Isolation and identification of antibacterial and anticancer substances from roots of Sophora flavescens Aiton

Sophora flavescens Aiton (Leguminosae) is a perennial shrub existing in the wild as well as being cultivated in Northeast Asian countries. The roots of this species are commercially available as the generic 'Kosam' in Korea, and it has been applied frequently in folk medicine as an antipyretic, analgesic, anthelmintic and a stomachic drug. Many researchers have examined the secondary metabolites of this species thoroughly since sophocarpine was first isolated first in 1934. This is because Sophora is a rich source of flavonoids with a wide range of biological activities such as anticancer, anti-inflammatory, and tyrosinase inhibitory properties. However, its antibacterial activities have not been tested by researchers. In this study, we isolated secondary metabolites which have antibacterial activities from roots of S.flavescens. Roots of S. flavescens were air-dried, chopped and extracted with MeOH. The combined extract was evaporated and the resultant extract suspended in water. The resuspended extract was partitioned with CHCl(3) and BuOH. BuOH extracts were purified by repeated column chromatography and recrystallization. As a result, five compounds were isolated, and identified as lavandulylated flavonoids (1-5). The structures of the isolated compounds were elucidated by spectroscopic methods (NMR, UV, IR, and MS) to be: Kushenol A (1), 2'-Methoxykurarinone (2), Sophoraflavanone G (3), Kurarinone (4) and Kurarinol (5). The five isolated compounds were tested for antibacterial activity against Bacillus subtilis, B. cereus, Staphylococcus aureus and Listeria monocytogenes. Compound 1 showed activity against B. subtilis, B. cereus, S. aureus and L. monocytogene, and compounds 3-5 exhibited activity against B. subtilis, B. cereus and S. aureus. In addition, the compounds were examined for anticancer activity against the human cancer cell lines A549 and SK-OV-3. As a result, compounds 1, 3 and 4 showed IC(50) values of 2.0 and 2.0 ppm (1), 2.1 and 1.8 ppm (3), and 2.7 and 2.0 ppm (4), respectively, against A549 and SK-OV-3.