Tetrapeptide-30 (PKEK) (CAS 1036207-61-0) is supplied by TCS NEXUS S.L. (Valencia, Spain) for European cosmetic formulators, brand R&D teams and B2B buyers reviewing cosmetic peptide raw material applications. A freely water-soluble peptide, it dissolves directly in aqueous concentrates without co-solvents at pH 4.5–7.0, with cool-down addition below 40°C recommended in standard serum and leave-on manufacturing protocols.
> Technical Specifications
| Product Name | Tetrapeptide-30 (PKEK) |
|---|---|
| Molecular Structure |  |
| CAS Number | 1036207-61-0 |
| Alias / Common Name | Tetrapeptide-30; PKEK; Pro-Lys-Glu-Lys-NH2 |
| Molecular Formula | C22H40N6O7 |
| Molecular Weight | 500.6 g/mol |
| INCI Name | Tetrapeptide-30 |
| Peptide Sequence | Pro-Lys-Glu-Lys-NH2 — PKEK (ET-1/EDNRB axis brightening tetrapeptide) |
| Functional Class | Synthetic tetrapeptide; ET-1 (endothelin-1) / EDNRB pathway modulator; melanogenesis brightening peptide; skin-tone evening active |
| Purity / Assay | ≥98% (HPLC); confirm by batch COA |
| Appearance | White to off-white powder |
| Solubility / Handling | Freely water-soluble; dissolves readily in deionised water or the aqueous phase at evaluation concentrations (0.001–0.01%) without co-solvent. Add during the cool-down phase below 40°C. |
| pH Stability | Optimal stability at pH 4.5–7.0. Confirm stability in the complete formulation base. |
| Storage | Store sealed below 25°C in a cool, dry location protected from direct light and moisture. Follow SDS and batch COA conditions. |
> Mechanism & Positioning
Tetrapeptide-30 (PKEK) is a synthetic tetrapeptide designed to modulate pigmentation through the ET-1 (endothelin-1) / EDNRB (endothelin receptor type B) signalling axis — a UV-triggered paracrine melanocyte activation pathway distinct from the α-MSH/MC1R route. Published Tetrapeptide-30 literature discusses modulation of ET-1 availability and EDNRB downstream signalling in the keratinocyte-melanocyte paracrine unit: UV-irradiated keratinocytes secrete ET-1, which binds EDNRB on melanocytes, activates PKC and raises intracellular Ca²⁺, driving MITF and tyrosinase upregulation. Cell-based keratinocyte-melanocyte co-culture studies document reduced EDNRB-mediated melanocyte activation and decreased melanin output following Tetrapeptide-30 treatment. Pigmentation inhibition model data also notes reductions in UVB-triggered hyperpigmentation in reconstructed skin models, consistent with ET-1 axis modulation. PKEK targets a different receptor from MC1R-acting brightening peptides, making it complementary in multi-mechanism brightening systems.
Tetrapeptide-30 builds a dual-axis brightening system with Hexapeptide-2 (Melanostatine 2) — targeting the α-MSH/MC1R pathway in parallel to PKEK’s ET-1/EDNRB axis — for comprehensive upstream MITF signal attenuation. Add tyrosinase-inhibiting actives such as arbutin or tranexamic acid for substrate-level melanin reduction, and Ergothioneine for antioxidant UV protection to reduce upstream melanogenic stimulus. Contact info@tcspeptides.com with project specification and target claim.
> Application Concepts
Even-Tone Serum and ET-1/EDNRB Pathway Brightening Architecture
Tetrapeptide-30 (PKEK) at 0.001–0.01% dissolves directly in the aqueous phase at cool-down below 40°C, integrating cleanly into clear brightening serums, ampoule concentrates and essence-serum hybrids. At pH 5.0–6.5, PKEK is compatible with niacinamide (4–5%), hyaluronic acid and standard cosmetic brightening bases. For a dual-peptide brightening serum targeting both α-MSH/MC1R (upstream UV keratinocyte response) and ET-1/EDNRB (UV paracrine activation), combine PKEK with Hexapeptide-2 at their individual evaluation concentrations in a common aqueous serum base at pH 5.5–6.5. Both are water-soluble with no co-dispersion requirement, enabling clean formulation in a single aqueous concentrate.
