Protective effect of hawthorn vitexin on the ethanol-injured DNA of BRL-3A hepatocytes.

ABSTRACT: Vitexin is a natural active ingredient in hawthorn leaves, which has a wide range of anti-tumor effects. This study was conducted to assess the protective effect of hawthorn vitexin on the ethanol-injured DNA of hepatocytes in vitro and to explore its mechanism. The effect of different concentrations of hawthorn vitexin on ethanol-injured hepatocytes was detected via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method to study the protective effect of hawthorn vitexin on ethanol-injured DNA damage in hepatocytes. Single-cell gel electrophoresis was used to observe the effect of hawthorn vitexin on ethanol-induced DNA damage in hepatocytes, and the Olive tail moment was measured. Cell physiological and biochemical indexes, such as superoxide dismutase activity, malonaldehyde content, and glutathione peroxidase activity, were detected with kits. The mRNA expression of the superoxide dismutase gene was measured via real-time quantitative polymerase chain reaction. It was showed that 0.2, 0.4, and 0.8 mg mL-1 hawthorn vitexin could significantly repair hepatocyte growth and ethanol-induced DNA damage. This effect was closely related to the improvement in superoxide dismutase, malonaldehyde, and glutathione peroxidase. Hawthorn vitexin could be used to repair ethanol-injured hepatocytes through antioxidation effects, and showed potential for the treatment of liver injury.

Self-defense of Escherichia coli against damages caused by nanoalumina.

Although studies showed effects of nanoalumina (nano-Al2O3) on Escherichia coli, no study completely provides understanding on how bacterial cells respond to damages, especially on how they initiate self-defense. In this study, we showed three types of responses of E. coli to damages caused by nano-Al2O3. Live, dead, and injured, bacteria showed improved survival rates reaching 104%, 116%, and 104% after exposure to 0.1, 1, and 10mmol/L of nano-Al2O3 respectively. Survival rates improved from 100% to 114%, corresponding to an exposure time of 0-9h, and from 100% to 127%, corresponding to 0-1000µg/L Al3+. Improvements were noted in survival rates of E. coli K12 MG1655, HB101, DH5α, and K12 MG1655 △lexA treated by nano-Al2O3 in Luria-Bertani (LB) exposure system or K12 MG1655 in LB, normal saline(NS) and H2O exposure system. Bacterial cells transformed from long rods to ellipsoidal or nearly spherical as form of self-preservation mechanism; this phenomenon may be related to changes in membrane potential induced by free Al3+ released from nano-Al2O3 particles. Molecular mechanism of this response involved inhibited gene expression of sythesis and metabolism of carbohydrates, lipids and proteins. Findings presented in this study may improve understanding of potential danger of nanomaterials and control their spread to environmen.