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Topical Collection "Phytoalexins: Fundamental Aspects and Applications"

A topical collection in Molecules (ISSN 1420-3049). This collection belongs to the section "Natural Products Chemistry".

Editors

Collection Editor
Prof. Dr. Philippe Jeandet

Research Unit Induced Resistance and Plant Bioprotection, SFR Condorcet FR CNRS 3417, Faculty of Sciences, University of Reims, PO Box. 1039, 51687 Reims cedex 02, France
Website | E-Mail
Phone: + 333 26 91 33 41
Interests: plant defense mechanisms and phytoalexins; particularly study of the grapevine (Vitis spp.) phytoalexins (resveratrol and derivatives): chemical synthesis; biosynthesis; chemical analyses; phytoalexin metabolism by Botrytis cinerea; bioproduction by plant cell suspension systems; antifungal activity and molecular engineering of resveratrol in plants and microbial cells
Collection Editor
Prof. Dr. Christophe Clément

Research Unit Induced Resistance and Plant Bioprotection, SFR Condorcet FR CNRS 3417, Faculty of Sciences, University of Reims, PO Box. 1039, 51687 Reims cedex 02, France
Website | E-Mail
Phone: + 333 26 91 33 39
Interests: plant response to biotic and abiotic stress; stimulation of plant defenses; defense metabolites; biocontrol of plant disease; cell culture; green biotechnology; bioproduction of plant defense metabolites

Topical Collection Information

Dear Colleagues,

Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such, they take part in an intricate defense system, which enables plants to control invading microorganisms. In addition to displaying antifungal activity in numerous plant-pathogen interactions, phytoalexins have been implicated in human health and disease as antioxidant, anticancer and cardioprotective agents, as well as being supposed to act positively in neurodegenerative illnesses. Phytoalexins display an enormous diversity belonging to various chemical families such as isoflavones, isoflavanones, pterocarpans, isoflavans, flavanones, coumestans, furanoacetylenes, phenylpropanoids, steroid glycoalkaloids, norsesquiterpenoids/sesquiterpenoids, coumarins, diterpenes, ent-kaurane-related diterpenoids, acidic sesquiterpenoids, 3-deoxyanthocyanidins, naphthaldehydes, indoles, stilbenes, etc. As phytoalexins constitute a very active field of research, we feel it necessary to open a Topical Collection dedicated to the fundamental aspects and applications of the research on these compounds. Original and review papers dealing with all aspects of phytoalexins, including structure elucidation; chemical synthesis; methods for phytoalexin analysis in plant extracts or biological fluids; biosynthesis studies including modulation of phytoalexin synthesis; engineering of phytoalexin biochemical pathways in plants and microbes; biological roles in health and disease; structure/activity relationships; phytoalexin metabolism in planta and by micro-organisms, transport mechanisms and bioproduction by microorganisms or plant cell systems, plant protection and biocontrol, etc., are welcome for inclusion in this Topical Collection of Molecules.

Prof. Dr. Philippe Jeandet
Prof. Dr. Christophe Clément
Dr. Eric Courot
Collection Editors

Manuscript Submission Information

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Keywords

  • phytoalexin structure elucidation
  • chemical synthesis
  • methods for phytoalexin analysis
  • biosynthetic studies and modulation of phytoalexin biosynthesis
  • molecular engineering in plants and microbes / applications
  • biological activity against microorganisms
  • role in human health
  • structure/activity relationships
  • plant and fungal metabolisms
  • transport mechanisms
  • bioproduction by microorganisms or plant cell systems including engineered organisms
  • plant protection and biocontrol

Related Special Issues

Published Papers (36 papers)

2018

Jump to: 2017, 2016, 2015, 2014

Open AccessArticle Resveratrol Suppresses Matrix Metalloproteinase-2 Activation Induced by Lipopolysaccharide in Mouse Osteoblasts via Interactions with AMP-Activated Protein Kinase and Suppressor of Cytokine Signaling 1
Molecules 2018, 23(9), 2327; https://doi.org/10.3390/molecules23092327
Received: 1 June 2018 / Revised: 4 September 2018 / Accepted: 8 September 2018 / Published: 12 September 2018
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Abstract
Porphyromonas endodontalis (P. endodontalis) lipopolysaccharide (LPS) is associated with the progression of bone resorption in periodontal and periapical diseases. Matrix metalloproteinase-2 (MMP-2) expression and activity are elevated in apical periodontitis and have been suggested to participate in bone resorption. Therefore, inhibiting
[...] Read more.
Porphyromonas endodontalis (P. endodontalis) lipopolysaccharide (LPS) is associated with the progression of bone resorption in periodontal and periapical diseases. Matrix metalloproteinase-2 (MMP-2) expression and activity are elevated in apical periodontitis and have been suggested to participate in bone resorption. Therefore, inhibiting MMP-2 activation may be considered a therapeutic strategy for treating apical periodontitis. Resveratrol is a natural non-flavonoid polyphenol that has been reported to have antioxidant, anti-cancer, and anti-inflammatory properties. However, the capacity of resveratrol to protect osteoblast cells from P. endodontalis LPS insults and the mechanism of its inhibitory effects on MMP-2 activation is poorly understood. Here, we demonstrate that cell viability is unchanged when 10 mg L−1 P. endodontalis LPS is used, and MMP-2 expression is drastically induced by P. endodontalis LPS in a concentration- and time-dependent manner. Twenty micromolar resveratrol did not reduce MC3T3-E1 cell viability. Resveratrol increased AMP-activated protein kinase (AMPK) phosphorylation, and Compound C, a specific AMPK inhibitor, partially abolished the resveratrol-mediated phosphorylation of AMPK. In addition, AMPK inhibition blocked the effects of resveratrol on MMP-2 expression and activity in LPS-induced MC3T3-E1 cells. Treatment with resveratrol also induced suppressor of cytokine signaling 1 (SOCS1) expression in MC3T3-E1 cells. SOCS1 siRNA negated the inhibitory effects of resveratrol on LPS-induced MMP-2 production. Additionally, resveratrol-induced SOCS1 upregulation was reduced by treatment with compound C. These results demonstrate that AMPK and SOCS1 activation are important signaling events during resveratrol-mediated inhibition of MMP-2 production in response to LPS in MC3T3-E1 cells, and there is crosstalk between AMPK and SOCS1 signaling. Full article
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Open AccessReview Resveratrol and Depression in Animal Models: A Systematic Review of the Biological Mechanisms
Molecules 2018, 23(9), 2197; https://doi.org/10.3390/molecules23092197
Received: 30 July 2018 / Revised: 25 August 2018 / Accepted: 28 August 2018 / Published: 30 August 2018
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Abstract
Depression is currently treated by pharmacotherapies that can elicit debilitating side effects for patients. Novel treatment options with limited side effects are currently being researched. Resveratrol is a polyphenol and phytoalexin found in the skins of grapes, red wine, Japanese knotweed, and peanuts.
[...] Read more.
Depression is currently treated by pharmacotherapies that can elicit debilitating side effects for patients. Novel treatment options with limited side effects are currently being researched. Resveratrol is a polyphenol and phytoalexin found in the skins of grapes, red wine, Japanese knotweed, and peanuts. It has been studied extensively for its antioxidant and anti-inflammatory properties. Resveratrol has also gained attention for its neuroprotective properties. The aim of the review was to examine the mechanisms by which resveratrol reduces depressive behaviors in animal models. In total, 22 studies met the established criteria for final review. Behavioral aspects of depression were investigated using validated measures such as the forced swimming test, tail suspension test, sucrose preference test, and open field test. While many physical measures were taken, three main biological mechanisms were explored: Regulation of the hypothalamic–pituitary–adrenal axis; decreased inflammation; and increased Brain-Derived Neurotrophic Factor and neurogenesis. Based on these findings, resveratrol may be deemed an effective treatment for depression in animal models at doses between 10–80 mg/kg/day, although higher doses had the most significant effects. Future studies should examine the effects of resveratrol on depression in humans to determine the eligibility of resveratrol as a natural antidepressant with less severe side effects. Full article
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Open AccessArticle Synergistic Effects of Resveratrol and Pyrimethanil against Botrytis cinerea on Grape
Molecules 2018, 23(6), 1455; https://doi.org/10.3390/molecules23061455
Received: 26 April 2018 / Revised: 12 June 2018 / Accepted: 12 June 2018 / Published: 15 June 2018
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Abstract
Botrytis cinerea is the pathogen of gray mold disease affecting a wide range of plant hosts, with consequential economic losses worldwide. The increased frequency of fungicide resistance of the pathogen challenges its disease management, and thus the development of alternative control strategies are
[...] Read more.
Botrytis cinerea is the pathogen of gray mold disease affecting a wide range of plant hosts, with consequential economic losses worldwide. The increased frequency of fungicide resistance of the pathogen challenges its disease management, and thus the development of alternative control strategies are urgently required. In this study, we showed excellent synergistic interactions between resveratrol and pyrimethanil. Significant synergistic values were recorded by the two-drug combination on the suppression of mycelial growth and conidia germination of B. cinerea. The combination of resveratrol and pyrimethanil caused malformation of mycelia. Moreover, the inoculation assay was conducted on table grape and consistent synergistic suppression of the two-drug combination was found in vivo. Our findings first revealed that the combination of resveratrol and pyrimethanil has synergistic effects against resistant B. cinerea and support the potential use of resveratrol as a promising adjuvant on the control of gray mold. Full article
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2017

