**Licorice as a Resource for Pharmacologically Active Phenolic Substances: Antioxidant and Antimicrobial Effects Active Phenolic Substances: Antioxidant and Antimicrobial Effects**

**Licorice as a Resource for Pharmacologically** 

Tsutomu Hatano, Eerdunbayaer, Yanmei Cui, Teruo Kuroda and Yuuki Shimozu Teruo Kuroda and Yuuki Shimozu Additional information is available at the end of the chapter

Tsutomu Hatano, Eerdunbayaer, Yanmei Cui,

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/66419

#### **Abstract**

The findings from our studies on licorice phenolics are summarized here. The following types of flavonoids, i.e., flavones, flavonols, flavanones, chalcones, isoflavones, isoflavanones, isoflavans, 3-arylcoumarins, coumestans, pterocarpans, 2-benzyldihydrobenzofuran-3-ones, benzyl phenyl ketones, 2-arylbenzofurans, and others, were identified by the structural studies. Among them, licochalcone A (chalcone), isolicoflavonol (flavonol), glycycoumarin (3-arylcoumarin), and glycyrrhisoflavone (isoflavone) displayed antihuman immunodeficiency virus effects, and also 8-(γ,γ-dimethylallyl)-wighteone (isoflavone) and 3′-(γ,γ-dimethylallyl)-kievitone (isoflavanone) showed potent antibacterial effects on methicillin-resistant *Staphylococcus aureus* (MRSA) strains. Licoricidin (isoflavan) suppressed the oxacillin resistance of the MRSA strains noticeably. Effects of phenolics with related structures isolated from *Psoralea corylifolia* were also examined, and bakuchiol (meroterpene), isobavachalcone, and corylifol B (chalcones) also showed potent effects on MRSA strains. Some licorice phenolics such as licoricidin (isoflavan), 8-(γ,γ-dimethylallyl)-wighteone (isoflavone), and gancaonin I (2-arylbenzofuran) also showed potent antibacterial effects on vancomycin-resistant *Enterococcus* (VRE) strains. The potency of the effects largely depended on their structures including the lipophilic prenyl or related substituents and also phenolic hydroxyl groups. Inhibitory effects of licorice phenolics on oxidative enzymes, in addition to their radical-scavenging effects, are also shown. The methods used in the structural studies and high-performance liquid chromatographic analysis of licorice extracts are described shortly, too.

**Keywords:** licorice, *Glycyrrhiza*, *Psoralea*, flavonoid, antimicrobial effect

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
