Acetyl tetrapeptide-5
is used in cosmetic eye formulations to decrease puffiness, eye bags, and dark circles by reducing edema and protecting proteins such as SOD from glycation
Alanine
Ala / A · hydrophobic residue · neutral charge
AOD-9604
is studied as an anti-obesity peptide that can reduce weight gain and increase fat oxidation in obese animal models with generally neutral effects on IGF-1 and glucose metabolism in early human trials
Arginine
Arg / R · basic residue · positive charge
Argireline
is a topical cosmetic peptide reported to decrease dynamic wrinkles by partially mimicking the mechanism of botulinum toxin in a non-invasive manner
Asparagine
Asn / N · polar residue · neutral charge
Aspartic acid
Asp / D · acidic residue · negative charge
BPC-157
is investigated for accelerating healing of gastrointestinal mucosa, tendons, ligaments, bone, and nervous tissue in preclinical models, with anti-inflammatory and pro-angiogenic effects
Comparison
While Melanotan I is approved in some regions for prevention of phototoxicity in erythropoietic protoporphyria and is studied as a skin-darkening, photoprotective peptide3444, Semaglutide is approved for type 2 diabetes and chronic weight management, significantly lowering HbA1c and body weight by modulating incretin pathways232480.
While Melanotan I works as a linear 13-amino-acid analog of α-MSH (afamelanotide) that selectively activates MC1R on melanocytes, increasing eumelanin synthesis and providing photoprotection3444, Semaglutide is a modified GLP-1(7–37) analog with three key changes—Ala8→Aib, Lys26 acylated with a C18 fatty diacid, and Lys34→Arg—resulting in a long-acting GLP-1 receptor agonist that enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite23647480.
Melanotan I
POMC
Semaglutide
GCG
Both peptides fall into a similar broad context as Hormone peptides, although the details of how they are used and discussed still diverge. Their typical research and application settings separate fairly clearly: Melanotan I is more often discussed in the realm of Dermatology and aesthetics, whereas Semaglutide is more often associated with the realm of Metabolic and endocrine and Cardiovascular health. Both appear to work through Receptor agonist, but the functional emphasis still separates, with Melanotan I leaning toward Melanogenesis modulation and Semaglutide leaning toward Metabolic regulation and Lipolysis and fat loss. Both are synthetic in origin and their development context also differs, with Melanotan I approved for Research use only while Semaglutide is approved. Melanotan I takes the form of a linear peptide, whereas Semaglutide is closer to a peptide conjugate, Melanotan I carries d-amino acid substitution features, while Semaglutide instead reflects lipidation changes; while their sequence patterns also diverge, with Melanotan I showing protein-mimetic sequence features and Semaglutide showing alpha-helical domain features.