Jump to: 2018, 2016, 2015, 2014

Open AccessFeature PaperEditorial Structure, Chemical Analysis, Biosynthesis, Metabolism, Molecular Engineering, and Biological Functions of Phytoalexins
Received: 23 December 2017 / Revised: 24 December 2017 / Accepted: 26 December 2017 / Published: 28 December 2017
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Abstract
Plants in their natural environment are facing large numbers of pathogenic microorganisms, mainly fungi and bacteria.[…] Full article
Open AccessFeature PaperArticle Resveratrol-Induced Changes in MicroRNA Expression in Primary Human Fibroblasts Harboring Carnitine-Palmitoyl Transferase-2 Gene Mutation, Leading to Fatty Acid Oxidation Deficiency
Received: 13 November 2017 / Revised: 11 December 2017 / Accepted: 16 December 2017 / Published: 22 December 2017
Cited by 1 | PDF Full-text (233 KB) | HTML Full-text | XML Full-text
Abstract
Carnitine palmitoyltransferase-2 (CPT2) is a mitochondrial enzyme involved in long-chain fatty acid entry into mitochondria for their β-oxidation and energy production. Two phenotypes are associated with the extremely reduced CPT2 activity in genetically deficient patients: neonatal lethality or, in milder forms,
[...] Read more.
Carnitine palmitoyltransferase-2 (CPT2) is a mitochondrial enzyme involved in long-chain fatty acid entry into mitochondria for their β-oxidation and energy production. Two phenotypes are associated with the extremely reduced CPT2 activity in genetically deficient patients: neonatal lethality or, in milder forms, myopathy. Resveratrol (RSV) is a phytophenol produced by grape plant in response to biotic or abiotic stresses that displays anti-oxidant properties, in particular through AP-1, NFκB, STAT-3, and COX pathways. Some beneficiary effects of RSV are due to its modulation of microRNA (miRNA) expression. RSV can enhance residual CPT2 activities in human fibroblasts derived from CPT2-deficient patients and restores normal fatty acid oxidation rates likely through stimulation of mitochondrial biogenesis. Here, we report changes in miRNA expression linked to CPT2-deficiency, and we identify miRNAs whose expression changed following RSV treatment of control or CPT2-deficient fibroblasts isolated from patients. Our findings suggest that RSV consumption might exert beneficiary effects in patients with CPT2-deficiency. Full article
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Open AccessArticle The Effect of Resveratrol on Cell Viability in the Burkitt’s Lymphoma Cell Line Ramos
Received: 17 November 2017 / Revised: 12 December 2017 / Accepted: 13 December 2017 / Published: 21 December 2017
Cited by 2 | PDF Full-text (3068 KB) | HTML Full-text | XML Full-text
Abstract
Resveratrol is a polyphenolic natural compound produced by a variety of crops. Currently, resveratrol is considered a multi-target anti-cancer agent with pleiotropic activity, including the ability to prevent the proliferation of malignant cells by inhibiting angiogenesis and curtailing invasive and metastatic factors in
[...] Read more.
Resveratrol is a polyphenolic natural compound produced by a variety of crops. Currently, resveratrol is considered a multi-target anti-cancer agent with pleiotropic activity, including the ability to prevent the proliferation of malignant cells by inhibiting angiogenesis and curtailing invasive and metastatic factors in many cancer models. However, the molecular mechanisms mediating resveratrol-specific effects on lymphoma cells remain unknown. To begin tackling this question, we treated the Burkitt’s lymphoma cell line Ramos with resveratrol and assessed cell survival and gene expression. Our results suggest that resveratrol shows a significant anti-proliferative and pro-apoptotic activity on Ramos cells, inducing the DNA damage response, DNA repairing, and modulating the expression of several genes that regulate the apoptotic process and their proliferative activity. Full article
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Open AccessCommunication Cytotoxicity of Labruscol, a New Resveratrol Dimer Produced by Grapevine Cell Suspensions, on Human Skin Melanoma Cancer Cell Line HT-144
Molecules 2017, 22(11), 1940; https://doi.org/10.3390/molecules22111940
Received: 4 October 2017 / Revised: 26 October 2017 / Accepted: 6 November 2017 / Published: 9 November 2017
Cited by 2 | PDF Full-text (986 KB) | HTML Full-text | XML Full-text
Abstract
A new resveratrol dimer (1) called labruscol, has been purified by centrifugal partition chromatography of a crude ethyl acetate stilbene extract obtained from elicited grapevine cell suspensions of Vitis labrusca L. cultured in a 14-liter stirred bioreactor. One dimensional (1D) and
[...] Read more.
A new resveratrol dimer (1) called labruscol, has been purified by centrifugal partition chromatography of a crude ethyl acetate stilbene extract obtained from elicited grapevine cell suspensions of Vitis labrusca L. cultured in a 14-liter stirred bioreactor. One dimensional (1D) and two dimensional (2D) nuclear magnetic resonance (NMR) analyses including 1H, 13C, heteronuclear single-quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), and correlation spectroscopy (COSY) as well as high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) were used to characterize this compound and to unambiguously identify it as a new stilbene dimer, though its relative stereochemistry remained unsolved. Labruscol was recovered as a pure compound (>93%) in sufficient amounts (41 mg) to allow assessment of its biological activity (cell viability, cell invasion and apoptotic activity) on two different cell lines, including one human skin melanoma cancer cell line HT-144 and a healthy human dermal fibroblast (HDF) line. This compound induced almost 100% of cell viability inhibition in the cancer line at a dose of 100 μM within 72 h of treatment. However, at all tested concentrations and treatment times, resveratrol displayed an inhibition of the cancer line viability higher than that of labruscol in the presence of fetal bovine serum. Both compounds also showed differential activities on healthy and cancer cell lines. Finally, labruscol at a concentration of 1.2 μM was shown to reduce cell invasion by 40%, although no similar activity was observed with resveratrol. The cytotoxic activity of this newly-identified dimer is discussed. Full article
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Open AccessArticle The Influence of Lead on Generation of Signalling Molecules and Accumulation of Flavonoids in Pea Seedlings in Response to Pea Aphid Infestation
Molecules 2017, 22(9), 1404; https://doi.org/10.3390/molecules22091404
Received: 30 June 2017 / Revised: 14 August 2017 / Accepted: 21 August 2017 / Published: 24 August 2017
