Lupenone from Erica multiflora Leaf Extract Stimulates Melanogenesis in B16 Murine Melanoma Cells through the Inhibition of ERK1/2 Activation
ABSTRACT Hypopigmentation diseases are usually managed using UVB light which increases the patients' risk for skin cancer. Here, we evaluated the melanogenesis stimulatory effects of leaf extracts of Erica multiflora, a medicinal plant from the Mediterranean region, and its active component, lup-20(29)-en-3-one, as possible therapeutic agents to address hypopigmentation disorders. B16 murine melanoma cells were treated with E. multiflora extracts or its active component lupenone to evaluate their effects on melanin biosynthesis. The mechanism underlying the observed effects was also determined. Bioactivity-guided fractionation of fifteen ethyl acetate fractions identified fraction 2 to have melanogenesis stimulatory effects due to its ability to decrease mitogen-activated protein kinase phosphorylated extracellular signal-regulated kinases 1 and 2 activation. Preparative TLC of ethyl acetate fraction 2 revealed the presence of lup-20(29)-en-3-one as the major bioactive component. B16 cells treated with lup-20(29)-en-3-one increased melanin content without cytotoxicity. To determine the mechanism for the observed effects of lup-20(29)-en-3-one, the tyrosinase enzyme activity, the tyrosinase protein expression, and the activation of phosphorylated extracellular signal-regulated kinases 1 and 2 were determined. In addition, the expression of the tyrosinase mRNA was quantified using real-time PCR. Results showed that lup-20(29)-en-3-one has no effect on the tyrosinase enzyme activity but can increase tyrosinase expression at both the transcriptional and translational levels. The increase in the tyrosinase mRNA expression was most likely due to the inhibited mitogen-activated protein kinase phosphorylated extracellular signal-regulated kinases 1 and 2 activation. We report for the first time that E. multiflora ethyl acetate extract and its active compound lup-20(29)-en-3-one stimulate melanogenesis by increasing the tyrosinase enzyme expression via mitogen-activated protein kinase phosphorylated extracellular signal-regulated kinases 1 and 2 phosphorylation inhibition, making it a possible treatment for hypopigmentation diseases.
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ABSTRACT: With the aim of characterizing the active ingredients lupenone and β-sitosterol in Rhizoma Musae samples a reversed-phase HPLC method for the separation of these two compounds in Rhizoma Musae samples was developed (regression coefficient > 0.9996). The method was further applied to quantify lupenone and β-sitosterol content in Rhizoma Musae samples cultured in different growth environments. Different variables such as geographical location, growth stage, and harvest time, demonstrated differential effects on lupenone and β-sitosterol levels. Moreover, we determined the optimum conditions for cultivation and harvesting of Rhizoma Musae herbs. Lupenone administration caused a significant reduction in fasting blood glucose (FBG) levels in diabetic rats at doses of 1.78, 5.33, and 16.00 mg·kg-1·day-1 for 14 days, the glycated hemoglobin (HbA1c) levels of diabetic rats also significantly reduced at doses of 5.33, and 16.00 mg·kg-1·day-1, indicating a robust antidiabetic activity. To our knowledge, this is the first report of an optimized HPLC method successfully applied to quantify lupenone and β-sitosterol, and its applicability in optimizing Rhizoma Musae growth. Animal experiments also showed for the first time that lupenone from Rhizoma Musae has anti-diabetic activity.Molecules 09/2014; 19(9):14114-14127. DOI:10.3390/molecules190914114 · 2.10 Impact Factor