en Food Safety and Hygiene Food Safety and Hygiene پژوهشي Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:normal"><b>Background</b>: The present study aimed to evaluate the <i>in-vitro</i> antioxidant and antimicrobial activity of Thymoquinone (TQ), Eugenol (EUG) and their synergistic effects in combination.</span><br> <span style="line-height:normal"><b>Materials:</b> The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), fractional inhibitory concentration (FIC), and disc diffusion tests were used to determine the antibacterial activity of TQ and EUG<span dir="RTL" lang="FA">.</span>&nbsp; Moreover, Reducing Power Assay and DPPH (2.2-diphenyl-2-picrylhydrazyl) tests were used to indicate the antioxidant ability of TQ and EUG. &nbsp;The combination index (CI) of these compounds was calculated to evaluate their interaction type.</span><br> <span style="line-height:normal"><b>Results:</b> Bacillus cereus, Listeria monocytogenes, and Shewanella SP were the most sensitive bacteria than other studied pathogens to TQ and EUG, with MIC 0.019, 0.07, and 0.07 mg/ml for TQ and 0.6, 0.6, and 0.6 mg/ml for EUG, respectively. &nbsp;The mixture of two ingredients showed a good antimicrobial and synergistic effects against all tested bacteria. The DPPH scavenging activity of the combination of TQ+ EUG were antagonistic in all combined concentrations except for TQ (5 mg/ml) + EUG (1.25 mg/ml) and TQ (2.5 mg/ml) + EUG (0.3 mg/ml) treatments.</span><br> <span style="line-height:normal"><b>Conclusion:</b> The obtained results provided a new combination of antimicrobial and antioxidant agents in drug delivery, especially in food preservation systems, to enhance food shelf life in the food industry.</span></span></span> Antimicrobial activity, Eugenol, Synergistic effects, Thymoquinone, 110 117 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-47-12&slc_lang=en&sid=1 Samira Yousefizadeh s.yousefizadeh1992@gmail.com 100319475328460012029 000000019125971X No Department of Food Safety and Hygiene, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran Majid Aminzare m.aminzare@zums.ac.ir 100319475328460012030 0000000323167420 No Department of Food Safety and Hygiene, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran hassan hassanzadazar hassanzadazar_h@zums.ac.ir 100319475328460012031 0000000278737593 Yes Department of Food Safety and Hygiene, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran