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1 February 2004 Protection from Inflammation, Immunosuppression and Carcinogenesis Induced by UV Radiation in Mice by Topical Pycnogenol®
Suzann Sime, Vivienne E. Reeve
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Pycnogenol® is a standardized extract of the bark of the French maritime pine, Pinus pinaster Ait., that has multiple biological effects, including antioxidant, anti-inflammatory and anticarcinogenic properties. This study describes the effect of topical application of lotions containing Pycnogenol® to Skh:hr hairless mice undergoing minimally inflammatory daily exposures to solar-simulated UV radiation (SSUV). We report that concentrations of Pycnogenol® of 0.05–0.2% applied to the irradiated dorsal skin immediately after exposure resulted in dose-dependent reduction of the inflammatory sunburn reaction, measured as its edema component. When mice received three consecutive daily exposures of minimally edematous SSUV, their ability to raise a contact hypersensitivity (CHS) reaction was suppressed by 54%. Pycnogenol® lotions applied postirradiation reduced this immunosuppression to 22% (0.05% Pycnogenol®) and 13% (0.1% Pycnogenol®). Furthermore, when CHS was suppressed by 71% with exogenous treatment with cis-urocanic acid, the putative epidermal mediator of photoimmunosuppression, 0.2% Pycnogenol® lotion reduced the immunosuppression to 18%. Chronic exposure to SSUV on 5 days/week for 10 weeks induced skin tumors from 11 weeks in both control mice and in mice receiving daily applications of 0.05% Pycnogenol®, but tumor appearance was significantly delayed until 20 weeks in mice receiving 0.2% Pycnogenol®. Furthermore, whereas 100% of control mice had at least one tumor by 30 weeks, and mice treated with 0.05% Pycnogenol® by 33 weeks, the maximum tumor prevalence in mice treated with 0.2% Pycnogenol® was significantly reduced to 85%, with some mice remaining tumor free. Average tumor multiplicity was also significantly reduced by 0.2% Pycnogenol®, from 5.2 in control mice to 3.5 at 35 weeks. Thus, topical Pycnogenol® offered significant and dose-dependent protection from SSUV-induced acute inflammation, immunosuppression and carcinogenesis, when applied to the skin after daily irradiation. Pycnogenol®, therefore, in addition to its recognized health benefits in other organs, appears to have potential in providing photoprotection for humans in a complementary role with sunscreens, having demonstrable activity when applied to the skin after, rather than before, UV exposure.

Suzann Sime and Vivienne E. Reeve "Protection from Inflammation, Immunosuppression and Carcinogenesis Induced by UV Radiation in Mice by Topical Pycnogenol®," Photochemistry and Photobiology 79(2), 193-198, (1 February 2004).<0193:PFIIAC>2.0.CO;2
Received: 14 August 2003; Accepted: 1 November 2003; Published: 1 February 2004

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