Comparative study on the antioxidant and biological activities of carvacrol, thymol, and eugenol derivatives

Four derivatives of thymol, carvacrol, and eugenol were synthesized: 4-(hydroxymethyl)-5-isopropyl-2-methylphenol, 4,4'-methylenebis(5-isopropyl-2-methyl)phenol, 4-allyl-6-(hydroxymethyl)-2-methoxyphenol, and 4-(hydroxymethyl)-2-isopropyl-5-methylphenol. The obtained derivatives showed remarkably better antioxidative properties according to 1,1-diphenyl-2-picrylhydrazyl assay (50% inhibitory concentrations = 4-156 microg/mL) and Rancimat assay (protection factors = 1.55-5.84) when compared with parent compounds and values similar to or better than those of butylated hydroxytoluene and vitamin C. At concentrations of 10 mM carvacrol derivatives had no toxic effect on viability of Escherichia coli K-12 (determined by minimum inhibitory concentrations). Other phenol derivatives showed reduced cytotoxic effect on E. coli K-12 at concentrations of 2-5 mM on the basis of 50% lethal dose measurements. In comparison with the parent compounds, phenol derivatives showed reduced cytotoxic effect for Saccharomyces cerevisiae cells (determined by yeast colony reduction). On the other hand, the majority of synthesized compounds had dose-dependent antiproliferative effects on human uterine carcinoma cells (HeLa), which makes them potentially interesting for the adjuvant experimental cancer treatments. The 4,4'-methylenebis(5-isopropyl-2-methyl)phenol derivative of carvacrol showed lower inhibiting capacity also for the HeLa cells, which makes this particular derivative attractive as an efficient antioxidant with negligible cytotoxic effects.     

Relationship between water and nitrogen uptake in nitrate‐ and ammonium‐supplied Phaseolus vulgaris L. plants

Sole ammonium supply provokes negative effects on dry‐mass formation, leaf growth, and water uptake of ammonium‐sensitive plants. To study the effects of N form on nutrient and water uptake and aquaporin expression, French bean plants were grown in a split‐root system. Five treatments were compared: homogeneous nitrate (NN) and ammonium (AA) supply; spatially separated supply of nitrate and ammonium (NA); and half of the root system supplied with N‐free nutrient solution, the other half with either nitrate (N0) or ammonium (A0). Ten days after onset of treatments, root dry mass (DM) and water‐uptake rate (WUR) were significantly reduced under ammonium compared to nitrate supply. WUR from nitrate‐supplied vessels was 80% higher than that from N‐free nutrient solution, while WUR from N‐free nutrient solution was 130% higher than that from ammonium‐supplied vessels. Potassium uptake was lower under ammonium supply and the ratio of N : K uptake of treatment AA was significantly higher compared to others. High K uptake from N‐free nutrient solution of A0 plants resulted in a ratio of N : K uptake comparable to nitrate‐supplied plants, but shoot growth resembled that to plants under sole ammonium supply. Within 24 h after onset of treatments, expression of aquaporin was lower under ammonium compared to nitrate supply. From these data, it can be concluded that reduced root water transport under ammonium supply is directly related to aquaporin activity.     

Both ApxI and ApxII of Actinobacillus pleuropneumoniae serotype 1 are necessary for full virulence

Most serotypes of A. pleuropneumoniae produce more than one toxin in vivo. To determine the value of the production of more than one toxin in the development of disease, we tested the pathogenicity of isogenic strains of A. pleuropneumoniae serotype 1 that are mutated in the toxin genes apxIA and/or apxIIA or in the transport genes apxIBD. Bacteria mutated in both apxIA and apxIIA, or in apxIBD, were unable to induce pathological lesions, thereby confirming the conclusion that ApxI and ApxII are essential for the pathogenesis of pleuropneumonia. Infection with isogenic strains lacking either ApxI or ApxII did not consistently lead to pleuropneumonia unlike the parent strain S4074. ApxII seemed at least as important as ApxI for the development of clinical and pathological symptoms. Only one of the four pigs inoculated with a mutant strain unable to produce ApxII developed mild pneumonia whereas two out of the three pigs inoculated with a mutant strain unable to produce ApxI developed more severe lesions. The results indicate that both ApxI and ApxII of A. pleuropneumoniae serotype 1 are necessary for full virulence.     

