Anti-Hyperpigmentation-Related Potential Activities in B16BL6 Cells and Chemical Composition of Essential Oil from Chamaecyparis pisifera Leaves

<b>Background/Objectives</b>: <i>Chamaecyparis pisifera</i> (<i>C. pisifera</i>; family Cupressaceae) is known to have insecticidal and antibacterial activities, but its effects on skin depigmentation-related activities have not been elucidated. Thus, in the present study, we aimed to investigate the anti-hyperpigmentation potential of <i>C. pisifera</i> var. filifera leaf essential oil (CPEO), specially focusing on responses related to melanogenesis and melanin transport, using B16BL6 cells. <b>Methods</b>: CPEO was extracted by steam distillation, and its composition was determined by GC/MS spectrometry. The biological activities of CPEO on B16BL6 melanoma cells were analyzed using the water soluble tetrazolium salt, BrdU incorporation, ELISA, and immunoblotting assays. <b>Results</b>: Twenty-eight components were identified in CPEO. CPEO was noncytotoxic to B16BL6 cells at 1-100 μg/mL and reduced serum-induced proliferation in B16BL6 cells. CPEO significantly inhibited α-MSH-stimulated increases in melanin synthesis and tyrosinase activity in the cells (e.g., at 100 μg/mL CPEO, melanin synthesis: 117.89 ± 0.00% vs. 571.94 ± 0.81% with α-MSH; tyrosinase activity: 73.62 ± 0.00% vs. 322.60 ± 3.10% with α-MSH). CPEO also downregulated the expression levels of melanogenesis-related proteins (MITF, tyrosinase, TRP-1 and -2) and melanosome transport-related proteins (Rab27a, melanophilin, myosin Va) in cells exposed to α-MSH. Moreover, the essential oil increased the phosphorylations of MAPKs (p38, ERK1/2, and JNK) in α-MSH-treated B16BL6 cells. In addition, CPEO reduced the ultraviolet A (UVA) induced increases in α-MSH levels in HaCaT cells. In addition, conditioned medium from HaCaT cells irradiated with UVA (CM-UVA) in the presence of CPEO reduced melanin synthesis and tyrosinase activity in B16BL6 cells (e.g., at CM-UVA with 100 μg/mL CPEO, melanin synthesis: 100.92 ± 0.99% vs. 134.44 ± 0.97% with CM-UVA; tyrosinase activity: 101.02 ± 1.81% vs. 133.77 ± 1.88% with CM-UVA). <b>Conclusions</b>: These findings suggest that CPEO inhibits melanin production (probably through the regulation of MAPKs) and transport-related activities in B16BL6 cells, and that CPEO may serve as a potential natural anti-hyperpigmentation or skin whitening.