Activité antimicrobienne de produits naturels originaires du Nord de l’Ontario

La multirésistance microbienne pose de grands problèmes au niveau de la santé publique. En fait, il ne reste que peu d’agents antimicrobiens effectifs contre certains microbes multirésistants. Les scientifiques sont donc à la recherche de nouveaux produits antimicrobiens. Cette recherche a évalué l’activité antimicrobienne de substances naturelles provenant de plantes originaires du Nord de l’Ontario. Vingt-cinq extraits, dix fractions et dix-neuf composés purs ont été testés contre des microbes pathogènes, soientEscherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa et Candida albicans. L’activité antimicrobienne des produits naturels a été observée en utilisant la technique de dosage sur microplaque qui emploie le résazurin, et la concentration minimale inhibitrice (CMI) des produits a été déterminée. Afin de démontrer que l’activité antimicrobienne des substances naturelles n’était pas limitée à une seule espèce, certains composés purs ont été testés contre des microbes secondaires, soient Streptococcus lactis, Mycobacterium phlei et Schizosaccharomyces octosporus. Quatre extraits de plantes (Chimaphila umbellata, Betula papyrifera, Rhus typhina et Fraxinus pennsylvanica) et six composés purs (acide gallique, éthyle gallate, acide cafféique, acide synapique, acide gentisique et acide chlorogénique) ont démontré une activité antibactérienne ou antifongique. Ces résultats démontrent que ces produits naturels ont le potentiel d’être développés en nouveaux agents antimicrobiens

Comparative genomics of the white-rot fungi, Phanerochaete carnosa and P. chrysosporium, to elucidate the genetic basis of the distinct wood types they colonize

BackgroundSoftwood is the predominant form of land plant biomass in the Northern hemisphere, and is among the most recalcitrant biomass resources to bioprocess technologies. The white rot fungus, Phanerochaete carnosa, has been isolated almost exclusively from softwoods, while most other known white-rot species, including Phanerochaete chrysosporium, were mainly isolated from hardwoods. Accordingly, it is anticipated that P. carnosa encodes a distinct set of enzymes and proteins that promote softwood decomposition. To elucidate the genetic basis of softwood bioconversion by a white-rot fungus, the present study reports the P. carnosa genome sequence and its comparative analysis with the previously reported P. chrysosporium genome.ResultsP. carnosa encodes a complete set of lignocellulose-active enzymes. Comparative genomic analysis revealed that P. carnosa is enriched with genes encoding manganese peroxidase, and that the most divergent glycoside hydrolase families were predicted to encode hemicellulases and glycoprotein degrading enzymes. Most remarkably, P. carnosa possesses one of the largest P450 contingents (266 P450s) among the sequenced and annotated wood-rotting basidiomycetes, nearly double that of P. chrysosporium. Along with metabolic pathway modeling, comparative growth studies on model compounds and chemical analyses of decomposed wood components showed greater tolerance of P. carnosa to various substrates including coniferous heartwood.ConclusionsThe P. carnosa genome is enriched with genes that encode P450 monooxygenases that can participate in extractives degradation, and manganese peroxidases involved in lignin degradation. The significant expansion of P450s in P. carnosa, along with differences in carbohydrate- and lignin-degrading enzymes, could be correlated to the utilization of heartwood and sapwood preparations from both coniferous and hardwood species

A Metabolomic and HPLC-MS/MS Analysis of the Foliar Phenolics, Flavonoids and Coumarins of the <i>Fraxinus</i> Species Resistant and Susceptible to Emerald Ash Borer

