Equipe PNSCM «Produits naturels - Synthèses - Chimie Médicinale, UMR CNRS 6226 Institut des Sciences chimiques de Rennes, UFR Sciences Pharmaceutiques et Biologiques, Univ. Rennes, Université Européenne de Bretagne, France.
J Photochem Photobiol B. 2012 Jun 4;111:17-26. doi: 10.1016/j.jphotobiol.2012.03.005. Epub 2012 Mar 24.
The adaptative capacity of lichens to UV radiation could be expressed by the production of photo-absorbing secondary metabolites in thalli. A preliminary screening performed on twelve lichen species by high performance thin layer chromatography (HPTLC) revealed five major compounds absorbing in the UVA (315-400nm) or UVB (280-315nm) ranges in Diploicia canescens. After phytochemical investigation of this lichen, twelve metabolites have been isolated and characterized. Those obtained in sufficient quantities were evaluated for their photoprotective capacities and compared to three referent sunscreens. Experimental spectra were compared to theoretical spectra as obtained at the TD-DFT level of theory. Different DFT functionals were tested to accurately reproduce the UV/Vis spectra of five depsidones, one diphenylether and two bisxanthones. Results indicate that absorption wavelengths and molecular extinction coefficients (oscillator strengths) obtained for the bisxanthones were similar to those of the UVA referent sunscreen.
地卷衣对紫外线辐射的适应能力可以通过其在叶状体中产生光吸收的次生代谢物来表达。通过高效薄层色谱法（HPTLC）对 12 种地衣物种进行的初步筛选，在 Diploicia canescens 中发现了五种在 UVA（315-400nm）或 UVB（280-315nm）范围内吸收的主要化合物。对这种地衣进行植物化学研究后，分离并鉴定了 12 种代谢产物。获得了足够数量的那些，并对它们的光保护能力进行了评估，并与三种参考防晒霜进行了比较。将实验光谱与在 TD-DFT 理论水平获得的理论光谱进行了比较。测试了不同的 DFT 泛函以准确地再现五种去甲二萜、一种二苯醚和两种双黄酮的 UV/Vis 光谱。结果表明，双黄酮的吸收波长和分子消光系数（振子强度）与 UVA 参考防晒霜的相似。
