Khellin and visnagin, furanochromones from Ammi visnaga (L.) Lam., as potential bioherbicides

Authors: TRAVAINI, MARIA - National University Of Rosario; SOSA, GUSTAVO - Investigaciones Biológicas En Agroquímicos Rosario (INBIOAR SA); CECCARELLI, EDUARDO - National University Of Rosario; WALTER, HELMUT - Agrofield Consulting; Cantrell, Charles; CARRILLO, NESTOR - National University Of Rosario; Dayan, Franck; Meepagala, Kumudini; Duke, Stephen

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2016
Publication Date: 11/28/2016
Publication URL: http://handle.nal.usda.gov/10113/5601205
Citation: Travaini, M.L., Sosa, G.M., Ceccarelli, E.A., Walter, H., Cantrell, C.L., Carrillo, N.J., Dayan, F.E., Meepagala, K.M., Duke, S.O. 2016. Khellin and visnagin, furanochromones from Amni visnaga (L.) Lam., as potential bioherbicides. Journal of Agricultural and Food Chemistry. 64:9475-9487.

Interpretive Summary: A great need exists for biochemical bioherbcides and herbicides with new and/or multiple modes of action. In this work, two herbicidal compounds, khellin and visnagin, were isolated and identified from the plant Ammi visnaga by bioassay-guided fractionation. They were found to be as active as the bioherbcide pelargonic acid on a variety of weeds in a variety of bioassays. Physiology studies indicated that the most herbicidally active compound, visnagin, may have more than one mode of action. These compounds or compounds derived from them could have potential as biochemical bioherbcides.

Technical Abstract: Plants constitute a source of novel and structurally diverse phytotoxic compounds to be explored in searching for effective and environmentally safe herbicides. From screening nearly 2400 plant extracts for their phytotoxicity, a dichloromethane extract of Ammi visnaga (L.) Lam. was selected for further study. Phytotoxicity-guided fractionation of this extract yielded two furanochromones: khellin and visnagin, whose herbicidal activity had not been described before. Khellin and visnagin inhibited the growth of lettuce (Lactuca sativa) (IC50 = 110 and 175 µM, respectively) and duckweed (Lemna paucicostata) (IC50 = 162 and 122 µM, respectively). Also, both compounds at 1 mM reduced the growth and germination of weeds: ryegrass (Lolium perenne), morningglory (Ipomea sp.), foxtail (Setaria italica) and millet (Panicum sp.). The inhibitory activities of these furanochromones were similar to those of acetochlor (0.54 mM) and glyphosate (0.75 mM) in these bioassays. During greenhouse studies visnagin was the most active, with significant contact postemergence herbicidal activity on velvetleaf (Abutilon theophrasti) and crabgrass (Digitaria sanguinalis) at 2 kg ai ha-1. Moreover, its effect on velvetleaf, crabgrass and barnyardgrass (Echinochloa crus-galli) at 4 kg ai ha-1 was comparable to the bioherbicide pelargonic acid at the same rate. The mode of action of khellin and visnagin is not a light-dependent process. Both compounds caused membrane destabilization, photosynthetic efficiency reduction, and cell division inhibition. These results support the potential of visnagin, and possibly khellin, as bioherbicides or lead molecules for the development of new herbicides.