Cited by 4 | PDF Full-text (19384 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The aim of this study was to investigate the effect of an abiotic factor, i.e., lead at various concentrations (low causing a hormesis effect and causing high toxicity effects), on the generation of signalling molecules in pea (Pisum sativum L. cv. Cysterski)
[...] Read more.
The aim of this study was to investigate the effect of an abiotic factor, i.e., lead at various concentrations (low causing a hormesis effect and causing high toxicity effects), on the generation of signalling molecules in pea (Pisum sativum L. cv. Cysterski) seedlings and then during infestation by the pea aphid (Acyrthosiphon pisum Harris). The second objective was to verify whether the presence of lead in pea seedling organs and induction of signalling pathways dependent on the concentration of this metal trigger defense responses to A. pisum. Therefore, the profile of flavonoids and expression levels of genes encoding enzymes of the flavonoid biosynthesis pathway (phenylalanine ammonialyase and chalcone synthase) were determined. A significant accumulation of total salicylic acid (TSA) and abscisic acid (ABA) was recorded in the roots and leaves of pea seedlings growing on lead-supplemented medium and next during infestation by aphids. Increased generation of these phytohormones strongly enhanced the biosynthesis of flavonoids, including a phytoalexin, pisatin. This research provides insights into the cross-talk between the abiotic (lead) and biotic factor (aphid infestation) on the level of the generation of signalling molecules and their role in the induction of flavonoid biosynthesis. Full article
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Open AccessArticle Inhibitors of the Detoxifying Enzyme of the Phytoalexin Brassinin Based on Quinoline and Isoquinoline Scaffolds
Molecules 2017, 22(8), 1345; https://doi.org/10.3390/molecules22081345
Received: 17 July 2017 / Accepted: 8 August 2017 / Published: 14 August 2017
Cited by 4 | PDF Full-text (2546 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The detoxification of the phytoalexin brassinin to indole-3-carboxaldehyde and S-methyl dithiocarbamate is catalyzed by brassinin oxidase (BOLm), an inducible fungal enzyme produced by the plant pathogen Leptosphaeria maculans. Twenty-six substituted quinolines and isoquinolines are synthesized and evaluated for antifungal activity against
[...] Read more.
The detoxification of the phytoalexin brassinin to indole-3-carboxaldehyde and S-methyl dithiocarbamate is catalyzed by brassinin oxidase (BOLm), an inducible fungal enzyme produced by the plant pathogen Leptosphaeria maculans. Twenty-six substituted quinolines and isoquinolines are synthesized and evaluated for antifungal activity against L. maculans and inhibition of BOLm. Eleven compounds that inhibit BOLm activity are reported, of which 3-ethyl-6-phenylquinoline displays the highest inhibitory effect. In general, substituted 3-phenylquinolines show significantly higher inhibitory activities than the corresponding 2-phenylquinolines. Overall, these results indicate that the quinoline scaffold is a good lead to design paldoxins (phytoalexin detoxification inhibitors) that inhibit the detoxification of brassinin by L. maculans. Full article
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Open AccessArticle Distinct Mechanisms of Biotic and Chemical Elicitors Enable Additive Elicitation of the Anticancer Phytoalexin Glyceollin I
Molecules 2017, 22(8), 1261; https://doi.org/10.3390/molecules22081261
Received: 16 June 2017 / Accepted: 25 July 2017 / Published: 27 July 2017
Cited by 2 | PDF Full-text (3438 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Phytoalexins are metabolites biosynthesized in plants in response to pathogen, environmental, and chemical stresses that often have potent bioactivities, rendering them promising for use as therapeutics or scaffolds for pharmaceutical development. Glyceollin I is an isoflavonoid phytoalexin from soybean that exhibits potent anticancer
[...] Read more.
Phytoalexins are metabolites biosynthesized in plants in response to pathogen, environmental, and chemical stresses that often have potent bioactivities, rendering them promising for use as therapeutics or scaffolds for pharmaceutical development. Glyceollin I is an isoflavonoid phytoalexin from soybean that exhibits potent anticancer activities and is not economical to synthesize. Here, we tested a range of source tissues from soybean, in addition to chemical and biotic elicitors, to understand how to enhance the bioproduction of glyceollin I. Combining the inorganic chemical silver nitrate (AgNO3) with the wall glucan elicitor (WGE) from the soybean pathogen Phytophthora sojae had an additive effect on the elicitation of soybean seeds, resulting in a yield of up to 745.1 µg gt−1 glyceollin I. The additive elicitation suggested that the biotic and chemical elicitors acted largely by separate mechanisms. WGE caused a major accumulation of phytoalexin gene transcripts, whereas AgNO3 inhibited and enhanced the degradation of glyceollin I and 6″-O-malonyldaidzin, respectively. Full article
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Open AccessArticle Systemic Induction of the Defensin and Phytoalexin Pisatin Pathways in Pea (Pisum sativum) against Aphanomyces euteiches by Acetylated and Nonacetylated Oligogalacturonides
Molecules 2017, 22(6), 1017; https://doi.org/10.3390/molecules22061017
Received: 24 May 2017 / Revised: 16 June 2017 / Accepted: 17 June 2017 / Published: 19 June 2017
Cited by 4 | PDF Full-text (2393 KB) | HTML Full-text | XML Full-text
Abstract
Oligogalacturonides (OGs) are known for their powerful ability to stimulate the plant immune system but little is known about their mode of action in pea (Pisum sativum). In the present study, we investigated the elicitor activity of two fractions of OGs,
[...] Read more.
Oligogalacturonides (OGs) are known for their powerful ability to stimulate the plant immune system but little is known about their mode of action in pea (Pisum sativum). In the present study, we investigated the elicitor activity of two fractions of OGs, with polymerization degrees (DPs) of 2–25, in pea against Aphanomyces euteiches. One fraction was nonacetylated (OGs − Ac) whereas the second one was 30% acetylated (OGs + Ac). OGs were applied by injecting the upper two rachises of the plants at three- and/or four-weeks-old. Five-week-old roots were inoculated with 105 zoospores of A. euteiches. The root infection level was determined at 7, 10 and 14 days after inoculation using the quantitative real-time polymerase chain reaction (qPCR). Results showed significant root infection reductions namely 58, 45 and 48% in the plants treated with 80 µg OGs + Ac and 59, 56 and 65% with 200 µg of OGs − Ac. Gene expression results showed the upregulation of genes involved in the antifungal defensins, lignans and the phytoalexin pisatin pathways and a priming effect in the basal defense, SA and ROS gene markers as a response to OGs. The reduction of the efficient dose in OGs + Ac is suggesting that acetylation is necessary for some specific responses. Our work provides the first evidence for the potential of OGs in the defense induction in pea against Aphanomyces root rot. Full article
