Accumulation of studies have shown that barrier dysfunction in the skin is closely related with UVB
irradiation. In our previous study, we found that a natural product from peanut, named ethanol extract of peanut
sprouts (EPS), was found to have a potent antioxidant activity by showing suppressive activities of the induced
expression of COX-2 and nerve growth factor expression in the compound 48/80-treated HaCaT cells, an in vitro
model for skin inflammation. Also, the anti-inflammatory activity of EPS was also confirmed in the animal model of
contact inflammation of oxazolone-induced contact dermatitis of mice in vivo. With these backgrounds, we studied
whether UVB-irradiation induced barrier dysfunction, which could be protected by EPS treatment, based on its strong
ROS-scavenging activity, in normal human epidermal keratinocytes (NHEKs). For cell experiments, cell viability of
post-irradiated NHEKs was checked by a MTT kit. For measuring ROS, cells were labelled with a DCF-DA, irradiated
with UVB at a dose of 50mJ/cm2, and then detected by a FACS analysis. RT-PCR experiments were performed to
check expression levels of biomarkers for terminal differentiation in the keratinocytes, including, keratin 1 and 10,
involucrin, loricrin, and filaggrin. We also check mRNA levels of IL-6 and IL-8, immunoinflammatory biomarkers, in the
UVB-irradiated NHEKs. From RT-PCR experiments, IL-6 and IL-8 were markedly up-regulated by UVB irradiation,
which were suppressed by EPS treatment in a dose-dependent manner. Keratins 1 and 10, and filaggrin were also
down-regulated by UVB irradiation, which were reversed by EPS treatment in a dose-dependent manner. However,
involucrin and loricrin were not modulated by either UVB irradiation or EPS treatment. In together, UVB-irradiation is
an important environmental factor to induce barrier dysfunction in the skin, which can be blocked by antioxidant
treatment. EPS is found to be a good candidate antioxidant to repair UVB-damaged skin barrier.

UVB irradiation induces barrier dysfunction in epidermal keratinocytes,  which can be repaired by ethanol extract of peanut sprouts,  a new antioxidant to be originated from peanuts