If you've been browsing brightening serums recently, you've probably noticed "377" listed as a key ingredient. It's often described as one of the most potent skin‑brightening agents available. But what exactly is it, and how does it work？ Here's a straightforward explanation.
What Is 377？
377 is the common name for phenylethyl resorcinol. It was originally developed by the German ingredient supplier Symrise and is marketed under the trade name SymWhite® 377. Its structure was inspired by a natural compound found in the bark of Scots pine trees, known for its brightening properties.
Chemically, it belongs to the resorcinol family – a group of compounds widely used in skincare for their ability to inhibit melanin production.
How Does 377 Work？
Skin tone is determined by melanin, a pigment produced by an enzyme called tyrosinase. 377 works by inhibiting tyrosinase activity – essentially blocking the enzyme that triggers pigment formation.
Its molecular shape is similar to that of tyrosine, the raw material for melanin. This allows it to "compete" for the enzyme's active site, preventing melanin from being produced. In fact, 377 is considered one of the most potent tyrosinase inhibitors available – significantly more effective than some traditional brightening agents like arbutin or kojic acid.
In addition to this primary mechanism, 377 also has antioxidant properties. It helps neutralise free radicals generated by UV exposure, which further reduces the risk of pigmentation formation. This dual action – direct enzyme inhibition plus antioxidant defence – makes it highly effective.
Key Benefits
Visible brightening – reduces dullness and yellowing, revealing a more radiant complexion
Dark spot fading – helps lighten hyperpigmentation, melasma, sun spots, and post‑acne marks
Preventive action – stops melanin production at its source, reducing the formation of new spots
Antioxidant support – provides additional protection against UV‑induced oxidative damage
Even tone – over time, helps balance overall skin colour for a clearer, more uniform look
Regulatory and Usage Considerations
377 is a potent ingredient, and its use is regulated in several markets. In some countries, it is approved only for specific product categories and at a maximum concentration. For example, many authorities permit up to 0.5% in leave‑on formulations. Products containing 377 may require special registration as a whitening or brightening treatment, depending on local regulations.
Because of its strength, 377 can cause irritation in some users – especially those with sensitive skin. Potential side effects include redness, stinging, or mild peeling.
To use it safely:
Always patch test before incorporating it into your routine
Start with lower concentrations if available
Pair it with soothing and moisturising ingredients (e.g., ceramides, panthenol, hyaluronic acid) to minimise irritation
Avoid combining with strong exfoliating acids (AHAs, BHAs) at the same time, as this can increase sensitivity
Use sunscreen daily – 377 helps with pigmentation, but it does not replace UV protection
Who Should Use 377？
377 is ideal for anyone dealing with:
Stubborn dark spots or hyperpigmentation
Uneven skin tone or general dullness
Melasma or sun‑induced pigmentation
It is less suitable for:
Extremely sensitive or reactive skin (without careful introduction)
Pregnant or breastfeeding women (consult a dermatologist first)
What to Expect
Visible improvements usually take 4–8 weeks of consistent use. Patience is essential – brightening is a gradual process. However, when used correctly, 377 delivers noticeable results that are often more pronounced than those from many other over‑the‑counter brighteners.
We Formulate Custom 377 Products
We manufacture custom serums, creams, and softgels containing 377 in our GMP‑certified facility in Guangzhou. We handle formulation stability, regulatory documentation, and packaging – ensuring your product meets market requirements.
Tell us your concept – we'll respond with a development plan and quote within 24 hours.
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