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Open AccessArticle 4-Hydroxy-7-methyl-3-phenylcoumarin Suppresses Aflatoxin Biosynthesis via Downregulation of aflK Expressing Versicolorin B Synthase in Aspergillus flavus
Molecules 2017, 22(5), 712; https://doi.org/10.3390/molecules22050712
Received: 17 December 2016 / Revised: 26 April 2017 / Accepted: 27 April 2017 / Published: 29 April 2017
Cited by 4 | PDF Full-text (869 KB) | HTML Full-text | XML Full-text
Abstract
Naturally occurring coumarins possess antibacterial and antifungal properties. In this study, these natural and synthetic coumarins were used to evaluate their antifungal activities against Aspergillus flavus, which produces aflatoxins. In addition to control antifungal activities, antiaflatoxigenic properties were also determined using a
[...] Read more.
Naturally occurring coumarins possess antibacterial and antifungal properties. In this study, these natural and synthetic coumarins were used to evaluate their antifungal activities against Aspergillus flavus, which produces aflatoxins. In addition to control antifungal activities, antiaflatoxigenic properties were also determined using a high-performance liquid chromatography in conjunction with fluorescence detection. In this study, 38 compounds tested and 4-hydroxy-7-methyl-3-phenyl coumarin showed potent antifungal and antiaflatoxigenic activities against A. flavus. Inhibitory mode of antiaflatoxigenic action by 4-hydroxy-7-methyl-3-phenyl coumarin was based on the downregulation of aflD, aflK, aflQ, and aflR in aflatoxin biosynthesis. In the cases of coumarins, antifungal and aflatoxigenic activities are highly related to the lack of diene moieties in the structures. In structurally related compounds, 2,3-dihydrobenzofuran exhibited antifungal and antiaflatoxigenic activities against A. flavus. The inhibitory mode of antiaflatoxigenic action by 2,3-dihydrobenzofuran was based on the inhibition of the transcription factor (aflS) in the aflatoxin biosynthesis pathway. These potent inhibitions of 2,3-dihydrobenzofuran and 4-hydroxy-7-methyl-3-phenyl coumarin on the Aspergillus growth and production of aflatoxins contribute to the development of new controlling agents to mitigate aflatoxin contamination. Full article
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Open AccessArticle Bactericidal Effect of Pterostilbene Alone and in Combination with Gentamicin against Human Pathogenic Bacteria
Molecules 2017, 22(3), 463; https://doi.org/10.3390/molecules22030463
Received: 17 February 2017 / Revised: 9 March 2017 / Accepted: 11 March 2017 / Published: 17 March 2017
Cited by 2 | PDF Full-text (4621 KB) | HTML Full-text | XML Full-text
Abstract
The antibacterial activity of pterostilbene in combination with gentamicin against six strains of Gram-positive and Gram-negative bacteria were investigated. The minimum inhibitory concentration and minimum bactericidal concentration of pterostilbene were determined using microdilution technique whereas the synergistic antibacterial activities of pterostilbene in combination
[...] Read more.
The antibacterial activity of pterostilbene in combination with gentamicin against six strains of Gram-positive and Gram-negative bacteria were investigated. The minimum inhibitory concentration and minimum bactericidal concentration of pterostilbene were determined using microdilution technique whereas the synergistic antibacterial activities of pterostilbene in combination with gentamicin were assessed using checkerboard assay and time-kill kinetic study. Results of the present study showed that the combination effects of pterostilbene with gentamicin were synergistic (FIC index < 0.5) against three susceptible bacteria strains: Staphylococcus aureus ATCC 25923, Escherichia coli O157 and Pseudomonas aeruginosa 15442. However, the time-kill study showed that the interaction was indifference which did not significantly differ from the gentamicin treatment. Furthermore, time-kill study showed that the growth of the tested bacteria was completely attenuated with 2 to 8 h treatment with 0.5 × MIC of pterostilbene and gentamicin. The identified combinations could be of effective therapeutic value against bacterial infections. These findings have potential implications in delaying the development of bacterial resistance as the antibacterial effect was achieved with the lower concentrations of antibacterial agents. Full article
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Open AccessArticle A Focused Multiple Reaction Monitoring (MRM) Quantitative Method for Bioactive Grapevine Stilbenes by Ultra-High-Performance Liquid Chromatography Coupled to Triple-Quadrupole Mass Spectrometry (UHPLC-QqQ)
Molecules 2017, 22(3), 418; https://doi.org/10.3390/molecules22030418
Received: 23 January 2017 / Revised: 1 March 2017 / Accepted: 1 March 2017 / Published: 7 March 2017
Cited by 3 | PDF Full-text (3908 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Grapevine stilbenes are a family of polyphenols which derive from trans-resveratrol having antifungal and antimicrobial properties, thus being considered as phytoalexins. In addition to their diverse bioactive properties in animal models, they highlight a strong potential in human health maintenance and promotion.
[...] Read more.
Grapevine stilbenes are a family of polyphenols which derive from trans-resveratrol having antifungal and antimicrobial properties, thus being considered as phytoalexins. In addition to their diverse bioactive properties in animal models, they highlight a strong potential in human health maintenance and promotion. Due to this relevance, highly-specific qualitative and quantitative methods of analysis are necessary to accurately analyze stilbenes in different matrices derived from grapevine. Here, we developed a rapid, sensitive, and specific analysis method using ultra-high-performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC-QqQ) in MRM mode to detect and quantify five grapevine stilbenes, trans-resveratrol, trans-piceid, trans-piceatannol, trans-pterostilbene, and trans-ε-viniferin, whose interest in relation to human health is continuously growing. The method was optimized to minimize in-source fragmentation of piceid and to avoid co-elution of cis-piceid and trans-resveratrol, as both are detected with resveratrol transitions. The applicability of the developed method of stilbene analysis was tested successfully in different complex matrices including cellular extracts of Vitis vinifera cell cultures, reaction media of biotransformation assays, and red wine. Full article
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2016

