Paul Angers

Characterization and use of essential oil from Thymus vulgaris against Botrytis cinerea and Rhizopus stolonifer in strawberry fruits

Abstract The essential oils from two clonal types of Thymus vulgaris (Laval-1 and Laval-2) were characterized and tested for antifungal activity. Contents were high in p -cymene, linalool, terpinen-4-ol and thymol which constituted 53.5% and 66.2% of Laval-1 and Laval-2 essential oils respectively. The essential oil volatiles from two clonal types exhibited antifungal activity against Botrytis cinerea and Rhizopus stolonifer , two common storage pathogens of strawberries ( Fragaria ananassa ). The inhibition of B. cinerea and R. stolonifer ranged from 26.5 to 63.5% and 5.5 to 50.5% respectively by oil from Laval-1, when exposed to concentrations of 50 to 200 ppm, while values of 36.9 to 90.5% and 11.5 to 65.8% were observed from oil from Laval-2. The decay of strawberry fruits caused by B. cinerea and R. stolonifer was controlled up to 73.6 and 73.0% respectively by volatiles from maximin concentration of Laval-1, and up to 75.8 and 74.8% from Laval-2. No visual phytotoxic symptoms were noticed for the observed period. Essential oil from Laval-2 exhibited higher antifungal activity which was related to its relatively higher content of antimicrobial compounds.

EVect of Chitosan on Growth and Toxin Production by Alternaria alternata f. sp. lycopersici

The antifungal activity of chitosan, a biopolymer of beta-1-4 glucosamine, against Alternaria alternata f. sp. lycopersici , causal agent of black mold of tomato, was investigated. Chitosan was incorporated into potato-dextrose broth at concentrations of 100-6400 mug ml - 1, and the growth and toxin production by the fungus were assessed after 15 days of incubation. At the higher concentrations, chitosan significantly aVected both fungal growth and toxin production. However, at lower concentrations toxin production was aVected more than growth. The fungus sporulated excessively in the presence of chitosan, but the spores were less viable. Chitosan also induced aggregation, abnormal shape, excessive branching and hyphal contortion of fungal cells, and leakage of proteins. The virulence of the toxin in culture filtrates of the fungus grown on diVerent concentrations of chitosan was assessed by administering toxin on tomato disks. The phospholipid content, electrolyte leakage and activities of xylanase and p...

Regiospecific analysis of conifer seed triacylglycerols by gas-liquid chromatography with particular emphasis on Δ5-olefinic acids

Dibutyroyl derivatives of monoacylglycerols (DBMAG) from conifer seed oil triacylglycerols (TAG) were prepared by partial deacylation of TAG with ethylmagnesium bromide followed by diesterification with n-butyryl chloride. The resulting mixtures were analyzed by gas-liquid chromatography (GCL) with 65% phenylmethyl silicon open tubular fused-silica capillary column operated under optimal conditions and separated according to both their fatty acid structures and their regiospecific distribution. Seed oils of 18 species from 5 conifer families (Pinaceae, Taxaceae, Cupressaceae, Cephalotaxaceae, and Podocarpaceae) were analyzed. The chromatograms showed a satisfactory resolution of DBMAG containing palmitic (16∶0) stearic (18∶0), taxoleic (cis-5, cis-9 18∶2), oleic (cis-9 18∶1), cis-vaccenic (cis-11 18∶1), pinolenic (cis-5, cis-9, cis-12 18∶3), linoleic (cis-9, cis-12 18∶2), α-linolenic (cis-9 cis-12, cis-15 18∶3), and an almost baseline resolution of DBMAG containing gondoic (cis-11 20∶1), cis-5, cis-11 20∶2, sciadonic (cis-5, cis-11, cis-14 20∶3), dihomolinoleic (cis-11 cis-14 20∶2), juniperonic (cis-5, cis-11, cis-14, cis-17 20∶4), and dihomo-α-linolenic (cis-11, cis-14, cis-17 20∶3) acids. We have observed that results for Pinus pinaster and P. koraiensis seed oils obtained with this new simple method compared favorably with literature data established with other usual regiospecific analytical techniques. Δ5-Olefinic acids are esterified mainly at the external positions of the glycerol backbone in all cases, in agreement with data obtained by other methodologies allowing validation of the GLC regiospecific method. To date, 45 gymnosperm species (mostly Coniferophytes) from 21 genera belonging to 9 families have been analyzed, all of them showing a definite enrichment of Δ5-olefinic acids in the external positions of TAG. These fatty acids (FA), with one exception only, represent between-2 and 8% of FA esterified to the internal positions. For some species, i.e., P. koraiensis and P. pinaster, this asymmetrical distribution was established by at least three analytical procedures and confirmed by stereospecific analysis of their seed TAG.

