Synthesis and Antimicrobial Activity of <i>Burkholderia</i> -Related 4-Hydroxy-3-methyl-2-alkenylquinolines (HMAQs) and Their <i>N</i> -Oxide Counterparts
Bibliographic record
Abstract
The Burkholderia genus offers a promising potential in medicine because of the diversity of biologically active natural products encoded in its genome. Some pathogenic Burkholderia spp. biosynthesize a specific class of antimicrobial 2-alkyl-4(1H)-quinolones, i.e., 4-hydroxy-3-methyl-2-alkenylquinolines (HMAQs) and their N-oxide derivatives (HMAQNOs). Herein, we report the synthesis of a series of six HMAQs and HMAQNOs featuring a trans-Δ2 double bond at the C2-alkyl chain. The quinolone scaffold was obtained via the Conrad–Limpach approach, while the (E)-2-alkenyl chain was inserted through Suzuki–Miyaura cross-coupling under microwave radiation without noticeable isomerization according to the optimized conditions. Subsequent oxidation of enolate-protected HMAQs cleanly led to the formation of HMAQNOs following cleavage of the ethyl carbonate group. Synthetic HMAQs and HMAQNOs were evaluated in vitro for their antimicrobial activity against different Gram-negative and Gram-positive bacteria as well as against molds and yeasts. The biological results support and extend the potential of HMAQs and HMAQNOs as antimicrobials, especially against Gram-positive bacteria. We also confirm the involvement of HMAQs in the autoregulation of the Hmq system in Burkholderia ambifaria.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| 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".