ABSTRACT
A potential natural melanogenesis inhibitor was discovered in the form of a sesquiterpene isolated from the flowers of Inula britannica, specifically 6-O-isobutyrylbritannilactone (IBL). We evaluated the antimelanogenesis effects of IBL on B16F10 melanocytes and zebrafish embryos. As a result, we found that 3-isobutyl-1-methylxanthine (IBMX)-induced melanin production was reduced in a dose-dependent manner in B16F10 cells by IBL. We also analyzed B16F10 cells that were and were not treated with IBMX, investigating the melanin concentration, tyrosinase activity, mRNA levels. We also studied the protein expressions of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related proteins (TRP1, and TRP2). Furthermore, we found that melanin synthesis and tyrosinase expression were also inhibited by IBL through the modulation of the following signaling pathways: ERK, phosphoinositide 3-kinase (PI3K)/AKT, and CREB. In addition, we studied antimelanogenic activity using zebrafish embryos and found that the embryos had significantly reduced pigmentation in the IBL-treated specimens compared to the untreated controls.
Subject(s)
Inula/chemistry , Lactones , Melanocytes/metabolism , Signal Transduction/drug effects , Skin Pigmentation/drug effects , Zebrafish/embryology , Animals , Cell Line, Tumor , Embryo, Nonmammalian/metabolism , Gene Expression Regulation, Developmental/drug effects , Humans , Lactones/chemistry , Lactones/pharmacology , Zebrafish Proteins/biosynthesisABSTRACT
In the search for novel, natural melanogenesis inhibitors, a new sesquiterpene, inularin, was isolated from the flowers of Inula britannica, and the structure was determined using spectroscopic and chemical methods. The antimelanogenic effects of inularin on B16F10 melanoma cells and zebrafish embryos were evaluated. Inularin dose-dependently reduced melanocyte-stimulating hormone-induced melanin production and L-DOPA oxidation in B16F10 cells. Zebrafish embryos were used to confirm the antimelanogenic activity. Inularin significantly decreased the pigmentation of embryos compared with untreated controls.
Subject(s)
Flowers/chemistry , Inula/chemistry , Melanins/metabolism , Sesquiterpenes , Animals , Cell Line, Tumor , Embryo, Nonmammalian/drug effects , Melanins/analysis , Melanoma/metabolism , Mice , Pigmentation/drug effects , Sesquiterpenes/chemistry , Sesquiterpenes/pharmacology , ZebrafishABSTRACT
2α-Hydroxyeudesma-4,11(13)-dien-8ß,12-olide (HEDO), a eudesmane-type sesquiterpene lactone belonging to large group of plant terpenoids isolated from Inula britannica, displays cytotoxic activity against diffuse large B cell lymphoma cells in vitro. However, the molecular mechanism of the anticancer effect remains unclear. In this study, we showed that HEDO inhibits cell growth by inducing apoptosis in lymphoma cell lines through its antiproliferative activity. HEDO increases the depolarization of mitochondrial membrane potential and upregulated intracellular reactive oxygen species (ROS). Furthermore, we examined the cell cycle effect, and our results provided evidence that the arrest of the cell cycle at the SubG0/G1 phase plays an important role in the ability of HEDO to inhibit cell growth in Ontario Cancer Institute (OCI)-LY3 lymphoma cells by preventing nuclear factor-kappa B (NF-κB) signaling. In addition, HEDO induced apoptosis by instigating the activation of Bcl-2-associated X (BAX) and cleaved caspase-3, decreasing B-cell lymphoma 2 (BCL2), B-cell lymphoma-extra large (BCL-XL), and procaspase 3 expression levels. Based on these findings, we suggest that HEDO has potential as an anticancer drug of lymphoma by inducing ROS-dependent accumulation of SubG0/G1 arrest and apoptosis in OCI-LY3 cells.