Rigin: anti-inflammatory skin-care peptide (Palmitoyl Tetrapeptide-7)
A lab-made peptide used in anti-aging cosmetics to help calm skin inflammation; a cosmetic ingredient, not an approved drug.
A researcher, an agent, or an algorithm wrote down the sequence and picked a target to hit.
An AI model like OpenFold3 or AlphaFold built a 3D structure and scored how well it fits the binding site.
A second contributor repeated the computation on their own hardware and the scores matched.
A chemistry service or a researcher ordered the sequence, it was manufactured, and mass spectrometry confirmed the right molecule was produced.
A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
Snapshot
Class: Cosmeceutical tetrapeptide; IgG Fc-derived immunomodulatory peptide
Evidence tier: In vitro / assay evidence
Status: Cosmetic ingredient (INCI: palmitoyl tetrapeptide-7); not an approved drug in any jurisdiction
Best-supported effect: IL-6 suppression in keratinocyte cell assays (in vitro); anti-aging skin effects in human studies have not been attributed to Rigin alone
Main caveat: Nearly all clinical data comes from multi-ingredient Matrixyl 3000 formulations; the standalone contribution of Rigin to any clinical endpoint in humans has not been isolated
What this is
Rigin (Gly-Gln-Pro-Arg) is a tetrapeptide originally isolated in 1981 from the heavy chain of human immunoglobulin G (IgG), at positions 224–227. It was identified as a structural analog of tuftsin — sharing a type VII β-turn conformation and broadly similar phagocytosis-stimulating activity — though the two peptides are distinct molecules from different IgG regions with independent research profiles.
In cosmeceutical use, Rigin is deployed in its palmitoylated form: Palmitoyl Tetrapeptide-7 (INCI name; formerly listed as Palmitoyl Tetrapeptide-3), abbreviated Pal-GQPR. The palmitoyl modification improves partition into the lipid-rich stratum corneum. Its primary cosmetic rationale is not collagen stimulation but suppression of interleukin-6 (IL-6), a pro-inflammatory cytokine implicated in chronic low-grade skin inflammation ("inflammaging") that drives extracellular matrix degradation and impaired collagen synthesis. Pal-GQPR is best known as one of two active components in the commercial Matrixyl 3000 complex, paired with Palmitoyl Tripeptide-1 (Pal-GHK).
Evidence map
| Evidence layer | Grade | What it supports |
|---|---|---|
| Human | Weak | 12-week multi-ingredient eye cream study (Matrixyl 3000) reported improvements in hydration, elasticity, and collagen density; attribution to Rigin specifically is not possible from a multi-component formulation |
| Animal | Weak — analog only | Hydrophobic Rigin analogs (palmitoyl and cholestanyl forms) reduced parasitemia and mortality in a mouse Plasmodium berghei malaria model via lymphocyte activation; this is analog evidence, not Pal-GQPR efficacy data |
| In vitro | Moderate | Sederma-conducted keratinocyte assays: 40–60% IL-6 suppression at 10–100 μM; up to 86% IL-6 suppression in UV-irradiated cells; phagocytosis-stimulating activity documented in the original 1981 discovery and confirmed in structural studies |
| Computational | Moderate | NMR and molecular dynamics studies characterize the type VII β-turn conformation of Rigin; simulation data supports the structural basis for immunomodulatory activity |
| Mechanism | Plausible | IL-6 suppression → reduced MMP expression and ECM degradation → indirect protection of dermal collagen integrity; phagocytosis stimulation via macrophage activation; both pathways are plausible but the link from in vitro IL-6 suppression to clinical anti-aging endpoints in humans has not been rigorously demonstrated |
Evidence concentration note: The in vitro efficacy data originates predominantly from Sederma (Croda subsidiary), the commercial developer of Palmitoyl Tetrapeptide-7. Independent replication of the keratinocyte IL-6 suppression data is not documented in available literature material.
Claim check
| Claim | Verdict | Evidence layer | Confidence |
|---|---|---|---|
| Suppresses IL-6 in skin keratinocytes (in vitro) | Supported (in vitro) | In vitro | Medium — Sederma-conducted assays; independent replication not documented in source |
| Anti-aging skin effects (hydration, elasticity, collagen density) attributable to Rigin alone | Not established | Human | Low — available clinical data is from multi-ingredient Matrixyl 3000 formulations; Rigin-specific contribution cannot be isolated |
| Phagocytosis stimulation equivalent to tuftsin | Supported (in vitro) | In vitro | Medium — original 1981 isolation study and structural characterization; activity is for the unmodified peptide, not Pal-GQPR specifically |
| Meaningful whole-body immune enhancement from topical cosmetic application | Not established | In vitro | Low — systemic absorption from topical cosmetic use is low; in vitro immunological activity does not establish clinically relevant systemic immune effects |
| Matrixyl 3000 (Pal-GHK + Pal-GQPR) clearly outperforms Pal-GHK alone at clinical anti-aging endpoints | Not established | Human | Low — head-to-head clinical data demonstrating that Pal-GQPR adds measurable benefit beyond Pal-GHK alone is limited |
| Safe and effective for human injection | Not established | None | High — no human injection data; cosmetic preparations are not sterile injectable products; immunomodulatory mechanism raises additional concern outside a controlled research setting |
Assay conditions
This section reports concentrations and conditions used in in vitro assays. It does not establish in vivo animal or human exposure.
