Usnic Acid Derivatives with Cytotoxic and Antifungal Activities from the Lichen Usnea longissima

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• 作者：Xuelong Yu ; Qiang Guo ; Guozhu Su ; Ailin Yang ; Zhongdong Hu ; Changhai Qu ; Zhe Wan ; Ruoyu Li ; Pengfei Tu ; Xingyun Chai
• 刊名：Journal of Natural Products
• 出版年：2016
• 出版时间：May 27, 2016
• 年：2016
• 卷：79
• 期：5
• 页码：1373-1380
• 全文大小：442K
• 年卷期：0
• ISSN：1520-6025

文摘

Eight usnic acid derivatives, that is, usenamines A–F (1–6), usone (7), and isousone (8), together with the known (+)-usnic acid (9), were isolated from the lichen Usnea longissima. Their structures were elucidated using 1D and 2D NMR and MS data, and the absolute configurations of compounds 1 and 2 were defined by single-crystal X-ray diffraction analyses. Compounds 1, 2, and 8 showed inhibitory effects on the growth of human hepatoma HepG2 cells with IC₅₀ values of 6.0–53.3 μM compared with methotrexate as the positive control, which had an IC₅₀ value of 15.8 μM. Furthermore, 1 induced apoptosis of HepG2 cells in a dose-dependent manner at concentrations of 0–15.0 μM. The isolated compounds were also evaluated for their antifungal and antibacterial activities, with 7 and 8 exhibiting weak inhibitory effects on fungal Trichophyton rubrum spp. with an MIC value of 41.0 μM.