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.