Deciphering the Anti-Listerial Activity and Phytochemical Composition of Licorice Root Extract Using LC-MS/MS in Combination with In Vitro and Computational Evaluations  
[PERSON]  
1 Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Lemesos 3603, Cyprus; [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (A.C.); [EMAIL_ADDRESS] (V.G.) [PERSON]  
1 Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Lemesos 3603, Cyprus; [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (A.C.); [EMAIL_ADDRESS] (V.G.) [PERSON]  
2 Department of Analytical Chemistry, University of Granada, c/Fuentenueva s/n, 18071 Granada, Spain; [EMAIL_ADDRESS]  
[PERSON]  
1 Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Lemesos 3603, Cyprus; [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (A.C.); [EMAIL_ADDRESS] (V.G.) [PERSON]  
3 Sutton Bonington Campus, University of Nottingham, College Road, Leicestershire LE12 5 RD, UK; [EMAIL_ADDRESS]  
[PERSON]  
4 Correspondence: [EMAIL_ADDRESS]; Tel. : +357-25002582445  
Gram-negative bacteria can cause foodborne infection; however, _Listeria monocytogenes_ is recognized as a major risk by the food industry. It is a Gram-positive, rod-shaped, foodborne pathogen that is considered the major causative agent responsible for serious diseases in both humans and animals. _L. monocytogenes_ can naturally contaminate a variety of refrigerated and ready-to-eat foods, such as milk and dairy products, vegetables, meat, poultry, and seafood products, and its growth is not prevented by low-temperature storage [2; 3]. Infections of human or animal hosts result in clinical presentations that range from asymptomatic carriers to septicemia, encephalitis, or abortions. It is noteworthy that, in the EU, it is zoonosis that has the highest case fatality rate of 10% [4]. As an adaptive, environmental organism, _L. monocytogenes_ is quite resistant to a range of standard physical and chemical food preservation methods; hence, there has been a growing interest in the application of synthetic and natural compounds to control _L. monocytogenes_ in food [5]. In the last decade, numerous plant extracts and essential oils have been evaluated as potential inhibitors of _L. monocytogenes_ bacteria, and the anti-literial potential of the extracts is mostly correlated with their phenolic composition; various mechanisms of action involving membranes, cytoplasm, and genetic material have been proposed for these compounds [6; 7]. Licorice is a native bush in Asia and the Mediterranean region that is used in traditional medicines and folk remedies to treat many diseases [8]. Currently, in vitro and in vivo studies have documented the diverse pharmacological properties of licorice, such as anti-inflammatory, anti-tussic and expectorant, anti-ulcerative, antioxidant, antiviral, anticarcinogenic and antimutagenic, hepato-protective, neuroprotective, anti-depressive, estrogenic and androgenic, and antimicrobial activities [9; 10; 11; 12]. Regarding antimicrobial activity, polar and supercritical fluid extracts of licorice root have strong inhibitory effects on Gram-positive bacteria and Gram-negative bacteria, such as _Staphylococcus aureus_, _Escherichia coli_, _Pseudomonas aeruginosa_, _Candida albicans_, and _Bacillus subtilis_. Based on the above inhibitory activities against bacteria, licorice root extracts may serve as an alternative therapy for treating diverse bacterial infections. Furthermore, possible mechanisms for the antimicrobial effects of licorice root phytochemicals have been proposed [13]. More specifically, 18\(\beta\)-glycyrrhetinic acid decreases the expression of key virulence genes of methicillin-resistant _S. aureus_[14]; licochalcone A inhibits biofilm formation [15]; licochalcone E reduces the production of \(\alpha\)-toxin [16]; liquiritigenin lowers the production of \(\alpha\)-hemolysin; and both licochalcone A and glabridin prevent yeast-hyphal transition [15; 17].