Screening of antimicrobial synergism between phenolic acids derivatives and UV-A light radiation

The objective of this study was to investigate synergistic antibacterial activity based on a combination UV-A light and three classes food grade compounds: benzoic acid derivatives, cinnamic gallates. By using Escherichia coli O157:H7 as the model strain, it observed that derivatives (ferulic acid, coumaric caffeic acid) one derivative (2,5-dihydroxybenzoic presented strong with radiation, where 1 mM levels these compounds plus 15 min (total dose 6.1 cm−2) led more than 7-log CFU mL−1 bacterial inactivation. In contrast, between most (benzoic gallic vanillic 2,5-dimethoxybenzoic were only after higher concentrations applied (10 mM). Lastly, from gallates tested (methyl gallate, ethyl propyl gallate), gallate showed synergism light, 10 approximately 6.5-log reduction. Presence antioxidant mitigated light-mediated 2,5-dihydroxybenzoic gallate. Similarly, significantly (P < 0.05) reduced against metabolic-inhibited cells (sodium azide pretreatment). On other hand, ferulic not affected by presence antioxidants or metabolic state cells. Due increasing concerns antimicrobial resistant (AMR) pathogens, also investigated proposed treatment AMR Salmonella. Combinations radiation able inactivate 6-log multi-drug Salmonella Typhimurium strain.