Abstract
The present study aimed to investigate the melanin synthesis effect of pine needle essential oil (PNEO) extracted using microwave-assisted extraction on α-MSH-induced B16F10 melanoma cells and its molecular mechanism of action. Cell Counting Kit-8 was used to measure the safe concentration of B16F10 cells after 24 and 48 h post-treatment. Tyrosinase (TYR) activity assay was used to examine intracellular enzyme viability; western blotting (WB) and reverse transcription-quantitative (RT-qPCR) assays were utilized to assess the transcription and expression of genes and proteins associated with melanogenesis. Relevant targets in the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway were verified by the addition of target inhibitors or activators. Results showed that PNEO decreased the levels of melanin and the activity of TYR in B16F10 cells. RT-qPCR and WB results showed that PNEO downregulated the expression of melanogenesis-related genes and proteins such as microphthalmia-associated transcription factor, TYR, TYR-related protein-1 and melanocortin 1 receptor, and reduced the levels of phosphorylated PKA and phosphorylated cyclic-AMP response binding protein. These results suggested that the inhibitory effect of PNEO on melanin production may be related to the cAMP/PKA pathway. Verification through the addition of target inhibitors or activators confirmed that PNEO regulates melanin synthesis and TYR activity through the cAMP/PKA signaling pathway.