New Helvolic Acid Derivatives with Antibacterial Activities from <i>Sarocladium oryzae</i> DX-THL3, an Endophytic Fungus from Dongxiang Wild Rice (<i>Oryza rufipogon</i> Griff.)
Zhi-Bin Zhang,
Si-Yao Du,
Bo Ji,
Chang-Jiu Ji,
Yi-Wen Xiao,
Ri-Ming Yan,
Du Zhu
Affiliations
Zhi-Bin Zhang
Key Laboratory of Protection and Utilization of Subtropical Plant Resources of Jiangxi Province, College of Life Science, Jiangxi Normal University, Nanchang 330022, China
Si-Yao Du
Key Laboratory of Protection and Utilization of Subtropical Plant Resources of Jiangxi Province, College of Life Science, Jiangxi Normal University, Nanchang 330022, China
Bo Ji
College of Life Science, Jiangxi Science and Technology Normal University, Nanchang 330013, China
Chang-Jiu Ji
College of Chemistry and Biological Engineering, Yichun University, Yichun 336000, China
Yi-Wen Xiao
Key Laboratory of Protection and Utilization of Subtropical Plant Resources of Jiangxi Province, College of Life Science, Jiangxi Normal University, Nanchang 330022, China
Ri-Ming Yan
Key Laboratory of Protection and Utilization of Subtropical Plant Resources of Jiangxi Province, College of Life Science, Jiangxi Normal University, Nanchang 330022, China
Du Zhu
Key Laboratory of Protection and Utilization of Subtropical Plant Resources of Jiangxi Province, College of Life Science, Jiangxi Normal University, Nanchang 330022, China
Three new helvolic acid derivatives (named sarocladilactone A (1), sarocladilactone B (2) and sarocladic acid A (3a)), together with five known compounds (6,16-diacetoxy-25-hy- droxy-3,7-dioxy-29-nordammara-1,17(20)-dien-21-oic acid (3b), helvolic acid (4), helvolinic acid (5), 6-desacetoxy-helvolic acid (6) and 1,2-dihydrohelvolic acid (7)), were isolated from the endophytic fungus DX-THL3, obtained from the leaf of Dongxiang wild rice (Oryza rufipogon Griff.). The structures of the new compounds were elucidated via HR-MS, extensive 1D and 2D NMR analysis and comparison with reported data. Compounds 1, 2, 4, 5, 6 and 7 exhibited potent antibacterial activities. In particular, sarocladilactone B (2), helvolinic acid (5) and 6-desacetoxy-helvolic acid (6) exhibited strongly Staphylococcus aureus inhibitory activity with minimum inhibitory concentration (MIC) values of 4, 1 and 4 μg/mL, respectively. The structure–activity relationship (SAR) of these compounds was primarily summarized.
