Inhibitory Activity of Hydroxytyrosol against Streptolysin O-Induced Hemolysis.

　Group A streptococcus is a bacterium that resides in the throat and skin and causes respiratory infection and occasionally glomerulonephritis and rheumatic fever. Streptolysin O (SLO) produced by Streptococcus pyogenes (S. pyogenes) binds to the cell membrane, particularly to that of white and red blood cells, and is toxic to the cells and tissue. In this study, we evaluated the inhibitory activity of water-soluble polyphenols in olives (Olea europaea) against SLO-induced hemolysis. Hydroxytyrosol inhibited SLO-induced hemolytic activity, and the amount required for 50% inhibition of hemolysis was 1.30 µg. These findings suggest that the water-soluble polyphenols contained in olives have inhibitory activity against SLO-induced hemolysis.

Inhibition of verotoxin (VT) 2 absorption into systemic blood from intestine by repeated administration of bovine immune colostral antibody against VT2 in mice.

BACKGROUND/PURPOSE: Whether absorption of verotoxin (VT) 2 from the intestine in mice is inhibited by administration bovine immune colostral antibody against VT2 was investigated. METHODS: Three-week-old mice were administered VT2 solution at 477.8 ng/mL or 955.6 ng/mL, and bovine immune colostral antibody against VT2 was then administered three times. Whey without antibody against VT2 was administered to control mice. Serum levels of VT2 were measured by fluorescence enzyme immunoassay. RESULTS: Serum levels of VT2 in mice administered VT2 solution at 477.8 ng/mL and bovine immune colostral antibody against VT2 scarcely changed. By contrast, serum levels of VT2 in control mice increased and peaked 12 hours after administration. Peak values were 15.4 ± 5.04 ng/mL. Furthermore, serum levels of VT2 at 12 hours and 16 hours in control mice were significantly higher than in mice administered bovine colostral antibody against VT2. Serum levels of VT2 in mice administered antibody at 955.6 ng/mL showed no significant differences between repeated administration of bovine immune colostral antibody and controls. CONCLUSION: These results suggest that absorption of VT2 from the intestine was inhibited by repeated administration of bovine immune colostral antibody against VT2 at early stages of Escherichia coli O157:H7 infection, whereas VT2 in the intestine remained at low levels.

Neutralizing activity of bovine colostral antibody against verotoxin derived from enterohemorrhagic Escherichia coli O157:H7 in mice.

The neutralization efficacy of bovine colostral antibody against verotoxin (VT) 1 and 2 was investigated. Cows were immunized with VT1 or VT2 fourteen times at 7-day intervals. A colostral antibody exhibiting high titers was obtained from immunized cows. Survival rates were evaluated in mice administered VT1 or VT2, and those infected with Escherichia coli (E. coli) O157:H7 producing VT1 or VT2. Survival rates after VT1 administration were 100% in the single-administration group, 90% in the repeat-administration group, and 78.6% in the control group. Survival rates after VT2 were 75.0% in the single-administration group, and 100% in the repeat-administration group. All mice in the control group died. Colostral antibody and fosfomycin (FOM) in the colostral antibody group and FOM and skim milk in the control group were administered three times per day for 5 days to mice infected with E. coli O157:H7 producing VT1 or VT2. Survival rates after inoculation with E. coli O157:H7 producing VT1 were 80.0% in the colostral antibody group, and 63.6% in the control group. Survival rates after inoculation with E. coli O157:H7 producing VT2 were 83.3% in the colostral antibody group, and 20.0% in the control group. The survival rate in mice without treatment following inoculation with E. coli O157:H7 producing VT2 was 88.2%. The survival rates in mice infected with E. coli O157:H7 strains producing VT1 or VT2 improved after administration of this colostral antibody, which exhibited neutralization efficacy against VT.

[Identification of chemical structure of antibacterial components against Legionella pneumophila in a coffee beverage].

We previously reported that certain constituents in brewed coffee exhibited antibacterial activities against a strain of Legionella pneumophila. The constituents showing antibacterial activities were included only in extracts cold with water or hot water. To determine the antibacterial substances in coffee extract, the extract was fractionated by HPLC using a UV/photodiode array detector. The optimum HPLC conditions for analysis were UV wavelength of 250 nm and eluents of methanol/acetic acid (10/90), pH 3.0. When several fractions separated by HPLC were investigated for antibacterial activities against L. pneumophila, it was found that three peak fractions exhibited strong antibacterial activities. Each product from these fractions was analyzed by NMR and LC-mass spectrometry, and the chemical structure of each was determined. It was shown that the antibacterial substances was were protocatechuic acid (3,4-dihydroxy benzoic acid), chlorogenic acid, and caffeic acid.