Light-Mediated Antifungal Activity of <i>Echinacea</i> Extracts
Bibliographic record
Abstract
This study demonstrated that plant extracts containing acetylenic isobutylamides and polyacetylenes, previously reported as occurring in Echinacea, have phototoxic antimicrobial activity against fungi, including clinically relevant pathogenic fungi. Results show that hexane extracts of Echinacea variably inhibit growth of yeast strains of Saccharomyces cerevisiae, Candida shehata, C. kefyr, C. albicans, C. steatulytica and C. tropicalis under near UV irradiation (phototoxicity) and to a lower extent without irradiation (conventional antifungal activity). The presence of polyacetylenes and alkylamides in extracts of different organs was confirmed in Echinacea purpurea by HPLC in agreement with previously reported data in the literature, and was related to phototoxic activity. Two representative pure compounds, undeca-2E,4Z-diene-8,10-diynoic acid isobutylamide and dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, were isolated from Echinacea purpurea root extracts, and compared in a disk assay (5 micrograms/disk) with the highly conjugated trideca-1-ene-3,5,7,9,10-pentayne (previously isolated in our laboratory and found here in E. purpurea). Significant phototoxicity was demonstrated by pure trideca-1-ene-3,5,7,9,10-pentayne, while only minor phototoxicity was induced by the other two acetylenic compounds. Phototoxic activity of Echinacea spp. is primarily attributed to the ketoalkenes and ketoalkynes abundantly present in the roots.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".