The Emerald Ash Borer (EAB), Agrilus planipennis, Fairmaire, an Asian invasive alien buprestid has devastated tens of millions of ash trees (Fraxinus spp.) in North America. Foliar phytochemicals of the genus Fraxinus (Oleaceae): Fraxinus pennsylvanica (Green ash), F. americana (White ash), F. profunda (Bush) Bush. (Pumpkin ash), F. quadrangulata Michx. (Blue ash), F. nigra Marsh. (Black ash) and F. mandshurica (Manchurian ash) were investigated using HPLC-MS/MS and untargeted metabolomics. HPLC-MS/MS help identified 26 compounds, including phenolics, flavonoids and coumarins in varying amounts. Hydroxycoumarins, esculetin, esculin, fraxetin, fraxin, fraxidin and scopoletin were isolated from blue, black and Manchurian ashes. High-throughput metabolomics revealed 35 metabolites, including terpenes, secoiridoids and lignans. Metabolomic profiling indicated several upregulated putative compounds from Manchurian ash, especially fraxinol, ligstroside, oleuropin, matairesinol, pinoresinol glucoside, 8-hydroxypinoresinol-4-glucoside, verbenalin, hydroxytyrosol-1-O-glucoside, totarol and ar-artemisene. Further, dicyclomine, aphidicolin, parthenolide, famciclovir, ar-turmerone and myriocin were identified upregulated in blue ash. Principal component analysis demonstrated a clear separation between Manchurian and blue ashes from black, green, white and pumpkin ashes. The presence of defensive compounds upregulated in Manchurian ash, suggests their potential role in providing constitutive resistance to EAB, and reflects its co-evolutionary history with A. planipennis, where they appear to coexist in their native habitats

Antioxidant Activity of the Lignins Derived from Fluidized-Bed Fast Pyrolysis

A challenge in recent years has been the rational use of forest and agriculture residues for the production of bio-fuel, biochemical, and other bioproducts. In this study, potentially useful compounds from pyrolytic lignins were identified by HPLC-MS/MS and untargeted metabolomics. The metabolites identified were 2-(4-allyl-2-methoxyphenoxy)-1-(4-hydroxy-3-methoxyphenyl)-1-propanol, benzyl benzoate, fisetinidol, phenyllactic acid, 2-phenylpropionic acid, 6,3′-dimethoxyflavone, and vanillin. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH), trolox equivalent antioxidant capacity (TEAC), and total phenolics content (TPC) per gram of pyrolytic lignin ranged from 14 to 503 mg ascorbic acid equivalents, 35 to 277 mg trolox equivalents, and 0.42 to 50 mg gallic acid equivalents, respectively. A very significant correlation was observed between the DPPH and TPC (r = 0.8663, p ≤ 0.0001), TEAC and TPC (r = 0.8044, p ≤ 0.0001), and DPPH and TEAC (r = 0.8851, p ≤ 0.0001). The polyphenolic compounds in the pyrolytic lignins which are responsible for radical scavenging activity and antioxidant properties can be readily profiled with HPLC-MS/MS combined with untargeted metabolomics. The results also suggest that DPPH, TEAC, and TPC assays are suitable methods for the measurement of antioxidant activity in a variety of pyrolytic lignins. These data show that the pyrolytic lignins can be considered as promising sources of natural antioxidants and value-added chemicals

The flavonoids of Psiadia Punctulata

Bull.Chem.Soc.Ethiop.,5(1), 37-40 (1991

The flavonoids of <i>Psiadia Punctulata</i>

Bull.Chem.Soc.Ethiop.,5(1), 37-40 (1991)

Bio-oil from pyrolysis of wood pellets using a microwave multimode oven and different microwave absorbers

Wood pellets were pyrolyzed using a microwave oven and different microwave power, apparatus set-up and microwave absorbers (none, Fe, and carbon). Pyrolysis was realized in a short time in the presence of Fe or carbon while it was incomplete if the absorber was not present. Furthermore when the absorber was present the shape of the pellets remained unaltered while if the absorber was not employed pellets were disaggregated. Three fractions were collected from each pyrolysis: a gas, a liquid also called bio-oil and a solid called bio-char. The bio-oil contained two phases and they were quantitatively characterized through a GC/MS-FID procedure using an internal standard according to a previously reported method. HPLC/MS, FTIR and 1H NMR spectroscopy were also employed for characterization of these liquids. Cellulose pyrolysis products were present in the upper phase such as water, acetic acid, furans (such as furfural), carbohydrates and their derivatives. Compounds from pyrolysis of lignin such as phenols and veratric acid were present in the bottom phase. The microwave assisted pyrolysis showed the possibility to efficiently convert wood pellets in different products. The main economical important components may be separated and used as chemicals, natural drugs or pesticides, while the remaining components, the solid and the gas may be used for energy production (solid and bio-oil). Solid may be also used for carbon sequestration

