Chemical composition,antibacterial and antifungal activities of flowerhead and root essential oils of Santolina chamaecyparissus L., growing wild in Tunisia

The antimicrobial properties of essential oil from various Santolina species have not been investigated enough in the previous studies dealing with the biological activities of medicinal plants. In Tunisia, Santolina chamaecyparissus L. (Asteraceae) is the only Santolina species recorded and is used as vermifuge and emmenagogue. The chemical composition, antibacterial and antifungal properties of essential oils from the flowerheads and roots of spontaneous S. chamaecyparissus growing in Tunisia and the chemical composition which leads to the Tunisian chemotype are investigated here for the first time. Essential oils isolated by hydro distillation from flowerheads and roots of S. chamaecyparissus were analyzed by GC and GC/MS. Two methods served for antimicrobial assays of the essential oils: diffusion in a solid medium and micro-well dilution assay. Antifungal tests were carried out by the agar incorporation method. Sixty-seven constituents were identified from the essential oil of the flowerhead. The major constituents were: 1,8-cineole and β-eudesmol. Two non identified compounds were present at the highest concentration in root oil. Flowerhead oil was characterized by high contents in monoterpenes and sesquiterpenes oxygenated compounds. The flowerhead essential oil demonstrated potent of antibacterial properties against Pseudomonas aeruginosa ATCC and Enterococcus faecalis ATCC, with MIC of 0.625 μg/ml. These findings demonstrate that the flowerhead essential oils of S. chamaecyparissus have excellent antibacterial properties and for this reason they could contribute to decrease the problem of microbial resistance to antibiotics.     

Erythrogenic toxins A, B and C: Occurrence of the genes and exotoxin formation from clinical Streptococcus pyogenes strains associated with streptococcal toxic shock-like syndrome

We report the study of 53 clinical isolates of group A streptococci, all from patients with streptococcal toxic shock-like syndrome. The strains were analysed for the occurrence of the genes of erythrogenic toxins (pyrogenic exotoxins) types A, B and C and in vitro production of these toxins. In contrast to reports indicating that 85% of the toxic shock-like syndrome-associated isolates contained the erythrogenic toxin A gene, only 58.5% of our strains harboured this gene. The erythrogenic toxin C gene was detected in 22.6% of the isolates. Erythrogenic toxin A and erythrogenic toxin B were produced by 68.7% and 58.3% of the strains containing either gene. For all group A streptococci, irrespective of clinical association, the erythrogenic toxin B gene was detected in all the isolates tested. Thus, it is difficult to define a specific role for erythrogenic toxin B in toxic shock-like syndrome as there was no clear correlation between this disease and the presence of toxin genes. Our results suggest the existence of other pathogenic factor(s) produced by group A streptococci which may stimulate human peripheral T lymphocytes in a manner similar to that of erythrogenic toxins, thus explaining different observations in previous epidemiological genetic studies.     

Two new secondary metabolites,saccharochlorines A and B,from a marine bacterium Saccharomonospora sp. KCTC-19160

Two new chlorinated secondary metabolites, saccharochlorines A and B (1 and 2), were isolated from the saline cultivation of a marine-derived bacterium Saccharomonospora sp. (KCTC-19160). The chemical structures of the saccharochlorines were elucidated by 2D NMR and MS spectroscopic data. Saccharochlorines A and B (1 and 2) exhibit weak inhibition of β-secretase (BACE1) in biochemical inhibitory assay, but they induced the release of Aβ (1–40) and Aβ (1–42) in H4-APP neuroglial cells. This discrepancy might be derived from the differences between the cellular and sub-cellular environments or the epigenetic stimulation of BACE1 expression.     

Application of polyethyleneimine cellulose for the class separation of steroidal carboxylic acids from neutral steroids and pigments in urine

Metabolites of corticosteroids that contain the 21-oic acid moiety are found in human urine. The acids from neutral steroids and urinary pigments have been separated by passing the mixture through a column of polyethyleneimine cellulose. The acids adhering to the column are quantitatively eluted with dilute formic acid. The purified preparation is suitable for derivatization and chromatographic analysis.     

Ultraviolet radiation, toxic chemicals and amphibian population declines

Abstract. As part of an overall ‘biodiversity crisis’, many amphibian populations are in decline throughout the world. Numerous factors have contributed to these declines, including habitat destruction, pathogens, increasing ultraviolet (UV) radiation, introduced non‐native species and contaminants. In this paper we review the contribution of increasing UV radiation and environmental contamination to the global decline of amphibian populations. Both UV radiation and environmental contaminants can affect amphibians at all life stages. Exposure to UV radiation and to certain contaminants can kill amphibians and induce sublethal affects in embryos, larvae and adults. Moreover, UV radiation and contaminants may interact with one another synergistically. Synergistic interactions of UV radiation with contaminants can enhance the detrimental effects of the contaminant and UV radiation.     

