Antimicrobial agents of 4-methoxysalicylaldehyde isolated from Periploca sepium oil against foodborne bacteria: structure-activity relationship

This study was designed to evaluate the antimicrobial activities of 4-methoxysalicylaldehyde isolated from Periploca sepium and its derivatives against six foodborne bacteria (Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, S. sonnei, Staphylococcus intermedius and S. aureus). Essential oil extracted from P. sepium roots exhibits strong antimicrobial activity against foodborne bacteria. The antimicrobial compound of P. sepium isolated by chromatographic techniques was identified as 4-methoxysalicylaldehyde. To compare the antimicrobial activities of 4-methoxysalicylaldehyde and its derivatives (4-hydroxysalicylaldehyde, salicylaldehyde, 3-methoxysalicylaldehyde, 5-methoxysalicylaldehyde, 3-methylsalicylaldehyde, and 5-methylsalicylaldehyde), the MIC test was performed. These activities were exhibited by 4-methoxysalicylaldehyde (MIC 30.1-67.3 mu g/mL) followed by 4-hydroxysalicylaldehyde (MIC 41.1-61.5 mu g/mL) and 4-methoxysalicylaldehyde (MIC 41.3-92.1 mu g/mL) against all tested microorganisms. The results indicate that 4-methoxysalicylaldehyde and its derivatives represent natural antimicrobial alternatives.