title: Cajanol inhibits the growth of Escherichia coli and Staphylococcus aureus by acting on membrane and DNA damage.
abstract: 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.
authors.affiliation: Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China.
authors.forename: Xiao-lei
authors.initials: XL
authors.lastname: Liu
authors.forename: Xin-jian
authors.initials: XJ
authors.lastname: Zhang
authors.forename: Yu-jie
authors.initials: YJ
authors.lastname: Fu
authors.forename: Yuan-gang
authors.initials: YG
authors.lastname: Zu
authors.forename: Nan
authors.initials: N
authors.lastname: Wu
authors.forename: Lu
authors.initials: L
authors.lastname: Liang
authors.forename: Thomas
authors.initials: T
authors.lastname: Efferth
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D036561:Cajanus / Q000737:chemistry*; D002462:Cell Membrane / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000254:growth & development; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000254:growth & development; D007529:Isoflavones / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D018517:Plant Roots / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D000094162:Phytoalexins
chemical_list: D000900:Anti-Bacterial Agents; D007529:Isoflavones; C471767:cajanol; D000094162:Phytoalexins