In the present study, the mechanism of antibacterial activity of
cajanol extracted from the roots of Cajanus cajan (L.) Millsp. towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was investigated. The antibacterial activity of
cajanol was evaluated towards six bacterial strains (Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Proteus vulgaris, and Pseudomonas aeruginosa) by the broth microdilution method. It showed strong antibacterial activity towards all bacteria tested with minimal inhibition concentration (MIC) values ranging from 98.90 µM to 197.8 µM.
Cajanol-induced death rates in the most sensitive strains ( E.COLI, 96.55 % and S. AUREUS, 97.25 %) were analyzed by flow cytometry. Furthermore, the activity of
cajanol on the membranes of E. coli and S. aureus was investigated by using
lecithin,
phosphate groups, and fluorescence microscopy.
Cajanol-induced DNA damage was observed by
agarose gel electrophoresis. In summary,
cajanol inhibited E. coli only by DNA damage, whereas S. aureus was inhibited by affecting both, the
lecithin and
phosphate groups on the cellular membrane and
DNA. The present study shows that
cajanol possesses antibacterial activity in vitro towards both gram-negative and gram-positive bacteria and therefore may be a promising candidate as an
antibacterial agent for the
therapy of microbial
infections.