In vitro: |
Bioorg Med Chem. 2009 Jan 1;17(1):35-41. | Tyrosinase inhibitory effects of 1,3-diphenylpropanes from Broussonetia kazinoki.[Pubmed: 19046886] | METHODS AND RESULTS: Six 1,3-diphenylpropanes exhibiting inhibitory activities against both the monophenolase and diphenolase actions of tyrosinase were isolated from the methanol (95%) extract of Broussonetia kazinoki. These compounds, 1-6, were identified as kazinol C (1), D (2), F (3), Broussonin C (4), kazinol S (5) and kazinol T (6). The latter two species (5 and 6) emerged to be new 1,3-diphenylpropanes which we fully spectroscopically characterized. The IC(50) values of compounds (1, 3-5) for monophenolase inhibition were determined to range between 0.43 and 17.9 microM. Compounds 1 and 3-5 also inhibited diphenolase significantly with IC(50) values of 22.8, 1.7, 0.57, and 26.9 microM, respectively.
CONCLUSIONS:
All four active tyrosinase inhibitors (1, 3-5) were competitive inhibitors. Interestigly they all mainfested simple reversible slow-binding inhibition against diphenolase.
The most potent inhibitor, Broussonin C diplayed the following kinetic parameters k(3)=0.0993 microM(-1)min(-1), k(4)=0.0048 min(-1), and K(i)(app)=0.0485 microM. |
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