Melanotan II Testing
MW: 1024.18 g/molHalf-life: ~30 minutes
Cyclic α-MSH analog; widely used as a tanning research peptide.
Mechanism of action
Cyclic α-MSH analog; non-selective melanocortin receptor agonist (MC1R, MC3R, MC4R, MC5R). MC1R activation drives melanogenesis (tanning); MC4R activation drives the sexual-response effects seen in PT-141.
Sequence & structure
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂
C-terminal amidation distinguishes it from PT-141 (free acid). Cyclic lactam bridge; verify cyclization.
Research areas
- ●Melanogenesis / tanning research
- ●Erectile function (overlaps with PT-141)
- ●Appetite suppression
What we test on Melanotan II
RP-HPLC, intact-mass LC-MS, cyclization confirmation, endotoxin.
Standard Sexual Health Panel
- ✓RP-HPLC purity
- ✓LC-MS (cyclization confirmation)
- ✓Disulfide bond mapping
Common impurities & failure modes
- Linear precursor
+18 Da; failed cyclization.
- PT-141 contamination
Same backbone, only differs in C-terminus; cross-contamination in poorly-segregated facilities.
- Racemization at D-Phe
Loss of receptor selectivity.