Antibacterial activity directed isolation of compounds from Punica granatum

Chemical investigation of the methanolic extract of pomegranate fruit following antibacterial activity directed isolation led to the isolation of pelargonidin-3-galactose, cyanidin-3-glucose, gallic acid, quercetin, and myricetin. All these compounds exhibited substantial activity against species of corynebacteria, staphylococci, streptococci, Bacillus subtilis, Shigella, Salmonella, Vibrio cholera, and Escherichia coli. However, all these compounds were more active against Gram-positive species. On comparing the activity of all the isolated pure compounds, it was found that gallic acid showed the highest antibacterial activity against all the tested sensitive strains and the activity of the remaining pure compounds was almost same due to the structural similarities of the compounds. The reason for antibacterial activity of all pure compounds was attributed to their phenolic structure.