ET-1/EDNRB Pathway vs MC1R Pathway — Addressing UV-Triggered Pigmentation at Two Paracrine Nodes
UV-triggered melanogenesis in skin involves a keratinocyte-to-melanocyte paracrine communication network with two key UV-induced ligands: α-MSH (from keratinocyte POMC) acting on MC1R, and ET-1 (secreted by UV-stimulated keratinocytes) acting on EDNRB. Both pathways converge on PKA/PKC signalling to activate MITF and tyrosinase. Tetrapeptide-30 (PKEK) targets the ET-1/EDNRB node; Hexapeptide-2 (Melanostatine 2) targets the α-MSH/MC1R node. Addressing both paracrine pathways simultaneously provides more complete MITF signal attenuation than either peptide alone. This dual-peptide approach is particularly relevant for chronic UV-triggered pigmentation (solar lentigines, post-UV hyperpigmentation) where both paracrine axes are co-activated.
Post-UV, Solar Lentigo and Melasma-Support Brightening Format Applications
Tetrapeptide-30 is positioned for three premium brightening market segments where ET-1 axis modulation is mechanistically relevant: post-UV brightening serums (UV-triggered ET-1/EDNRB axis activation), solar lentigo concentrates (focal chronic ET-1/EDNRB overactivation in lesional skin), and melasma-support formulations. PKEK at 0.001–0.01% integrates into gentle, fragrance-free serums appropriate for daily use on post-UV or sensitised skin. In melasma-support positioning, combine PKEK and Hexapeptide-2 with tranexamic acid (2–3%) for plasminogen/uPA-driven melanocyte activation inhibition, providing three non-redundant brightening mechanisms in a premium concentrate. Confirm formulation pH ≥5.0 to maintain tranexamic acid compatibility alongside both peptides.
> Handling & Formulation Notes
Dissolve Tetrapeptide-30 (PKEK) directly in deionised water or the aqueous phase at target concentrations (0.001–0.01%) without co-solvent or pre-dispersion. Add the aqueous solution at cool-down below 40°C. No PG pre-dispersion or special dissolution step is required at evaluation concentrations. For concentrations above 0.05%, prepare a 1% aqueous stock solution and add the calculated aliquot at cool-down.
Confirm stability of Tetrapeptide-30 (PKEK) in the complete formulation at 40°C/75% RH for 12 weeks before scale-up. Formulate at pH 4.5–7.0; a finished serum pH of 5.5–6.5 is optimal for PKEK stability. Monitor pH stability after incorporating all brightening actives, particularly ascorbic acid or AHA co-ingredients that can reduce formulation pH. Follow SDS and batch COA for storage and handling. EDTA at ≤0.1% is compatible as a chelating buffer; avoid strong oxidising agents (H₂O₂ ≥1%, benzoyl peroxide) and high-pH systems above pH 8.0.
> Supply & Documentation
Tetrapeptide-30 (PKEK) (CAS 1036207-61-0) is available from TCS NEXUS S.L. (Valencia, Spain) for B2B cosmetic raw material projects. Standard documentation: COA, TDS, SDS. Sample and bulk quantities are discussed on a per-project basis; contact info@tcspeptides.com to initiate a sourcing review.
TCS NEXUS S.L. supports procurement and formulation teams in Germany, France, Italy, Spain, the United Kingdom, the Netherlands, Belgium, Poland, Sweden and Portugal, as well as international buyers in the United States, Canada, Japan, South Korea, Australia and New Zealand.
> Packaging & Storage
Tetrapeptide-30 (PKEK) is supplied in sealed aluminium foil bags or bulk containers. Minimum quantities and packaging configurations are confirmed per order. Store below 25°C in a cool, dry location, away from moisture and direct light. Follow batch COA and SDS for specific storage and handling conditions.
> FAQ
What is Tetrapeptide-30 (PKEK)?
Tetrapeptide-30 (PKEK) (CAS 1036207-61-0) is a cosmetic raw material supplied by TCS NEXUS S.L. (Valencia, Spain) for B2B cosmetic formulators. In cosmetic literature, Tetrapeptide-30 (PKEK) is positioned as a melanin-inhibiting brightening peptide that acts upstream of tyrosinase — evaluated in even-tone serums and spot-treatment formulations targeting post-inflammatory hyperpigmentation, UV-induced discolouration and uneven skin tone. TCS NEXUS S.L. supplies Tetrapeptide-30 as a pure synthetic tetrapeptide (Pro-Lys-Glu-Lys) for B2B cosmetic formulators.
What is the CAS number for Tetrapeptide-30 (PKEK)?
The CAS number for Tetrapeptide-30 (PKEK) is 1036207-61-0. The INCI name for cosmetic regulatory documentation and CPNP notification is Tetrapeptide-30; confirm CAS 1036207-61-0 and INCI identity against the batch COA when building product files.
