Bacterial Agents/pharmacology , Glycyrrhetinic Acid/pharmacology , Pneumonia, Bacterial/prevention & control , Staphylococcal Infections/microbiology , Staphylococcal Infections/prevention & control , Animals , Cell Line, Tumor , Humans , Male , Mice , Mice, Inbred C57BL , Microbial Sensitivity Tests , Molecular Structure , Pneumonia, Bacterial/microbiology , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Staphylococcus aureusABSTRACT
Staphylococcus aureus causes a broad range of life-threatening diseases in humans. The pathogenicity of this micro-organism is largely dependent upon its virulence factors. One of the most extensively studied virulence factors is the extracellular protein α-toxin. In this study, we show that allicin, an organosulfur compound, was active against S. aureus with MICs ranged from 32 to 64 µg/mL. Haemolysis, Western blot and real-time RT-PCR assays were used to evaluate the effects of allicin on S. aureus α-toxin production and on the levels of gene expression, respectively. The results of our study indicated that sub-inhibitory concentrations of allicin decreased the production of α-toxin in both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in a dose-dependent manner. Furthermore, the transcriptional levels of agr (accessory gene regulator) in S. aureus were inhibited by allicin. Therefore, allicin may be useful in the treatment of α-toxin-producing S. aureus infections.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Toxins/metabolism , Hemolysin Proteins/metabolism , Methicillin-Resistant Staphylococcus aureus/metabolism , Sulfinic Acids/pharmacology , Animals , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Bacterial Toxins/genetics , Culture Media, Conditioned , Disulfides , Hemolysin Proteins/genetics , Hemolysis , Methicillin-Resistant Staphylococcus aureus/drug effects , Methicillin-Resistant Staphylococcus aureus/growth & development , Microbial Sensitivity Tests , Rabbits , Trans-Activators/genetics , Trans-Activators/metabolism , Transcription, GeneticABSTRACT
The objective of this study was to evaluate the immunomodulatory effects of cinobufagin (CBG) isolated from Chan Su (Venenum Bufonis) in vitro. In this paper, our results show that CBG significantly stimulated cell proliferation of splenocytes and peritoneal macrophages (PMΦ) and markedly enhanced the phagocytic activation of PMΦ. CBG also significantly increased CD4(+)CD8(+) double-positive T-cell populations and the percentage of S-phase cells of splenic lymphocytes. The levels of several Th1 cytokines, including interferon-γ and tumor necrosis factor-α, are significantly increased after CBG treatment, whereas the levels of the Th2 cytokine interleukin-4 and interleukin-10 are significantly decreased. As a result, the ratio of Th1/Th2 also increased. Taken together, these results indicated that CBG had potential immune system regulatory effects and suggested that this compound could be developed as a novel immunotherapeutic agent to treat immune-mediated diseases such as cancer.
Subject(s)
Amphibian Venoms/pharmacology , Bufanolides/chemistry , Bufanolides/pharmacology , Cytokines/drug effects , Immunologic Factors/pharmacology , Macrophages, Peritoneal/drug effects , Amphibian Venoms/chemistry , Amphibian Venoms/immunology , Amphibian Venoms/isolation & purification , Animals , Bufanolides/immunology , Bufanolides/isolation & purification , Cytokines/metabolism , Immunologic Factors/chemistry , Immunologic Factors/immunology , Immunologic Factors/isolation & purification , Interferon-gamma/analysis , Interleukin-10/analysis , Interleukin-4/analysis , Molecular Structure , Spleen/cytology , Spleen/drug effects , Spleen/immunology , Th1 Cells/drug effects , Th2 Cells/drug effects , Tumor Necrosis Factor-alpha/analysisABSTRACT
The present study aimed to evaluate the antimicrobial activity of peppermint oil against Staphylococcus aureus, and further investigate the influence of peppermint oil on S. aureus virulence-related exoprotein production. The data show that peppermint oil, which contained high contents of menthone, isomenthone, neomenthol, menthol, and menthyl acetate, was active against S. aureus with minimal inhibitory concentrations (MICs) ranging from 64-256 µg/mL, and the production of S. aureus exotoxins was decreased by subinhibitory concentrations of peppermint oil in a dose-dependent manner. The findings suggest that peppermint oil may potentially be used to aid in the treatment of S. aureus infections.
Subject(s)
Exotoxins/metabolism , Plant Oils/pharmacology , Staphylococcus aureus/drug effects , Staphylococcus aureus/metabolism , Animals , Antiemetics/pharmacology , Antiemetics/therapeutic use , Exotoxins/genetics , Gas Chromatography-Mass Spectrometry/methods , Hemolysis/drug effects , Mentha piperita , Microbial Sensitivity Tests , Plant Oils/chemistry , Plant Oils/therapeutic use , Rabbits , Staphylococcal Infections/drug therapy , Staphylococcus aureus/pathogenicity , Transcription, Genetic/drug effectsABSTRACT
In this study we investigated the antimicrobial activity of magnolol on Staphylococcus aureus. The minimal inhibitory concentrations of magnolol against 31 S. aureus strains ranged from 4-32 microg/mL. In addition, hemolysin assays, Western blotting, and real-time RT-PCR were performed to investigate the effect of magnolol on alpha-toxin secretion by both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The results indicated that sub-inhibitory concentrations of magnolol dose-dependently inhibited the transcription of hla (the gene encoding alpha-toxin) in S. aureus, resulting in a reduction of alpha-toxin secretion and, thus, hemolytic activities.
