Assessment of cyclobutane pyrimidine dimers by digital photography in human skin

UV-induced skin's green autofluorescence is a biomarker for both non-invasive evaluations of the dosages of UV exposures of the skin and non-invasive prediction of UV-induced skin damage

It is crucial to discover biomarkers for non-invasive evaluations of the dosages of UV exposures to a person during post-UV exposure period, and for non-invasive prediction of UV-induced skin damage. Our current study has obtained findings: UVB exposures produced dose-dependent increases in skin's green autofluorescence (AF) intensity of mice, which were significantly associated with the UVB dosages. The UVC-induced green AF increases were dose dependent, which were highly associated with the UVC dosages. Moreover, both previous reports and our current study have collectively shown significant association between UVB/UVC dosages and UVB/UVC-induced skin damage. Collectively, our study has indicated that the UVB/UVC-induced skin's AF are first biomarkers for both non-invasive evaluations of the dosages of UV exposures to a person during post-UV exposure period and non-invasive and label-free prediction of UVB/UVC-induced skin damage.

Licoricidin, an isoflavonoid isolated from Glycyrrhiza uralensis Fisher, prevents UVA-induced photoaging of human dermal fibroblasts

OBJECTIVE

Licoricidin is an isoflavonoid isolated from Glycyrrhiza uralensis Fisher. In this study, we investigated the effects of licoricidin on photoaging of UVA-irradiated human dermal fibroblasts (HDFs).

METHODS

In vitro reactive oxygen species (ROS) scavenging activity, cellular protective effect and inhibition of elastase activity was determined by Fe³⁺ -EDTA/H₂ O₂ systems, photohaemolysis and elastase activity assay, respectively. Anti-oxidative capacity of the compound was evaluated by fluorescent ELISA and 2', 7'-dichlorofluorescin-diacetate (DCF-DA) assay. The expression of protein and phosphorylation was examined using Western blot.

RESULTS

The ROS scavenging activity (OSC₅₀ ) of licoricidin was 2.77 μM. It was 3.1-fold higher than that of L-ascorbic acid. Its protective effects were confirmed in a study of ¹ O₂ -induced cellular damage to human erythrocytes. The τ₅₀ value of 10 μM of licoricidin was 71.0 min; this was markedly higher than that obtained with α-tocopherol (37.0 min). The elastase inhibitory activity of licoricidin (IC₅₀ of 61.2 μM) was 2.1-fold more potent than that of oleanolic acid. Licoricidin markedly reduced the UVA-induced intracellular ROS in a concentration-dependent manner. Western blot revealed that licoricidin attenuated the UVA-dependent induction of MMP-1 protein. Mechanistically, this appeared to be due to licoricidin-dependent inhibition of mitogen-activated protein kinases (MAPK) phosphorylation, which resulted in decreased c-Jun activation and reduced c-Jun and c-Fos expression.

CONCLUSION

Licoricidin blocks UVA-induced photoaging via ROS scavenging. This activity converges to limit the activity of MMP-1. These data suggest that licoricidin may be considered as an active ingredient in new topically applied anti-ageing formulations.

Effects of UV Rays and Thymol/Thymus vulgaris L. Extract in an ex vivo Human Skin Model: Morphological and Genotoxicological Assessment

Ultraviolet (UV) radiation is the major environmental factor affecting functions of the skin. Compounds rich in polyphenols, such as Thymus vulgaris leaf extract and thymol, have been proposed for the prevention of UV-induced skin damage. We compared the acute effects induced by UVA and UVB rays on epidermal morphology and proliferation, cytotoxicity, and genotoxicity. Normal human skin explants were obtained from young healthy women (n = 7) after informed consent and cultured at the air-liquid interface overnight. After 24 h, the samples were divided in 2 groups: the former exposed to UVA (16 or 24 J/cm2) and the latter irradiated with UVB (0.24 or 0.72 J/cm2). One hour after the end of irradiation, supernatants were collected for evaluation of the lactate dehydrogenase activity. Twenty-four hours after UVB exposure, biopsies were processed for light and transmission electron microscopy analysis, proliferation, cytotoxicity, and genotoxicity. UVB and UVA rays induced early inhibition of cell proliferation and DNA damage compared to controls. In particular, UVB rays were always more cytotoxic and genotoxic than UVA ones. For this reason, we evaluated the effect of either T. vulgaris L. extract (1.82 µg/ml) or thymol (1 µg/ml) on all samples treated for 1 h before UVB irradiation. While Thymus had a protective action for all of the endpoints evaluated, the action of the extract was less pronounced on epidermal proliferation and morphological features. The results presented in this study could be the basis for investigating the mechanism of thymol and T. vulgaris L. extract against the damage induced by UV radiation.