title: Inhibitory effects of (S)- and (R)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acids on tyrosinase activity.
abstract: The inhibition of (R)-, (S)-, and (+/-)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acids (HTCCA) on mushroom tyrosinase was evaluated. All HTCCAs inhibited the tyrosinase activity. The ID(50) values were 1.88, 1.84, and 1.88 for the (R)-, (S)-, and (+/-)-HTCCAs, respectively. The inhibition kinetics analyzed by Hanes-Woolf plots indicated that both (R)- and (S)-HTCCAs are competitive inhibitors of the tyrosinase, with K(i) values of 0.83 and 0.61 mM, respectively. Dimethyl sulfoxide (DMSO) was also tested for its direct inhibitory activity against the tyrosinase and its potential influence on the tyrosinase inhibitory effects of (R)- and (S)-HTCCAs. DMSO, a widely used solvent for tyrosinase inhibitors, was found to dose-dependently inhibit the tyrosinase activity. Addition of DMSO in a tyrosinase digest containing either (R)- or (S)-HTCCA further dose-dependently reduced the tyrosinase activity. These data indicated a potential to use a HTCCA as a tyrosinase inhibitor in food, cosmetic, and medicinal products and a need to improve the solvent system for the studies of tyrosinase inhibitions.
authors.affiliation: Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado 80523, USA. yu@cahs.colostate.edu
authors.forename: Liangli
authors.initials: L
authors.lastname: Yu
mesh_terms: D000363:Agaricales / Q000201:enzymology; D002839:Chromans / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors*
chemical_list: D002839:Chromans; D004791:Enzyme Inhibitors; D014442:Monophenol Monooxygenase; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D004121:Dimethyl Sulfoxide