Melatonin (N-acetyl-5-methoxytryptamine) bulk powder for formulators

Melatonin is not a peptide. It is a small indoleamine, N-acetyl-5-methoxytryptamine, and it appears on this site because Pepti, Guangzhou makes it on the same production line and under the same supply terms as the peptide raw materials: bulk powder from 5 g, cold-chain shipping, a lot certificate of analysis with every shipment and a safety data sheet on request. Formulators of scalp tonics and night serums ask for it under the INCI name Melatonin, and their questions are practical: how a lipophilic powder gets into a water-based product, why a clear solution turns yellow, and which markets allow it in a cosmetic at all.

This page answers those three questions with identity data, handling chemistry and a regulatory caveat. The material is the neutral molecule, CAS 73-31-4.

Identity and naming

Melatonin has one chemical identity and several names. PubChem gives the systematic name N-[2-(5-methoxy-1H-indol-3-yl)ethyl]acetamide; chemists write N-acetyl-5-methoxytryptamine; CosIng and the INCI dictionary use the single word Melatonin; some catalogues print melatonine or MLT. All refer to the same molecule: CAS 73-31-4, PubChem CID 896, formula C13H16N2O2, molecular weight 232.3 g/mol.

Two points matter for the paperwork. The material is a neutral molecule rather than a salt, so there is no hydrochloride or sodium form to confuse it with. And melatonin is an amide, not a free amine: the amide nitrogen does not protonate at cosmetic pH, so the molecule cannot be pulled into water by acidifying the base. The sequence field in the identity table is a dash, as for every non-peptide active on this site.

Appearance, solubility and handling

The powder is white to off-white and crystalline. A cream or yellow tint in a fresh container usually means it has seen light or air for too long; melatonin oxidises, and its degradation products are coloured. Keep the container closed, dark and cold: 2–8 °C protected from light for working stock, −20 °C for long-term storage, as printed on the lot COA with a retest date. The powder is not notably hygroscopic, so weighing is uneventful.

Solubility is the first bench problem. Melatonin dissolves poorly in water, well in ethanol and glycols, and adequately in oils and esters. Three routes work: dissolve it in a small volume of ethanol or glycol and add the concentrate to the water phase under stirring; dissolve it in the oil phase of an emulsion; or carry it in a solubiliser system already in use for lipophilic actives. Whichever route is chosen, clarity is confirmed after a cold cycle in the buyer's own base.

What the published literature reports

Slominski and colleagues review evidence that melatonin, widely known as a pineal hormone, is also synthesised and metabolised in skin, acts through membrane receptors and receptor-independent pathways, and functions as an antioxidant and protective factor against ultraviolet-induced damage in cutaneous cell and tissue models (Slominski A, Tobin DJ, Zmijewski MA, Wortsman J, Paus R. Trends Endocrinol Metab, 2008).

The EU Scientific Committee on Consumer Safety assessed melatonin for cosmetic use, recorded that CosIng indicates it as an antioxidant in cosmetic products, and in opinion SCCS/1315/10 of 24 March 2010 concluded that melatonin in hair products at 0.0033% w/w does not pose a risk to the health of the consumer; the opinion covers that product type and concentration only (SCCS/1315/10, Opinion on Melatonin, 2010).

Neither source is a specification for this raw material or a claim about any finished product.

Formulation notes for the bench

The notes below are chemistry, not efficacy.

• Light. Melatonin absorbs in the ultraviolet and photodegrades. Add it in the cool-down phase, keep bulk solutions covered and specify opaque or amber packaging. A clear bottle on a lit shelf is the usual reason a melatonin product discolours.
• Oxygen and oxidisers. The indole ring is oxidisable. Keep peroxides and strong oxidising agents out of the same phase. A yellow-to-brown drift in colour is the stability signal to watch.
• pH. There is no ionisable group within the cosmetic pH range, so solubility and stability change little between mildly acidic and neutral bases. Strongly alkaline bases accelerate degradation.
• Chelators. A chelator in the water phase is compatible and helps by binding the trace iron and copper that catalyse oxidation.
• Co-solvent crash-out. Melatonin carried into water by a co-solvent can crystallise on cooling; test the finished product cold and, if crystals form, use more co-solvent, an oil-phase route or a lower use level.
• Regulatory status. Melatonin is listed in CosIng, but several markets classify it as a medicinal substance and exclude it from cosmetics or limit it to certain product types. Check every target market before the formula is finalised; Pepti supplies identity and purity documentation, not a market status.

The use level is the formulator's decision, set from their own stability and tolerance work.

Specification and documents for this material

Each lot of melatonin is accompanied by a certificate of analysis reporting HPLC purity, mass-spectrometry identity against the expected molecular weight, appearance, and the storage and retest statements. A safety data sheet in the standard 16-section format is available; both documents name Pepti, Guangzhou as the manufacturer.

No public batch record for melatonin is listed in the Pepti COA library yet. The lot COA is issued with the shipment. For orientation, the public records Pepti publishes for its other compounds currently fall between 98.4% and 99.8% HPLC purity; the figure for a melatonin lot is the one on that lot's COA.

Public batch records

No public batch record is listed for this compound in the manufacturer's library yet. The lot you receive carries its own COA with HPLC purity, MS identity and lot number; ask for the current lot's COA with your quote. The library itself is at peptioem.com/coa.