Photoprotective effect of verbascoside from Buddleja cordata in SKH-1 mice exposed to acute and chronic UV-B radiation / Efecto fotoprotector del verbascósido de Buddleja cordata en ratones SKH-1 expuestos de forma aguda y crónica a laradiación UV-B

Ultraviolet radiation (UVR) is involved in both sunburn and the development of skin cancer, which has a high incidence worldwide. Strategies to reduce these effects include the use of photoprotective substances. The aim of this work was to investigate the photoprotective effect of verbascoside isolated from the methanolic extract of Buddleja cordata (BCME) in SKH-1 mice exposed to acute and chronic UV-B radiation. The mouse dorsal area was evaluated macroscopically and microscopically for diagnosis; verbascoside penetration into mouse skin was investigated in vivo by the tape stripping method. After acute UV-B exposure, 100 percent of irradiated mice that had been protected with verbascoside showed no signs of sunburn or of inflammatory processes. After chronic exposure, 100 percent of unprotected mice showed skin carcinomas; in contrast, in mice topically treated with either BCME or verbascoside, the presence of lesions was decreased by 90 percent. These results prove that verbascoside penetrates through the skin of mice and suggest that verbascoside and BCME may potentially prevent photodamage on mice’s skin after acute and chronic UVR exposure.

La radiación ultravioleta (RUV) provoca quemaduras solares y el desarrollo de cáncer de piel. El objetivo de este trabajo fue investigar el efecto fotoprotector del verbascósido obtenido del extracto metanólico de Buddleja cordata (EMBC) en ratones SKH-1 expuestos a RUV-B de manera aguda y crónica. El diagnóstico histológico se llevó a cabo en la piel de la zona dorsal de los ratones. La penetración del verbascósido fue cuantificada mediante la técnica de la cinta adhesiva. En el experimento agudo, el 100 por ciento de los ratones protegidos con verbascósido no evidenciaron signos de quemadura ni procesos inflamatorios. En el experimento crónico los ratones sin protección e irradiados presentaron carcinomas cutáneos. En contraste en los ratones protegidos con EMBC o verbascósido las lesiones disminuyeron un 90 por ciento en ambos grupos. El verbascósido penetró en la piel del ratón. Los resultados sugieren que el EMBC y el verbascósido previenen el fotodaño en la piel de ratones expuestos de forma aguda o crónica a la RUV.

Cutaneous solar ultraviolet exposure and clinical aspects of photodamage.

Solar ultraviolet (UV) radiation reaching the earth is a combination of UVB (290-320 nm) and UVA (320-400 nm) wavelengths. Since UVA is less energetic than UVB, UVB has long been thought to be the factor responsible for the damaging effects of solar radiation. But with modern tools such as in vitro models, it has been proven that UVA plays a major role. The objective of this review is to show how skin may be exposed to UV light and to highlight the clinical aspects of UV-induced skin damages with the respective contribution of UVB or UVA. Even if UVA is less energetic than UVB, it is more abundant and penetrates deeper into the skin, reaching as far as the dermis. Various factors also influence skin exposure to UV light: the latitude, season, and time of the day. Acute as well as chronic sun exposure induces short- and long-term clinical damages. Erythema and pigmentation are immediate responses of normal human skin exposed to UV radiation. The long-term effects are photoaging and photocarcinogenesis. In particular, UVA appears to play a major role in the deterioration of dermal structure leading to the photoaged appearance of the skin.

Photoprotection and vitamin D status: A study on awareness, knowledge and attitude towards sun protection in general population from Kuwait, and its relation with vitamin D levels.

Background: The primary cause of skin cancers is exposure to ultraviolet (UV) radiation. And, for decades sun protection has been promoted in various public health education campaigns. Recently, however, vitamin D deficiency has been related to increased risk of skin cancers. And, skin being the primary site for the synthesis of active form of vitamin D, excessive sun protection could lead to vitamin D-deficient states. But, the results have so far been conflicting. Aims: To study the level of awareness, knowledge and attitude of representative groups from the general population from Kuwait towards sun protection. And, also study the correlation of the level of sun protective measures used and vitamin D levels in these groups. Methods: The study constituted of two main parts. First part comprised a questionnaire-based survey of representative group of people aged 18 and above to assess their knowledge, awareness and attitude towards sun protection. The second part consisted of measuring serum vitamin D levels in 150 volunteers amongst the responders of the questionnaire, who had been regularly using sunscreens for at least 2 years and compare to the levels seen in 150 age and sex-matched responders of similar skin phototypes, who had never used sunscreens. Results: Out of the total of 1044 responders, 80% of them had adequate knowledge of the beneficial and harmful effects of sun exposure, and had been using sunscreens regularly, and adopting other sun protective measures in their daily life. The levels of vitamin D were found to be deficient in both sunscreen users and those who had never used sunscreens. The difference between the two groups was statistically insignificant (60.67% vs 54.67%; P value>0.001). Conclusion: Population at large seems to be adequately informed about the beneficial and deleterious effects of sun exposure. Vitamin D levels are deficient in majority of our people, and there is a need to do larger surveys covering all parts of the country and give supplemental doses of vitamin D to those found deficient.