Direct Answer
Pentapeptide-18 (trade name Leuphasyl; INCI Pentapeptide-18) is a synthetic [D-Ala2] analog of the endogenous opioid pentapeptide Leu-enkephalin (sequence H-Tyr-D-Ala-Gly-Phe-Leu-OH). It is marketed as a "neuro-cosmetic" for the appearance of expression lines via a proposed PRE-synaptic (enkephalin/opioid) mechanism — distinct from the POST-synaptic SNARE-targeting peptides Argireline and SNAP-8. Its structural basis is well-established; independent controlled human anti-wrinkle efficacy data are limited.
Summary Table
Evidence Level
Low
AI Summary
Pentapeptide-18 (INCI Pentapeptide-18; trade name Leuphasyl) is a synthetic [D-Ala2] analog of the opioid pentapeptide Leu-enkephalin, marketed as a "neuro-cosmetic" for expression lines. Its proposed mechanism is pre-synaptic (enkephalin/opioid modulation of acetylcholine release), distinct from the post-synaptic SNARE mechanism of Argireline (acetyl hexapeptide-8) and SNAP-8 (acetyl octapeptide-3), which is why they are often combined. The enkephalin-analog structural basis is well-established (Hughes et al., Nature 1975), but topical anti-wrinkle efficacy is not established by independent controlled human trials and rests on manufacturer/preclinical data.
Key Information
Classification
Key Takeaways
- Synthetic [D-Ala2] analog of the endogenous opioid pentapeptide Leu-enkephalin (INCI Pentapeptide-18; trade name Leuphasyl)
- Sequence H-Tyr-D-Ala-Gly-Phe-Leu-OH; CAS 64963-01-5; PubChem CID 10099522 (C29H39N5O7, MW 569.65)
- Proposed PRE-synaptic mechanism (enkephalin/opioid modulation of acetylcholine release) — distinct from the POST-synaptic SNARE mechanism of Argireline (acetyl hexapeptide-8) and SNAP-8 (acetyl octapeptide-3)
- Complementary mechanisms are the rationale for combining it with Argireline/SNAP-8 in formulations
- Structural basis well-established; independent controlled human anti-wrinkle efficacy data are limited (low)
- Cosmetic ingredient, not an approved medicine
Scientific Overview
What is Pentapeptide-18 (Leuphasyl)?
Pentapeptide-18 (INCI Pentapeptide-18; trade name Leuphasyl, Lipotec/Lubrizol) is a synthetic pentapeptide, sequence H-Tyr-D-Ala-Gly-Phe-Leu-OH (CAS 64963-01-5; molecular formula C29H39N5O7; molecular weight 569.65 g/mol; PubChem CID 10099522). It is the [D-Ala2] analog of Leu-enkephalin, one of the two endogenous opioid pentapeptides identified in the brain by Hughes, Kosterlitz and colleagues (Nature, 1975). The D-alanine substitution at position 2 is a common enkephalin-stabilizing modification.
In Plain English
Pentapeptide-18, sold as Leuphasyl, is a lab-made version of Leu-enkephalin — one of the body's natural opioid peptides. In cosmetics it is proposed to calm the nerve signals that make facial muscles contract, softening the look of expression lines, and it is thought to work by a different route than the popular 'Argireline'-type peptides (which is why formulators sometimes combine them). What the molecule IS is well-established chemistry; whether the topical cosmetic actually reduces wrinkles is not shown by independent controlled human trials — those claims come from manufacturer/preclinical data.
Scientific Details
Pentapeptide-18 (Leuphasyl) is a topically marketed "neuro-cosmetic" peptide, structurally a [D-Ala2] analog of Leu-enkephalin (H-Tyr-D-Ala-Gly-Phe-Leu-OH). Its proposed cosmetic mechanism is PRE-synaptic: modulation of acetylcholine release at the neuromuscular junction via the enkephalin/opioid pathway, reducing muscle contraction and thereby softening expression lines. This is mechanistically DISTINCT from the POST-synaptic SNARE-interfering peptides acetyl hexapeptide-8 (Argireline) and acetyl octapeptide-3 (SNAP-8) — the complementary targets are the rationale for combining them in formulations. The enkephalin-analog structural basis is well-established (Hughes et al., Nature 1975, the enkephalin-discovery paper), but there is no independent, controlled human trial isolating Pentapeptide-18 anti-wrinkle efficacy; topical efficacy claims rest on manufacturer/preclinical materials.
How It Works
Pentapeptide-18 is a synthetic analog of the endogenous opioid pentapeptide Leu-enkephalin. Its proposed cosmetic action is PRE-synaptic: acting through the enkephalin/opioid pathway to modulate (reduce) acetylcholine release at the neuromuscular junction, which is proposed to lessen muscle contraction and soften the appearance of expression lines. This differs from Argireline (acetyl hexapeptide-8) and SNAP-8 (acetyl octapeptide-3), which act POST-synaptically by interfering with the SNARE complex that mediates neurotransmitter vesicle release — the two mechanisms are complementary, which is why the peptides are often combined. IMPORTANT: the enkephalin-analog identity is well-established chemistry, but the anti-wrinkle efficacy of the topical cosmetic is NOT established by independent controlled human trials — it rests on manufacturer/preclinical data and is not asserted here as proven.
