Inhibition of skin pigmentation by an extract of Lepidium apetalum and its possible implication in IL-6 mediated signaling

Pigment Cell Res. 2005 Dec;18(6):439-46. doi: 10.1111/j.1600-0749.2005.00266.x.


The development of effective skin-lightening agents is an increasingly important area of research aimed at the treatment of hyperpigmentation induced by UV irradiation or by medical conditions such as melasma, postinflammatory melanoderma and solar lentigo. Although some inhibit tyrosinase, identifying and understanding the mechanisms of action of other agents is an important goal if more effective pigmentation inhibitors are to be developed. We present here that an extract of Lepidium apetalum (ELA) decreased UV-induced skin pigmentation in brown guinea pigs and melanogenesis of HM3KO human melanoma cells. Interestingly, ELA did not reduce melanogenesis in HM3KO cells unless they were co-cultivated in keratinocyte-conditioned medium prepared by culturing keratinocytes with ELA. Under these conditions, ELA decreased tyrosinase mRNA and protein expression as well as melanin content via an ELA-mediated increase in keratinocyte IL-6 production which in turn was shown to decrease in the expression Mitf, a transcription factor implicated in tyrosinase gene expression and melanocyte differentiation. The results reveal that ELA may be an effective inhibitor of hyperpigmentation caused by UV irradiation or by pigmented skin disorders through a mechanism involving IL-6-mediated downregulation of Mitf rather than a direct inhibition of tyrosinase activity.

MeSH terms

  • Animals
  • Blotting, Western
  • Cell Differentiation
  • Cell Proliferation / drug effects
  • Cell Proliferation / radiation effects
  • Cells, Cultured
  • Down-Regulation
  • Enzyme-Linked Immunosorbent Assay
  • Guinea Pigs
  • Interleukin-6 / metabolism*
  • Keratinocytes / cytology
  • Keratinocytes / drug effects
  • Keratinocytes / radiation effects
  • Lepidium / chemistry*
  • Melanins / metabolism
  • Melanoma / drug therapy
  • Melanoma / etiology
  • Microphthalmia-Associated Transcription Factor / antagonists & inhibitors
  • Microphthalmia-Associated Transcription Factor / metabolism
  • Monophenol Monooxygenase / genetics
  • Monophenol Monooxygenase / metabolism
  • Plant Extracts / pharmacology*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Seeds / chemistry
  • Signal Transduction
  • Skin Pigmentation / drug effects*
  • Skin Pigmentation / radiation effects
  • Ultraviolet Rays


  • Interleukin-6
  • Melanins
  • Microphthalmia-Associated Transcription Factor
  • Plant Extracts
  • RNA, Messenger
  • Monophenol Monooxygenase