Isolation of 6-hydroxy-L-tryptophan from the fruiting body of Lyophyllum decastes for use as a tyrosinase inhibitor

• Published in: Bioscience, biotechnology, and biochemistry Vol. 83; no. 10; pp. 1800 - 1806
• Main Authors: Ishihara, Atsushi, Sugai, Naomi, Bito, Tomohiro, Ube, Naoki, Ueno, Kotomi, Okuda, Yasuhito, Fukushima-Sakuno, Emi
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 03.10.2019; Oxford University Press
• Subjects: 5-Hydroxytryptophan - isolation & purification; 5-Hydroxytryptophan - pharmacology; 6-hydroxy-L-tryptophan; Agaricales - metabolism; Chromatography, High Pressure Liquid; Enzyme Inhibitors - pharmacology; Inhibitory Concentration 50; Lyophyllum decastes; Monophenol Monooxygenase - antagonists & inhibitors; Mushroom; tyrosinase inhibitor; tyrosinase inhibitor; 6-hydroxy-L-tryptophan; Lyophyllum decastes; Mushroom
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1080/09168451.2019.1621157

Tyrosinase is the key enzyme that controls melanin formation. We found that a hot water extract of the lyophilized fruiting body of the fungus Lyophyllum decastes inhibited tyrosinase from Agaricus bisporus. The extract was fractionated by ODS column chromatography, and an active compound was obtained by purification through successive preparative HPLC using an ODS and a HILIC column. Using spectroscopic data, the compound was identified to be an uncommon amino acid, 6-hydroxytryptophan. 6-Hydroxy-L-tryptophan and 6-hydroxy-D-tryptophan were prepared through a Fenton reaction from L-tryptophan and D-tryptophan, respectively. The active compound was determined to be 6-hydroxy-L-tryptophan by comparison of their circular dichroism spectra and retention time on HPLC analysis of the N α -(5-fluoro-2,4-dinitrophenyl)-L-leuciamide derivative with those of 6-hydroxy-L-tryptophan and 6-hydroxy-D-tryptophan. A Lineweaver-Burk plot of the enzyme reaction in the presence of 6-hydroxy-L-tryptophan indicated that this compound was a competitive inhibitor. The IC 50 values of 6-hydroxy-L-tryptophan was 0.23 mM. The tyrosinase inhibitor, 6-hydroxy-L-tryptophan, was isolated from the hot water extract of Lyophyllum decastes fruiting body.