# Oxytocin

> Neurohypophysial nonapeptide with a disulfide-closed ring

All products are sold strictly for laboratory research use only. Not for human or veterinary use.

- Web page: https://peptidemedixeu.com/en/products/oxytocin/
- Brand: Peptide Medix EU
- Category: [Libido & Sexual Function](https://peptidemedixeu.com/en/collections/libido-peptides/)
- Purity: ≥99% by HPLC; lot-matched COA
- CAS number: 50-56-6
- from €38 (EUR)

## Sizes and prices (EUR)

| Size | Price | SKU |
| --- | --- | --- |
| 2 mg | €38 | OXYTOCIN-2-MG |
| 5 mg | €63 | OXYTOCIN-5-MG |
| 10 mg | €97 | OXYTOCIN-10-MG |

_Catalog prices at build time; the web page and checkout are authoritative._

## Specifications

- **CAS number:** 50-56-6
- **Molecular formula:** C43H66N12O12S2
- **Molecular weight:** 1007.19 g/mol
- **Amino acid sequence:** Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 (disulfide bridge Cys1–Cys6)
- **Peptide class:** Cyclic nonapeptide; neurohypophysial hormone
- **Form:** Lyophilized white powder, sealed glass vial
- **Purity:** ≥99% by HPLC; lot-matched COA
- **Available sizes:** 2 mg, 5 mg, 10 mg
- **Solubility:** Freely soluble in water and bacteriostatic water; also soluble in dilute acetic acid
- **Receptor target:** Oxytocin receptor (OXTR); partial cross-reactivity at vasopressin receptors
- **Approximate activity conversion:** Roughly 1 IU ≈ 2 µg of synthetic oxytocin (see COA for lot-specific values)
- **Research areas:** Social behaviour and bonding models, stress and anxiety research, smooth-muscle physiology, OXTR pharmacology
- **Storage:** Lyophilized: −20 °C, desiccated and protected from light. Reconstituted: 2–8 °C, aliquoted to avoid repeated freeze–thaw

## Description

Oxytocin is a nine-residue hormone made in the supraoptic and paraventricular nuclei of the hypothalamus and secreted from the posterior pituitary. Structurally it consists of a six-membered ring, closed by a disulfide bond between the cysteines in positions 1 and 6, plus a three-residue tail ending in a C-terminal amide. Only two positions separate it from vasopressin, so cross-reactivity at vasopressin receptors is a constant consideration when designing oxytocin experiments.

Research on oxytocin splits into two largely separate bodies of work. The peripheral one is classical endocrinology — OXTR-driven contraction of smooth muscle in uterine and mammary tissue, characterised in depth since the 1950s, when Vincent du Vigneaud's synthesis made it the first polypeptide hormone ever produced chemically and earned him a Nobel Prize. The central one is more recent and deals with oxytocin-releasing projections inside the brain, investigated in animal models of social recognition, pair bonding, stress reactivity and anxiety-related behaviour.

## Frequently asked questions

### In what form is it delivered?

As lyophilised powder in a sealed, desiccated glass vial containing 2 mg, 5 mg or 10 mg. Dry peptide is much more stable than a solution, so it copes with shipping at room temperature; store it dry at −20 °C until you reconstitute.

### Is purity confirmed independently?

Yes. Reverse-phase HPLC (≥99%) and mass spectrometry characterise each lot, and the certificate for your lot can be requested. The batch number on the vial matches the COA, so your data trace back to a specific analysis.

### Why is oxytocin more delicate than many peptides?

The Cys1–Cys6 disulfide defines its active ring, and reducing agents, alkaline pH or trace metals can break or reshuffle it. Standard precautions: keep solutions cold, slightly acidic, free of metals and freshly made.

### How close is oxytocin to vasopressin?

The two nonapeptides differ only at positions 3 and 8, yet they act through different receptor families. Because of that likeness, cross-reactivity at vasopressin receptors is a genuine risk, and careful oxytocin studies routinely include selectivity controls and receptor-specific antagonists.

### What can I reconstitute it with?

Sterile or bacteriostatic water dissolves it easily; dilute acetic acid is an alternative when a lower pH benefits stability in your assay. Add the solvent slowly down the glass, swirl gently, and use low-binding tubes for dilute working solutions to reduce losses on surfaces.

---

All products offered on this website are intended solely for in-vitro laboratory research and development by qualified professionals. They are not drugs, foods, cosmetics or dietary supplements, and are not intended to diagnose, treat, cure or prevent any disease. Products must not be introduced into humans or animals in any manner. By purchasing, you confirm that you are a qualified researcher and accept full responsibility for handling and storage in accordance with applicable laws.

Peptide Medix EU · https://peptidemedixeu.com/en/products/oxytocin/