Glabrene and Isoliquiritigenin as Tyrosinase Inhibitors from Licorice Roots

Abstract

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 inhibitory effect of licorice extract on tyrosinase activity was higher than that expected from the level of glabridin in the extract. This led us to test for other components that may contribute to this strong inhibitory activity. Results indicated that glabrene and isoliquiritigenin (2',4',4-trihydroxychalcone) in the licorice extract can inhibit both mono- and diphenolase tyrosinase activities. The IC(50) values for glabrene and isoliquiritigenin were 3.5 and 8.1 microM, respectively, when tyrosine was used as substrate. The effects of glabrene and isoliquiritigenin on tyrosinase activity were dose-dependent and correlated to their ability to inhibit melanin formation in melanocytes. This is the first study indicating that glabrene and isoliquiritigenin exert varying degrees of inhibition on tyrosinase-dependent melanin biosynthesis, suggesting that isoflavenes and chalcones may serve as candidates for skin-lightening agents.

Inhibition of melanogenesis by Gaillardia aristata flower extract

“…In addition, as the amount of total phenolics of GAE (200 μg/mL) was higher than that of gallic acid (100 μg/mL), the antioxidant capacity of GAE perhaps derived from polyphenolic constituents of GAE. Flavonoids including polyphenol have antioxidant and antimelanogenic activities [31][32][33]. The main mechanism of flavonoids having the depigmenting effect may be the ROS-scavenger properties and the ability to chelate metals at the active site of metalloenzymes [34].…”

Effect of quercetin derivatives on melanogenesis stimulation of melanoma cells

“…4, one of the flavonol and widely distributed in plants including onion, guava leaves and seaweeds, exhibits potent tyrosinase inhibitory activity [38,39]. Glabridin, an isoflavan derivatives, was isolated from Allamanda cathartica stem as potent tyrosinase inhibitor [40,41]. Artocarbene, chlorophorin, norartocarpanone, and 4-propylresorcinol including 2,4-substituted resorcinol moiety induce high tyrosinase inhibitory activity [42,43].…”

Tyrosinase activity of Greyia flanaganii (Bolus) constituents

“…Tyrosinase is known to be the key enzyme in melanin biosynthesis (Nerya et al 2003). Over-activity of this enzyme leads to overproduction of melanin leading to hyper-pigmentation of the skin.…”

“…Overproduction of melanin can be prevented by avoiding excessive UV light exposure and can be treated with skin-lightening agents such as bleaching hydroquinone, kojic acid and retinoids (Halder et al 2004). Some commercially available chemical and fungal derived skin-lightening agents have been proven to have chronic, cytotoxic and mutagenic effects on humans (Nerya et al 2003;Wang et al 2006;Wu et al 2003). Therefore, there is a need for alternative herbal derived and pharmaceutical agents for the treatment of hyper-pigmentation of the human skin.…”