Glabrene and isoliquiritigenin as tyrosinase inhibitors from licorice roots.

Tyrosinase is known to be a key enzyme in melanin biosynthesis, involved in determining the color of mammalian skin and hair. Various dermatological disorders, such as melasama, age spots, and sites of actinic damage, arise from the accumulation of an excessive level of epidermal pigmentation. The inadequacy of current therapies to treat these conditions as well as high cytotoxicity and mutagenicity, poor skin penetration, and low stability of formulations led us to seek new whitening agents to meet the medical requirements for depigmenting agents.

The effect of oxidative stress on ERalpha and ERbeta expression.

The formation of intracellular reactive oxygen and nitrogen species (ROS and RNS) has been implicated in the pathogenesis of a variety of diseases. In excess, ROS and their byproducts may cause oxidative damage and be cytotoxic to cells. Recently, it has been established that these oxidants can also act as subcellular messengers in gene regulatory and signal transduction pathways.

Estrogen-like activity of glabrene and other constituents isolated from licorice root.

Licorice root extract and its major isoflavan, glabridin, exhibited varying degrees of estrogen receptor (ER) agonism in different tissues in vitro and in vivo. Animals fed with licorice extract, compared with estradiol and glabridin, showed an increase in creatine kinase (CK) activity, a known marker for estrogen responsive genes, which was higher than expected from the levels of glabridin in the extract. This led us to test for other components that may contribute to this strong estrogen agonist activity.