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A non-targeted metabolomics approach to evaluate the effects of biomass growth and chitosan elicitation on primary and secondary metabolism of Hypericum perforatum in vitro roots
Full text linkAntifungal activity of dimethyl sulfoxide against Botrytis cinerea and phytotoxicity on tomato and lettuce plants
Full text linkFor the first time the antifungal activity of dimethyl sulfoxide (DMSO) was evaluated against Botrytis cinerea, that it is one of the phytopathogenic fungi which causes the greatest damage in agriculture. In in-vitro tests, the greatest inhibitory effect of DMSO on fungal grow was recorded at pH 6. A significant growth inhibition was caused by 0.5% DMSO at 96 h post-inoculation. With higher DMSO concentrations, significant effects were recorded starting from 48 h post-inoculation. As the medium pH decreased, the inhibitory effect of DMSO also decreased. At pH 4 and 5 significant growth inhibition was caused by 1% DMSO starting from 72 h post-inoculation. At all tested pH values, a total growth inhibition was caused by ≥ 2% DMSO. On tomato leaves infected with B. cinerea, 2% DMSO significantly decreased the extent of damaged leaf area. The administration of DMSO at concentrations ranging from 0.5 to 2% through nebulization on leaves of young Solanum lycopersicum and Lactuca sativa plants did not change the chlorophyll fluorescence (Fv/Fm and ΦPSII) at any of the experimental times. Overall, the data obtained suggest that, at the concentrations tested, DMSO is toxic to B. cinerea, while it is well tolerated by lettuce and tomato plants
A non-targeted metabolomics approach to evaluate the effects of biomass growth and chitosan elicitation on primary and secondary metabolism of Hypericum perforatum in vitro roots
No full textHypericum perforatum L. is a medicinal plant commonly used worldwide for the treatment of mild and moderate depression due to its wide range of bioactive compounds. H. perforatum regenerated roots have been proposed as an efficacious in vitro system to biosynthesize pharmaceutically useful secondary metabolites. In the present study, a metabolomic platform, which integrates an nuclear magnetic resonance (NMR)-based metabolic profiling and analysis of variance-simultaneous component analysis (ASCA), has been applied in order to characterize the changes of the primary and secondary metabolism of H. perforatum regenerated roots induced by an achieved high biomass density in a confined growth environment or in response to chitosan treatment.The ASCA modelling applied to NMR-based metabolic profiling allowed to recognize the effects due to biomass growth rate changes and chitosan treatment. With an high biomass density, associated to a decelerating biomass growth rate, the levels of tryptophan, fructose, shikimic acid, and epicatechin increased, whereas γ-aminobutyric acid and histidine decreased. In response to chitosan elicitation, the biomass growth was arrested and valine, isoleucine, glutamine, γ-aminobutyric acid, fructose, sucrose, polyunsaturated fatty acids, epicatechin, xanthones, dimethylallyl-pyrophosphate, and stigmasterol levels increased, while histidine levels decreased. The metabolic profiling of regenerated roots shows how the cultures respond to different stress conditions: production of epicatechin in response to high biomass density and production of epicatechin, xanthones and isoprenoids in response to chitosan-treatment. This approach can be applied to define suitable protocols to produce the desired secondary metabolites with different bioactivities
"A non-targeted metabolic profiling”di radici rigenerate in vitro di Hypericum perforatum L.
