The Function And Molecular Mechanism Of Silymarin On The Intestinal Bacteria

Silymarin,a bioactive extract from the known plant Silybum marianum,is known for its hepatoprotective effects.Recently,silymarin has been reported to exhibit various biological activities,including antimicrobial activity,but the mode of interaction remains unknown.Tn5 is a commonly used convenient tool on gram-negative bacteria in regard to the molecular level.Tn5 has been applied in large-scale sequencing,selection of plant pathogens,salt tolerance engineering bacteria screening,and the study of antibiotics resistanc.This work is mainly divided into two parts.The first part of the study focused on the antibacterial interactions of silymarin with six genera of bacteria isolated from different sources,including four environmental strains(Exiguobacterium sp.CR3,Cellulosimicrobium sp.CR5,Staphylococcus sp.CR9 and Pseudomonas sp.CR13)and two enteric strains(Citrobacter sp.CR10 and Enterococcus sp.CR11).Silymarin of high concentration exhibited antibacterial potential against mostly environmental bacteria rather than intestinal strains.Substrate utilization assay and full-wavelength scanning revealed that enteric bacteria instead of environmental bacteria could catabolize silymarin as sole carbon source.The integrity of the bacterial membrane on exposure to silymarin was checked using scanning electron microscopy,which confirmed severe cellular damage of the environmental bacteria.The other part is concentrated to explore the mechanism of silymarin interacting with intestinal bacteria,transposon insertion mutation are used to get of mutant strains with lower silymarin resisitance.The data suggested that silymarin can affect the function of 23 S rRNA gene,acetolactate synthase 3 catalytic subunit,16 S ribosomal RNA,histone-like DNA-binding protein.Through the above research,we concluded that silymarin can change the cell permeability,destroy the structure of cell surface,penetrate the cell and act on specific ribosomal subunits,inhibiting the synthesis of protein,thereby inhibiti the normal growth of bacteria.Through the above research,we found that the silymarin play different roles on different populations of intestinal bacteria,Gut bacteria can promote the use of silymarin,this provides important clues for reasonable interpretation of silymarin mechanism of intestinal bacteria,but also for the natural products used in the prevention and treatment of intestinal bacteria related diseases.