Sepiwhite MSH undecylenoyl phenylalanine brightening ingredient guide cover

Sepiwhite MSH (Undecylenoyl Phenylalanine): A Brand Owner’s Guide to This Brightening Active

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Written & researched by Thanawat Charoen, Ingredients & Product Innovation Researcher · Reviewed by Creaton Poh · Published by OEM2YOU · Last reviewed September 2026

Brightening is the largest single request we see from new skincare brands in Malaysia, and most briefs arrive with the same shortlist: niacinamide, vitamin C, arbutin, maybe tranexamic acid. Sepiwhite™ MSH is rarely on the list, which is a pity, because it works on a different step of pigmentation from every one of those — and that is exactly what makes it useful.

This guide explains what the ingredient is, what the published evidence actually says, how it behaves in a formula, and what a brand owner should ask a manufacturer before building a product around it.

Quick answer

Sepiwhite™ MSH is Seppic’s trade name for Undecylenoyl Phenylalanine, an amino acid (phenylalanine) joined to a fatty acid derived from castor oil. It is positioned as an alpha-MSH antagonist: it interferes with the hormonal signal that tells pigment cells to switch tyrosinase on. Seppic’s stated use level is 2%. Its best-documented use is alongside niacinamide, which works on a later step (pigment transfer), and a published double-blind study found the combination outperformed niacinamide alone. The main formulation catch is pH: the molecule is an acid that only dissolves in water once it is neutralised, so it does not drop straight into a low-pH serum.

Key takeaways

  • It acts upstream of most brighteners — on the signal, not the enzyme or the pigment transfer — so it pairs rather than competes.
  • The strongest independent evidence is for the 1% Sepiwhite + 5% niacinamide combination (Bissett et al., 2009).
  • It is a powder that needs neutralising to go into a water phase; it is also soluble in oils and alcohol.
  • Seppic lists it as Halal certified, COSMOS approved and vegan — but an ingredient certificate does not certify your finished product.
  • On a Malaysian label, stay with cosmetic wording — “brightens”, “evens skin tone”, “reduces the appearance of dark spots”. “Treats melasma” is a medical claim.

What is Sepiwhite MSH?

Property Value
INCI Undecylenoyl Phenylalanine
CAS 175357-18-3
Supplier Seppic (France)
Form Powder, single component, preservative-free
Stated use level 2% (a 0.2% “QD” grade exists for Japanese quasi-drug formulas)
Supplier-stated certifications Halal certified, COSMOS Approved, NATRUE, vegan, ISO 16128 natural origin >99%
Independent safety review Covered by the US Cosmetic Ingredient Review (CIR) assessment of amino acid alkyl amides

Why it is different from the brighteners you already know

Skin pigmentation is a chain of steps. UV and inflammation trigger a signal (alpha-MSH), the signal switches on tyrosinase inside the pigment cell, tyrosinase makes melanin, and melanin is then transferred into the surrounding skin cells where you see it. Most brighteners pick one link:

Step in the chain Typical ingredient
The signal (alpha-MSH) Undecylenoyl phenylalanine (Sepiwhite MSH)
The enzyme (tyrosinase) Arbutin, kojic acid, vitamin C derivatives
Transfer into skin cells Niacinamide
Removing pigmented cells faster AHAs, PHAs

That is why the ingredient earns its place in a brief: it is not a fifth way of doing what niacinamide already does. It lets a formula cover two different steps without stacking two ingredients that do the same job.

What the evidence says

The most useful study for a brand owner is independent of the supplier’s own dossier. In Bissett et al., Journal of Cosmetic Dermatology (2009), two double-blind, vehicle-controlled studies ran for eight weeks on facial hyperpigmentation. A formula with 1% undecylenoyl phenylalanine reduced the appearance of hyperpigmentation versus vehicle, and the combination of 1% undecylenoyl phenylalanine with 5% niacinamide performed better than 5% niacinamide alone. An earlier in-vitro paper in the Journal of the American Academy of Dermatology reported the same additive effect with niacinamide and N-acetyl glucosamine.

