The Role of Phytochemistry in Attacking the Leafy Spurge (Euphorbia esula) Problem

Abstract

Individual chemical constituents isolated and char acterized from the noxious weed Euphorbia esula were assessed biologically and/or chemotaxonomically in relation to the allelopathy of E. esula, the allelopathy of Antennaria microphylla to E. esula, and the insect biological control of E. esula. Kaemferol 3-glucuronide and 1-hexacosanol obtained from aqueous extracts of E. esula are considered important allelochemicals in this weed. Biological assays, utilizing E. esula test systems, support hydroquinone and arbutin (obtained from extractives of A. microphylla) as major participants in the allelopathy of A. microphylla to E. esula. The distribution of triterpenes ( α, β-amyrin and δ -amyrenone) and unique jatrophane diterpenes charac terized in E. esula leaf and root extracts have strong potential for the chemotaxonomic differenti ation of E. esula varieties relative to insect biological control of this weed. Leafy spurge (Euphorbia esula) is a dicotyledonous, herbaceous, deeprooted, perennial noxious weed infesting more than four million acres of open rangeland in the upper great plains of the United States and the prairies of Canada. This lateciferous plant is toxic to live stock ( 1_), allelopathic to desirable forage plants (2^) and poses a serious threat to livestock production on open rangelands.While leafy spurge can be controlled by herbicides (3) or vigorous cultivation, the cost of control is continuous since current chemical means do not eradicate this weed. More than 20 million dollars a year is spent for the control of this plant, and its agroeconomic impact is greater than 12 million dollars per year in the state of North Dakota alone (4). Recent research efforts on the leafy spurge problem have concentrated on increased herbicide effi ciency and the successful application of insect biological control methods. This paper summarizes the results of phytochemical examinations of plant-plant and plant-insect interactions involving leafy spurgeThis chapter not subject to U.S.

Phytotoxic Allelochemicals From Roots and Root Exudates of Leafy Spurge (Euphorbia esulaL.)

“…7 Two slightly different methylated ellagic acids (3,3',4-tri-O-methyl and 3,4,4'-tri-O-methyl) from those we found have been reported to be inhibitors of auxin transport in chestnut root cuttings, perhaps accounting for the difficulty of obtaining chestnut plants from root cuttings. 19 The decreased root branching we observed when Arabidopsis was treated with ellagic acid (and derivatives) might arise from a similar mechanism.…”

“…5 Studies of leafy spurge biochemistry have identified several phytotoxins, including the relatively strong phytotoxins kaempferol-3-glucuronide and 1-hexaconsanol in aqueous extracts of the whole plant, 6 and moderately phytotoxic esulone jatrophane diterpenes in leafy spurge roots. 7,8,9 However, in a comparison of ether extracts of leafy spurge roots from North Dakota, Montana, Oregon, and Austria (where the leafy spurge is not a problem weed), only the North Dakota samples had high concentrations of jatrophane diterpenes. 9 3,3'-Di-O-methylellagic acid 4-b-D-xyloside and 3,3'-di-O-methylellagic acid 4-D-glucoside have also been isolated from leafy spurge roots, but the phytotoxicity of these compounds has not been assessed due to poor solubility.…”

“…9 3,3'-Di-O-methylellagic acid 4-b-D-xyloside and 3,3'-di-O-methylellagic acid 4-D-glucoside have also been isolated from leafy spurge roots, but the phytotoxicity of these compounds has not been assessed due to poor solubility. 7 Further, using bioassay-guided fractionations of aboveground tissue extracts, ingenol diterpenes have been identified as toxins in leafy spurge that may affect cattle. 10,11 Recently, several studies have focused on the isolation and characterization of potentially allelopathic substances released by plant roots.…”

Allelopathic effects of aqueous and organic fractions of Euphorbia dracunculoides Lam. on germination and seedling growth of chickpea and wheat

“…Among 7500 species of Euphorbiaceae, many are known as weeds that exert allelopathic activity on crops. The allelopathic potential of extracts, residues and root secretions of Euphorbia corollata L. (Rice, 1964), E. esula L. (Manners, 1987), E. geniculata Ortega (Sugha, 1979), E. granulata Forssk (Hussain, 1980), E. hirta L. (Tiwari et al, 1985), E. prostrata Aiton (Alsaadawi et al, 1990), E. hierosolymitana Boiss. (Abu-Romman et al, 2010) and E. helioscopia L. (Qasem, 1995;Tanveer et al, 2010) have been reported against crops like pea, tomato, wheat, chickpea, cotton, alfalfa, lettuce, groundnut, and soybean.…”

Implications of weeds of genus euphorbia for crop production: a review

“…Elmore & Paul (1983) reported high concentration of phenolics in E. supina and E. maculata, which is supported by previous findings of Rice (1969), who reported phenolics and gallic acid in E. supine. Wanger et al, (1970), Manners & Wong (1985), Manners (1987), Manners & Davis (1987) and Qin et al (2006) have identified several phototoxins, including relatively strong phytotoxins Kaempferol-3-glucuronide and I-hexaconsanol in aqueous extracts of the whole plant, and moderately diterpenes jatrophane in leafy spurge roots. Euphorbia esula (Evans & Kinghorn, 1977;Roberts & Olson, 1999;Zhi Qiang et al, 2008) and E. heliescopia (Jiangbo et al, 2010) contains di-and tri-terpenoids and condensed tannins.…”