Jump to: 2018, 2017, 2015, 2014

Open AccessArticle Enhanced Stilbene Production and Excretion in Vitis vinifera cv Pinot Noir Hairy Root Cultures
Molecules 2016, 21(12), 1703; https://doi.org/10.3390/molecules21121703
Received: 14 October 2016 / Revised: 2 December 2016 / Accepted: 7 December 2016 / Published: 10 December 2016
Cited by 4 | PDF Full-text (3201 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Stilbenes are defense molecules produced by grapevine in response to stresses including various elicitors and signal molecules. Together with their prominent role in planta, stilbenes have been the center of much attention in recent decades due to their pharmaceutical properties. With the aim
[...] Read more.
Stilbenes are defense molecules produced by grapevine in response to stresses including various elicitors and signal molecules. Together with their prominent role in planta, stilbenes have been the center of much attention in recent decades due to their pharmaceutical properties. With the aim of setting up a cost-effective and high purity production of resveratrol derivatives, hairy root lines were established from Vitis vinifera cv Pinot Noir 40024 to study the organ-specific production of various stilbenes. Biomass increase and stilbene production by roots were monitored during flask experiments. Although there was a constitutive production of stilbenes in roots, an induction of stilbene synthesis by methyl jasmonate (MeJA) after 18 days of growth led to further accumulation of ε-viniferin, δ-viniferin, resveratrol and piceid. The use of 100 µM MeJA after 18 days of culture in the presence of methyl-β-cyclodextrins (MCDs) improved production levels, which reached 1034µg/g fresh weight (FW) in roots and 165 mg/L in the extracellular medium, corresponding to five-and 570-foldincrease in comparison to control. Whereas a low level of stilbene excretion was measured in controls, addition of MeJA induced excretion of up to 37% of total stilbenes. The use of MCDs increased the excretion phenomenon even more, reaching up to 98%. Our results demonstrate the ability of grapevine hairy roots to produce various stilbenes. This production was significantly improved in response to elicitation by methyl jasmonate and/or MCDs. This supports the interest of using hairy roots as a potentially valuable system for producing resveratrol derivatives. Full article
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Open AccessReview Antiproliferative Effect of Indole Phytoalexins
Molecules 2016, 21(12), 1626; https://doi.org/10.3390/molecules21121626
Received: 18 October 2016 / Revised: 15 November 2016 / Accepted: 22 November 2016 / Published: 26 November 2016
Cited by 11 | PDF Full-text (572 KB) | HTML Full-text | XML Full-text
Abstract
Indole phytoalexins from crucifers have been shown to exhibit significant anti-cancer, chemopreventive, and antiproliferative activity. Phytoalexins are natural low molecular antimicrobial compounds that are synthesized and accumulated in plants after their exposure to pathogenic microorganisms. Most interestingly, crucifers appear to be the only
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Indole phytoalexins from crucifers have been shown to exhibit significant anti-cancer, chemopreventive, and antiproliferative activity. Phytoalexins are natural low molecular antimicrobial compounds that are synthesized and accumulated in plants after their exposure to pathogenic microorganisms. Most interestingly, crucifers appear to be the only plant family producing sulfur-containing indole phytoalexins. The mechanisms underlying its anti-cancer properties are unknown. Isolation from cruciferous plants does not provide sufficient quantities of indole phytoalexins and, for biological screening, they are usually obtainable through synthesis. Understanding the molecular mechanism of the action of these substances and their structure-activity relationships is quite important in the development of new analogs with a more favorable profile of biological activities. In this review, we present the key features of indole phytoalexins, mainly their antiproliferative ativities. Full article
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Open AccessArticle Simultaneous Ultra Performance Liquid Chromatography Determination and Antioxidant Activity of Linarin, Luteolin, Chlorogenic Acid and Apigenin in Different Parts of Compositae Species
Molecules 2016, 21(11), 1609; https://doi.org/10.3390/molecules21111609
Received: 30 September 2016 / Revised: 11 November 2016 / Accepted: 17 November 2016 / Published: 23 November 2016
Cited by 4 | PDF Full-text (969 KB) | HTML Full-text | XML Full-text
Abstract
Linarin (LA), luteolin (LE), chlorogenic acid (CA) and apigenin (AP) are four major flavonoids with various promising bioactivities found in Compositae (COP) species. A reliable, reproducible and accurate method for the simultaneous and quantitative determination of these four major flavonoids by Ultra Performance
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Linarin (LA), luteolin (LE), chlorogenic acid (CA) and apigenin (AP) are four major flavonoids with various promising bioactivities found in Compositae (COP) species. A reliable, reproducible and accurate method for the simultaneous and quantitative determination of these four major flavonoids by Ultra Performance Liquid Chromatography (UPLC) analysis was developed. This method should be appropriate for the quality assurance of COP. The UPLC separation was carried out using an octadecylsilane (ODS) Hypersil (2.1 mm × 250 mm, 1.9 μm) and a mobile phase composed of acetonitrile and 0.1% formic acid in water at a flow rate 0.44 mL/min and ultraviolet (UV) detection 254 nm. Gradient elution was employed. The method was precise, with relative standard deviation below 3.0% and showed excellent linearity (R2 > 0.999). The recoveries for the four flavonoids in COP were between 95.49%–106.23%. The average contents of LA, LE, CA and AP in different parts (flower, leave and stem) of COP were between 0.64–1.47 g/100 g, 0.66–0.89 g/100 g, 0.32–0.52 g/100 g and 0.16–0.18 g/100 g, respectively. The method was accurate and reproducible and it can provide a quantitative basis for quality control of COP. Full article
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2015

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Open AccessEditorial Phytoalexins: Current Progress and Future Prospects
Molecules 2015, 20(2), 2770-2774; https://doi.org/10.3390/molecules20022770
Received: 2 February 2015 / Accepted: 4 February 2015 / Published: 5 February 2015
Cited by 16 | PDF Full-text (623 KB) | HTML Full-text | XML Full-text
Abstract
Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In the 1950s, research on phytoalexins
[...] Read more.
Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In the 1950s, research on phytoalexins started with progress in their biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity, as well as mechanisms of their synthesis and catabolism by microorganisms. Elucidation of the biosynthesis of numerous phytoalexins also permitted the use of molecular biology tools for the exploration of the genes encoding enzymes of their synthesis pathways and their regulators. This has led to potential applications for increasing plant resistance to diseases. Phytoalexins display an enormous diversity belonging to various chemical families such as for instance, phenolics, terpenoids, furanoacetylenes, steroid glycoalkaloids, sulfur-containing compounds and indoles.[...] Full article
Open AccessArticle A Sorghum MYB Transcription Factor Induces 3-Deoxyanthocyanidins and Enhances Resistance against Leaf Blights in Maize
Molecules 2015, 20(2), 2388-2404; https://doi.org/10.3390/molecules20022388
Received: 14 October 2014 / Accepted: 22 January 2015 / Published: 30 January 2015
Cited by 17 | PDF Full-text (871 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Sorghum responds to the ingress of the fungal pathogen Colletotrichum sublineolum through the biosynthesis of 3-deoxyanthocyanidin phytoalexins at the site of primary infection. Biosynthesis of 3-deoxyanthocyanidins in sorghum requires a MYB transcription factor encoded by yellow seed1 (y1), an orthologue of
[...] Read more.
Sorghum responds to the ingress of the fungal pathogen Colletotrichum sublineolum through the biosynthesis of 3-deoxyanthocyanidin phytoalexins at the site of primary infection. Biosynthesis of 3-deoxyanthocyanidins in sorghum requires a MYB transcription factor encoded by yellow seed1 (y1), an orthologue of the maize gene pericarp color1 (p1). Maize lines with a functional p1 and flavonoid structural genes do not produce foliar 3-deoxyanthocyanidins in response to fungal ingress. To perform a comparative metabolic analysis of sorghum and maize 3-deoxyanthocyanidin biosynthetic pathways, we developed transgenic maize lines expressing the sorghum y1 gene. In maize, the y1 transgene phenocopied p1-regulated pigment accumulation in the pericarp and cob glumes. LC-MS profiling of fungus-challenged Y1-maize leaves showed induction of 3-deoxyanthocyanidins, specifically luteolinidin. Y1-maize plants also induced constitutive and higher levels of flavonoids in leaves. In response to Colletotrichum graminicola, Y1-maize showed a resistance response. Full article
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2014

