Allelopathic Potential of Echinacea angustifolia's Ethanolic Root Extracts
Bibliographic record
Abstract
The narrow-leafed purple coneflower (Echinacea angustifolia D.C.) is a perennial native to North America. Echinacea angustifolia is found on dry prairies from Texas to Saskatchewan, west to the Rocky Mountains and east to Minnesota. Echinacea angustifolia produces many biologically active compounds that have shown allelopathic effects on lettuce (Lactuca sativa), switchgrass (Panicum virgatum) and prairie dropseed (Sporobolus heterolopis). Natural allelopathic chemicals have the potential of being used for the production of herbicides that are environmentally safe. These allelopathic compounds possess components that could be used in the development of new herbicides. The objectives of this work are to identify the ethanol soluble compounds of E. angustifolia and to examine their potential for use as natural herbicides. The allelopathic potential of ethanol soluble compounds from E. angustifolia roots from five populations (South Dakota, North Dakota, Wyoming, Kansas, and Nebraska) were examined. A common allelopathy bioassay was performed using lettuce seeds germinated in the presence of the ethanol extracts pipetted on filter paper. The extracts were brought to dryness and were resuspended in deionized water. Analysis of the seed assay was completed by measuring percent germination and root elongation of 25 lettuce seeds per replication for extracts from each of 100 E. angustifolia plants (20 plants per population). Results from the lettuce seed bioassay experiment showed that germination in the presence of Echinacea extracts ranged from 100% to 0%. As collection sites moved southward, the allelopathic potential tends to decrease. Root extracts were concentrated by evaporation and analyzed by reverse phase high performance liquid chromatography (HPLC) using a C-18 column. Absorbancy was measured at 210-nm and 254-nm. HPLC analyses revealed eleven significant peaks in all populations. The parameters of germination, root elongation and peak area were used to conduct a multiple regression analyses. These results showed that compounds identified as peak numbers three and six contribute to 72 % of the allelopathic effects of E. angustifolia root extracts. Lettuce seed germination assays showed that peaks three and six caused significant reductions in both germination and root elongation. The combined peaks were found to have an additive effect on root elongation but a synergistic effect on germination. Since peaks three and six were of most interest they were further identified by comparison HPLC analyses performed by Bauer and Remiger (1989) and NMR (nuclear magnetic resonance) at the University of Illinois, Urbanna. Peak three was identified as undeca-2E-ene-8, 10-diynoic acid isobutylarnide and peak six was identified as dodeca-2E,4E,8, 10E-tetraenoic acid isobutylarnide.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".