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The peptide literature, summarized and graded.

Every paper distilled to a plain-language summary with an honest evidence grade — from strong human trials to animal-only signals. 2 papers indexed and counting.

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Filtered by #melanotan · clear

In vitro

Investigation of the stability profile of therapeutic α-MSH analogue: Insights from liquid chromatography-high resolution mass spectrometry analysis of afamelanotide.

This study investigated the chemical and physical stability of afamelanotide (melanotan-1), a synthetic 13-amino acid peptidomimetic of α-melanocyte stimulating hormone (α-MSH) approved as an orphan drug for erythropoietic protoporphyria. Researchers subjected the compound to a range of stress conditions — acidic, basic, neutral, oxidative, UV light exposure, and elevated temperature (60°C) — following International Council for Harmonisation (ICH) guidelines Q1A(R2) and Q5C. Using gradient reversed-phase HPLC coupled with ultra-high-performance liquid chromatography–high resolution tandem mass spectrometry (UHPLC-HRMS/MS), the team identified and structurally characterized 14 distinct degradation products. Collision-induced dissociation fragmentation patterns enabled detailed elucidation of each product's structure. Key degradation pathways identified included truncation, methylation, deacetylation, and oxidation. The analytical method was validated per ICH Q2(R1) guidelines. This work is purely analytical and pharmaceutical in nature — it does not involve human subjects, animals, or cell-based experiments. Its primary value lies in establishing a comprehensive stability profile of afamelanotide to inform rational drug formulation design. No clinical outcomes, efficacy, or safety data in biological systems were assessed.

#melanotan #afamelanotide

Journal of pharmaceutical and biomedical analysis · Jan 2026DOI ↗

In vitro

5-Hydroxypyrroloindoline Affords Tryptathionine and 2,2'-bis-Indole Peptide Staples: Application to Melanotan-II.

This study explores novel peptide stapling strategies inspired by natural product motifs found in fungal toxins (amatoxins, phallotoxins) and the alkaloid staurosporine. The researchers developed a chemical method using a 5-hydroxypyrroloindoline building block that can react with either a cysteine thiol (forming a tryptathionine staple) or a tryptophan indole (forming a 2,2'-bis-indole staple) to create constrained macrocyclic peptide structures. The authors applied these two stapling approaches to α-melanocyte-stimulating hormone (α-MSH), using the Melanotan-II scaffold as a model, with careful protecting group strategies to achieve chemoselectivity between the two staple types. Both classes of stapled peptides were evaluated for binding affinity at the melanocortin receptor, and the study reports that both series achieved nanomolar inhibition constants (Ki values), with at least one compound reaching sub-nanomolar Ki. Limitations include that all work is conducted in vitro (binding assays and synthetic chemistry), with no cell-based functional data, animal studies, or human data reported. The study is primarily a proof-of-concept for expanding the chemical toolbox of peptide stapling using underexplored natural product-derived cross-links.

#melanotan

Chemistry (Weinheim an der Bergstrasse, Germany) · Feb 2024DOI ↗