Tetrahydrocurcumin (
THC) has been well known for its superior
antioxidant properties. Therefore, it is speculated that it might be effective to relieve oxidative stress-induced diseases, such as skin
hyperpigmentation. In this work, an in vitro B16F10
melanoma cell model was used to study the impact of
THC on the melanogenic process under stressed conditions. It was demonstrated that
THC could effectively inhibit the α-
MSH (
melanocyte-stimulating hormone) induced
melanin production in B16F10
melanoma cells and the expressions of three key
enzymes involved with the biosynthetic process of
melanin,
tyrosinase (TYR),
tyrosinase-related
protein 1 (TRP-1), and
tyrosinase-related
protein 2 (TRP-2), were all significantly reduced. In addition, an in vitro human keratinocyte cell model was used to investigate the potential protective role of
THC on H2O2-induced cytotoxicity. It was found that
THC could prevent H2O2-induced oxidative stress based on the results of both the cell viability study and the intracellular ROS (
reactive oxygen species) study assessed by the flow cytometry. Last,
THC was formulated into a
lecithin based nanoemulsion, and an in vitro Franz diffusion cell study using Strat-M® membrane concluded that the nanoemulsion could significantly enhance the membrane permeation compared to the unformatted
THC suspension. This research demonstrated the anti-melanogenic benefits of
THC on the
melanoma and keratinocyte cell models and the topical delivery efficacy could be significantly enhanced using a
lecithin based nanoemulsion.