Tyrosinase enzyme and its inhibitors: An update of the literature

Facial hyperpigmentation commonly includes melasma, post-inflammatory hyperpigmentation, and solar lentigines. These common skin conditions may affect patients' quality of life and are usually due to impairment in the melanin production or alteration in the tyrosinase activity. Among tyrosinase inhibitors, hydroquinone is the most used in clinical practice, despite its prolonged administration can be associated with adverse effects (cancer, exogenous ochronosis). New natural and synthetic compounds were proposed as inhibitors of copper-containing human tyrosinase such as kojic acid, α-arbutin, thiamidol, and resorcinol derivatives. Data of the most recent literature were collected despite some results still need to be obtained against mushroom tyrosinase enzyme, which may unpredictably affect inhibition studies. New insights came from the structure-activity relationships among different scaffolds to better comprehend the enzyme-inhibitor interactions in the continuous search of safer and more potent cosmetic agents used alone or in combination with other drugs.