| Context | System | Assay condition | Timepoint | Endpoint | Limitation |
|---|---|---|---|---|---|
| Keratinocyte IL-6 suppression assay | Human keratinocyte culture | 10–100 μM Pal-GQPR | Not individually extracted in source | IL-6 secretion | Manufacturer-conducted (Sederma); in vitro concentration does not reflect deliverable in vivo skin levels; independent replication not documented |
| UV-irradiated keratinocyte assay | Human keratinocyte culture, UV-irradiated | Pal-GQPR (concentration not individually extracted) | Not individually extracted in source | IL-6 suppression (up to 86% reduction) | Same laboratory and sponsor limitations; UV-irradiated culture is a model for UV-induced inflammation, not a replicated human endpoint |
| Phagocytosis assay | In vitro immunological assay | Unmodified Rigin (GQPR), concentration not individually extracted | Not individually extracted in source | Phagocytosis activity vs. tuftsin | Conducted on the unmodified peptide; relevance to the palmitoylated cosmetic form (Pal-GQPR) at cosmetic concentrations is not directly established |
Assay limitations
- All primary efficacy assay data for Pal-GQPR originates from Sederma, the commercial developer. Independent laboratory replication of the IL-6 suppression data is not present in available literature material.
- In vitro IL-6 suppression at 10–100 μM does not translate directly to in vivo skin levels. Palmitoylation improves stratum corneum partitioning, but only a small fraction of topically applied Pal-GQPR is estimated to reach viable keratinocytes in typical commercial formulations. The delivery gap between assay concentrations and achievable in vivo levels is explicitly acknowledged in available literature.
- Phagocytosis assay data is for the unmodified tetrapeptide (GQPR), not the palmitoylated cosmetic form. Whether Pal-GQPR retains equivalent immunological activity at cosmetic delivery levels is not established by published research.
- The 12-week multi-ingredient eye cream study describes improvements in skin hydration, elasticity, and collagen density, but Matrixyl 3000 contains Pal-GHK in addition to Pal-GQPR. Attribution of any clinical endpoint to Rigin specifically is not possible from this study design; this data is cited here as context only, not as isolated Rigin efficacy.
- No animal toxicology data for Pal-GQPR (the cosmetic form) is identified. Animal data in available literature is for hydrophobic analogs (palmitoyl and cholestanyl forms) tested against malaria infection — a different compound class and indication.
- No systemic or injectable human safety data exists in available literature material.
Regulatory status
| Region / body | Status | Notes |
|---|---|---|
| US (FDA) | Cosmetic ingredient; not an approved drug | Regulated under US cosmetic law; OTC sale in finished cosmetic formulations is permitted; no drug approval for wrinkles, inflammation, or any medical indication; cosmetic label claims only |
| EU | Permitted cosmetic ingredient | Listed in CosIng database; CIR (Cosmetic Ingredient Review) has assessed palmitoyl tetrapeptide-7 as safe for cosmetic use at typical formulation levels (per available sources; not independently refreshed in this card) |
| UK, Canada, Australia, Japan | Permitted as cosmetic ingredient | Per available sources, broad international permission in major markets; individual country verification not performed in this card |
| WADA | Not prohibited | Per available sources, Pal-GQPR is not listed on the WADA Prohibited List; topical cosmetic use has negligible systemic exposure; per available sources, not independently refreshed |
No drug approval identified in any jurisdiction. This card describes a cosmeceutical ingredient, not an approved medicine.
Mechanism
Rigin (GQPR) was identified from the Fc region of human IgG heavy chain (positions 224–227) and adopts a type VII β-turn conformation, structurally analogous to tuftsin. This conformation has been characterized by NMR spectroscopy and molecular dynamics simulation.
In its palmitoylated cosmetic form (Pal-GQPR), the primary proposed mechanism is suppression of IL-6 secretion from keratinocytes. IL-6 is a pro-inflammatory cytokine that drives a cycle of chronic low-grade skin inflammation: elevated IL-6 promotes matrix metalloproteinase (MMP) expression, extracellular matrix (ECM) degradation, and impaired collagen synthesis — a process implicated in photoaging and the "inflammaging" model of skin senescence. By reducing IL-6 output from keratinocytes in response to UV and other inflammatory stimuli, Pal-GQPR may indirectly protect dermal collagen and ECM integrity. Additional proposed effects include inhibition of MMP activity and stimulation of laminin IV/V and collagen VII production, though these are less thoroughly characterized in available literature.
