Melanin protects the skin from UV radiation but overproduction can cause hyperpigmentation, often triggered by UV-induced melanogenesis. This process begins when keratinocytes release α-MSH, which binds to MC1R on melanocytes, activating cAMP and MAPK pathways that boost melanin synthesis. Marine-derived ingredients like fish skin collagen peptides are gaining interest for their skin benefits. While known for hydration and anti-aging, their anti-melanogenic mechanisms remain underexplored. This study investigates how fish skin collagen peptides affect melanin production and the molecular pathways involved.
Methods
Fish skin collagen peptides were extracted using ultrasound and enzymatic hydrolysis. B16F10 murine melanoma cells were used in both 2D and 3D culture models to assess cytotoxicity and melanin content. Intracellular signaling was analyzed using Western blotting, cAMP assays, and Fontana-Masson staining. The interaction between peptides and MC1R was confirmed using the DARTS assay and molecular docking. Zebrafish embryos were used for in vivo validation of anti-melanogenic effects. Peptide profiling was done via HPLC-MS/MS, and statistical analysis used one-way ANOVA with Dunnett’s test.
Key Findings
• Collagen peptides did not exhibit significant cytotoxicity at concentrations up to 800 μg/mL in B16F10 cells.
• Collagen peptides significantly reduced extracellular and intracellular melanin content in both 2D and 3D murine melanoma cell culture models in a concentration-dependent manner.
• Collagen peptides downregulated the protein expression of key enzymes involved in melanin synthesis, specifically tyrosinase, Trp-1, and Trp-2.
• Collagen peptides inhibited the cAMP/CREB/MITF signaling pathway by reducing intracellular cAMP levels, attenuating CREB phosphorylation, and decreasing the expression of MITF, a key transcription factor for tyrosinase, Trp-1, and Trp-2.
• Collagen peptides regulated the MAPK signaling pathway by inhibiting the phosphorylation of ERK and p38, which are involved in regulating MITF expression and phosphorylation. Collagen peptides did not affect JNK phosphorylation.
• Collagen peptides directly interact with the MC1R protein, as demonstrated by the DARTS assay, where they attenuated pronase-induced degradation of MC1R.
• Peptide profiling identified 40 peptides from fish skin collagen. Molecular docking simulations showed binding between these peptides and the α-MSH binding pocket of the MC1R protein.
• Shorter peptide sequences generally had lower binding energies to MC1R, suggesting better binding affinity, with the four peptides with the lowest binding energies being primary candidates for direct MC1R inhibition.
• Collagen peptides attenuated melanin pigmentation in zebrafish embryos in a concentration-dependent manner, demonstrating anti-melanogenic efficacy in a more complex biological system.
Fish skin collagen peptides showed strong potential to inhibit melanin synthesis in vitro and in vivo. They suppressed key signaling pathways (cAMP/CREB/MITF and MAPK) by directly interacting with the MC1R receptor, reducing expression of melanin-producing enzymes. Shorter peptides had higher MC1R binding affinity, suggesting a structure-activity relationship. These findings position collagen peptides as promising candidates for use in skin-whitening and dermatological applications. Further clinical validation in humans is needed to confirm their efficacy and safety.
Link to the study: https://www.sciencedirect.com/science/article/pii/S1756464625002622
