Protective Effect of Ethanol Extract of Legundi (Vitex trifolia L.) Leaves against Staphylococcus aureus in Drosophila Infection Model

Research to discover certain medicinal plants' antibacterial activity against Staphylococcus
aureus was mostly performed in vitro. The purpose of this research was to investigate the antibacterial
activity of ethanol extract of legundi leaves (EELL) against S. aureus using model organism Drosophila
melanogaster. The extract was prepared by the maceration method using 70% ethanol. The antibacterial
activities of EELL were determined by using fly survival assay and bacterial colony-forming assay. Fly
survival assay was conducted to investigate the extracts' ability to enhance the survival of D.
melanogaster (host) upon S. aureus infection. The results demonstrated that both EELL were able to
increase the survival rate of the S. aureus-infected Drosophila. Furthermore, a colony-forming assay
was carried out to determine the growth of bacteria in the host body that has been considered an
important pathogenic factor for the host. The result found that the number of bacteria recovered from
the EELL-treated infected flies was significantly lower than the ones obtained from the infected flies
without any treatments. Overall, EELL protects the S. aureus-infected hosts, suggesting the potential
antibacterial effect of EELL against S. aureus.