AUTHOR=Chen Jia , Zheng Guowei , Zhang Yu , Aisa Haji A. , Hao Xiao-Jiang 

TITLE=Phytotoxic Terpenoids from Ligularia cymbulifera Roots

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.02033

DOI=10.3389/fpls.2016.02033

ISSN=1664-462X

ABSTRACT=<p><italic>Ligularia cymbulifera</italic> is 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 (<bold>1</bold> and <bold>2</bold>), together with seven other known terpenoids (<bold>3–9</bold>), were isolated from the roots of <italic>L. cymbulifera</italic>. The structures of <bold>1</bold> and <bold>2</bold> were determined by spectroscopic methods and single-crystal X-ray diffraction. Each compound showed phytotoxic activities against <italic>Arabidopsis thaliana</italic>, and each was detected and identified in rhizosphere soil by UHPLC-MS. Compound <bold>3</bold> was the most potent phytotoxin, showing remarkable inhibition against both seedling growth (EC<sub>50</sub> = 30.33 ± 0.94 μg/mL) and seed germination (EC<sub>50</sub> = 155.13 ± 0.52 μg/mL), with an average content in rhizosphere soil of 3.44 μg/g. These results indicate that terpenoids in <italic>L. cymbulifera</italic> roots might be released as phytotoxins in rhizosphere soil to interfere with neighboring plants.</p>