Fatty acid profiles of polar and neutral lipids of ten species of higher basidiomycetes indigenous to eastern Canada

Neutral and polar lipid contents of ten species of edible mushrooms indigenous to Eastern Canada belonging to the families Agaricaceae, Amanitaceae, Boletaceae, Coprinaceae, Ganodermataceae, and Lycoperdaceae were analysed. The total lipid content of the species analysed ranged from 3.1% (Ganoderma applanatum) to 16% (w/w) d.w. (Amanita vaginata) and averaged 8.6% (w/w) d.w. Polar lipids accounted for more than 50% of the total lipids in most species and differences were observed between neutral and polar lipid contents according to the species analysed. In both lipid fractions, high proportions of unsaturated fatty acids (FAs) ranging from 62.7 to 82.3% (polar lipids) and 59.8 to 82.5% (neutral lipids) of the total FAs were observed. Analysis of FA profiles showed that both neutral and polar lipids were mainly composed of linoleic (18:2 Delta9c,12c), oleic (18:1 Delta9c), and palmitic (16:0) acids. Significant differences (P<0.05) in the contents of specific FAs were observed between mushroom species. Among the 44 FAs detected in the species analysed, the occurrence of cis-11-heptadecenoic (17:1 Delta11c) acid is reported for the first time in basidiomycetes, while elaidic acid (18:1 Delta9t) is reported for the first time in fungi.

Evidence for (1,5) Sigmatropic Rearrangements of CLA in Heated Oils

Linoleic acid was heated at 200°C under helium. Analysis of degradation products by GC on a long polar open tubular capillary column showed the presence of CLA isomers. The identified mono trans CLA isomers were cis-9, trans-11, trans-9, cis-11, trans-10, cis-12, cis-10, trans-12, trans-8, cis-10, and cis-11, trans-13 18:2 acids. Oils containing different levels of linoleic acid (peanut, sesame seed, and safflower seed oils) were also heat treated, resulting in similar CLA distributions. Elution order was confirmed using cis-9, trans-11 and trans-10, cis-12 acid methyl esters standards and their respective configuration isomers (trans-9, cis-11, cis-10, trans-12), obtained after mild selenium-catalyzed isomerization. These results indicated that two conjugated mono trans isomers of 18:2 acid, cis-8, trans-10 and trans-11, cis-13 18:2 were absent from the series, thus strongly suggesting that some constraints were preventing their formation. By heating pure methyl rumenate (cis-9, trans-11 18:2) under similar conditions, isomerization resulted principally in a nearly equimolar mixture of methyl rumenate and trans-8, cis-10 18:2. Similarly, the methyl ester of trans-10, cis-12 18:2 acid was partially transformed into cis-11, trans-13 18:2 acid. Respective geometrical isomers were also formed in trace amounts. A concerted pericyclic isomerization mechanism, a [1,5] sigmatropic rearrangement, is proposed that limits the conjugated system to isomerization from a cis-trans acid to a trans-cis acid, and vice versa. This mechanism is consistent with undetected cis-8, trans-10 and trans-11, cis-13 18:2 isomers in heated oils containing linoleic acid.

Volatile Compounds from Grape Skin, Juice and Wine from Five Interspecific Hybrid Grape Cultivars Grown in Québec (Canada) for Wine Production.

Developed from crosses between Vitis vinifera and North American Vitis species, interspecific hybrid grape varieties are becoming economically significant in northern areas, where they are now extensively grown for wine production. However, the varietal differences between interspecific hybrids are not well defined, nor are the relationships between hybrid grape and wine composition, which causes significant drawbacks in the development of viticulture and winemaking of northern wines. In an effort to increase our understanding of interspecific hybrids, we have characterized the free volatile compounds profiles of berries (juice and skin) and wines of five red hybrid varieties (Frontenac, Marquette, Maréchal Foch, Sabrevois and St. Croix) grown in Québec (Canada), using GC-MS(TOF)-SPME. In grapes and wines, significantly higher levels of C6 and other fatty acid degradation products (FADP) were found in Frontenac, Maréchal Foch and Marquette. Terpenes were primarily located in the skin, with Marquette showing the highest level for these compounds. Both the level of terpenes and the level of FADP in grape were strongly correlated with their respective levels in wine, as demonstrated by the redundancy analyses. Nonanal, (E,Z)-2,6-nonadienal, β-damascenone, ethyl octanoate and isoamyl acetate showed the highest OAVs in the wines of the studied varieties.

