Glabridin may inhibit melanogenesis by one of two mechanisms:

1. Inhibition of the production of active oxygen species: (0₂)

2. Inhibition of tyrosine: Human tyrosinase is an essential enzyme, which regulates the production of melanin, a group of brown to black pigments in the skin and eyes of humans.

It is a known fact that a number of reactions (e.g. inflammatory, etc.) are induced when human skin is exposed to UV radiation. The membrane phospholipids of the skin tissue are damaged by UV-induced active oxygen. Histological changes occur in the skin that manifest as erythemas and skin pigmentation. Active oxygen is one of the species that induces skin pigmentation. Thus, prevention of its production is linked to inhibition of melanogenesis. To test this, an assay was performed to study the inhibitory effect of glabridin on superoxide anion production. As shown in Figure 2, glabridin inhibited superoxide (active oxygen) formation at concentrations from 0.33 µg/ml to 33.3 µg/ml.

Thus, licorice may be useful for treating conditions like melasma or pigmentation of skin due to sun-exposure.