Journal of Chemical Ecology

, Volume 31, Issue 7, pp 1657-1668

First online:

Potential Allelochemicals from an Invasive Weed Mikania micrantha H.B.K.

  • Hua ShaoAffiliated withSouth China Institute of Botany, Chinese Academy of Sciences
  • , Shaolin PengAffiliated withSouth China Institute of Botany, Chinese Academy of Sciences
  • , Xiaoyi WeiAffiliated withSouth China Institute of Botany, Chinese Academy of Sciences
  • , Deqing ZhangAffiliated withGluck Research Center, University of Kentucky
  • , Chi ZhangAffiliated withSouth China Institute of Botany, Chinese Academy of SciencesSchool of Forestry and Wildlife Sciences, Auburn University Email author 

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Phytotoxicity-directed extraction and fractionation of the aerial parts of Mikania micrantha H.B.K. led to the isolation and identification of three sesquiterpenoids: dihydromikanolide, deoxymikanolide, and 2,3-epoxy-1-hydroxy-4,9-germacradiene-12,8:15,6-diolide. These sesquiterpenoids inhibited both germination and seedling growth of tested species with deoxymikanolide possessing the strongest phytotoxicity. In a bioassay against lettuce (Lectuca sativa L.), deoxymikanolide reduced radicle elongation at low concentration (IC50 = 47 μg/ml); dihydromikanolide showed a weaker effect (IC50 = 96 μg/ml), and 2,3-epoxy-1-hydroxy-4,9-germacradiene-12,8:15,6-diolide exhibited the least effect (IC50 = 242 μg/ml). Deoxymikanolide caused yellowish lesions at the root tips of lettuce at a concentration of 50 μg/ml, and a 250 μg/ml solution killed lettuce seedlings. A bioassay against the monocot ryegrass (Lolium multiforum) revealed similar results on radicle elongation, which implied that the growth inhibition by these compounds was not selective. To evaluate their phytotoxicity to plants in natural habitats, three common companion tree species in south China, Acacia mangium, Eucalyptus robusta, and Pinus massoniana, were also tested and similar results were obtained. This is the first report on the isolation of 2,3-epoxy-1-hydroxy-4,9-germacradiene-12,8:15,6-diolide as a naturally occurring product.

Key Words

Phytotoxicity allelochemical Mikania micrantha exotic species dihydromikanolide deoxymikanolide 2,3-epoxy-1-hydroxy-4 9-germacradiene-12,8: 15,6-diolide.