Seppic’s own claims go further — efficacy on phototypes II to V, and faster visible results when combined with AHAs. Those are supplier data; they are useful for choosing the ingredient, but they are not evidence for your finished product. If you want to print a percentage on the box, you need a test on your own formula.

How it behaves in a formula

This is where most of the cost and delay hides, and where a brand owner benefits from knowing enough to ask the right question.

  • It is an acid. In its supplied form it is essentially insoluble in water. To go into the water phase it is neutralised with a base until it dissolves (Seppic and distributors describe solubility at around neutral pH). In practice the formulator pre-dissolves it, then brings the rest of the formula to a final pH at which it stays dissolved.
  • Low-pH formulas are the problem case. If the finished product is pushed too acidic, the molecule can come back out of solution as fine crystals or haze. That rules out simply adding it to a strong AHA toner. It can be done in a combined product, but it is a formulation project, not a line-item swap.
  • It is oil- and alcohol-soluble too. That gives a formulator a second route in emulsions and some hydro-alcoholic formats.
  • It is a powder with no carrier, so the INCI list stays short — one ingredient on the label, not three.

An illustrative starting framework

The table below shows how a brightening serum built around the published combination is usually structured. It is a framework for discussion with your manufacturer, not a validated formula — percentages, the thickener and the preservative system all change with the final texture and packaging.

Phase Ingredient role Indicative %
A Water, humectants (glycerin, butylene glycol), chelator to 100
B Undecylenoyl phenylalanine, pre-neutralised in part of the water 1–2
C Niacinamide 4–5
D Polymer thickener suited to the final pH 0.3–1
E Preservative system, final pH adjustment q.s.

What to ask your OEM manufacturer

  1. “What final pH will this sit at, and how do you stop it crystallising?” A manufacturer who has used it will answer immediately. One who has not will tell you it is “just 2%”.
  2. “Is this the 2% grade or the QD grade?” They are dosed very differently and are not interchangeable in a quotation.
  3. “Will you run stability in my actual packaging, including cold cycling?” Crystallisation often only shows after a cold transport leg.
  4. “Do you hold the halal certificate for this lot, or only the supplier’s declaration?” For a brand selling on halal, those are different claims. See our halal cosmetics manufacturing guide.

What you can say on the label in Malaysia

Under NPRA’s cosmetic framework, a brightening product can speak to the appearance of the skin — brighter, more even-looking, reduced appearance of dark spots. It cannot claim to treat a skin condition. “Melasma treatment” or “removes pigmentation disease” moves the product out of the cosmetic category altogether. The claims rules are published in NPRA’s Guideline for Cosmetic Claims, and the notification process is covered in our NPRA notification guide.

Frequently asked questions

Is Sepiwhite MSH the same as undecylenoyl phenylalanine?

Sepiwhite™ MSH is Seppic’s trade name for undecylenoyl phenylalanine. Other suppliers sell the same INCI under different names, and quality and documentation vary by source.

Can I use it with vitamin C?

Mechanistically, yes — they act on different steps. The practical issue is pH: pure ascorbic acid needs a low pH, which works against keeping undecylenoyl phenylalanine dissolved. A stable vitamin C derivative is usually the easier pairing.

Is it suitable for sensitive skin?

It is used widely in leave-on products and is covered by an independent CIR safety assessment. As with any leave-on product, a finished-product safety assessment and, ideally, a patch test on the final formula are still required.

Does 2% make the product expensive?

It is a specialty active, so it costs more per kilogram than a commodity brightener. At a 1–2% dose the effect on unit cost depends heavily on pack size — ask for the formula cost with and without it, not the raw-material price. Our MOQ and pricing guide explains what drives the number.

Is it halal?

Seppic lists it as Halal certified. For a Malaysian halal claim, what counts is the certificate held for the material your manufacturer actually buys, and the certification of the finished product.

Sources & references

Disclosure

OEM2YOU is a cosmetics manufacturer. We are not affiliated with Seppic and received nothing for this article. Ingredient data is drawn from the supplier’s published information and the peer-reviewed sources above; practical formulation notes reflect general manufacturing experience and are not a substitute for a tested formula.

Update history

September 2026 — First published.