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Open AccessArticle EDTA a Novel Inducer of Pisatin, a Phytoalexin Indicator of the Non-Host Resistance in Peas
Molecules 2015, 20(1), 24-34; https://doi.org/10.3390/molecules20010024
Received: 11 October 2014 / Accepted: 17 December 2014 / Published: 23 December 2014
Cited by 11 | PDF Full-text (1847 KB) | HTML Full-text | XML Full-text
Abstract
Pea pod endocarp suppresses the growth of an inappropriate fungus or non-pathogen by generating a “non-host resistance response” that completely suppresses growth of the challenging fungus within 6 h. Most of the components of this resistance response including pisatin production can be elicited
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Pea pod endocarp suppresses the growth of an inappropriate fungus or non-pathogen by generating a “non-host resistance response” that completely suppresses growth of the challenging fungus within 6 h. Most of the components of this resistance response including pisatin production can be elicited by an extensive number of both biotic and abiotic inducers. Thus this phytoalexin serves as an indicator to be used in evaluating the chemical properties of inducers that can initiate the resistance response. Many of the pisatin inducers are reported to interact with DNA and potentially cause DNA damage. Here we propose that EDTA (ethylenediaminetetraacetic acid) is an elicitor to evoke non-host resistance in plants. EDTA is manufactured as a chelating agent, however at low concentration it is a strong elicitor, inducing the phytoalexin pisatin, cellular DNA damage and defense-responsive genes. It is capable of activating complete resistance in peas against a pea pathogen. Since there is also an accompanying fragmentation of pea DNA and alteration in the size of pea nuclei, the potential biochemical insult as a metal chelator may not be its primary action. The potential effects of EDTA on the structure of DNA within pea chromatin may assist the transcription of plant defense genes. Full article
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Open AccessReview Deciphering the Role of Phytoalexins in Plant-Microorganism Interactions and Human Health
Molecules 2014, 19(11), 18033-18056; https://doi.org/10.3390/molecules191118033
Received: 17 September 2014 / Revised: 29 October 2014 / Accepted: 29 October 2014 / Published: 5 November 2014
Cited by 42 | PDF Full-text (304 KB) | HTML Full-text | XML Full-text
Abstract
Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In this review we present the
[...] Read more.
Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In this review we present the key features of this diverse group of molecules, namely their chemical structures, biosynthesis, regulatory mechanisms, biological activities, metabolism and molecular engineering. Full article
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Open AccessArticle Study of Leaf Metabolome Modifications Induced by UV-C Radiations in Representative Vitis, Cissus and Cannabis Species by LC-MS Based Metabolomics and Antioxidant Assays
Molecules 2014, 19(9), 14004-14021; https://doi.org/10.3390/molecules190914004
Received: 10 June 2014 / Revised: 14 August 2014 / Accepted: 27 August 2014 / Published: 5 September 2014
Cited by 16 | PDF Full-text (1304 KB) | HTML Full-text | XML Full-text
Abstract
UV-C radiation is known to induce metabolic modifications in plants, particularly to secondary metabolite biosynthesis. To assess these modifications from a global and untargeted perspective, the effects of the UV-C radiation of the leaves of three different model plant species, Cissus antarctica Vent
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UV-C radiation is known to induce metabolic modifications in plants, particularly to secondary metabolite biosynthesis. To assess these modifications from a global and untargeted perspective, the effects of the UV-C radiation of the leaves of three different model plant species, Cissus antarctica Vent. (Vitaceae), Vitis vinifera L. (Vitaceae) and Cannabis sativa L. (Cannabaceae), were evaluated by an LC-HRMS-based metabolomic approach. The approach enabled the detection of significant metabolite modifications in the three species studied. For all species, clear modifications of phenylpropanoid metabolism were detected that led to an increased level of stilbene derivatives. Interestingly, resveratrol and piceid levels were strongly induced by the UV-C treatment of C. antarctica leaves. In contrast, both flavonoids and stilbene polymers were upregulated in UV-C-treated Vitis leaves. In Cannabis, important changes in cinnamic acid amides and stilbene-related compounds were also detected. Overall, our results highlighted phytoalexin induction upon UV-C radiation. To evaluate whether UV-C stress radiation could enhance the biosynthesis of bioactive compounds, the antioxidant activity of extracts from control and UV-C-treated leaves was measured. The results showed increased antioxidant activity in UV-C-treated V. vinifera extracts. Full article
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Open AccessArticle Effects of Endogenous Signals and Fusarium oxysporum on the Mechanism Regulating Genistein Synthesis and Accumulation in Yellow Lupine and Their Impact on Plant Cell Cytoskeleton
Molecules 2014, 19(9), 13392-13421; https://doi.org/10.3390/molecules190913392
Received: 26 April 2014 / Revised: 7 August 2014 / Accepted: 18 August 2014 / Published: 29 August 2014
Cited by 11 | PDF Full-text (5565 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The aim of the study was to examine cross-talk interactions of soluble sugars (sucrose, glucose and fructose) and infection caused by Fusarium oxysporum f.sp. lupini on the synthesis of genistein in embryo axes of Lupinus luteus L.cv. Juno. Genistein is a free aglycone,
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The aim of the study was to examine cross-talk interactions of soluble sugars (sucrose, glucose and fructose) and infection caused by Fusarium oxysporum f.sp. lupini on the synthesis of genistein in embryo axes of Lupinus luteus L.cv. Juno. Genistein is a free aglycone, highly reactive and with the potential to inhibit fungal infection and development of plant diseases. As signal molecules, sugars strongly stimulated accumulation of isoflavones, including genistein, and the expression of the isoflavonoid biosynthetic genes. Infection significantly enhanced the synthesis of genistein and other isoflavone aglycones in cells of embryo axes of yellow lupine with high endogenous sugar levels. The activity of β-glucosidase, the enzyme that releases free aglycones from their glucoside bindings, was higher in the infected tissues than in the control ones. At the same time, a very strong generation of the superoxide anion radical was observed in tissues with high sugar contents already in the initial stage of infection. During later stages after inoculation, a strong generation of semiquinone radicals was observed, which level was relatively higher in tissues deficient in sugars than in those with high sugar levels. Observations of actin and tubulin cytoskeletons in cells of infected embryo axes cultured on the medium with sucrose, as well as the medium without sugar, showed significant differences in their organization. Full article
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Open AccessArticle Effectiveness of Phenolic Compounds against Citrus Green Mould
Molecules 2014, 19(8), 12500-12508; https://doi.org/10.3390/molecules190812500
Received: 4 May 2014 / Revised: 31 July 2014 / Accepted: 1 August 2014 / Published: 18 August 2014
Cited by 15 | PDF Full-text (666 KB) | HTML Full-text | XML Full-text
Abstract
Stored citrus fruit suffer huge losses because of the development of green mould caused by Penicillium digitatum. Usually synthetic fungicides are employed to control this disease, but their use is facing some obstacles, such public concern about possible adverse effects on human
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Stored citrus fruit suffer huge losses because of the development of green mould caused by Penicillium digitatum. Usually synthetic fungicides are employed to control this disease, but their use is facing some obstacles, such public concern about possible adverse effects on human and environmental health and the development of resistant pathogen populations. In the present study quercetin, scopoletin and scoparone—phenolic compounds present in several agricultural commodities and associated with response to stresses—were firstly tested in vitro against P. digitatum and then applied in vivo on oranges cv. Navelina. Fruits were wound-treated (100 µg), pathogen-inoculated, stored and surveyed for disease incidence and severity. Although only a minor (≤13%) control effect on P. digitatum growth was recorded in vitro, the in vivo trial results were encouraging. In fact, on phenolic-treated oranges, symptoms appeared at 6 days post-inoculation (DPI), i.e., with a 2 day-delay as compared to the untreated control. Moreover, at 8 DPI, quercetin, scopoletin, and scoparone significantly reduced disease incidence and severity by 69%–40% and 85%–70%, respectively, as compared to the control. At 14 DPI, scoparone was the most active molecule. Based on the results, these compounds might represent an interesting alternative to synthetic fungicides. Full article
