50644 Brightening and Anti-Hyperpigmentation Efficacy Validation of the Formulation with Phenylethyl Resorcinol Using Multi-Methodology: In Vitro 3D Skin Model and Clinical Trial

Hyperpigmentation is an early sign of aging skin that can be triggered by factors such as UV and inflammation which induces solar lentigines and post-inflammatory hyperpigmentation (PIH), respectively. A formulation was designed with phenylethyl resorcinol, antioxidants, and anti-inflammatory ingredients to reduce hyperpigmentation through multiple pathways. The objective was to validate the brightening efficacy of the formulation based on pre-clinical and clinical studies. In vitro 3D melanin skin models were used to assess the ability of the formulation to inhibit and reduce melanin synthesis. In both assessments, the formulation significantly improved brightness, melanin content, and distribution compared with a negative control. The clinical efficacy of the formulation was tested in two, randomized, controlled clinical studies, a UV-induced pigmentation model (n=30) and an 8-week treatment followed by 2-week regression on solar lentigines (n=29) and acne PIH (n=27). In the UV-induced pigmentation model, the subjects were treated with UVB exposure followed by formulation application. UV-induced pigmentation and redness level were significantly reduced at week 4, compared with blank control (p<0.05). This indicates improvement in skin brightening and recovery post UV exposure. Clinical study showed significant improvement in solar lentigines and acne PIH, as well as skin radiance, sallowness, and translucency from dermatologist grading, at week 8 compared with baseline (p<0.05). Skin brightening effect was maintained even after product use was stopped for 2 weeks. Thus, this formulation reduces hyperpigmentation and redness post UV and is effective on different types of hyperpigmentation including solar lentigines and acne PIH with long-term use.