Anti-Salmonella activity of alkyl gallates

A series of alkyl gallates (3,4,5-trihydroxybenzoates) was synthesized and tested for their antibacterial activity against Salmonella choleraesuis. Nonyl (C-9) and octyl (C-8) gallates were noted to be the most effective against this food-borne bacterium, each with a minimum bactericidal concentration (MBC) of 12.5 mug/mL, followed by decyl (C-10) gallate, with a MBC of 25 mug/mL. Dodecyl (C-12) gallate exhibited activity against S. choleraesuis, with a MBC of 50 mug/mL. Propyl (C-3) gallate showed no activity against S. choleraesuis up to 3200 mug/mL. The length of the alkyl group is not a major contributor but plays a role in eliciting the activity to a large extent. The same series of alkyl gallates, regardless of alkyl chain length, all showed nearly the same potent scavenging activity on the 1,1-diphenyl-2-picrylhydrazyl radical, indicating that the length of the alkyl group is not associated with the activity.