Absorption and metabolism of conjugated α-linolenic acid given as free fatty acids or triacylglycerols in rats

BackgroundConjugated linoleic acid (CLA) is a group of polyunsaturated fatty acids which have been extensively studied in the past two decades. However, conjugated octadecatrienoic acid such as cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15, recently identified, have not been extensively investigated. This work presents bioavailability and tissue incorporation of a mixture of conjugated octadecatrienoic (CLnA) acids ingested as free fatty acids (FFA) and triacylglycerols (TAG).ResultsMale Wistar rats were fed rumenic acid (RA: cis-9,trans-11 18:2) and a CLnA mixture (cis-9,trans-11,cis-15 18:3 and cis-9,trans-13,cis-15 18:3) as FFA and TAG for 8 days. RA and CLnA were both totally absorbed when given as FFA as well as TAG. Both isomers of CLnA as FFA or TAG were incorporated into neutral lipids. Metabolites up to 22:6 conjugated isomers were present in liver and plasma phospholipids of rats fed the CLnA diets.ConclusionFinally, CLnA are as well absorbed as RA in vivo and their incorporation into tissues and bioconversion are similar when ingested as FFA or as TAG.

Metabolic profiling of photoautotrophic and photomixotrophic potato plantlets (Solanum tuberosum) provides new insights into acclimatization

Conventional photomixotrophic micropropagation systems are inefficient due to the high rates of mortality upon the transfer of plantlets from in vitro to ex vitro conditions. Exogenous medium sugar has been suggested to be the major cause of this problem. The aim of this study was to investigate the role of sucrose supply on the metabolic profile of in vitro-grown potato plantlets subjected to different tissue culture conditions consisting of Murashige and Skoog medium and without sucrose [photoautotrophic (PAT) condition] or with 3% sucrose [photomixotrophic (PMT) condition]. Using gas chromatography–mass spectrometry, we identified a set of 51 different metabolites in leaf tissues during the rooting phase. Most growth parameters, such as shoot length, leaf fresh weight, leaf number, and leaf area/plant, were significantly lower under PMT than under PAT conditions. Moreover, photosynthesis was inhibited due to partial stomatal closure under PMT conditions. The metabolomic profiles along with principal component analysis and hierarchical cluster analysis revealed that the two treatments were characterized by distinct metabolic signatures. PAT leaves were characterized by the accumulation of urea and erythritol. In comparison, PMT leaves were characterized by the accumulation of metabolites belonging to the primary metabolism and catecholamines as well as compounds related to abiotic stress conditions, such as proline, hydroxyproline, asparagine, γ-aminobutyric acid (GABA), soluble sugars, and myo-inositol.

Involvement of 5-HT2 receptors in the antinociceptive effect of Uncaria tomentosa

Uncaria tomentosa (Willd.) DC (Rubiaceae) is a vine that grows in the Amazon rainforest. Its bark decoctions are used by Peruvian Indians to treat several diseases. Chemically, it consists mainly of oxindole alkaloids. An industrial fraction of U. tomentosa (UT fraction), containing 95% oxindole alkaloids, was used in this study in order to characterize its antinociceptive activity in chemical (acetic acid-induced abdominal writhing, formalin and capsaicin tests) and thermal (tail-flick and hot-plate tests) models of nociception in mice. UT fraction given by the i.p. route dose-dependently suppressed the behavioural response to the chemical stimuli in the models indicated and increased latencies in the thermal stimuli models. The antinociception caused by UT fraction in the formalin test was significantly attenuated by i.p. treatment of mice with ketanserin (5-HT2 receptor antagonist), but was not affected by naltrexone (opioid receptor antagonist), atropine (a nonselective muscarinic antagonist), l-arginine (precursor of nitric oxide), prazosin (alpha1-adrenoceptor antagonist), yohimbine (alpha2-adrenoceptor antagonist), and reserpine (a monoamine depleter). Together, these results indicate that UT fraction produces dose-related antinociception in several models of chemical and thermal pain through mechanisms that involve an interaction with 5-HT2 receptors.

A novel synthesis of unsaturated spiro compounds based on reactions of bifunctional organometallic reagents

Abstract Z-allylic dibromides regio- and stereoselectively prepared were reacted with the sodium enolate of ethyl acetoacetate or di(α-ethoxyvinyl)cuprate to yield, after hydrolysis, and decarboxylation in the case where the enolate of ethylacetoacetate was the nucleophile, the corresponding ketones. After reduction and bromination, the products were converted into the appropriate organometallic compounds and reacted with selected cyclic anhydrides and β-halo-α,β-unsaturated cyclic ketones. The spiro compounds so obtained are key intermediates for the synthesis of naturally occurring spiro sesquiterpenes.