Inhibitory Effect of Red Koji Extracts on Mushroom Tyrosinase
Journal
Journal of Agricultural and Food Chemistry
Journal Volume
51
Journal Issue
15
Pages
4240-4246
ISSN
0021-8561
Date Issued
2003-06-11
Author(s)
Abstract
Red koji has been recognized as a cholesterol-lowering diet supplement because of it contains fungi metabolites, monacolins, which reduce cholesterol synthesis by inhibiting HMG-CoA reductase. In this study, water extracts of red koji were loaded onto a C18 cartridge, and the acetonitrile eluate was collected as test fraction. Red koji water extracts and its C18 cartridge acetonitrile eluent had total phenols concentrations of 5.57 and 1.89 mg/g of red koji and condensed tannins concentrations of 2.71 and 1.20 mg/g of red koji, respectively. Both exhibited an antioxidant activity and an inhibitory activity to mushroom tyrosinase. The higher antioxidant activity of the red koji acetonitrile eluent was due to the existence of a high percentage of condensed tannins. The results from the kinetic study for inhibition of mushroom tyrosinase by red koji extracts showed that the compounds in the extracts competitively inhibited the oxidation of tyrosine catalyzed by mushroom tyrosinase with an ID50 of 5.57 mg/mL.
Subjects
Antioxidants
DL-DOPA
Folin-Ciocalteu
Free radical scavenging activity
Polyphenols
Red koji
Red yeast rice
Tyrosinase
Tyrosinase inhibitor
Vanillin-HCl assay
SDGs
Publisher
American Chemical Society
Type
journal article