What's on the label is the measured result — net peptide mass, not gross powder weight, plus RP-HPLC purity, on a lot-numbered COA for every batch.
Net peptide mass and RP-HPLC purity — a lot-numbered COA for every batch.
Net peptide mass + HPLC purity, per lot.
PCAC will review 7 peptides for the 503A bulks list, BPC-157, KPV, TB-500, MOTS-c, Emideltide, Semax, Epitalon. Read our briefing →
PCAC will review 7 peptides for the 503A bulks list. Read →
FDA PCAC reviews 7 peptides in July. Read →
Pineal hormone · sleep / circadian-rhythm research compound
PeptideXpo buyer fit
This PeptideXpo page is intentionally positioned for distributors, OEM buyers, and procurement teams comparing Melatonin inside a wider peptide catalog. It is not trying to be the deepest single-molecule monograph; the differentiated intent is assortment planning, export-ready documentation, fill-size comparison, and whether this SKU belongs in a broader buyer program.
Overview
Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine hormone synthesized primarily by the pineal gland during the dark phase of the circadian cycle. Although technically a small-molecule rather than a peptide, melatonin sits in the longevity category here because of its frequent co-formulation with peptide longevity research products (especially Epitalon, which acts in part by modulating pineal melatonin secretion) and its established role in sleep, circadian-rhythm, and antioxidant research. Melatonin is approved in many jurisdictions as a dietary supplement, in some as a prescription medication for sleep and jet-lag indications, and is the most-studied molecule in chronobiology research. PeptideXpo supplies Melatonin at ≥99.0% HPLC purity, lyophilized 10 mg fill. As a small molecule rather than a peptide, the relevant analytical methods include RP-HPLC for chemical purity, UV-Vis absorbance for identity, and GC-MS or LC-MS for residual-solvent and impurity profiling. Standard 10 mg fill matches typical research and compounding workflows. Melatonin is photosensitive and the storage spec includes light protection; while the molecule is stable at room temperature in light-protected packaging, refrigerated storage extends shelf life and is recommended for long-term hold.
Who buys this, and why
Buyers for longevity-class peptides span research labs working on telomere, collagen, and circadian-rhythm models, plus cosmetic-formulation OEMs incorporating peptides like GHK-Cu into anti-aging finished products. Copper peptides in particular require attention to chelator-free water and EDTA-free buffers in downstream formulation work, incompatibility there is the most common cause of "the peptide didn't work" support tickets in this class.
Primary buyer fit: academic and contract research laboratories and 503A / 503B compounding pharmacies.
Specifications
Documentation available on request
Regulatory note
Sold for research and for use as a cosmetic ingredient where the receiving formulator's regulatory framework permits (e.g. EU cosmetic regulation 1223/2009, FDA cosmetic-monograph framework, equivalent regimes). Not a finished dosage form. Cosmetic-finished-product safety responsibility remains with the brand owner.
Frequently asked questions
No, melatonin is an indoleamine, a small molecule derived from the amino acid tryptophan through a four-step enzymatic pathway. It's not a peptide and the analytical methods used to characterize melatonin differ from those used for peptides. We include it in the catalog because melatonin is commonly co-formulated with peptide longevity research products, especially Epitalon (which acts in part through pineal-melatonin pathway modulation). Buyers should not confuse the analytical packet for melatonin (RP-HPLC for chemical purity, UV-Vis, residual-solvent profiling) with the analytical packet for peptide products (HPLC, mass spec, sequence verification).
Epitalon is hypothesized to act in part by modulating endogenous pineal melatonin secretion, the molecule was originally identified through fractionation of pineal-gland tetrapeptide extracts, and several published Khavinson-school studies have measured restoration of age-decline melatonin rhythms in elderly subjects given Epitalon. Combining direct Melatonin supplementation with Epitalon is therefore a common workflow in Khavinson-class longevity research: the Melatonin provides immediate exogenous hormone, while the Epitalon hypothesis is that it helps restore the underlying pineal-secretion capacity. PeptideXpo's Melatonin and Epitalon products are commonly ordered together for these workflows.
Melatonin is photosensitive, exposure to visible light (especially UV wavelengths) initiates photochemical degradation pathways that produce kynuramine derivatives and other byproducts. The degradation accelerates in solution but also occurs in the solid lyophilized form on prolonged light exposure. The operational consequence is amber-glass or opaque-container storage rather than clear glass, with the vial kept in a dark environment between uses. Solid lyophilized melatonin protected from light is stable for the standard 24-month re-test window at room temperature; refrigerated storage extends shelf life further but is not strictly necessary for the lyophilized form.
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