Phenolic-rich Pomegranate Peel Extract: In Vitro, Cellular, and In Vivo Activities for Skin Hyperpigmentation Treatment

The pomegranate phenolics are reported to have cutaneous benefits and to be effective in treating skin disorders, including hyperpigmentation. In this context, a preparation method was developed by which to obtain phenolic-rich pomegranate peel extract. Sinapic acid was presented as the major pomegranate peel phenolics, followed by gallic and ellagic acids, and 4 additional phenolics. The extract exhibited strong antioxidant activity with an in vitro tyrosinase inhibitory effect. The skin hyperpigmentation treating potency was confirmed by the suppression of cellular melanogenesis through tyrosinase and TRP-2 inhibitions as examined in the B16F10 melanoma cells. Cellular antioxidant and proliferative activities of the extract toward human dermal fibroblasts were evidenced, as well as an inhibitory effect against MMP-2. The extract was developed into the stable serum and mask. The products were proved to be non-irritated in 30 Thai volunteers participating in a single application closed patch test. A split-face, randomized, double-blind, placebo-controlled test of the skin lightening effect was evaluated in the 30 volunteers over 28 consecutive daily treatments and monitored by the Mexameter MX 18. The active serum and mask were better in facial skin lightening efficacy than the placebo (p < 0.005). That was in accordance with the sensory evaluation scored by the volunteers. Phenolic-rich pomegranate peel extract is evidenced as a safe herbal derived material promising for skin hyperpigmentation treatment. Supportive information regarding chemical and biological profiles is presented with the confirmed safety and cutaneous benefits in volunteers.