Lichens are symbiotic photosynthesizing organisms with thalli formed by fungi and algae/cyanobacteria that possess high stress tolerance. One of the factors that contributes to the ability of a lichen to tolerate harsh environmental conditions is the presence of unique metabolites, including high-molecular-weight dark pigments termed melanins. The chemical composition and structure of lichen melanins remain poorly studied. We analyzed the elemental composition, the main functional groups, and the physicochemical properties of melanin extracted from Cetraria islandica and Pseudevernia furfuracea lichens. Based on the C/N ratio, this pigment is allomelanin. We also identified functional groups that provide photoprotective and antioxidant properties of melanin. Melanin synthesis might be an essential defense mechanism contributing to the survival of lichens under exposure to UV radiation.

中文翻译：

---

来自 Lichens Cetraria islandica 和 Pseudevernia furfuracea 的黑色素：结构特征和物理化学性质

地衣是共生的光合作用生物，由真菌和藻类/蓝细菌形成的具有高抗逆性的菌体。导致地衣能够耐受恶劣环境条件的因素之一是存在独特的代谢物，包括称为黑色素的高分子量黑色素。地衣黑色素的化学成分和结构仍然缺乏研究。我们分析了从 Cetraria islandica 和 Pseudevernia furfuracea 地衣中提取的黑色素的元素组成、主要官能团和理化性质。根据 C/N 比，这种色素是异黑色素。我们还确定了提供黑色素光保护和抗氧化特性的官能团。