Intestinal translocation of Streptococcus suis type 2 EF+ in pigs

Sepsis with subsequent multisystem organ failure after translocation of bacteria from the gut is a serious risk associated with stress situations. We showed that intestinal bacterial translocation could be one of the pathways for pathogenic Streptococcus suis infections in the pig. In 24 piglets weighing 10-14 kg, free of the extracellular factor (EF+) producing phenotype of S. suis serotype 2, a silicon canula was placed in the proximal jejunum to enable intestinal inoculation and bypassing the upper alimentary tract. The pigs were individually housed. After stress induction in 18 pigs by means of a truck drive in individual cages for 1h, pigs were inoculated through the intestinal canula either with S. suis type 2 EF+ or with growth medium only, and put back in their original housing. The six not transported pigs were also inoculated with the same strain. To prevent oral self-infection, faeces were collected in a bag that was glued around the anus. Clinical and behavioral symptoms were recorded for 72 h post inoculation, and then the animals were sacrificed for pathological and bacteriological examination. In three animals, the inoculation strain was re-isolated from mesenterial lymph nodes and typically affected organs. No S. suis type 2 EF+ was detected by specific polymerase chain reaction (PCR) in any of the tonsil-swabs and -homogenates. We concluded that infection of the organs had taken place after bacterial translocation out of the gut and that the intestinal tract can be a porte d'entree for S. suis type 2 EF+.     

Changes in soil chemistry and element uptake by Oak seedlings after application of soil amendment

ABSTRACT

The purpose of this study is to investigate the effect of cellulosic wastes and nanoscale zero-valent iron (nZVI) on the soil properties and the nutrient uptake by Quercus castaneifolia C.A.Mey seedlings. The seedlings were planted in pots (unpolluted soil) and cadmium (Cd) was added to the pots in three concentrations (10, 20, 30?mg.kg^?1). Cellulosic wastes were mixed with the soil (at the same time as the planting) in four levels (W: 0, 10, 20, 30?g.100g^?1 soil). The reduction method was used to prepare nZVI, then the nanoparticles were injected into the polluted pots in four levels (N: 0, 1, 2, and 3?mg.kg^?1). The lowest concentration of Cd in leaves, stems and roots and for all the contamination levels was observed in N3. All the cellulosic wastes and N3 significantly increased the soil pH at all the levels of contamination. An increasing trend of the soil carbon (C) content was observed by adding the cellulosic wastes. The highest pH and C content were observed in W3. The lowest bioavailable Cd contents for all the contamination levels was observed in N3. According to the results, nZVI and cellulosic wastes could help the plants establishing in heavy metal-polluted lands.     

Functional genomic analysis of the Wnt-wingless signaling pathway

The Wnt-Wingless (Wg) pathway is one of a core set of evolutionarily conserved signaling pathways that regulates many aspects of metazoan development. Aberrant Wnt signaling has been linked to human disease. In the present study, we used a genomewide RNA interference (RNAi) screen in Drosophila cells to screen for regulators of the Wnt pathway. We identified 238 potential regulators, which include known pathway components, genes with functions not previously linked to this pathway, and genes with no previously assigned functions. Reciprocal-Best-Blast analyses reveal that 50% of the genes identified in the screen have human orthologs, of which approximately 18% are associated with human disease. Functional assays of selected genes from the cell-based screen in Drosophila, mammalian cells, and zebrafish embryos demonstrated that these genes have evolutionarily conserved functions in Wnt signaling. High-throughput RNAi screens in cultured cells, followed by functional analyses in model organisms, prove to be a rapid means of identifying regulators of signaling pathways implicated in development and disease.     