Plant Sources of Chinese Herbal Remedies: Effects on Pratylenchus vulnus and Meloidogyne javanica

More than 500 plant species, used alone or in combination, are documented in Chinese traditional medicine to have activity against helminth and micro-invertebrate pests of humans. We subjected 153 candidate medicines or their plant sources to multilevel screening for effectiveness against plant-parasitic nematodes. For extracts effective in preliminary screens, we determined time-course and concentration-response relationships. Seventy-three of the aqueous extracts of medicines or their plant sources killed either Meloidogyne javanica juveniles or Pratylenchus vulnus (mixed stages), or both, within a 24-hour exposure period. Of 64 remedies reported as antihelminthics, 36 were effective; of 21 classi- fied as purgatives, 13 killed the nematodes; of 29 indicated as generally effective against pests, 13 killed the nematodes. Sources of extracts effective against one or both species of plant-parasitic nematodes are either the whole plant or vegetative, storage or reproductive components of the plants. Effective plants include both annuals and perennials, range from grasses and herbs to woody trees, and represent 46 plant families.     

Ichtyotoxic activity of extracts from Mexican marine macroalgae

Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderately toxic, if the organism behaved abnormally but death did notoccur, and non-toxic if the fish did not display any change. 79% species were ichtyotoxic to some degree. Extracts of 39 species were toxic, with at least one extract with lethal effects, 19 were moderately toxic and 15 species were non-toxic. Only the extracts ofDictyota bartayresiana, Dictyota cervicornis,Lobophora variegata, Bryothamnion triquetrum and Laurencia obtusa were toxic in all three solvents. The acetone and ethanol extracts were more active, and therefore are more suitable for extraction of toxic substances. This revised version was published online in August 2006 with corrections to the Cover Date.     

Identification and in silico prediction of metabolites of tebufenozide derivatives by major human cytochrome P450 isoforms

Cytochrome P450 (CYP) enzymes constitute a superfamily of heme-containing monooxygenases. CYPs are involved in the metabolism of many chemicals such as drugs and agrochemicals. Therefore, examining the metabolic reactions by each CYP isoform is important to elucidate their substrate recognition mechanisms. The clarification of these mechanisms may be useful not only for the development of new drugs and agrochemicals, but also for risk assessment of chemicals. In our previous study, we identified the metabolites of tebufenozide, an insect growth regulator, formed by two human CYP isoforms: CYP3A4 and CYP2C19. The accessibility of each site of tebufenozide to the reaction center of CYP enzymes and the susceptibility of each hydrogen atom for metabolism by CYP enzymes were evaluated by a docking simulation and hydrogen atom abstraction energy estimation at the density functional theory level, respectively. In this study, the same in silico prediction method was applied to the metabolites of tebufenozide derivatives by major human CYPs (CYP1A2, 2C9, 2C19, 2D6, and 3A4). In addition, the production rate of the metabolites by CYP3A4 was quantitively analyzed by frequency based on docking simulation and hydrogen atom abstraction energy using the classical QSAR approach. Then, the obtained QSAR model was applied to predict the sites of metabolism and the metabolite production order by each CYP isoform.     

Production and effects of volatile organic compounds during interspecific interactions

Competition between mycelia of saprotrophic cord-forming basidiomycetes occurs both within dead woody resources and in the soil-litter interface, and involves a variety of antagonistic mechanisms including the production of volatile organic compounds (VOCs). The antagonistic potential of VOC profiles from interactions in wood blocks and in soil microcosms was assessed using shared headspace experiments, and the profile of VOCs emitted over the course of interactions elucidated using solid phase microextraction (SPME) with gas chromatography-mass spectrometry (GC–MS). Quantitative and qualitative changes in VOC production occurred in interactions compared to self-pairing controls, with different VOC profiles from fungi growing in wood blocks compared to soil trays. There were both stimulatory and inhibitory effects of VOCs on target mycelial extension rate, hyphal coverage and fractal dimension. VOC-mediated effects were greater in self-pairing controls compared to interactions, and differed depending on the substratum in which the VOC-producing fungi were growing.     

Identification and Distribution of Phenylacetic Acid in the Brain of the Rat

Abstract: Phenylacetic acid, the major metabolite of phenylethylamine, has been identified and quantitated in rat brain regions by capillary column high-resolution gas chromatography mass spectrometry. Its distribution is heterogeneous and correlates with that of phenylethylamine. The values obtained were (ng/g ± SEM): whole brain, 31.2 ± 2.7; caudate nucleus, 64.6 ± 6.5; hypothalamus, 60.1 ± 7.4; cerebellum, 31.3 ± 2.9; brainstem, 33.1 ± 3.3, and the "rest," 27.6 ± 3.0.