Solar ultraviolet-induced erythema in human skin and nuclear factor-kappa-B-dependent gene expression in keratinocytes are modulated by a French maritime pine bark extract

The procyanidin-rich French maritime pine bark extract Pycnogenol (PBE) has been investigated for its effect in protecting human skin against solar UV -simulated light-induced erythema. Twenty-one volunteers were given an oral supplementation of Pycnogenol: 1.10 mg/kg body weight (b. wt.)/d for the f irst 4 weeks and 1.66 mg/kg b. wt./d for the next 4 weeks. The minimal eryt hema dose (MED) was measured twice before supplementation (baseline MED), o nce after the first 4 weeks of supplementation, and a last time at the end of the study. The UVR dose necessary to achieve 1 MED was significantly inc reased during PBE supplementation. Since the activation of the pro-inflamma tory and redox-regulated transcription factor NF-kappaB is thought to play a major role in UVR-induced erythema, the effect of PBE was also investigat ed in the human keratinocyte cell line HaCaT. PBE, added to the cell cultur e medium, inhibited UVR-induced NF-kappaB-dependent gene expression in a co ncentration-dependent manner. However, NF-kappaB-DNA-binding activity was n ot prevented, suggesting that PBE affects the transactivation capacity of N F-kappaB. These data indicate that oral supplementation of PBE reduces eryt hema in the skin. Inhibition of NF-kappaB-dependent gene expression by PBE possibly contributes to the observed increase in MED. (C) 2001 Elsevier Sci ence Inc.