Tyrosinase is the rate-limiting enzyme critical for melanin synthesis. It controls pigmentation in the skin. Activation of tyrosinase is currently the most common approach in the development of tanning and haircare products. Pratol is a 7-hydroxy-4-methoxyflavone found in Trifolium pratense. In this study, we investigated the effects of pratol on melanogenesis. We also studied the mechanism of action of pratol in B16F10 mouse melanoma cells. The cells were treated with various concentrations (6.25, 12.5, 25, and 50 μM) of pratol to observe its effects. The results showed that pratol significantly increased melanin content and tyrosinase activity in the cells without being cytotoxic. In addition, pratol strongly increased the expression of tyrosinase and tyrosinase-related protein-1 and 2 by enhancing the expression of microphthalmia-associated transcription factor. Furthermore, pratol stimulated melanogenesis via the phosphorylation of p38, c-Jun N-terminal kinases (JNK), and extracellular signal–regulated kinase (ERK). The findings from an assay searching for the inhibitor revealed that SB203580 (a specific p38 inhibitor) or SP600125 (a p-JNK inhibitor) attenuated pratol-induced cellular tyrosinase activity whereas PD98059 (an ERK inhibitor) did not. Additionally, pratol interfered with the phosphorylation of p-AKT. We also found that pratol-induced melanogenesis was reversed by H89, which is a specific protein kinase A inhibitor. The results suggest that, owing to its multi-functional properties, pratol may be a potential tanning agent or a therapeutic agent for hair depigmentation in the cosmetic industry.

This study was carried out to investigate the antimelanogenic effects of a Polygonum tinctorium flower extract obtained using red nuruk, a traditional Jeju barley-based fermentation starter. We also studied the mechanism of action of the P. tinctorium fermented flower extract (PTFFE) in mouse melanoma cells (B16F10). Cells were treated with various concentrations (62.5, 125 and 250 μg/mL) of PTFFE and the results showed that PTFFE significantly decreased the melanin content and tyrosinase activity without being cytotoxic. In addition, PTFFE strongly inhibited the expression of tyrosinase and tyrosinase-related protein 2 by decreasing the expression of the microphthalmia-associated transcription factor, as shown by a western blot assay. Furthermore, PTFFE inhibited melanogenesis via upregulation of the phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B, also known as AKT. We also used inhibitors such as PD98059 (a specific ERK inhibitor) or LY294002 (an AKT inhibitor) to determine whether the signaling pathways are involved. High-performance liquid chromatography fingerprinting showed the presence of a quercetin glucoside (isoquercitrin) and quercetin in PTFFE. To test the potential for PTFFE application as a cosmetic material, we also performed a primary skin irritation test on human skin. In this assay, PTFFE did not induce any adverse reactions at the treatment dose. Based on these results, we suggest that PTFFE may be considered a potential antimelanogenesis candidate for topical applications.

In this study, in order to explore the anti-melanogenic effect of PFE (Paederia foetida L. extract) and suggest its availability, B16F10 cells, which are murine melanoma cells, were stimulated with alpha-Melanocyte-stimulating hormone (α-MSH) to conduct an in vitro experiment. Treatment with PFE in B16F10 cells with activated melanogenesis due to stimulants showed that PFE significantly inhibits melanin content as well as intracellular tyrosinase activity within a range that does not cause cytotoxicity. In addition, Western blot assay demonstrated that PFE strongly inhibited the protein expression of not only tyrosinase-related protein (TRP)-1, -2, and tyrosinase, but also microphthalmia-associated transcription factor (MITF). Moreover, mechanism studies have shown that PFE processing inhibited the activation of melanin production by regulating the phosphorylation of each mitogen-activated protein kinase (MAPK) family in the MAPK signaling pathway. To test the biocompatibility of PFE on human skin, a primary skin irritation test was performed. The results revealed that PFE did not have any side effects on human skin. These findings suggest that PFE holds great potential as a skin whitening agent and in the prevention of hyperpigmentation disorders.

Young Min Woo, Jae Yong Seo, Soo-ya Kim, Ji Hyun Cha, Hyun Dae Cho, Young Kwon Cha, Ju Tae Jeong, Sung Min Park, Hwa Sun Ryu, Jae Mun Kim, Moon Hoy Kim, Hee-Taek Kim, Yong-Min Kim, Kwang Sik Joo, Sun Mi Lee, JungNo Lee, and Andre Kim. Microbiol. Biotechnol. Lett. 2022;50:533-47. https://doi.org/10.48022/mbl.2206.06011

Heat shock treatment-induced skin aging causes a thickened epidermis, increased matrix metalloproteinase (MMP)-1 expression, collagen degradation, and deep wrinkles. In this study, we investigated the effect of manassantin B in preventing heat shock treatment-induced aging. We first separated manassantin B (MB) from the roots of Saururus chinensis, and the structure was identified using ¹H- and ¹³C-NMR spectroscopy. RT-PCR and western blotting were applied to investigate the anti-aging effect of manassantin B. Manassantin B decreased MMP-1 expression through transient receptor potential vanilloid (TRPV) 1 channel inhibition and significantly increased procollagen expression. In addition, manassantin B suppressed MAPK phosphorylation in a dose-dependent manner. Our results suggest that manassantin B, the active ingredient in S. chinensis, can be effectively used to inhibit heat shock treatment-induced skin aging.