How does Tetrapeptide-30 (PKEK) even tone — what is the endothelin-1 mechanism?
Tetrapeptide-30 (PKEK, Pro-Lys-Glu-Lys) works on a different brightening route from tyrosinase or MC1R: it is discussed as modulating the endothelin-1 (ET-1) / EDNRB signalling axis, through which keratinocytes tell melanocytes to make pigment — particularly after UV exposure. By damping that inflammatory pigment signal it is positioned for even-tone and post-UV brightening claim directions.
What use level of Tetrapeptide-30 is typical, and how should it be evaluated?
There is no one-size-fits-all dose: establish the use level conservatively for your base and claim; it is often a trade solution, so confirm your dosing basis. We supply the pure material with COA — contact info@tcspeptides.com to align documentation.
Which actives pair with Tetrapeptide-30 in a multi-target tone system?
Because it acts on the endothelin pigment-signalling route, Tetrapeptide-30 complements brighteners on other routes — MC1R peptides such as Nonapeptide-1 and Hexapeptide-2, tyrosinase-focused alpha-arbutin and vitamin C, and niacinamide (melanosome transfer) — for a multi-target even-tone system. It is water-soluble; keep the system near pH 4.5–7.0 and confirm combined stability.
What makes Tetrapeptide-30 distinct — the endothelin route and post-UV focus?
Its distinctive angle is the endothelin-1 / EDNRB axis — the keratinocyte-to-melanocyte pigment signal that is strongly triggered by UV — so Tetrapeptide-30 is positioned for post-UV and inflammation-related uneven tone, a route different from MC1R antagonists or tyrosinase inhibitors. That complementarity is why it slots into multi-target brightening systems. Tetrapeptide-30 is freely water-soluble.
What addition temperature is recommended for Tetrapeptide-30 (PKEK) during manufacturing?
Introduce Tetrapeptide-30 (PKEK) during the cool-down phase at temperatures below 40°C; avoid prolonged exposure above this threshold. Standard aqueous or emulsion cool-down protocols are fully compatible with this addition requirement. Confirm thermal stability in the specific manufacturing process with accelerated stability data before committing to production scale.
What pH range keeps Tetrapeptide-30 stable in a finished formula?
Tetrapeptide-30 is most stable at roughly pH 4.5–7.0; confirm the finished-product pH after all actives are incorporated and check compatibility with low-pH brighteners such as vitamin C.
Is Tetrapeptide-30 (PKEK) compatible with other actives in multi-active cosmetic systems?
Tetrapeptide-30 (PKEK) is compatible with standard cosmetic actives at pH 4.5–7.0 in aqueous or emulsion systems. Evaluate combined system pH drift, clarity and assay retention; confirm preservative compatibility. Run accelerated stability testing at 40°C/75% RH before scale-up.
Is Tetrapeptide-30 (INCI) compliant with EU Cosmetics Regulation 1223/2009?
Tetrapeptide-30 is not listed as a restricted, prohibited or regulated substance under EU Cosmetics Regulation 1223/2009 Annexes II–VI. The finished product manufacturer is responsible for the CPSR and CPNP notification. Use CAS 1036207-61-0 and INCI name Tetrapeptide-30 consistently in all regulatory documentation; confirm purity and identity against the batch COA.
How should Tetrapeptide-30 (PKEK) be stored?
Store Tetrapeptide-30 (PKEK) sealed below 25°C in a cool, dry location protected from direct light and moisture. Once opened, reseal the container immediately. Follow specific storage and handling conditions stated in the SDS and batch COA. Confirm shelf life for the specific batch before incorporating into production formulations.
What documentation does TCS NEXUS S.L. provide for Tetrapeptide-30 (PKEK)?
TCS NEXUS S.L. provides COA (confirming CAS 1036207-61-0 and HPLC purity ≥98% (HPLC)), TDS (Technical Data Sheet) and SDS (Safety Data Sheet) for Tetrapeptide-30 (PKEK). Additional documentation such as specification sheets and INCI confirmation letters is available on a per-project basis. Contact info@tcspeptides.com to initiate a documentation and sourcing discussion.
What MOQ and sample options are available for Tetrapeptide-30 (PKEK)?
Sample and bulk quantities for Tetrapeptide-30 (PKEK) are confirmed on a per-project basis through TCS NEXUS S.L. Minimum order quantities depend on current stock, packaging configuration and project scope. R&D teams are encouraged to request samples for stability and concentration-range evaluation before bulk planning. Contact info@tcspeptides.com with project specification to begin a sourcing review.
> Technical Support and Samples
Request COA documents, sample availability, or support for custom synthesis.