# Pentapeptide-18 (Leuphasyl)

> [D-Ala2]leucine-enkephalin analogue for neurotransmitter-release research

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

- Web page: https://peptidemedixeu.com/en/products/pentapeptide-18/
- Brand: Peptide Medix EU
- Category: [Cosmetic Signal Peptides](https://peptidemedixeu.com/en/collections/cosmetic-peptides/)
- Purity: ≥99% by HPLC; lot-matched COA available
- CAS number: 64963-01-5
- from €178 (EUR)

## Sizes and prices (EUR)

| Size | Price | SKU |
| --- | --- | --- |
| 200 mg | €178 | PENTAPEPTIDE-18-200-MG |

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

## Specifications

- **CAS number:** 64963-01-5
- **Molecular formula:** C29H39N5O7
- **Molecular weight:** 569.65 g/mol
- **Amino acid sequence:** Tyr-D-Ala-Gly-Phe-Leu-OH
- **Chain length:** 5 residues
- **Peptide class:** Synthetic enkephalin-related pentapeptide
- **Form:** Lyophilized powder, sealed glass vial
- **Purity:** ≥99% by HPLC; lot-matched COA available
- **Available size:** 200 mg
- **Also known as:** Leuphasyl, Pentapeptide-18, [D-Ala2]leucine-enkephalin
- **Research areas:** Neurotransmitter-release models, contraction-associated assays and comparative cosmetic-peptide formulation
- **Storage:** −20 °C lyophilized; protect from light and moisture

## Description

Pentapeptide-18 — sold as Leuphasyl and also known as [D-Ala2]leucine-enkephalin — is a synthetic peptide of five residues: Tyr-D-Ala-Gly-Phe-Leu. Native leucine-enkephalin reads Tyr-Gly-Gly-Phe-Leu, so the D-alanine replaces the first of its two glycines; this fixes the stereochemistry and is a classic trick from enkephalin structure–activity research to slow cleavage by aminopeptidases. The compound is registered under CAS 64963-01-5, formula C29H39N5O7, molecular weight 569.65 g/mol.

In cosmetic-peptide research, Pentapeptide-18 has been examined in model systems for neurotransmitter release and contraction, often next to Argireline, SNAP-8, Syn-AKE or Vialox. These act at different proposed steps, so a meaningful study compares them in the same cells, tissue and vehicle rather than lumping them together as interchangeable “expression peptides”. Unlike the palmitoylated actives it is often benchmarked against, Pentapeptide-18 has no lipid attached and behaves as a normal water-soluble small peptide — which affects both how it must be formulated and what a permeation experiment can realistically show.

## Frequently asked questions

### What sequence defines Pentapeptide-18?

Tyr-D-Ala-Gly-Phe-Leu-OH. The D-configuration of the alanine in position 2 is part of its identity and must be preserved in analytical records and in any comparison materials.

### Is it identical to leucine-enkephalin?

Closely related, but not the same. Pentapeptide-18 is [D-Ala2]leucine-enkephalin; swapping in D-alanine alters its conformation and enzymatic stability compared with the natural all-L peptide.

### How is it different from Argireline or Syn-AKE?

All three have distinct sequences and proposed targets: Pentapeptide-18 is enkephalin-related, Argireline is a hexapeptide derived from SNAP-25, and Syn-AKE is a modified diaminobutyroyl benzylamide. They should be treated as separate products.

### Which purity documents can I obtain?

It is released at ≥99% by reversed-phase HPLC, and the certificate of analysis for your lot is available. Mass confirmation should match the free-acid form containing D-Ala.

### What storage conditions apply?

Store the lyophilised peptide at −20 °C, sealed and away from light and humidity. Refrigerate short-term working solutions, and use aliquots for longer studies to minimise repeated freezing and thawing.

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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/pentapeptide-18/