Antibacterial evaluation of 1,4-benzoquinone derivatives.

We investigated the antibacterial activity of some new 2-aryl-3,5-dimethoxy-1,4-benzoquinone derivatives, previously prepared from 2,6-dimethoxy-1,4-benzoquinone by Suzuki cross-coupling reactions, to find effective antibacterial agents. The antibacterial activity was first tested in vitro by the disk diffusion assay against two gram-positive and two gram-negative bacteria, and then the minimum inhibitory concentration (MIC) of active compounds was determined. The results showed that some 2-aryl-3,5-dimethoxy-1,4-benzoquinone derivatives inhibit growth of both gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), microorganisms that cause food poisoning and rheumatic fever. This study points out the antibacterial activity of some 2-aryl-3,5-dimethoxy-1,4-benzoquinone derivatives.

Quantitative determination of the enantiomeric composition of thalidomide solutions by electrospray ionization tandem mass spectrometry.

Rapid and simple chiral analysis of thalidomide solutions is demonstrated by using electrospray ionization tandem mass spectrometry and analysis of cluster ion dissociation by the kinetic method. Average deviations of 1% between the actual and experimental enantiomeric compositions are observed.

Utilization of nitriles by yeasts isolated from a Brazilian gold mine.

Yeast strains from the genera Candida, Debaryomyces, Aureobasidium, Geotrichum, Pichia, Rhodotorula, Tremella, Hanseniaspora, and Cryptococcus were isolated from samples of a gold mine from liquid extraction circuit. These strains were tested for their ability to utilize acetonitrile at 12 mM as the sole nitrogen source. The yeasts that grew using acetonitrile at 12 mM were tested in the presence of acetonitrile, isobutyronitrile, methacrylnitrile, and propionitrile at concentrations of 12, 24, 48, 97, and 120 mM. One strain was selected for each nitrile and the concentration of nitrile in which the best growth occurred. Cryptococcus sp. strain UFMG-Y28 had a better growth on 120 mM propionitrile and 97 mM acetonitrile, Rhodotorula glutinis strain UFMG-Y5 on 48 mM methacrylnitrile, and Cryptococcus flavus strain UFMG-Y61 on 120 mM isobutyronitrile. The utilization of different nitriles and amides by yeast strains involves hydrolysis in a two-step reaction mediated by both inducible and intracellular nitrile hydratase and amidase.