An independent biosynthetic route to frame a xanthanolide‐type sesquiterpene lactone in Asteraceae
Bibliographic record
Abstract
Xanthanolides, also described as seco-guaianolides, are unique sesquiterpene lactones (STLs) with diverse bioactivities. Most of xanthanolides are 12,8-olides based on the position of their lactone ring. The biosynthetic pathway leading to xanthanolides has hitherto been elusive, especially how nature creates the xanthane skeleton is a long-standing question. This study reports the elucidation of a complete biosynthetic pathway to the important 12,8-xanthanolide 8-epi-xanthatin. The xanthane-type backbone is directly derived from the central precursor germacrene-type sesquiterpene, germacrene A acid, via oxidative rearrangement, catalyzed by an unusual cytochrome P450. Subsequently, a 12,8-lactone ring is formed within this xanthane-type backbone resulting in xanthanolides. The biosynthetic pathway for xanthanolides contrasts with the previously unified biosynthetic route for diverse 12,6-guaianolides, in which a 12,6-lactone ring formation precedes the transformation of a germacrene-type skeleton into a guaiane-type structure. The discovery of the full biosynthetic pathway of 8-epi-xanthantin opens new opportunities for producing xanthanolides in microbial organisms using synthetic biology strategies.
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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 | 0.000 | 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) | 0.000 | 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".