The unmodified peptide (GQPR) also stimulates phagocytosis at levels comparable to tuftsin, activating macrophage-mediated cellular clearance. This activity is well-documented for the bare tetrapeptide and supported by the original 1981 isolation study and subsequent structural work. Whether Pal-GQPR at cosmetic delivery levels retains meaningful immunological activity beyond local keratinocyte IL-6 suppression is not established in available literature.
Hydrophobic Rigin analogs (palmitoyl and cholestanyl-conjugated forms distinct from the cosmetic Pal-GQPR) demonstrated protection against Plasmodium berghei malaria in mice, operating through lymphocyte activation pathways rather than macrophage-mediated phagocytosis. This represents analog data and does not constitute evidence for the cosmetic Pal-GQPR formulation.
Target confidence: The IL-6 suppression pathway is inferred from in vitro keratinocyte assay data. No receptor-level binding data for Pal-GQPR is extracted in this card. The mechanism of action at the molecular level (how Pal-GQPR suppresses IL-6 secretion at a receptor or signaling level) is not fully characterized in available literature material.
Chemistry
| Field | Value |
|---|---|
| Sequence (bare tetrapeptide) | Gly-Gln-Pro-Arg (GQPR) |
| INCI name | Palmitoyl tetrapeptide-7 (formerly palmitoyl tetrapeptide-3) |
| Length | 4 amino acids |
| Topology | Linear |
| Modification | N-terminal palmitoyl (C16) conjugation (Pal-GQPR); lipidated |
| Conformation | Type VII β-turn (characterized by NMR and molecular dynamics) |
| Origin | Fragment of human IgG heavy chain, positions 224–227 |
| Source in cosmetics | Typically 50–200 ppm (0.005–0.02%) in finished formulations |
| Sequence confidence | Verified (original 1981 isolation; structural studies confirmed) |
Open questions
- Independent replication of IL-6 suppression: All keratinocyte IL-6 assay data in the available literature originates from Sederma, the commercial developer. Independent laboratory confirmation of the IL-6 suppression data and its magnitude (40–86%) has not been documented. Whether the in vitro findings replicate across laboratories and assay systems is unknown.
- Standalone human efficacy: No controlled human trial on Rigin or Pal-GQPR as the sole active has been conducted or reported in available literature. All available human clinical evidence comes from Matrixyl 3000 (Pal-GHK + Pal-GQPR) multi-ingredient formulations. Whether Pal-GQPR contributes meaningfully to clinical endpoints beyond what Pal-GHK provides alone has not been established.
- In vivo delivery: The fraction of topically applied Pal-GQPR that reaches viable keratinocytes in real-world formulations is poorly quantified. The gap between assay concentrations (10–100 μM) and achievable skin delivery levels is acknowledged in available literature but not formally quantified across commercial product types.
- Translation from IL-6 suppression to clinical endpoints: The mechanistic chain from in vitro cytokine suppression in keratinocyte culture to measurable reduction in skin aging endpoints (wrinkle depth, dermis thickness, collagen density) in humans is plausible but not rigorously demonstrated. IL-6 is one of many factors in skin aging biology.
- Long-term safety of sustained topical use: Most studied durations are 8–12 weeks. Whether chronic, continuous application over years sustains benefit, produces attenuation, or generates unrecognized signals from prolonged immunomodulatory influence at the skin level has not been studied.
- Immunological relevance of Pal-GQPR in active skin disease: the phagocytosis-stimulating and cytokine-modulating properties may be unpredictable in the context of autoimmune skin conditions (psoriasis, lupus-related skin disease). The clinical implications of applying an immunomodulatory peptide to inflamed or immunologically active skin are not characterized.
Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.
Could Rigin, by suppressing the persistent high IL-6 in diabetic wounds, restore the ability of skin cells to migrate and close the wound, which chronic inflammation currently prevents?
Diabetic wounds that will not heal lead to amputations for hundreds of thousands of people every year. If Rigin can suppress the specific inflammatory signal blocking wound closure, it could be formulated into a topical gel applied to diabetic ulcers, potentially preventing amputations in a patient population with few current topical anti-inflammatory options.
Does Rigin reduce the inflammatory signal IL-6 in skin cells by mimicking the antibody fragment it came from and activating an immune-dampening receptor on those cells?
If true, Rigin could be developed far beyond cosmetics as a treatment for chronic inflammatory skin conditions like psoriasis or atopic dermatitis, where IL-6 drives persistent inflammation. It would also validate a new class of anti-inflammatory drugs based on short IgG-derived peptides that activate the body's own immune braking system.
▸3-letter notation
▸citationbibtex
@peptide{pep10952,
sequence = {GQPR},
target = {},
author = {peptidemodel},
year = {2026},
status = {designed}
}