title: Inhibitory and Acceleratory Effects of Inonotus obliquus on Tyrosinase Activity and Melanin Formation in B16 Melanoma Cells.
abstract: The aim of the present study is to preliminarily investigate the antimelanogenesis effect of Inonotus obliquus extracts by cell-free mushroom tyrosinase assay. It was found that petroleum ether and n-butanol extracts might contain unknown potential tyrosinase inhibitors, while its ethyl acetate extract might contain some unknown accelerators. Six compounds were isolated and their structures were identified by interpretation of NMR data and nicotinic acid was first discovered in Inonotus obliquus. In cells testing, betulin and trametenolic acid decreased tyrosinase activity and melanin content, while inotodiol and lanosterol significantly increased tyrosinase activity and melanin content, showing an AC⁡50 of 9.74 and 8.43 μM, respectively. Nicotinie acid, 3β,22,25-trihydroxy-lanosta-8-ene, had a little or no effect on tyrosinase. Betulin exhibited a mode of noncompetitive inhibition with a K I = K IS of 0.4 μM on tyrosinase activity showing an IC50 of 5.13 μM and being more effective than kojic acid (6.43 μM), and trametenolic acid exhibited a mode of mixed inhibition with a K I of 0.9 μM, K IS of 0.5 μM, and an IC50 of 7.25 μM. We proposed betulin and trametenolic acid as a new candidate of potent tyrosinase inhibitors and inotodiol and lanosterol as accelerators that could be used as therapeutic agent.
authors.affiliation: College of Chinese Medicinal Materials, Jilin Agricultural University, Changchun 130118, China.
authors.forename: Zheng-Fei
authors.initials: ZF
authors.lastname: Yan
authors.affiliation: College of Chinese Medicinal Materials, Jilin Agricultural University, Changchun 130118, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Engineering Research Center of Edible and Medicinal Fungi, Ministry of Education, Jilin Agricultural University, Changchun 130118, China.
authors.forename: Feng-Hua
authors.identifier: 0000-0002-0846-7743
authors.initials: FH
authors.lastname: Tian
authors.affiliation: College of Chinese Medicinal Materials, Jilin Agricultural University, Changchun 130118, China.
authors.forename: Xin-Xin
authors.initials: XX
authors.lastname: Mao
authors.affiliation: Engineering Research Center of Edible and Medicinal Fungi, Ministry of Education, Jilin Agricultural University, Changchun 130118, China.
authors.forename: Yu
authors.identifier: 0000-0002-8937-0416
authors.initials: Y
authors.lastname: Li
authors.affiliation: Engineering Research Center of Edible and Medicinal Fungi, Ministry of Education, Jilin Agricultural University, Changchun 130118, China.
authors.forename: Chang-Tian
authors.identifier: 0000-0001-6498-8642
authors.initials: CT
authors.lastname: Li