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Open AccessReview Maslinic Acid, a Natural Phytoalexin-Type Triterpene from Olives — A Promising Nutraceutical?
Molecules 2014, 19(8), 11538-11559; https://doi.org/10.3390/molecules190811538
Received: 20 June 2014 / Revised: 21 July 2014 / Accepted: 23 July 2014 / Published: 4 August 2014
Cited by 38 | PDF Full-text (475 KB) | HTML Full-text | XML Full-text
Abstract
Maslinic acid is a pentacyclic triterpene found in a variety of natural sources, ranging from herbal remedies used in traditional Asian medicine to edible vegetables and fruits present in the Mediterranean diet. In recent years, several studies have proved that maslinic acid exerts
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Maslinic acid is a pentacyclic triterpene found in a variety of natural sources, ranging from herbal remedies used in traditional Asian medicine to edible vegetables and fruits present in the Mediterranean diet. In recent years, several studies have proved that maslinic acid exerts a wide range of biological activities, i.e. antitumor, antidiabetic, antioxidant, cardioprotective, neuroprotective, antiparasitic and growth-stimulating. Experimental models used for the assessment of maslinic acid effects include established cell lines, which have been often used to elucidate the underlying mechanisms of action, and also animal models of different disorders, which have confirmed the effects of the triterpene in vivo. Overall, and supported by the lack of adverse effects in mice, the results provide evidence of the potential of maslinic acid as a nutraceutical, not only for health promotion, but also as a therapeutic adjuvant in the treatment of several disorders. Full article
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Open AccessArticle Analysis on Blast Fungus-Responsive Characters of a Flavonoid Phytoalexin Sakuranetin; Accumulation in Infected Rice Leaves, Antifungal Activity and Detoxification by Fungus
Molecules 2014, 19(8), 11404-11418; https://doi.org/10.3390/molecules190811404
Received: 3 April 2014 / Revised: 17 July 2014 / Accepted: 23 July 2014 / Published: 4 August 2014
Cited by 21 | PDF Full-text (3475 KB) | HTML Full-text | XML Full-text
Abstract
To understand the role of the rice flavonoid phytoalexin (PA) sakuranetin for blast resistance, the fungus-responsive characteristics were studied. Young rice leaves in a resistant line exhibited hypersensitive reaction (HR) within 3 days post inoculation (dpi) of a spore suspension, and an increase
[...] Read more.
To understand the role of the rice flavonoid phytoalexin (PA) sakuranetin for blast resistance, the fungus-responsive characteristics were studied. Young rice leaves in a resistant line exhibited hypersensitive reaction (HR) within 3 days post inoculation (dpi) of a spore suspension, and an increase in sakuranetin was detected at 3 dpi, increasing to 4-fold at 4 dpi. In the susceptible line, increased sakuranetin was detected at 4 dpi, but not at 3 dpi, by which a large fungus mass has accumulated without HR. Induced expression of a PA biosynthesis gene OsNOMT for naringenin 7-O-methyltransferase was found before accumulation of sakuranetin in both cultivars. The antifungal activity of sakuranetin was considerably higher than that of the major rice diterpenoid PA momilactone A in vitro and in vivo under similar experimental conditions. The decrease and detoxification of sakuranetin were detected in both solid and liquid mycelium cultures, and they took place slower than those of momilactone A. Estimated local concentration of sakuranetin at HR lesions was thought to be effective for fungus restriction, while that at enlarged lesions in susceptible rice was insufficient. These results indicate possible involvement of sakuranetin in blast resistance and its specific relation to blast fungus. Full article
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Open AccessArticle ROS-Dependent Antiproliferative Effect of Brassinin Derivative Homobrassinin in Human Colorectal Cancer Caco2 Cells
Molecules 2014, 19(8), 10877-10897; https://doi.org/10.3390/molecules190810877
Received: 30 April 2014 / Revised: 17 July 2014 / Accepted: 18 July 2014 / Published: 25 July 2014
Cited by 20 | PDF Full-text (3727 KB) | HTML Full-text | XML Full-text
Abstract
This study was designed to examine the in vitro antiproliferative effect of brassinin and its derivatives on human cancer cell lines. Among seven tested compounds, homobrassinin (K1; N-[2-(indol-3-yl)ethyl]-S-methyldithiocarbamate) exhibited the most potent activity with IC50 = 8.0 μM in human
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This study was designed to examine the in vitro antiproliferative effect of brassinin and its derivatives on human cancer cell lines. Among seven tested compounds, homobrassinin (K1; N-[2-(indol-3-yl)ethyl]-S-methyldithiocarbamate) exhibited the most potent activity with IC50 = 8.0 μM in human colorectal Caco2 cells and was selected for further studies. The flow cytometric analysis revealed a K1-induced increase in the G2/M phase associated with dysregulation of α-tubulin, α1-tubulin and β5-tubulin expression. These findings suggest that the inhibitory effect of K1 can be mediated via inhibition of microtubule formation. Furthermore, simultaneously with G2/M arrest, K1 also increased population of cells with sub-G1 DNA content which is considered to be a marker of apoptotic cell death. Apoptosis was also confirmed by annexin V/PI double staining, DNA fragmentation assay and chromatin condensation assay. The apoptosis was associated with the loss of mitochondrial membrane potential (MMP), caspase-3 activation as well as intracellular reactive oxygen species (ROS) production. Moreover, the antioxidant Trolox blocked ROS production, changes in MMP and decreased K1 cytotoxicity, which confirmed the important role of ROS in cell apoptosis. Taken together, our data demonstrate that K1 induces ROS-dependent apoptosis in Caco2 cells and provide the rationale for further in vivo anticancer investigation. Full article
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Open AccessArticle Transcriptional Responses of the Bdtf1-Deletion Mutant to the Phytoalexin Brassinin in the Necrotrophic Fungus Alternaria brassicicola
Molecules 2014, 19(8), 10717-10732; https://doi.org/10.3390/molecules190810717
Received: 8 May 2014 / Revised: 9 July 2014 / Accepted: 10 July 2014 / Published: 24 July 2014
Cited by 6 | PDF Full-text (1167 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Brassica species produce the antifungal indolyl compounds brassinin and its derivatives, during microbial infection. The fungal pathogen Alternaria brassicicola detoxifies brassinin and possibly its derivatives. This ability is an important property for the successful infection of brassicaceous plants. Previously, we identified a transcription
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Brassica species produce the antifungal indolyl compounds brassinin and its derivatives, during microbial infection. The fungal pathogen Alternaria brassicicola detoxifies brassinin and possibly its derivatives. This ability is an important property for the successful infection of brassicaceous plants. Previously, we identified a transcription factor, Bdtf1, essential for the detoxification of brassinin and full virulence. To discover genes that encode putative brassinin-digesting enzymes, we compared gene expression profiles between a mutant strain of the transcription factor and wild-type A. brassicicola under two different experimental conditions. A total of 170 and 388 genes were expressed at higher levels in the mutants than the wild type during the infection of host plants and saprophytic growth in the presence of brassinin, respectively. In contrast, 93 and 560 genes were expressed, respectively, at lower levels in the mutant than the wild type under the two conditions. Fifteen of these genes were expressed at lower levels in the mutant than in the wild type under both conditions. These genes were assumed to be important for the detoxification of brassinin and included Bdtf1 and 10 putative enzymes. This list of genes provides a resource for the discovery of enzyme-coding genes important in the chemical modification of brassinin. Full article
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Open AccessArticle MALDI Mass Spectrometry Imaging for the Simultaneous Location of Resveratrol, Pterostilbene and Viniferins on Grapevine Leaves
