Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 10, 1996
Publication Date: N/A
Interpretive Summary: Meadowfoam is a commercial oilseed crop grown in the Willamette Valley of Oregon for its oil which is used in the manufacture of cosmetics, lubricants, and plastics. After the oil is extracted from the seed, no uses for the remaining seedmeal have been found, so it has been landfilled. As part of an ongoing project examining alternative weed control methods, we observed reduced weed populations in fields that had been treated with the seedmeal. We identified the chemical, termed 3-MPAN, that was primarily responsible for the weed inhibition. 3-MPAN has relatively low toxicity to animals and would rapidly break down in the environment, so that residues would not be of concern. In addition to its weed inhibitory effects, the seedmeal would also act as a fertilizer/soil amendment and could be used by organic food producers for weed control.
Technical Abstract: Field studies indicated that meadowfoam (Limnanthes alba Hartweg ex. Benth.) seedmeal suppressed weed populations when incorporated into the soil. Ethyl ether, ethanol and water extracts of the seedmeal were prepared and bioassayed against velvetleaf and wheat. Both the ethyl ether and ethanol fractions, but not the water extract, inhibited velvetleaf and wheat radicle elongation. Fractionation of the extracts indicated that (3-methoxyphenyl)acetonitrile (3-MPAN) was the active compound from both extracts, comprising >97% of the active ethanol fraction. 3-Methoxybenzyl isothiocyanate, which had been previously shown to be the major breakdown product of glucolimnanthin, the major L. alba glucosinolate, was not detected in either extract. Radicle elongation of velvetleaf and wheat were inhibited by 3-MPAN with I50 (the concentration required to inhibit growth by 50%) values of approximately 4 x 10**-4 M (velvetleaf) and 7 x 10**-4 M (wheat).