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

这项研究的目的是研究基于紫外线-A光和三类食品级化合物（苯甲酸衍生物，肉桂酸衍生物和没食子酸酯）的协同抗菌活性。通过使用大肠杆菌O157：H7作为模型菌株，观察到三种肉桂酸衍生物（阿魏酸，香豆酸和咖啡酸）和一种苯甲酸衍生物（2,5-二羟基苯甲酸）具有很强的协同抗菌活性。 UV-A光辐射，其中这些化合物的1 mM水平加上15分钟的UV-A光（总光剂量为6.1 cm ^-2）导致CFU mL ^-1超过7 log细菌灭活。相反，只有在使用较高浓度的这些化合物（10 mM）后，才能观察到UV-A光与大多数苯甲酸衍生物（苯甲酸，没食子酸，香草酸和2,5-二甲氧基苯甲酸）之间的协同抗菌活性。最后，在测试的三种没食子酸酯中（没食子酸甲酯，没食子酸乙酯和没食子酸丙酯），只有没食子酸丙酯对UV-A光表现出强烈的抗菌协同作用，其中10 mM没食子酸丙酯和15分钟的UV-A光导致大约6.5 -细菌减少的对数。抗氧化剂化合物的存在减轻了没食子酸，2,5-二羟基苯甲酸和没食子酸丙酯的光介导的抗菌活性。同样，这些化合物的光介导的抗菌活性也显着（P <0.05）抵抗代谢抑制的细菌细胞（叠氮化钠预处理）。另一方面，阿魏酸和UV-A光之间的抗菌协同作用不受抗氧化剂的存在或细菌细胞的代谢状态的影响。由于人们越来越关注抗菌素耐药性（AMR）病原体，因此该研究还研究了拟议的AMR沙门氏菌协同治疗方法。1 mM的阿魏酸或1 mM的2,5-二羟基苯甲酸与UV-A光辐射的组合能够灭活耐多药鼠伤寒沙门氏菌菌株的6对数以上。