No full textIn the present study, a metabolomic platform, which integrates an nuclear magnetic resonance (NMR)-based metabolic profiling and analysis of variance-simultaneous component analysis (ASCA), has been applied in order to characterize the changes of the primary and secondary metabolism of H. perforatum regenerated roots induced by an achieved high biomass density in a confined growth environment or in response to chitosan treatment.The ASCA modelling applied to NMR-based metabolic profiling allowed to recognize the effects due to biomass growth rate changes and chitosan treatment
Studio del metabolismo primario e secondario di colture di radici di Hypericum perforatum mediante risonanza magnetica nucleare
No full textIn vitro antimicrobial activity of plant extracts against Pseudomonas syringae pv. actinidiae causal agent of bacterial canker in kiwifruit
No full textPseudomonas syringae pv. actinidiae (Psa), the causal agent of bacterial canker of kiwifruit, is considered the main pathogen of yellow-, green- and red-fleshed kiwifruit. All major kiwifruit producing countries in the world have been affected by this bacterial pathogen, leading to substantial economic losses. The control of bacterial canker of kiwifruit is based only on preventive methods or on the use of copper compounds that can cause phytotoxicity problems. In this study, the in vitro antibacterial activity of seven different plant extracts against eight Psa strains has been evaluated. The inhibition of 100% of the Psa growth was observed, after 24 h, for the extracts of Polygonum cuspidatum roots (POL-roots), Hypericum perforatum roots elicited with chitosan oligosaccharides (HYP-COS roots) and non-fermented grape pomace (ITA-pomace). The strongest antibacterial activity was exhibited by POL-roots, with a geometric mean of minimum inhibitory concentration of 100% of growth (GMMIC100) of 105.11 μg/mL after 24 h, and with a GMMIC100 value of 148.65 μg/mL after 48 h. Moreover, POL-roots extract showed the best bactericidal activity with a GMMBC of 210.22 μg/mL. No phytotoxic activity was observed up to 15 days in the leaves of Actinidia chinensis “Belen” treated with plant extracts at 500 μg/mL
Acetic acid acts as an elicitor exerting a chitosan-like effect on xanthone biosynthesis in Hypericum perforatum L. root cultures
No full textHypericum perforatum L. (Hypericaceae), popularly known as St. John’s wort, is a medicinal plant widely used in folk medicine [1]. It is known mainly for its antidepressant activity, and nowadays St. John’s wort preparations are among the most widely prescribed drugs for depression in many European countries [2]. Since the secondary metabolites responsible for the antidepressant activity (e.g. hyperforins and hypericins) are mainly accumulated in leaves and flowers, the chemical composition and the medicinal properties of aerial parts have been extensively investigated [3]. Differently the root has been poorly studied and only recently it has been recognized as an attractive source of bioactive secondary metabolites [4]. We have recently demonstrated that H. perforatum root cultures constitutively produce xanthones at higher levels than the root of the plant and that they respond to chitosan (CHIT) elicitation with a significant increase in xanthone production [5]. Xanthones are a wide and structurally diverse group of polyphenols produced by a restricted number of plants, fungi, lichens, and bacteria with multiple bioactivities [6]. In the present study, CHIT was administered to H. perforatum root cultures using three different elicitation protocols, and the increase in xanthone production was evaluated through HPLC. The best results (550 % xanthone increase) were obtained by subjecting the roots to a single elicitation with 200 mg l-1 CHIT and maintaining the elicitor in the culture medium for 1 week. To discriminate the effect of CHIT from that of the solvent, control experiments were performed by administering acetic acid alone at the same concentration used for CHIT solubilization. Unexpectedly, acetic acid caused an increase in xanthone production comparable to that observed in response to CHIT. Feeding experiments with 13C-labeled acetic acid demonstrated that this compound is not incorporated into the xanthone skeleton. Other short-chain monocarboxylic acids (i.e. propionic and butyric acid) had little or no effect on the production of xanthones. These results indicate that acetic acid acts as a specific signal molecule, able to significantly enhance xanthone biosynthesis in H. perforatum root cultures
In vitro antifungal activity of extracts obtained from Hypericum perforatum adventitious roots cultured in a mist bioreactor against planktonic cells and biofilm of Malassezia furfur
No full textExtracts of Hypericum perforatum roots grown in a bioreactor showed activity against planktonic cells and biofilm of Malassezia furfur. Dried biomass, obtained from roots grown under controlled conditions in a ROOTec mist bioreactor, has been extracted with solvents of increasing polarity (i.e. chloroform, ethyl acetate and methanol). The methanolic fraction was the richest in xanthones (2.86 ± 0.43 mg g− 1 DW) as revealed by HPLC. The minimal inhibitory concentration of the methanol extract against M. furfur planktonic cells was 16 μg mL− 1. The inhibition percentage of biofilm formation, at a concentration of 16 μg mL− 1, ranged from 14% to 39%. The results show that H. perforatum root extracts could be used as new antifungal agents in the treatment of Malassezia infections
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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