Herbicidal and Antifungal Xanthone Derivatives from the Alga-Derived Fungus <i>Aspergillus versicolor</i> D5
Dong‐Lin Zhao, Xiaobin Han, Mei Wang, Yuntao Zeng, Yiqiang Li, Guo-Yong Ma, Jing Liu, Cai‐Juan Zheng, Mingxia Wen, Zhifan Zhang, Peng Zhang, Chengsheng Zhang
Abstract
Fungi have been proved as promising and prolific sources of functional secondary metabolites with potent agricultural applications. In this study, 14 xanthone derivatives (1–14), including six new ones, versicones I–N (1–4, 7, 11), and a biogenetically related derivative (15), were isolated from the alga-derived fungus Aspergillus versicolor D5. Their structures were elucidated by comprehensive spectroscopic methods. Versicone L (4) exhibited a broad antifungal spectrum and prominent inhibitory effects on Botrytis cinerea at a minimum inhibitory concentration (MIC) of 152 μM, 7-fold stronger than that of the positive control, carbendazim (MIC = 1.05 × 103 μM). Dihydrosterigmatocystin (13) showed strong antifungal activity toward B. cinerea at MIC = 38.3 μM, almost 30-fold stronger than that of carbendazim. Meanwhile, 13 exhibited potent herbicidal activity toward Amaranthus retroflexus L. with an MIC of 24.5 μM, approximately 4-fold stronger than that of the positive control, glyphosate (MIC = 94.7 μM). Additionally, 13 also displayed remarkable activity against other weeds belonging to Amaranth sp. Analysis of the structure–herbicidal activity relationship indicated that the bifuranic ring played an important role in xanthone phytotoxicity and the presence of a double bond in the furan ring could decrease phytotoxicity. This study indicated that xanthones can be served as promising candidates for lead compounds of agrochemicals.