Mechanism of Action
Pre-synaptic enkephalin/opioid modulation of neurotransmitter release
mechanistic
As a synthetic [D-Ala2] analog of Leu-enkephalin, Pentapeptide-18 is proposed to act PRE-synaptically via the enkephalin/opioid pathway to reduce acetylcholine release at the neuromuscular junction, softening muscle contraction (expression lines). This is DISTINCT from the POST-synaptic SNARE-complex mechanism of Argireline / SNAP-8. The structural (enkephalin-analog) basis is well-established; the cosmetic mechanism is proposed and not established by controlled human efficacy studies isolating the peptide.
Evidence Level
Human Evidence
No independent, controlled human trial isolating Pentapeptide-18 anti-wrinkle efficacy is cited. Marketed efficacy rests on manufacturer/preclinical materials and multi-ingredient formulation studies, which cannot attribute effects to the peptide alone.
Animal Evidence
No animal efficacy studies specific to Pentapeptide-18 are cited.
Cell Evidence
The peptide is a well-characterized synthetic analog of Leu-enkephalin (structural basis established via the enkephalin-discovery literature); a demonstrated pre-synaptic cosmetic mechanism in human skin is not established.
Mechanistic Evidence
The pre-synaptic enkephalin/opioid mechanism is a proposal by analogy to Leu-enkephalin, distinct from the post-synaptic SNARE mechanism of Argireline/SNAP-8; it is not demonstrated for the topical cosmetic.
Limitations
The structural (enkephalin-analog) basis is well-established, but anti-wrinkle efficacy is not established by independent controlled human trials. Interpret marketed claims cautiously.
Why This Grade
Rated low: the identity of Pentapeptide-18 as a synthetic Leu-enkephalin analog is well-established chemistry (the enkephalins were characterized in a foundational Nature paper), which places it above a purely preclinical/uncharacterized compound — but its topical anti-wrinkle EFFICACY has no independent, controlled human trial and rests on manufacturer/preclinical data. Strong structural basis; unproven cosmetic efficacy.
Frequently Asked Questions
What is Pentapeptide-18 (Leuphasyl)?
Pentapeptide-18 (trade name Leuphasyl, INCI Pentapeptide-18) is a synthetic 5-amino-acid peptide (H-Tyr-D-Ala-Gly-Phe-Leu-OH) — a [D-Ala2] analog of Leu-enkephalin, one of the body's natural opioid pentapeptides. It is used in 'neuro-cosmetic' anti-wrinkle products marketed for the appearance of expression lines.
How is Pentapeptide-18 described to work?
It is proposed to act PRE-synaptically: as an enkephalin analog, it is thought to modulate (reduce) acetylcholine release at the neuromuscular junction via the opioid/enkephalin pathway, softening muscle contraction and expression lines. This is a proposed mechanism — the enkephalin-analog chemistry is well-established, but a demonstrated cosmetic mechanism in human skin is not.
How does it differ from Argireline (acetyl hexapeptide-8) and SNAP-8 (acetyl octapeptide-3)?
They target different points of the same pathway. Pentapeptide-18 (Leuphasyl) is proposed to act PRE-synaptically (enkephalin/opioid modulation of neurotransmitter release), while Argireline and SNAP-8 act POST-synaptically by interfering with the SNARE complex that releases neurotransmitter vesicles. Because the mechanisms are complementary, the peptides are often combined in formulations.
Is there strong evidence that Pentapeptide-18 reduces wrinkles?
No. The molecule's identity as a Leu-enkephalin analog is well-established chemistry, but there is no independent, controlled human trial isolating Pentapeptide-18 anti-wrinkle efficacy — the marketed benefits rest on manufacturer/preclinical data and multi-ingredient formulation studies. Treat efficacy claims cautiously.
References
- Identification of two related pentapeptides from the brain with potent opiate agonist activity. Nature. (Independent academic research — the foundational enkephalin-discovery paper by Hughes, Kosterlitz et al. (Unit for Research on Addictive Drugs, University of Aberdeen); no formal conflict-of-interest statement in the 1975-era record.)Supports ONLY the STRUCTURAL BASIS — that Leuphasyl (Pentapeptide-18) is a synthetic analog of Leu-enkephalin, the endogenous opioid pentapeptide identified here. It does NOT support any anti-wrinkle / cosmetic efficacy claim.Mechanisticdoi:10.1038/258577a0 →
Alternative Names
- Pentapeptide-18
- Leuphasyl
- [D-Ala2]-Leu-enkephalin analog
- Tyr-D-Ala-Gly-Phe-Leu
Risks & Safety
- Not a medicine; used as a cosmetic ingredient with the usual patch-test considerations
- Anti-wrinkle efficacy is not established by independent controlled human trials — marketed effects rest on manufacturer/preclinical data
- Much available data involve multi-ingredient formulations, so effects cannot be attributed to the peptide alone
Claim Boundaries
ION BLUE is an educational research aggregator. This content summarizes published scientific literature and, where noted, manufacturer/supplier materials. It is not medically reviewed, is not medical advice, and is not a recommendation to use any substance. Consult a licensed healthcare provider. This entry summarizes the well-established enkephalin-analog structural basis and a proposed pre-synaptic cosmetic mechanism; it does NOT assert established anti-wrinkle efficacy for Pentapeptide-18 and is not a recommendation to use the ingredient.
This page summarizes published research and is for informational purposes only; it is not medical advice.