The protective effects of Rhodiola crenulata extracts on Drosophila melanogaster gut immunity induced by bacteria and SDS toxicity.

The aim of this study was to observe the effect of the Rhodiola crenulata extracts on gut immunity of Drosophila melanogaster. Wild-type flies fed standard cornmeal-yeast medium were used as controls. Experimental groups were supplemented with 2.5% R. crenulata aqueous extracts in standard medium. Survival rate was determined by feeding pathogenic microorganisms and toxic compounds. The levels of reactive oxygen species and dead cells were detected by dihydroethidium and 7-amino-actinomycin D staining, respectively. The expression of antimicrobial peptides was evaluated by quantitative polymerase chain reaction, and morphological change of the intestine was imaged by an Axioskop 2 plus microscope. The results demonstrate that R. crenulata increased the survival rates of adult flies and expression of antimicrobial peptide genes after pathogen or toxic compound ingestion. Moreover, decreased levels of reactive oxygen species and epithelial cell death were associated with results in improved intestinal morphology. The pharmacological action of R. crenulata from Tibet was greater than that from Sichuan. These results indicate that the R. crenulata extracts from Tibet had better pharmacological effect on D. melanogaster gut immunity after ingestion of pathogens and toxic compounds. These results may provide the pharmacological basis for prevention of inflammatory diseases of the intestine.