Antibacterial Effect of Gallic Acid against Aeromonas hydrophila and Aeromonas sobria Through Damaging Membrane Integrity.

In the study, we investigated the antibacterial activity and mechanism of gallic acid against Aeromonas hydrophila and Aeromonas sobria. Gallic acid showed strong antimicrobial activity against the two bacteria. Furthermore, the antibacterial mechanism of gallic acid (0, 3, 6, 12 mM) was performed by membrane integrity assay and scanning electron microscopy (SEM) assay. The results showed that gallic acid notably increased the released material absorption value at 260, 280 nm and electric conductivity in a dose-dependent manner. Moreover, the SEM assay showed that gallic acid induced severe shrink of bacterial intima and irregular morphology in a dose-dependent manner. The SDS-PAGE profiles further confirmed that gallic acid could damage bacterial cells. These results indicated gallic acid exhibited antibacterial effect by destroying membrane integrity of A. hydrophila and A. sobria. Hence, gallic acid has great potential as a new natural food preservative in food fresh-keeping and storage.

A 4-week study of four 3-monochloropropane-1,2-diol diesters on lipid metabolism in C57BL/6J mice.

3-Monochloropropane-1,2-diol (3-MCPD) esters have been detected in many foods, which have become a new safety issue worldwide. In the study, we investigated the effect of four 3-MCPD diesters (palmitate diester: CDP; stearate diester: CDS; oleate diester: CDO; linoleate diester: CDL) on lipid metabolism in C57BL/6J mice. The results showed that CDP, CDS, CDO and CDL significantly increased the serum TC, LDL-C levels and liver TG, TC levels at dose of 16.5µmol/kg/day. These results indicated that 3-MCPD diesters could potentially cause hyperlipidemia in C57BL/6J mice. Moreover, oil red O staining confirmed fat accumulation in liver induced by 3-MCPD diesters. Our work will provide more information for safety evaluation of 3-MCPD diesters. However, whether free 3-MCPD or free fatty acids or combined action compensates for the hyperlipidemia effects should be elucidated in the future.

Tubeimoside-1 inhibits the proliferation and activation of mouse T lymphocytes through signal transduction pathways.

Tubeimoside-1 (TBMS1) is one of the important components in Bolbostemma paniculatum (Maxim.) Franque. In the study, its immunosuppressive effects on murine T lymphocyte responses were evaluated in vitro and in vivo. The data showed that TBMS1 inhibited ConA-induced T lymphocyte proliferation, decreased the ratio of CD4(+)/CD8(+), suppressed IL-2, IFN-γ, IL-4 and IL-6 production and mRNA expression, down-regulate activation of NF-κB, NFAT2 and AP-1 signal transduction pathways in vitro. In addition, administration of TBMS1 significantly inhibited T cell-mediated DTH response in vivo. These findings indicated that TBMS1 inhibits the proliferation and activation of T lymphocytes in mice.

Nonalcoholic fatty liver disease induced by 13-week oral administration of 1,3-dichloro-2-propanol in C57BL/6J mice.

1,3-Dichloro-2-propanol (1,3-DCP) is a food born chloropropanol contaminant that has been detected during the production process of a wide range of foods. In this study, we investigated the effect of 1,3-DCP on lipid metabolism of mice after 13-week subchronic exposure. The data showed that 1,3-DCP (0.05-0.5mg/kg/day) could induce nonalcoholic fatty liver disease (NAFLD) in C57BL/6J mice and the NOAEL was 0.01mg/kg/day. In addition, we studied the signaling pathway to see how 1,3-DCP worked. The data showed that NAFLD induced by 1,3-DCP was due to the dysregulation of AMPK signaling pathway. As far as we are aware, this is the first study to use 13-week subchronic toxicology to investigate the effect of 1,3-DCP on the development of NAFLD in mice. Our study provided evidence for diet contaminants in the development of NAFLD and furthered the safety evaluation of 1,3-DCP through subchronic exposure.