Jozef Dobias

Phenolic acids inhibit chloroplast mutagenesis in Euglena gracilis

The mutagenicity (bleaching activity) of ofloxacin (43 microM) and acridine orange (AO) (13.5 microM) in Euglena gracilis is inhibited by plant phenolics. Caffeic acid (CA), p-coumaric acid (PCA), ferulic acid (FA) and gentisic acid (GA) (25, 50, 100 and 250 microM) exhibited a significant concentration-dependent inhibitory effect against ofloxacin-induced mutagenicity, which was very effectively eliminated by the highest concentration of all four of those phenolic acids. The mutagenicity of AO was also significantly reduced in the presence of CA, PCA and FA (25, 50, 100 and 250 microM). However, GA exhibited no significant activity, even at the concentration of 250 microM. Based on the UV spectrophotometric measurements, we suggest that the antimutagenic effect of CA, PCA, FA and GA resulted from the scavenging of reactive oxygen species (ROS) produced by ofloxacin. On the other hand, the reduction of AO-induced mutagenicity correlates with the binding capabilities of CA, PCA and FA, with the exception of GA.

Antimutagens reduce ofloxacin-induced bleaching in Euglena gracilis.

The genotoxic effect of ofloxacin was significantly decreased by standard antimutagens (sodium selenite, ascorbic acid, butylated hydroxyanisole and butylated hydroxytoluene) in the unicellular flagellate Euglena gracilis. The antiofloxacin activity of sodium selenite was also documented by a bacterial test in which the repair-proficient strain Salmonella typhimurium TA102 was used.

Antimutagenicity of milk fermented byEnterococcus fœcium

The diethyl ether extracts isolated from unfermented milk and milk fermented byEnterococcus fœcium exhibited dose-dependent inhibition of mutagenesis induced by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), nitrovin (NIT), 5-nitro-2-furylacrylic acid (NFA) and UV-irradiation on the Ames bacterial test (Salmonella typhimurium strains TA97 and TA100) and the unicellular flagellateEuglena gracilis. Overall, the fermented milk extract was the most active against UV-irradiation, less active against NIT and MNNG, and the least active against NFA on bacteria. The highest antibleaching effects were observed against MNNG. The differences between antimutagenic effects from fermented and unfermented milk extracts were determined to be statistically significant at the 0.95 CI level.

Giant mitochondria in chloroplast-deprivedEuglena gracilis late after N-succinimidylofloxacin treatment

Euglena gracilis cells were treated with N-succinimidylofloxacin. After two years of cultivation of chloroplast-free mutants a number of anomalous mitochondria have been observed. Aberrant mitochondria about 5–8 μm long and wide with unusual shape, disfigured mitochondria with enormous size, giant swollen oval-shaped megamitochondria, narrow and very long (50–60 μm) mitochondria localized at the cell perimeter were found in addition to normal mitochondria. The volume percentage of aberrant mitochondria in 58% of cells reached 65%. Swollen mitochondria probably do not fulfil the mitochondrial function and may cause cell death with subsequent elimination of injured mitochondria.

Synergic activity of selenium and probiotic bacteriumEnterococcus faecium M-74 against selected mutagens inSalmonella assay

Concentrated extracts of MRS (De Man-Rogosa-Sharpe) media in which probiotic bacteriumEnterococcus faecium strain M-74 was grown exerted different antimutagenic activity against ofloxacin-,N-methyl,N′-nitro-N-nitrosoguanidine- and sodium 5-nitro-2-furylacrylate-induced mutagenicity inSalmonella typhimurium assay depending on the presence (+Se) or absence of disodium selenite pentahydrate (−Se). The antimutagenicity of MRS(+Se) extract was higher than that of MRS(−Se) extract. Selenium enhanced also the antimutagenic effect of both live and killed cells ofE. faecium M-74, respectively. The live bacteria decreased the mutagenicity of selected substances more than killed cells. Synergic activity of selenium with the bacterium was also manifested.

Antimutagenicity of a suberin extract from Quercus suber cork.

The possible protective effect of a suberin extract from Quercus suber cork on acridine orange (AO)-, ofloxacin- and UV radiation-induced mutagenicity (bleaching activity) in Euglena gracilis was examined. To our knowledge, the present results are the first attempt to analyse suberin in relation to mutagenicity of some chemicals. Suberin exhibits a significant dose-dependent protective effect against AO-induced mutagenicity and the concentration of 500 micrograms/ml completely eliminates the Euglena-bleaching activity of AO. The mutagenicity of ofloxacin is also significantly reduced in the presence of suberin (125, 250 and 500 micrograms/ml). However, the moderate protective effect of suberin on UV radiation-induced mutagenicity was observed only at concentrations 500 and 1000 micrograms/ml. Our data shows that suberin extract from Q. suber cork possess antimutagenic properties and can be included in the group of natural antimutagens acting in a desmutagenic manner.

Selenium enhances the antimutagenic activity of probiotic bacterium Enterococcus faecium M-74

The antibacterial activity of the probiotic bacterium Enterococcus faecium M-74 was assessed on De Man–Rogosa–Sharpe (MRS), Todd–Hewitt (T–H), M17 (M-17) and brain heart infusion (BHI) media with sodium selenite pentahydrate (+Se) and without sodium selenite pentahydrate (−Se) under aerobic or anaerobic conditions against nine bacterial pathogens. The highest antibacterial activity was found to be in the MRS medium under anaerobic conditions. There were no differences in the antibacterial activity between MRS(+Se) and MRS(−Se) media. The antimutagenic activity of MRS(+Se) and MRS(−Se) extracts after culture with E. faecium M-74 as well as of live and killed cells of E. faecium M-74 grown in the presence or absence of Se against the genotoxicity of ofloxacin (OFL) and acridine orange (AO) was determined in the Euglena gracilis assay. The MRS(+Se) extracts showed a significantly higher activity in reducing the genotoxicity of OFL and AO than MRS(−Se) extracts. The live cells of the probiotic strain M-74 exhibited higher antimutagenic activity than the killed bacterial cells, but differed depending on the mutagen used. However, the live bacterial cells grown in the presence of Se showed significantly higher antimutagenic activity. These results suggest a potential benefit for the future development of new Se-enriched probiotics exhibiting higher antimutagenic properties.

Tetracycline reduces fluoroquinolones-induced bleaching of Euglena gracilis

Inhibitory activity of tetracycline against ofloxacin- and fleroxacin-induced bleaching of green and etiolated Euglena gracilis was examined. Tetracycline hydrochloride in concentrations of 83-2079 microM in the light partially inhibited the bleaching activity of 83 microM ofloxacin and of 162 microM fleroxacin. In the dark, the TC inhibition of the fluoroquinolones-induced bleaching activity was most obvious, the white colony counts were all decreased. The total inhibition of bleaching was observed in 43 microM ofloxacin and 81 microM fleroxacin both in light and darkness. Cell growth was not significantly influenced by ofloxacin, fleroxacin and tetracycline in the light or darkness. Cell growth was not significantly influenced by ofloxacin, fleroxacin and tetracycline in the light or darkness. Inhibition of ofloxacin-induced Euglena bleaching by tetracycline was more effective in etiolated cells. TC at 0-416 microM did not influence the growth of ofloxacin (2.15 microM)-induced Salmonella typhimurium revertants.