Constituents from the Formosan apple reduce tyrosinase activity in human epidermal melanocytes

Yi Pei Lin, Feng-Lin Hsu, Chien Shu Chen, Ji Wang Chern, Mei Hsien Lee

Research output: Contribution to journalArticlepeer-review

77 Citations (Scopus)


Tyrosinase is a copper-containing monooxygenase that catalyzes melanin synthesis in skin melanocytes. Herein, 13 compounds from the Formosan apple (Malus doumeri var. formosana), an indigenous Taiwanese plant, were isolated and identified. The active constituents were identified as 3-hydroxyphloretin (7) and catechol (9); they exhibited potent hydroxyl radical-scavenging (IC50 values, 0.6 and 1.1 μM) and cellular tyrosinase-reducing activities (IC50 values, 32 and 22 μM) in human epidermal melanocytes. In addition, we evaluated the level of several tyrosinase-related proteins by Western blot analysis. In contrast to 3-hydroxyphloretin (7), which showed no effect on the level of these proteins, catechol (9) reduced their activity and the expression of the respective genes, as determined by quantitative real-time PCR. In a kinetic analysis of mushroom tyrosinase, 3-hydroxyphloretin (7) was a competitive inhibitor. These two constituents exhibited metal-coordinating interactions with copper ions in a virtual model of molecular docking with human tyrosinase. Thus, 3-hydroxyphloretin (7) and catechol (9) were the most active constituents from the Formosan apple; they exhibited anti-oxidant and tyrosinase reducing activities, suggesting their possible use as cosmetic agents.

Original languageEnglish
Pages (from-to)1189-1199
Number of pages11
Issue number8
Publication statusPublished - Apr 2007


  • 3-Hydroxyphloretin
  • Catechol
  • Formosan apple
  • Human epidermal melanocytes
  • Malus doumeri var. formosana
  • Molecular docking
  • Quantitative real-time PCR
  • Rosaceae
  • Tyrosinase

ASJC Scopus subject areas

  • Plant Science
  • Biochemistry
  • Molecular Biology
  • Organic Chemistry
  • Drug Discovery


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