Phenylethyl Resorcinol
Phenylethyl Resorcinol (also known by the trade name SymWhite 377) is a skin-lightening and antioxidant active ingredient derived from a molecule that exists naturally in pine trees. Its IUPAC name is 1,3-Benzenediol, 4-(1-Phenylethyl)- and its CAS number is 85-27-8. It is used in a wide range of brightening and depigmenting cosmetic formulations, often combined with other skin-lightening actives.
Phenylethyl Resorcinol functions as a skin brightener and antioxidant. Manufacturer clinical data suggests 0.5% is more effective than 1% kojic acid for skin lightening; however, an independent 2013 study (80 participants, 12 weeks) using it in combination with three other actives found only moderate results, with 57% of participants showing at least a moderate response and 17% showing no improvement.
The independent 2013 study tested phenylethyl resorcinol in combination with other actives (disodium glycerophosphate, L-leucine, and undecylenoyl phenylalanine), making it difficult to isolate its individual contribution to the observed results.
