3-Hydroxypyridin-4(1H)-one Derivatives as pqs Quorum Sensing Inhibitors Attenuate Virulence and Reduce Antibiotic Resistance in Pseudomonas aeruginosa.

The development of quorum sensing inhibitors capable of decreasing the production of virulence factors is an effective strategy to overcome resistance in Pseudomonas aeruginosa due to the less selective pressure exerted on bacteria. In this study, a series of 3-hydroxypyridin-4(1H)-one derivatives bearing a 4-aminomethyl-1,2,3-triazole linker were designed and synthesized as antivirulence agents against P. aeruginosa. The most potent derivative 16e was identified as a selective inhibitor of the pqs system (IC50 = 3.7 µM) and its related virulence factor pyocyanin (IC50 = 2.7 µM). In addition, 16e exhibited moderate biofilm inhibition and significant inhibition of P. aeruginosa motility phenotypes with low cytotoxicity. Compound 16e showed an obvious antibacterial synergistic effect in combination with antibiotics such as ciprofloxacin and tobramycin in in vitro and in vivo Caenorhabditis elegans infection models. Overall, the excellent antivirulence properties of compound 16e make it a potential antibiotic adjuvant for the treatment of P. aeruginosa infections that may be advanced into preclinical development in the future.

New Pqs Quorum Sensing System Inhibitor as an Antibacterial Synergist against Multidrug-Resistant Pseudomonas aeruginosa.

Development of new bacterial biofilm inhibitors as antibacterial synergists is an effective strategy to solve the resistance of Pseudomonas aeruginosa. In this paper, a series of 3-hydroxy-pyridin-4(1H)-ones were synthesized and evaluated, and the hit compound (20p) was identified with the effects of inhibiting the production of pyocyanin (IC50 = 8.6 µM) and biofilm formation (IC50 = 4.5 µM). Mechanistic studies confirmed that 20p inhibits the formation of bacterial biofilm by inhibiting the expression of pqsA, blocking pqs quorum sensing system quinolone biosynthesis. Moreover, we systematically investigated the bactericidal effects of combining currently approved antibiotics for CF including tobramycin, ciprofloxacin, and colistin E with 20p, which showed obvious antibacterial synergy to overcome antibiotics resistance in multidrug-resistant P. aeruginosa biofilms. The result indicates that compound 20p may be used in the future as a potentially novel antibacterial synergist candidate for the treatment of P. aeruginosa infections.

Novel 2-Substituted 3-Hydroxy-1,6-dimethylpyridin-4(1H)-ones as Dual-Acting Biofilm Inhibitors of Pseudomonas aeruginosa.

2-Heptyl-3-hydroxy-4(1H)-quinolone (PQS), a compound from P. aeruginosa, functions as both a quorum sensing (QS) regulator and a potent iron chelator to induce expression of pyoverdine and pyochelin which are involved in high-affinity iron transport systems. A potential dual-acting antibiofilm strategy requires molecules designed to interfere with iron uptake and the QS system of P. aeruginosa. A series of 2-substituted 3-hydroxy-1,6-dimethylpyridin-4-ones have been designed, synthesized, and tested as biofilm inhibitors of P. aeruginosa. One compound, N-((1,3,6-trimethyl-4-oxo-1,4-dihydropyridin-2-yl)methyl)hexanamide (10d), exhibits 68.67% biofilm inhibitory activity at 20 µM. Further mechanistic studies have confirmed that this compound not only inhibits the QS systems of P. aeruginosa but also acts as an iron chelator to compete strongly with pyoverdine, causing iron deficiency in bacteria. The pyoverdine receptor FpvA was revealed as the target of 10d by the Pvds mutant strain, fpvA-overexpressed strain, and in silico studies.

[Changes of myocardial enzymes in patients with acute carbon monoxide poisoning].

OBJECTIVE: To study the clinical significance of changes of serum myocardial enzymes in patients with acute carbon monoxide poisoning. METHODS: To determine the dynamic changes of the activity of myocardial enzymes and ECG in 62 patients with acute CO poisoning. RESULTS: In patients with acute CO poisoning 5 kinds of myocardial enzymes begin to increase within 24 hours, the activities of aspartate aminotransferase (AST), creatine phosphokinase (CPK), lactic dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (alpha-HBDH), CPK isoenzyme (CK-MB) were (20.2 +/- 12.3), (151.6 +/- 91.8), (146.8 +/- 50.4), (154.8 +/- 47.7), (13.8 +/- 8.1) U/L respectively, while those in control group were (12.1 +/- 6.7), (90.6 +/- 17.3), (118.7 +/- 13.5), (89.9 +/- 27.9), (5.9 +/- 3.3) U/L respectively. There was significant difference between two groups (P < 0.01); 3 d later, the activities of 5 enzymes were still increased [(21.3 +/- 12.3), (105.8 +/- 51.4), (144.8 +/- 51.4), (159.8 +/- 35.4), (16.2 +/- 9.1) U/L respectively]. 7 and 12 d later, the activities of alpha-HBDH and CK-MB were still higher than those of control (P < 0.01). LDH(1) and LDH(2) increased to peak value in 24 h after poisoning (35.3 +/- 5.8), (43.8 +/- 5.7) U/L vs (24.8 +/- 3.9), (36.9 +/- 4.3) U/L, P < 0.01. The abnormal rate of serum LDH(1) was 78.7%, LDH(2) 58.3%, LDH 45.2%, CK-MB 37.1%, alpha-HBDH 33.6% and the abnormal rate of ECG was less than 10%. CONCLUSION: Acute carbon monoxide poisoning may cause myocardial injury. Determination of serum myocardial enzymes may contribute to showing myocardial injury, early diagnosis and treatment, results of treatment and prognosis.