Pit and mound influence on soil features in an Oriental Beech (Fagus orientalis Lipsky) forest

Windthrow, i.e. the felling of trees by wind, occurs continually in forest ecosystems. The uprooting of old trees creates multiple microsites (e.g. pit and mound landscape) that are the main source of soil heterogeneity. To determine the impact of pit and mound landscapes on soil features, a beech forest of the Langa district (Mazandaran province, Northern Iran) was studied. An area of 25 ha was considered for this study wherein three microsites were distinguished, including pit bottom (pit), mount top (mound) and level areas (closed canopy). In this area, 22 uprooted trees were also found. Soil samples were collected at different depths (i.e. 0–15, 15–30 and 30–45 cm) from all microsites and analysed. Our study shows that windthrow events should be considered as an important factor in influencing forest ecosystem, as they affect physical (i.e. density, texture and water content), chemical (i.e. pH, organic C, total N, cation exchange capacity and available nutrients) and biological (i.e. soil microbial respiration and earthworm density/biomass) characteristics of soil, thus resulting in pit and mound microsites that may strongly differ with respect to the closed canopy.     

Metabolism of the food-associated carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine by human intestinal microbiota

2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine is a putative human carcinogenic heterocyclic aromatic amine formed from meat and fish during cooking. Although the formation of hazardous PhIP metabolites by mammalian enzymes is well-documented, nothing is known about the PhIP transformation potency of human intestinal bacteria. In this study, the in vitro metabolism of PhIP by human fecal samples was investigated. Following anaerobic incubation of PhIP with stools freshly collected from six healthy volunteers, we found that PhIP was extensively transformed by the human intestinal bacteria. HPLC analysis showed that the six human fecal microbiota transformed PhIP with efficiencies from 47 to 95% after 72 h incubation, resulting in one major derivative. ESI-MS/MS, HRMS, 1D (1H, 13C, DEPT) and 2D (gCOSY, gTOCSY, gHMBC, gHSQC) NMR, and IC analysis elucidated the complete chemical identity of the microbial PhIP metabolite as 7-hydroxy-5-methyl-3-phenyl-6,7,8,9-tetrahydropyrido[3',2':4,5]imidazo[1,2-a]pyrimidin-5-ium chloride. At present, no information is available about the biological activity of this newly discovered bacterial PhIP metabolite. Our findings however suggest that bacteria derived from the human intestine play a key role in the activation or detoxification of PhIP, a digestive fate ignored so far in risk assessments. Moreover, the variation in transformation efficiency between the human microbiota indicates interindividual differences in the ability to convert PhIP. This may predict individual susceptibility to carcinogenic risk from this suspected dietary carcinogen.     

Basis for antagonism by sodium bentazon of tritosulfuron toxicity to white bean (Phaseolus vulgaris L.)

White bean (Phaseolus vulgaris L.) was used to study the antagonism caused by Na-bentazon on the phytotoxic action of the sulfonylurea (SU) herbicide tritosulfuron. After 168 h, uptake and translocation of [14C]tritosulfuron were reduced by 60 and 89%, respectively, when Na-bentazon was added to the mixture. Addition of (NH4)2SO4 or replacement of Na-bentazon with NH4-bentazon completely eliminated the negative effects on [14C]tritosulfuron uptake but not on its translocation. Scanning electron microscopy revealed that a mixture of Na-bentazon plus tritosulfuron plus DASH HC (0.156%) formed a rough layer of grain-like crystals on the leaf surface, whereas the addition of (NH4)2SO4 or replacement of Na-bentazon with NH4-bentazon resulted in amorphous deposits that may be more easily absorbed. The antagonism of tritosulfuron's phytotoxicity by Na-bentazon involves two separate processes, chemical (uptake effect) and biochemical (translocation effect).