Bibliographic record
Abstract
Due to the growth number of infectious diseases, a huge demand of new antimicrobial agents are required.In this regard, Thiobarbituric acid (TBA) moieties were explored.As its name indicates, TBA is the sulfur version of the barbituric acid.The work in barbituric moieties dated long ago in 1864 by Baeyer, when it was reported that these barbituric derivatives can be used as anesthetics, sedative or anticonvulsive agents.In the present work and taking advantage that TBA structure shows several points where diversity can be introduced, therefore several functionalities were introduced in the TBA analogues and their antimicrobial properties were studied in Gram-positive and Gram-negative bacteria.(Chapter 1) These are the chemical modifications explored: i) N-substitution, where this site can be substituted with a symmetrical substituents; ii) reaction at C-5 position owing to the high acidity of the protons which includes acylation, acetylation, Schiff bases, Knoevenagel condensation thioamide and enamine formation.The antimicrobial activity screening for the synthesized compounds were against Gram-positive (S. aureus and B. subtilus) and Gram negative (E. coli and P. aeruginosa) bacteria.Among all thiobabituric derivatives synthesized, Boc-Phe-TBA showed a promising activity, which confirms that TBA could be an excellent scaffold when combined with N-protected amino acids for developing antimicrobial compounds.(Chapter 2)The characterization of 20 thiobarbituric derivatives was carried out in different spectroscopy techniques such as: Nuclear Magnetic Resonance (NMR), Ultra violet spectroscopy, Infra-Red spectroscopy and single X-ray crystallography.In NMR characterization the acetylation of TBA was the most interesting due to the fact that this type of compound have the tendency of forming Enol and Keto tautomerism.This was proved by NMR and also by theoretical calculation, and the results confirm that the 1 H NMR for this compound (A01) showed resonance at 17.72 ppm (singlet) for OH.This indicate that the enol form is more stable than the keto form.In UV characterization due to the fact TBA derivatives are not known aromatic and yet they are UV active.Therefore the absorption of few TBA derivatives were study in different solvents hence these showed absorption iv at maximum wavelength (max) in the range of 322 -285 nm respectively.For IR characterization, these derivatives (A01, A02, A03, A04, A06, A10, A12, A13, A14 and A17) were evaluated, and showed absorption stretching frequency of thiocarbonyl (C=S) in three different ranges, 1395-1570 cm -1 , 1260-11420 cm -1 and 940 -1140 cm -1 .For X-ray crystallography, crystals of A01, A02, A06, A13, A17 and A18 were obtained by hot recrystallization from ethanol and the intramolecular H-Bonding formation was observed in all cases, intermolecular H-bonding was observed for A17.(Chapter 3) v DECLARATION I Plagiarism declaration I, Sikabwe Noki declare that 1.The research work reported in this thesis, except where otherwise indicated,
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.002 |
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".