title: Ustiloxin G, a New Cyclopeptide Mycotoxin from Rice False Smut Balls.
abstract: Ustiloxins were cyclopeptide mycotoxins from rice false smut balls (FSBs) that formed in rice spikelets infected by the fungal pathogenUstilaginoidea virens. To investigate the chemical diversity of these metabolites and their bioactivities, one new cyclopeptide, ustiloxin G (1), together with four known congeners-ustiloxins A (2), B (3), D (4), and F (5)-were isolated from water extract of rice FSBs. Their structures were elucidated by analyses of their physical and spectroscopic data, including ultraviolet spectrometry (UV), infrared spectroscopy (IR), 1D and 2D nuclear magnetic resonance (NMR), and high-resolution electrospray ionization-mass spectrometry (HR-ESI-MS). All the compounds were evaluated for their cytotoxic as well as radicle and germ elongation inhibitory activities. Ustiloxin B (3) showed the best activity against the cell line BGC-823 with an IC50value of 1.03 µM, while ustiloxin G (1) showed moderate activity against the cell lines A549 and A375 with IC50values of 36.5 µM and 22.5 µM, respectively. Ustiloxins A (2), B (3), and G (1) showed strong inhibition of radicle and germ elongation of rice seeds. When their concentrations were at 200 µg/mL, the inhibitory ratios of radicle and germ elongation were more than 90% and 50%, respectively, the same effect as that of positive control (glyphosate). They also induced abnormal swelling of the roots and germs of rice seedlings.
authors.affiliation: Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China. wangxiaohan99@126.com.
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China. wangjiancau@163.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China. dwlai@cau.edu.cn.
authors.forename: Daowan
authors.initials: D
authors.lastname: Lai
authors.affiliation: Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China. wwxcau@163.com.
authors.forename: Weixuan
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100050, China. jgdai@imm.ac.cn.
authors.forename: Jungui
authors.initials: J
authors.lastname: Dai
authors.affiliation: Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China. lgzhou@cau.edu.cn.
authors.forename: Ligang
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, China. liuyang01@caas.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D006999:Hypocreales; D015394:Molecular Structure; D009183:Mycotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D012275:Oryza / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D010935:Plant Diseases / Q000382:microbiology; D012639:Seeds / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology
chemical_list: D009183:Mycotoxins; D010456:Peptides, Cyclic; C000624645:ustilitoxin G
keywords: Villosiclava virens; cyclopeptide; cytotoxicity; mycotoxin; phytotoxicity; rice false smut balls; rice false smut disease; ustiloxin G