Action of Tyrosinase on Ortho-Substituted Phenols: Possible Influence on Browning and Melanogenesis

• Published in: Journal of agricultural and food chemistry 2012-06, Vol.60 (25), p.6447-6453
• Main Authors: Garcia-Molina, Maria del Mar, Muñoz-Muñoz, Jose Luis, Garcia-Molina, Francisco, García-Ruiz, Pedro Antonio, Garcia-Canovas, Francisco
• Format: Article
• Language: English
• Subjects: Agaricales - chemistry; Agaricales - enzymology; Aroma and flavouring agent industries; Biological and medical sciences; butylated hydroxyanisole; carvacrol; Enzyme Inhibitors - chemistry; enzyme substrates; eugenol; Food industries; Fundamental and applied biological sciences. Psychology; Fungal Proteins - antagonists & inhibitors; Fungal Proteins - chemistry; guaiacol; Kinetics; L-dopa; melanogenesis; Molecular Structure; Monophenol Monooxygenase - antagonists & inhibitors; Monophenol Monooxygenase - chemistry; Phenols - chemistry; Substrate Specificity; thymol
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf301238q

The action of tyrosinase on ortho-substituted monophenols (thymol, carvacrol, guaiacol, butylated hydroxyanisole, eugenol, and isoeugenol) was studied. These monophenols inhibit melanogenesis because they act as alternative substrates to l-tyrosine and l-Dopa in the monophenolase and diphenolase activities, respectively, despite the steric hindrance on the part of the substituent in ortho position with respect to the hydroxyl group. We kinetically characterize the action of tyrosinase on these substrates and assess its possible effect on browning and melanognesis. In general, these compounds are poor substrates of the enzyme, with high Michaelis constant values, K m, and low catalytic constant values, k cat, so that the catalytic efficiency k cat/K m is low: thymol, 161 ± 4 M–1 s–1; carvacrol, 95 ± 7 M–1 s–1; guaiacol, 1160 ± 101 M–1 s–1.