A simple procedure for chromatographic analysis of bio-oils from pyrolysis

A simple procedure was suggested for the chromatographic analyses of bio-oils from pyrolysis of various feedstock employing different technologies. An acetonitrile solution of each bio-oil was prepared without any extraction or other sample pretreatments. Preliminary thin layer chromatography showed a large number of compounds having a broad range of retention factors (Rfs) among 0–1. Products having a retention factor over 0.9 were mainly detected by GC while some other compounds were only identified by HPLC. GC/MS-FID analysis was used to identify and quantify compounds using peak areas and relative response factors (RRFs). A new equation was proposed to estimate RRFs of compounds identified via their MS spectra when experimental RRFs were not readily available. The novel procedure was employed to characterize bio-oils from pyrolysis of wood of different source or obtained using different pyrolysis procedure. Using this RRF method guaiacol, furfural, butan-2-one, levoglucosan, acetic acid and many other compounds were quantified in bio-oil samples. Different amount of them were found as a function of the type of wood, and pyrolysis conditions adopted. For instance levoglucosan was the main compound using carbon as MW absorber however acetic acid was prevalent when a MW absorber was not employed and both of them were absent in bio-oils from classical heating. The HPLC/MS of bio-oils showed cyclohexancarboxylic acid, 1,2,4-trimethoxybenzene and 2,6-dimethylphenol among the main products present in all bio-oils. On the contrary 4-hydroxyacetophenone and (3,4,5-trimethoxy) acetophenone were present in bio-oil from pyrolysis of wood using MW oven and 2,5-furandiylmethanol when a MW oven without any absorber was employed. Cyclohexanone was present in bio-oils obtained with a thermal heating or a MW oven without any absorber

Potassium Source and Biofertilizer Influence K Release and Fruit Yield of Mango (<i>Mangifera indica</i> L.): A Three-Year Field Study in Sandy Soils

Arid degraded soils have a coarse texture and poor organic matter content, which reduces the activity of microorganisms and soil enzymes, and thus the soil quality, plant yield and quality decrease. Potassium solubilizing bacteria (KSB) have been suggested to increase the activity of soil enzymes and increase the release of potassium from natural K-feldspar in the arid degraded soil, and thus potentially reduce the rates of the application of chemical fertilizers. Field studies were conducted for three successive growing seasons in an organic farming system to investigate the effects of K-feldspar and KSB (Bacillus cereus) on K release, soil fertility, and fruit yield of mango plants (Mangifera indica L.). The maximum growth of mango plants was found in the treatments inoculated with KSB. KSB increased soil available N, P, K, and the activity of dehydrogenase and alkaline phosphatase enzymes by 10, 7, 18, 54, and 52%, respectively. KSB increased the fruit yield of mango by 23, 27, and 23% in the first, second, and third growing seasons, respectively. The partial (up to 50%) substitution of chemical K-fertilizer with K-feldspar gave fruit yield and quality very close to that fertilized with the full chemical K-fertilizer. The release rate of K (over all the treatments) varied between 0.18 and 0.64 mg kg−1 of soil per day. KSB significantly increased the K release rate. The application of chemical K-fertilizer gave the highest K release, while substitution with K-feldspar reduced the release of K. Natural K-feldspar contains 8.2% K but is poorly soluble when applied alone. KSB increased the soil quality parameters and enhanced the growth and quality of mango fruit. The fruit yield of mango, under KSB inoculation and fertilization with different K sources, ranged between 9.14 to 17.14 t ha−1. The replacement of 50% of chemical K-fertilizer with natural K-feldspar caused a decrease in the fruit yield by 17, 8, and 2.7% in the first, second, and third years, respectively. The substitution of chemical K-fertilizer with K-feldspar up to 50% with KSB is a good strategy to reduce the excessive use of chemical K-fertilizer. B. cereus and natural K-feldspar have the potential to improve soil health and mango plant productivity in low fertile arid soils