Inhibition of melanogenesis by jineol from Scolopendra subspinipes mutilans via MAP-Kinase mediated MITF downregulation and the proteasomal degradation of tyrosinase

Abstract

In this study, the authors investigated the anti-melanogenic effects of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans, the mechanisms responsible for its inhibition of melanogenesis in melan-a cells, and its antioxidant efficacy. Mushroom tyrosinase activities and melanin contents were determined in melan-a cells, and the protein and mRNA levels of MITF, tyrosinase, TYRP-1, and TYRP-2 were assessed. Jineol exhibited significant, concentration-dependent antioxidant effects as determined by DPPH, ABTS, CUPRAC, and FRAP assays. Jineol significantly inhibited mushroom tyrosinase activity by functioning as an uncompetitive inhibitor, and markedly inhibited melanin production and intracellular tyrosinase activity in melan-a cells. In addition, jineol abolished the expressions of tyrosinase, TYRP-1, TYRP-2, and MITF, thereby blocking melanin production and interfering with the phosphorylations of ERK1/2 and p38. Furthermore, specific inhibitors of ERK1/2 and p38 prevented melanogenesis inhibition by jineol, and the proteasome inhibitor (MG-132) prevented jineol-induced reductions in cellular tyrosinase levels. Taken together, jineol was found to stimulate MAP-kinase (ERK1/2 and p38) phosphorylation and the proteolytic degradation pathway, which led to the degradations of MITF and tyrosinase, and to suppress the productions of melanin.

Discovery of new depigmenting compounds and their efficacy to treat hyperpigmentation: Evidence from in vitro study

“…Modulation of p38 phosphorylation prevented excessive melanin synthesis through the accelerated degradation of melanogenic enzymes . Norartocarpetin (C 15 H 10 O 6 ), a flavone, which can be found in plants such as A communis , Artocarpus heterophyllus, and Artocarpus dadah was proposed to downregulate MITF expression via JNK‐ and p38‐dependent pathway .…”

“…ERK and JNK phosphorylation causes MITF ubiquitination and degradation, whereby downregulating melanin biosynthesis . Similar to norartocarpetin A, other compounds such as Morinda citrifolia extract, sesamol (C 7 H 6 O 3 ) of Sesamun indicum L., and jineol (C 9 H 7 O 2 N) of Scolopendra subspinipes also induce phosphorylation of p38 MAPK in melan‐a and B16 cells . Chinese herbal formula composed of tubers of hyacinth orchid ( Bletilla striata (Thunb.)…”

“…Melanoma cell lines were normally grown in medium such as McCoy’s 5A, Dulbecco’s modified Eagle’s medium (DMEM), Ham’s F12/DMEM, Ham’s F12, DMEM, MEM, or RPMI‐1640 . In particular, DMEM with high glucose content is more preferable for growth of B16 cell lines and melanin synthesis than other media .…”

“…McCoy's 5A, Dulbecco's modified Eagle's medium (DMEM), Ham's F12/DMEM, Ham's F12, DMEM, MEM, or RPMI-1640. 70,74,109,111,118 In particular, DMEM with high glucose content is more preferable for growth of B16 cell lines and melanin synthesis than other media. 7 High glucose media may provide sufficient energy in a form of ATP to support fast cell proliferation of melanoma cell line.…”

“…106 Analysis of TYR activity has also been reported via TYR zymography whereby intracellular TYR in gels (ie, SDS-PAGE) reacts with l-DOPA solution, and the intensity of the bands formed was visualized by a software (ie, ImageQuantTM LAS 4000 mini, Gel-Print System). 50,74,103 Tyrosinase luciferase reporter assay has been also demonstrated using Renilla luciferase expression vector for the determination of intracellular TYR activity. 60 On the other hand, TYRimmunohistochemical fluorescence assay utilizes specific primary antibody with combination of a FITC-secondary antibody, which can be subsequently visualized using a fluorescence microscope.…”