Effect of structure on antibiotic action of new 9-(ethylthio)acridines.

Six new 9-(ethylthio)acridine derivatives were examined for antibacterial and antifungal activities with 10 bacterial and 8 yeast strains. The only active compounds were 2- and 3-amino derivatives. The observed MICs (mg/L) for 2-amino-9-(ethylthio)acridine (possessing the highest biological activity) were 12 (P. mirabilis), 30 (B. subtillis), 60 (C. freundii), 90 (E. coli), 128 (E. vulneris) and 500 (S. marcescens and S. aureus). Both amino derivatives have also lowest half-wave potential (E1/2) and field Swain-Lupton constants (describing oxidoreduction behavior) what supports the importance of acridine ion formation in the mechanism of antimicrobial action.

An HPTLC method for the determination and the purity control of ciprofloxacin HCl in coated tablets.

A high-performance thin-layer chromatographic method (HPTLC) has been developed for the determination and the purity control of a synthetic fluoroquinolone antibiotic ciprofloxacin hydrochloride in coated tablets when desfluoro compound, ethylene diamine compound, by-compound A and fluoroquinolonic acid are considered as impurities. Silica gel F254 was used as a stationary phase and a mixture of acetonitrile, ammonia 25%, methanol and methylene chloride (1:2:4:4, v/v/v/v) as a mobile phase. The method was validated in terms of linearity (range), selectivity (placebo and related compounds), precision, accuracy (Recovery), system suitability (repeatability, peak symmetry, resolution) and impurities limit of detection (LOD). The analysis of variance (ANOVA) and t-test were applied to correlate the results of ciprofloxacin hydrochloride determination in coated tablets by means of the HPTLC method and the official British Pharmacopoeia (BP 1999) high-performance liquid chromatographic (HPLC) method.

Study on the aggregation of teicoplanin.

The aggregation of teicoplanin was studied in four solutions: 0.06 M phosphate buffers pH 4.3 and 6.3, both with and without 10% (v/v) of acetonitrile. Conductometry, capillary electrophoresis, cyclic voltammetry, and static light scattering were employed to determine the critical micelle concentration (CMC) of teicoplanin. Dynamic light scattering was used to give an additional information on the size and the size distribution of the particles formed. While the CMC was found in solutions without acetonitrile, attempts to detect any CMC failed in solutions containing acetonitrile. The results point out to different solvating mechanism in solutions with and without acetonitrile, leading to two different schemes of association.

Antifungal properties of substituted 1-phenyl-5-mercaptotetrazoles and their oxidation product, 5-bis-(1-phenyltetrazolyl)disulfide.

The antifungal effect of substituted 1-phenyl-5-mercaptotetrazoles was tested with Candida tropicalis, C. pseudotropicalis, C. mogii, Trichosporon cutaneum, Cryptococcus albidus and S. cerevisiae. Candida strains exhibited the lowest sensitivity to the compounds; the most sensitive was S. cerevisiae. The MIC values ranged from 40 to > 1000 mg/mL. The antifungal effect of halogenated compounds decreased in the series of bromo > chloro > fluoro derivatives. The electrochemical oxidation of substituted 1-phenyl-5-mercaptotetrazole derivatives in an acetonitrile medium was studied as a model for the enzymic oxidation of the substance, including study of the effect of water, perchloric and trifluoromethanesulfuric acids on E1/2 and I1. 5-Bis-(1-phenyltetrazolyl)disulfide, the compound with no antifungal effect, has been identified as the main oxidation product of 1-phenyl-5-mercaptotetrazole.

Degradation of polycyclic aromatic hydrocarbons by the copper(II)-hydrogen peroxide system.

A non-enzymic system containing CuSO4 (10 mmol/L) and hydrogen peroxide (100 mmol/L) was used for the degradation of three polycyclic aromatic hydrocarbons: phenanthrene, fluoranthene, and pyrene (all at 10 mmol/L). The system degraded the compounds rapidly and efficiently. After 1 d at room temperature, more than 80% of pyrene, phenanthrene, and fluoranthene disappeared. Several products are formed during the reaction including a black precipitate.

Antifungal effects of new heterocyclic compounds, 6H-pyrimido[2,1-a]isoindole derivatives.

Minimal inhibitory concentrations for 10 new condensed isoindole derivatives were established by the agar diffusion method. Benzo[b]-6H-pyrimido[2,1-a]isoindole-4-one exhibited a broad antifungal effect; the observed MIC (mg/L) were 7 (K. lactis), 8 (C. pseudotropicalis), 17 (W. fluorescens), 22 (E. magnusii), 31 (P. membranaefaciens), 32 (S. alluvius) and 32 (S. cerevisiae). The compound also inhibited the growth of B. subtilis (MIC 9 mg/L). No effect on the growth of E. coli was found.