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Title: Tabanone a new phytotoxic constituent of cogongrass (Imperta culindrica)

item CERDEIRA, ANTONIO - Brazilian Department Of Agriculture
item Cantrell, Charles
item Dayan, Franck
item BYRD, JOHN - Mississippi State University
item Duke, Stephen

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2011
Publication Date: 12/26/2011
Citation: Cerdeira, A., Cantrell, C.L., Dayan, F.E., Byrd, J., Duke, S.O. 2011. Tabanone a new phytotoxic constituent of cogongrass (Imperta culindrica). Weed Science. 60:212-218.

Interpretive Summary: Cogongrass (Imperata cylindrica) is an invasive weed species in both agriculture and natural areas of the U.S. Southeast. Part of its success as an invader has been attributed allelopathy, the trait of using natural herbicides to impede competing plant species. A new phytotoxin (natural herbicide) named tabanone was discovered in the essential oil of cogongrass. However, this compound alone cannot account for all of the allelopathic activity of this virulent weed.

Technical Abstract: Cogongrass [Imperata cylindrica (L.) Beauv.] is a troublesome invasive weedy species with reported allelopathic properties. The phytotoxicity of different constituents isolated from roots and aerial parts of this species was evaluated on Lactuca sativa and Agrostis stolonifera. No significant phytotoxic activity was detected in the methylene chloride, methanol, or water extracts when tested at 1.0 mg mL-1. However, the total essential oil extracts of cogongrass aerial parts was active. Bioactivity-guided fractionation of this extract using silica gel column chromatography led to the identification of megastigmatrienone, 3,5,5-trimethyl-4-butenylidene-2-cyclohexen-1-one (also called tabanone), as a mixture of four stereoisomers responsible for most of the activity. Tabanone inhibited growth of frond area of Lemna paucicostata, root growth of Allium cepa, and fresh weight gain of Lactuca sativa with I50 values of 0.094, 3.6, and 6.5 mM, respectively. The target site of tabanone is not known, but its mode of action results in rapid loss of membrane integrity and subsequent reduction in the rate of photosynthetic electron flow.