Licorice extract is one of the most commonly employed ingredients in cosmetics for skin lightening.It is obtained from the root of Glycyrrhia glabra Linnera. 

Efficacy 

Active ingredients in licorice extract include liquiritin, glabridin, and licochalcone A. Licorice extract improves hyperpigmentation through dispersion of melanin, inhibition of melanin biosynthesis, and inhibition of cyclooxygenase activity, which in turn decreases free radical production. Glabridin is the main component of licorice extract; it is a polyphenolic flavonoid, which has been shown to prevent ultraviolet B (UVB)-induced pigmentation.

Furthermore, glabridin enacts anti-inflammatory effects through inhibition of superoxide anion and cyclooxygenase activity.

Related research

Liquiritin, another component of licorice extract, has been shown to be efficacious in lightening melasma lesions. In a study of 20 subjects with melasma, one gram of liquiritin cream was applied daily for four weeks, with results ranging from satisfactory to excellent and an objective reduction in pigment intensity in 70% of patients treated with liquiritin.However, additional studies are indicated to further substantiate the hypopigmenting action of licorice extract and its components.