2-(2-Nitrovinyl) furan exacerbates oxidative stress response of Escherichia coli to bacteriostatic and bactericidal antibiotics

Access to 2-Alkenyl-furans via a Cascade of Pd-Catalyzed Cyclization/Coupling Followed by Oxidative Aromatization with DDQ

An unprecedented DDQ-mediated oxidative aromatization of 2-bezylidene-dihydrofurans yielding 2-alkenyl-furans is disclosed. Integration of this transformation with a prior Pd-catalyzed reaction of α-propargylic-β-ketoesters and (hetero)aryl halides into a one-pot cascade process opens a direct modular route to highly substituted 2-vinyl-furans. Experimental and computational studies reveal that the crucial step of the oxidative-aromatization involves facile hydride transfer from the dihydrofuran ring to the O-center of DDQ.

Isobologram Analysis: A Comprehensive Review of Methodology and Current Research

Drug combination is a common method for clinical disease treatment. Whether the combination of drugs is reasonable often affects the result of the disease treatment. Many methods have been used to evaluate interaction between drugs to date. Isobologram analysis has been mathematically proven and widely used to evaluate drug interactions. In this paper, the principle of isobologram analysis and its application in drug interaction evaluation are summarized. The applications of the similar cotoxicity coefficient and fractional inhibitory concentration index in the evaluation of drug interaction are also reviewed. This work is expected to evaluate the effect of formulations scientifically and provide scientific judgment standards for the development of formulations and clinical drug compatibility.

Lophirones B and C induce oxidative cellular death pathway in Acinetobacter baumannii by inhibiting DNA gyrase

We evaluated the inactivation of DNA gyrase on the oxidative stress response and sensitivity of A. baumannii to lophirones B and C. The sensitivity of parental and the mutant strains of A. baumannii to lophirones B and C was determined using minimum inhibitory concentration (MIC) and time-kill sensitivity. Inactivation of sodB, katG, recA enhanced the sensitivity of A. baumannii to lophirones B and C. Furthermore, this inactivation increased the accumulation of superoxide anion radical and hydrogen peroxide in lophirones B and C-treated A. baumannii, which was reversed in the presence of thiourea. Inactivation of gyrA stalled lophirones B and C-mediated ROS accumulation in A. baumannii. In addition, lophirones B and C raised the Fe²⁺ contents of A. baumannii. Dipyridyl (Fe chelator) reversed the sensitivity of A. baumannii to lophirones B and C. Lophirones significantly lowered the NAD+/NADH ratio of A. baumannii. The results of this study revealed that the impact of DNA gyrase in lophirones B and C-mediated ROS accumulation, Fe²⁺ release and cell death.

Contributions of reactive oxygen species, oxidative DNA damage and glutathione depletion to the sensitivity of Acinetobacter baumannii to 2-(2-nitrovinyl) furan

2-(2-nitrovinyl) furan is a broad-spectrum antibacterial agent with activity against Gram-positive and Gram-negative bacteria. In this study, the contributions of reactive oxygen species, oxidative DNA damage and glutathione depletion to its activity against Acinetobacter baumannii was investigated. Inactivation of sodB, katG and recA lowered the minimum inhibitory concentration of 2-(2-nitrovinyl) furan. Furthermore, the inactivation increased the superoxide anion radical and hydrogen peroxide contents of 2-(2-nitrovinyl) furan-treated A. baumannii. Antioxidant (thiourea) reversed the elevated levels of superoxide anion radical and hydrogen peroxide. In addition, thiourea lowered the susceptibility of A. baumannii to 2-(2-nitrovinyl) furan. 2-(2-nitrovinyl) furan depleted reduced glutathione (GSH) contents of parental, sodB, katG and recA strains of A. baumannii. NAD+/NADH ratio parental, sodB, katG and recA strains of A. baumannii exposed to 2-(2-nitrovinyl) furan increased significantly. Inactivation of type-I NADH dehydrogenase lowered the reactive oxygen species generation in 2-(2-nitrovinyl) furan-treated A. baumannii. It is evident from this study that 2-(2-nitrovinyl) furan stimulates respiratory chain activity of A. baumannii leading to enhanced ROS generation, which depletes GSH and reacts with Fe²⁺ to produce hydroxyl radical that damage DNA.

Ferulic acid potentiates the antibacterial activity of quinolone-based antibiotics against Acinetobacter baumannii

Ferulic acid is a cinnamic derivative of phenolic acid and its pharmacophore (catechol) is responsible for antioxidant, prooxidant and antibacterial activities. In this study, we evaluated the influence of ferulic acid on the antibacterial activity of quinolone-based antibiotics against Acinetobacter baumannii. The minimum inhibitory concentration of ferulic acid against Acinetobacter baumannii AB5075 were considerably lowered for ΔsodB and ΔkatG mutants. Checkerboard assay shows synergistic interactions between ferulic acid and quinolones. In a murine sepsis model, ferulic acid potentiated the antibacterial activities of quinolones. Ferulic acid amplified quinolones-induced redox imbalance by increasing superoxide ion generation, NAD+/NADH ratio and ADP/ATP ratio. Conversely, the level of reduced glutathione was significantly lowered. We conclude that ferulic acid potentiates the antibacterial activity of quinolone-based antibiotics against A. baumannii by increasing ROS generation, energy metabolism and electron transport chain activity with a concomitant decrease in glutathione.