皮膚老化包括內在及外在老化，其中日光的照射和環境的汙染為增加外在老化的 主要因素。過去其他學者的研究顯示，日光的曝曬和環境污染都會增加活性氧（ROS） 的生成，例如單重態分子氧，超氧陰離子自由基或過氧化自由基，這些都會導致光氧 化壓力的產生。紫外線照射所產生的光氧化壓力是經由光依賴性形成的活性氧物質來 誘導產生的。這些活性介質與細胞脂質、蛋白質和DNA 的化學反應被認為在疾病的 病理生化中影響皮膚等光暴露組織的光老化過程中扮演著重要的角色。在皮膚的防禦 系統中，無論酶或非酶物質都是可以對抗活性氧的作用。但是，如果活性氧在皮膚中 過量生成，則會造成皮膚的老化、癌症的發生或皺紋的產生。靈芝中的成份Tsugaric acid 具有多種生物醫學功效，如抗衰老和抗氧化作用。因此，本篇研究主要的目標是 評估指標性成份Tsugaric acid 對皮膚光老化的保護作用，著重探討Tsugaric acid 的作 用機轉和抗光傷害的能力。透過本篇的研究，我們希望可以發現用於護膚的理想靈芝 成份，並可在將來發展成抗光老化製劑。

Skin aging includes intrinsic and extrinsic aging. The factors enhancing the extrinsic aging is sunlight exposure and environmental pollution. Previous studies have shown that both sunlight exposure and environment pollution increase the production of reactive oxygen species (ROS), such as singlet molecular oxygen, superoxide radical anion or peroxyl radicals. These lead to photooxidative stress. Photooxidative stress is induced by UV-irradiation via light-dependent formation of reactive oxygen species. Chemical reactions of these reactive intermediates with cellular lipids, proteins and DNA are thought to play a role in the pathobiochemistry of disease affecting light-exposed tissues such as the skin. In skin, the defense system including the enzymatic or nonenzymatic substances can overcome against the ROS. However, if the ROS is overproduced in skin, it causes skin aging, cancer, or wrinkle. The compounds of Ganoderma tsugae, tsugaric acid, show a variety of biomedical efficacies such as antiaging and antioxidation. Therefore, the goal of this study is to evaluate the protective effects of tsugaric acid on skin photoaging. Furthermore, the mechanism on anti-photo injury of tsugaric acid was investigated. From this study, an ideal compound extracted from Ganoderma tsugae, tsugaric acid, was discovered, which might be developed for skin care as an anti-photoaging agent in the future.