title: Kurarinol, tyrosinase inhibitor isolated from the root of Sophora flavescens.
abstract: It is well known that flavanones, sophoraflavanone G 1, kurarinone 2, and kurarinol 3, from the root of Sophora flavescens, have extremely strong tyrosinase inhibitory activity. This study delineates the principal pharmacological features of kurarinol 3 that lead to inhibition of the oxidation of l-tyrosine to melanin by mushroom tyrosinase (IC(50) of 100 nM). The inhibition kinetics analyses unveil that compounds 1 and 2 are noncompetitive inhibitors. However similar analysis shows kurarinol 3 to be a competitive inhibitor. Compounds 1 and 2 exhibited potent antibacterial activity with 10 microg/disk against Gram-positive bacteria, whereas kurarinol 3 did not ostend any antibacterial activity. Interestingly, kurarinol 3 inhibits production of melanin in S. bikiniensis without affecting the growth of microorganism. It is thus distinctly different from the other tyrosinase inhibitors 1 and 2. In addition, kurarinol 3 manifests relatively low cytotoxic activity (EC(50)>30 microM) compared to 1 and 2. To account for these observations, we conducted molecular modeling studies. These suggested that the lavandulyl group within 3 is instrumental in the interaction with the enzyme. More specifically, the terminal hydroxy function within the lavandulyl group is most important for optimal binding.
authors.affiliation: Department of Applied Life Science (BK21 Program), EB-NCRC, Institute of Agriculture & Life Science, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Y B
authors.initials: YB
authors.lastname: Ryu
authors.forename: I M
authors.initials: IM
authors.lastname: Westwood
authors.forename: N S
authors.initials: NS
authors.lastname: Kang
authors.forename: H Y
authors.initials: HY
authors.lastname: Kim
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
authors.forename: Y H
authors.initials: YH
authors.lastname: Moon
authors.forename: K H
authors.initials: KH
authors.lastname: Park
mesh_terms: D001665:Binding Sites; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D008543:Melanins / Q000096:biosynthesis; D008958:Models, Molecular; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry*; D029909:Sophora / Q000737:chemistry*; D013302:Streptomyces / Q000187:drug effects / Q000378:metabolism
chemical_list: D005419:Flavonoids; D008543:Melanins; D010455:Peptides; C526229:kurarinol