Figure 2
From: D-tyrosine adds an anti-melanogenic effect to cosmetic peptides
Pentapeptide-18 with terminal D-tyrosine suppresses the melanogenesis induced by α-MSH and UVB. (A,B) MNT-1 cells were either treated with 1 μM of α-MSH plus the indicated concentrations of peptides for 24 h (A) or irradiated with 100 mJ/cm2 UVB and treated with 500 μM of peptides for 24 h (B). Protein expression was measured by Western blot analysis and mRNA expression was analyzed by RT-PCR (top panel). The mean percentages of melanin content ± SD are shown; *P < 0.05 and **P < 0.01 (middle panel). MNT-1 cells were plated on 12-well plates, treated with 500 μM of indicated peptide plus α-MSH (1 μM) for 24 h, or irradiated with 100 mJ/cm2 UVB and treated with 500 μM of peptides for 24 h and reacted with L-DOPA at 37 °C for 3 h. Bright-field microscopic images are shown. Scale bars = 20 μm. Relative amounts of stained regions were measured with the ImageJ program; *P < 0.05 (bottom panel). (C) MNT-1 cells were either treated with 100 nM of α-MSH with/without 250 μM of C-D for 72 h. mRNA expression was analyzed by RT-PCR (left panel). The mean percentages of melanin content ± SD are shown; *P < 0.05 and **P < 0.01 (right panel).
