title: Phytotoxic Terpenoids fromLigularia cymbuliferaRoots.
abstract: Ligularia cymbuliferais one of the predominant species in the Hengduan Mountains, China, and has led to a decrease in the amount of forage grass in this area. However, little is known about the mechanism behind its predominance. In this study, two novel eremophilane sesquiterpenes, ligulacymirin A and B (1and2), together with seven other known terpenoids (3-9), were isolated from the roots ofL. cymbulifera. The structures of1and2were determined by spectroscopic methods and single-crystal X-ray diffraction. Each compound showed phytotoxic activities againstArabidopsis thaliana, and each was detected and identified in rhizosphere soil by UHPLC-MS. Compound3was the most potent phytotoxin, showing remarkable inhibition against both seedling growth (EC50= 30.33 ± 0.94 μg/mL) and seed germination (EC50= 155.13 ± 0.52 μg/mL), with an average content in rhizosphere soil of 3.44 μg/g. These results indicate that terpenoids inL. cymbuliferaroots might be released as phytotoxins in rhizosphere soil to interfere with neighboring plants.
authors.affiliation: The Key Laboratory of Plant Resources and Chemistry of Arid Zone, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of SciencesUrumqi, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China; Graduate School of Chinese Academy of SciencesBeijing, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Chen
authors.affiliation: Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences Kunming, China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences Kunming, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: The Key Laboratory of Plant Resources and Chemistry of Arid Zone, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences Urumqi, China.
authors.forename: Haji A
authors.initials: HA
authors.lastname: Aisa
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences Kunming, China.
authors.forename: Xiao-Jiang
authors.initials: XJ
authors.lastname: Hao
keywords: Ligularia cymbulifera; eremophilane sesquiterpenes; ligulacymirin A; ligulacymirin B; phytotoxic activity