The overproduction and accumulation of melanin causes hyperpigmentation and abnormal melanism, such as freckles, solar lentigines, and dark spots, which many people consider to be aesthetically undesirable. The cosmetics industry has responded by marketing a variety of skin whitening products; however, only a few skin depigmenting agents are legally approved. In Taiwan, the Ministry of Health and Welfare has authorized the use of only ten agents. Although one of these agents, kojic acid, remains commercially available in Taiwan, it has been banned in Japan due to concerns that it is carcinogenic.

Researchers in academia and industry have been actively searching for new whitening agents that are safe as well as effective. Among them is Prof. Kuan-Chen Cheng, who works at the Institute of Biotechnology and Institute of Food Science and Technology of the College of Bioresources and Agriculture. Prof. Cheng's research team has shown that mycelium extracts of Ganoderma formosanum, an endemic species of Ganoderma in Taiwan, can act as an effective demelanizing agent. Moreover, their study is the first one to use animal subjects to demonstrate the whitening effects of this local fungus, commonly known as lingzhi.

Tyrosinase is a crucial enzyme promoting the formation of melanin. Researchers have been searching for specific molecules capable of inhibiting tyrosinase's activity or volume of protein expression in hopes of creating safe, new whitening agents. The lead author of this study, PhD candidate Kai-Di Hsu, spent one year testing a variety of fermentation conditions in order to cultivate G. fromosanum mycelium and improve the production of its extracts. Hsu found that the ethyl acetate fraction of G. fromosanum ethanolic extract (GFE-EA) produces the highest inhibition of tyrosinase activity among the fractions tested.

Using in vitro cell experimentation, Hsu discovered that GFE-EA reduced melanin production by 40% to 80%. In addition to running cell experiments, Hsu and his teammates sought the technical support of the TechComm Zebrafish Core at the College of Life Science to conduct in vivo animal tests using zebrafish larvae.

Zebrafish are considered ideal for testing melanogenic regulatory compounds due to their rapid pigment formation during embryonic development and are an effective model for drug, toxicology, and cosmetics testing because their embryos undergo percutaneous absorption of small compounds through skin and gills. The in vivo tests showed that, unlike kojic acid, GFE-EA neither leads to morphological malformations or mortality, nor significantly influences heart rate. Moreover, GFE-EA required just one-seventh of the dosage of kojic acid to achieve a comparable depigmentation effect.

Prof. Cheng affirms that the liquid fermentation technology employed in this study greatly reduces the raw materials cost of G. fromosanum and that the team is currently applying for a patent for its innovative extract production process.

The team's study, "Extract of Ganoderma formosanum Mycelium as a Highly Potent Tyrosinase Inhibitor," was published in Nature Publishing Group's online journal Scientific Reports in September.