Antioxidants as skin-lightening agents.
Antioxidants serve to reduce oxidation of tyrosine to DOPA quinone and therefore are shown to have skin-lightening activity (64).
In addition, they act in the melanogenesis pathway, reducing the synthesis of melanin.
Exposure to UV radiation results in the generation of free radicals.
It has been identified that ROS (reactive oxygen species) are able to oxidize tyrosinase and DOPA to melanin, and this is one of the major causes for tanning (65).
Although antioxidants are present in tissues, they may not be able to reduce the radicals, depending on the extent of UV exposure.
Inflammation is a source of free radicals.
Hence the quenching of free radicals would also help in reducing the synthesis of melanin, thereby contributing to skin depigmentation effects (66).
The use of phytic acid, glutathione (Figure 4), and ubiquinone as popular skin-lightening agents is due to their strong antioxidant nature (67–68).
Melanin synthesis in melanocytes is accompanied by the generation of hydrogen peroxide that can lead to the formation of ROS that further increase the proliferation of melanocytes