Study summary · research use only
A gel-forming α-MSH analog promotes lasting melanogenesis
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This in vitro and in vivo study, using rats and frogs, examined gel-forming analogs of α-MSH-related peptides, including acylated afamelanotide (DDE313) and ACTH1-24 (DDE314), which self-assemble into liquid gels. The DDE313 and DDE314 analogs formed liquid gels at 6-20% concentration and had increased viscosity above 2.5% compared to the original analogs. Gel formation reduced DDE313's passage through Centricon filters, and subcutaneous injection of the DDE313 gel in rats led to sustained presence of the peptide in circulation for more than 12 days. DDE313 darkened the skin of frogs for more than 4 weeks, while frogs injected with an equivalent dose of afamelanotide lost the tanning response within a few days. The authors suggest these self-assembled gels allow sustained melanocortin receptor activation.
Abstract
The α-MSH peptide plays a significant role in the regulation of pigmentation via the melanocortin 1 receptor (MC1R). It increases the DNA repair capacity of melanocytes and reduces the incidence of skin cancers. As such, α-MSH analogs could have the utility for protecting against UV-induced skin DNA damage in susceptible patients. Recently, α-MSH analogs have been approved for the treatment of erythropoietic protoporphyria, hypoactive sexual desire, or pediatric obesity. However, the delivery of these drugs requires inconvenient implants or frequent injections. We recently found that select palmitoylated melanocortin analogs such as afamelanotide and adrenocorticotropin peptides self-assemble to form liquid gels in situ. To explore the utility of these novel analogs, we studied their pharmacological characteristics in vitro and in vivo. Acylated afamelanotide (DDE 313) and ACTH1-24 (DDE314) analogs form liquid gels at 6-20% and have a significantly increased viscosity at >2.5% compared to original analogs. Using the DDE313 analog as a prototype, we showed gel-formation reduces the passage of DDE313 through Centricon filters, and subcutaneous injection of analog gel in rats leads to the sustained presence of the peptide in circulation for >12 days. In addition, DDE313 darkened the skin of frogs for >4 weeks, whereas those injected with an equivalent dose of afamelanotide lost the tanning response within a few days. Because self-assembled gels allow sustained activation of melanocortin receptors, further studies of these analogs may allow the development of effective and convenient tanning therapies to prophylactically protect against UV-induced malignant transformation of skin cells in susceptible patients.
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