Planta Med 2012; 78 - PI103
DOI: 10.1055/s-0032-1320790

Luteolin prevents UV-induced skin damage and MMP-1 activation by interfering with the P38-MAPK pathway and IL-20 release

U Wölfle 1, A Heinemann 2, PR Esser 3, B Haarhaus 1, SF Martin 3, CM Schempp 1
  • 1Competence Center skintegral,
  • 2Molecular Dermatology
  • 3Allergy Research Group, Department of Dermatology, University Medical Center Freiburg

Ultraviolet radiation induces DNA damage, oxidative stress and extracellar matrix degradation which can result in skin inflammation, photoaging and photocarcinogenesis. The flavonoid luteolin is a potent antioxidant that is present in higher amounts in the dyers weld, Reseda luteola. We investigated UV-protective and antioxidant properties of a luteolin-rich dry extract from Reseda luteola (RL) in human keratinocytes in vitro, ex vivo and in vivo. Furthermore, we investigated direct and indirect effects of RL on dermal fibroblasts as major targets of photoaging. Spectrophotometric measurements revealed extinction maxima of RL in the UVB and UVA range. UV transmission below 370nm was <10%. In human skin, RL effectively reduced the formation of UVB-induced cyclobutane pyrimidine dimers. The antioxidative activity of RL was assessed in the H2DCFDA-assay performed with UVB-irradiated keratinocytes. RL was much more effective (EC50 3µg/ml) than N-acetylcysteine (EC50 847µg/ml). RL also inhibited UVB-induced skin erythema as well as cyclooxygenase-2 upregulation and PGE2 expression in human skin. Next, we assessed the role of conditioned supernatants from keratinocytes irradiated with solar simulated radiation (SSR) on non-irradiated dermal fibroblasts. In keratinocytes, RL inhibited SSR-induced production of the proinflammatory cytokine IL-20, that is associated with skin aging via interference with the p38 MAPK pathway. Similarly, keratinocyte supernatant-induced IL-6 and MMP-1 expression in fibroblasts was reduced by pre-treatment of keratinocytes with RL.

These data suggest that RL may protect human skin from UV-induced damage by a combination of UV-absorbing, DNA protective, antioxidant, anti-inflammatory and extracellular matrix protecting properties.