Oxytocin (Acetate): A Research Peptide Overview

Oxytocin is a cyclic nonapeptide with the sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂, closed by a disulfide bridge between Cys1 and Cys6. It occupies a landmark place in peptide chemistry: Vincent du Vigneaud sequenced and synthesized it in the early 1950s — the first peptide hormone to be made synthetically — work recognised with the 1955 Nobel Prize in Chemistry. As the acetate salt it carries CAS number 6233-83-6, the molecular formula C43H66N12O12S2 · xC2H4O2, and a free-peptide molecular weight of 1007.19 g/mol.

As a research reference material it is supplied as a lyophilized powder and characterised by HPLC for purity and mass spectrometry for identity.

In the laboratory, oxytocin is used in binding and activation assays at the oxytocin receptor (OXTR), a G-protein-coupled receptor, and in broader GPCR-signaling pathway research in cell models, including selectivity work against the closely related vasopressin receptors.

Because of its disulfide bridge it is also a standard model compound in disulfide-peptide stability and degradation studies, and it serves as an analytical reference standard. These are in vitro research applications only, and no medical claims are made here.

Lyophilized peptides are generally kept cold, dry, and out of light to preserve stability. Oxytocin is stored long-term at -20°C (-4°F), protected from moisture and direct light, with original labeling retained so the batch stays traceable.

This overview does not cover preparation or use of any kind. That falls outside laboratory research reference use, and we do not provide that guidance.

Oxytocin is a famously degradation-prone molecule: the disulfide bridge can scramble into dimers and polymers, and the Gln and Asn residues can deamidate — degradation chemistry documented extensively in the pharmaceutical-stability literature. Those impurities can hide near the parent peak in a lazy analysis.

Purity by HPLC and identity by mass spectrometry answer two different questions, and for a molecule with this degradation profile a per-batch Certificate of Analysis — tied to the exact lot you receive — matters more than for almost any other peptide in a catalog.

Before relying on any batch, confirm three things: purity (an HPLC percentage), identity (a mass-spectrometry confirmation), and a traceable lot number with a test date. If the supplier lets you look up that batch’s report, you can match the documentation to the vial in hand.

Transparency note on our own catalog: the current TrueBatch oxytocin lot is with an independent third-party lab now, and its page says exactly that — the full Certificate of Analysis publishes the moment results are in. No TrueBatch lot is marked verified without its own report.

Is oxytocin an approved drug? Yes — synthetic oxytocin is the active ingredient of FDA-approved prescription medications used in clinical settings. The material described here is not a drug product and is not a substitute for one: it is a laboratory reference standard supplied strictly for analytical and in vitro research, and nothing on this site is medical guidance.

Is oxytocin legal in the US? Oxytocin is not a scheduled substance under the Controlled Substances Act. It is lawfully supplied as a reference material for laboratory research, and for no other purpose; nothing on this site should be read as a claim otherwise.

Why a lyophilized vial and not another format? Reference material is quantified by mass and stability-characterised in lyophilized form, which is what a per-batch certificate can actually describe — particularly relevant for a molecule with oxytocin’s degradation profile. Other formats fall outside laboratory reference use, so we do not offer them.