Redox Mechanisms and Reactive Oxygen Species in Antibiotic Action and Resistance
Bibliographic record
Abstract
The majority of antibiotics in clinical and agricultural use are derived from secondary metabolites of bacteria, fungi, and plants. This chapter discusses the roles of redox chemical biology in antibiotic action and resistance. Bleomycin is a glycopeptide anticancer antibiotic produced by Streptomyces verticillus. Antimicrobial toxicity is dependent on the reduction of the nitro group via electron transport components, generating a nitro anion radical and breakdown compounds such as nitroso and hydroxylamine derivatives. The nitro anion radicals generated through the reduction by ferredoxin or flavodoxin, may oxidize from the presence of molecular oxygen. Bacterial killing was attenuated by the addition of the iron chelator 2,2'-dipyridyl and the radical scavenger thiourea. The physiological state of microbes also has an important role in reactive oxygen species (ROS) and antibiotic action. Pseudomonas aeruginosa in liquid culture was more susceptible to oxidative stress generated by the antibiotics ceftazidime or piperacillin than during biofilm growth. MexR is a stable homodimer and functions as a transcriptional repressor and is a member of the MarA family transcriptional regulators. Redox and ROS have long been underexplored in antibiotic action and resistance but studies over the past decade have unequivocally demonstrated their importance in this field.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.005 |
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".