Antimicrobial effect and resistant regulation of Glycyrrhiza uralensis on methicillin-resistant Staphylococcus aureus.

In the present study, we investigated antimicrobial activity of Glycyrrhiza uralensis against various strains of methicillin-resistant Staphylococcus aureus (MRSA) (KCCM 11812, 40510, 40512). Glycyrrhiza uralensis was extracted by 80% MeOH and fractionated by organic solutions. The extract and fractions showed antimicrobial activity against standard S. aureus as well as MRSA. In the minimum inhibitory concentration test, G. uralensis showed 0.25 mg mL(-1) in hexane fraction and 0.10-0.12 mg mL(-1) in chloroform fraction. Especially, chloroform fraction showed 2.5 times higher antimicrobial activity than penicillin. Furthermore, chloroform fraction correlated with MRSA gene expression (MecA, MecI, MecRI, FemA). These results suggest that G. uralensis may have potent antimicrobial activity and thus, this medicinal herb can be a suitable phytotherapeutic agent for treating MRSA infections.