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 Liraglutide is approved for type 2 diabetes and weight management, improving glycemic control and inducing weight loss through GLP-1–mediated insulinotropic, glucagonostatic, and appetite-suppressing actions6880, Melanotan II is studied as a tanning and libido-enhancing agent; increases melanin production and can reduce food intake and modulate sexual arousal in animal models and humans3545.
While Liraglutide works as a human GLP-1 analog with a single amino-acid substitution (Lys34→Arg) and a C16 palmitoyl fatty acid attached to Lys26 via a glutamate linker, producing a long-acting GLP-1 receptor agonist6880, Melanotan II is a cyclic heptapeptide melanocortin analog (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) that acts as a non-selective, high-potency agonist at MC1R, MC3R, MC4R, and MC5R, influencing pigmentation, appetite, and sexual behavior3545.
Liraglutide
GCG
Melanotan II
POMC
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: Liraglutide is more often discussed in the realm of Metabolic and endocrine, whereas Melanotan II is more often associated with the realm of Dermatology and aesthetics and Reproductive health. Both appear to work through Receptor agonist, but the functional emphasis still separates, with Liraglutide leaning toward Metabolic regulation and Lipolysis and fat loss and Melanotan II leaning toward Melanogenesis modulation. Both are synthetic in origin and their development context also differs, with Liraglutide approved while Melanotan II is approved for Research use only. Liraglutide takes the form of a peptide conjugate, whereas Melanotan II is closer to a cyclic peptide, Liraglutide carries palmitoylation features, while Melanotan II instead reflects acetylation changes; while their sequence patterns also diverge, with Liraglutide showing alpha-helical domain features and Melanotan II showing protein-mimetic sequence features.