Molecules 2014, 19(7), 10587-10600; https://doi.org/10.3390/molecules190710587
Received: 4 May 2014 / Revised: 1 July 2014 / Accepted: 16 July 2014 / Published: 21 July 2014
Cited by 15 | PDF Full-text (739 KB) | HTML Full-text | XML Full-text
Abstract
To investigate the in-situ response to a stress, grapevine leaves have been subjected to mass spectrometry imaging (MSI) experiments. The Matrix Assisted Laser Desorption/Ionisation (MALDI) approach using different matrices has been evaluated. Among all the tested matrices, the 2,5-dihydroxybenzoic acid (DHB) was found
[...] Read more.
To investigate the in-situ response to a stress, grapevine leaves have been subjected to mass spectrometry imaging (MSI) experiments. The Matrix Assisted Laser Desorption/Ionisation (MALDI) approach using different matrices has been evaluated. Among all the tested matrices, the 2,5-dihydroxybenzoic acid (DHB) was found to be the most efficient matrix allowing a broader range of detected stilbene phytoalexins. Resveratrol, but also more toxic compounds against fungi such as pterostilbene and viniferins, were identified and mapped. Their spatial distributions on grapevine leaves irradiated by UV show their specific colocation around the veins. Moreover, MALDI MSI reveals that resveratrol (and piceids) and viniferins are not specifically located on the same area when leaves are infected by Plasmopara viticola. Results obtained by MALDI mass spectrometry imaging demonstrate that this technique would be essential to improve the level of knowledge concerning the role of the stilbene phytoalexins involved in a stress event. Full article
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Open AccessReview Red Card for Pathogens: Phytoalexins in Sorghum and Maize
Molecules 2014, 19(7), 9114-9133; https://doi.org/10.3390/molecules19079114
Received: 19 May 2014 / Revised: 26 June 2014 / Accepted: 26 June 2014 / Published: 30 June 2014
Cited by 14 | PDF Full-text (1077 KB) | HTML Full-text | XML Full-text
Abstract
Cereal crop plants such as maize and sorghum are constantly being attacked by a great variety of pathogens that cause large economic losses. Plants protect themselves against pathogens by synthesizing antimicrobial compounds, which include phytoalexins. In this review we summarize the current knowledge
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Cereal crop plants such as maize and sorghum are constantly being attacked by a great variety of pathogens that cause large economic losses. Plants protect themselves against pathogens by synthesizing antimicrobial compounds, which include phytoalexins. In this review we summarize the current knowledge on phytoalexins produced by sorghum (luteolinidin, apigeninidin) and maize (zealexin, kauralexin, DIMBOA and HDMBOA). For these molecules, we highlight biosynthetic pathways, known intermediates, proposed enzymes, and mechanisms of elicitation. Finally, we discuss the involvement of phytoalexins in plant resistance and their possible application in technology, medicine and agriculture. For those whose world is round we tried to set the scene in the context of a hypothetical football game in which pathogens fight with phytoalexins on the different playing fields provided by maize and sorghum. Full article
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Open AccessArticle Inhibition of Cancer Derived Cell Lines Proliferation by Synthesized Hydroxylated Stilbenes and New Ferrocenyl-Stilbene Analogs. Comparison with Resveratrol
Molecules 2014, 19(6), 7850-7868; https://doi.org/10.3390/molecules19067850
Received: 29 April 2014 / Revised: 27 May 2014 / Accepted: 28 May 2014 / Published: 11 June 2014
Cited by 11 | PDF Full-text (552 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Further advances in understanding the mechanism of action of resveratrol and its application require new analogs to identify the structural determinants for the cell proliferation inhibition potency. Therefore, we synthesized new trans-resveratrol derivatives by using the Wittig and Heck methods, thus modifying
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Further advances in understanding the mechanism of action of resveratrol and its application require new analogs to identify the structural determinants for the cell proliferation inhibition potency. Therefore, we synthesized new trans-resveratrol derivatives by using the Wittig and Heck methods, thus modifying the hydroxylation and methoxylation patterns of the parent molecule. Moreover, we also synthesized new ferrocenylstilbene analogs by using an original protective group in the Wittig procedure. By performing cell proliferation assays we observed that the resveratrol derivatives show inhibition on the human colorectal tumor SW480 cell line. On the other hand, cell viability/cytotoxicity assays showed a weaker effects on the human hepatoblastoma HepG2 cell line. Importantly, the lack of effect on non-tumor cells (IEC18 intestinal epithelium cells) demonstrates the selectivity of these molecules for cancer cells. Here, we show that the numbers and positions of hydroxy and methoxy groups are crucial for the inhibition efficacy. In addition, the presence of at least one phenolic group is essential for the antitumoral activity. Moreover, in the series of ferrocenylstilbene analogs, the presence of a hidden phenolic function allows for a better solubilization in the cellular environment and significantly increases the antitumoral activity. Full article
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Open AccessArticle Antimicrobial Activity of Resveratrol Analogues
Molecules 2014, 19(6), 7679-7688; https://doi.org/10.3390/molecules19067679
Received: 25 April 2014 / Revised: 3 June 2014 / Accepted: 5 June 2014 / Published: 10 June 2014
Cited by 16 | PDF Full-text (519 KB) | HTML Full-text | XML Full-text
Abstract
Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13
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Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of activity ranging from low to high. Six of them, including the most active ones, were subsequently tested on the development of Botrytis cinerea (fungus responsible for grey mold). The results obtained allowed us to identify the most active stilbenes against both grapevine pathogens, to compare the antimicrobial activity of the evaluated series of stilbenes, and to discuss the relationship between their chemical structure (number and position of methoxy and hydroxy groups) and antimicrobial activity. Full article
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Open AccessArticle Regulation of Plant Immunity through Modulation of Phytoalexin Synthesis
Molecules 2014, 19(6), 7480-7496; https://doi.org/10.3390/molecules19067480
Received: 15 April 2014 / Revised: 29 May 2014 / Accepted: 30 May 2014 / Published: 6 June 2014
Cited by 9 | PDF Full-text (458 KB) | HTML Full-text | XML Full-text
Abstract
Soybean hairy roots transformed with the resveratrol synthase and resveratrol oxymethyl transferase genes driven by constitutive Arabidopsis actin and CsVMV promoters were characterized. Transformed hairy roots accumulated glycoside conjugates of the stilbenic compound resveratrol and the related compound pterostilbene, which are normally not
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Soybean hairy roots transformed with the resveratrol synthase and resveratrol oxymethyl transferase genes driven by constitutive Arabidopsis actin and CsVMV promoters were characterized. Transformed hairy roots accumulated glycoside conjugates of the stilbenic compound resveratrol and the related compound pterostilbene, which are normally not synthesized by soybean plants. Expression of the non-native stilbenic phytoalexin synthesis in soybean hairy roots increased their resistance to the soybean pathogen Rhizoctonia solani. The expression of the AhRS3 gene resulted in 20% to 50% decreased root necrosis compared to that of untransformed hairy roots. The expression of two genes, the AhRS3 and ROMT, required for pterostilbene synthesis in soybean, resulted in significantly lower root necrosis (ranging from 0% to 7%) in transgenic roots than in untransformed hairy roots that had about 84% necrosis. Overexpression of the soybean prenyltransferase (dimethylallyltransferase) G4DT gene in soybean hairy roots increased accumulation of the native phytoalexin glyceollin resulting in decreased root necrosis. Full article
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Open AccessReview Resveratrol and Calcium Signaling: Molecular Mechanisms and Clinical Relevance
Molecules 2014, 19(6), 7327-7340; https://doi.org/10.3390/molecules19067327
Received: 16 April 2014 / Revised: 23 May 2014 / Accepted: 23 May 2014 / Published: 5 June 2014
Cited by 23 | PDF Full-text (250 KB) | HTML Full-text | XML Full-text
Abstract
Resveratrol is a naturally occurring compound contributing to cellular defense mechanisms in plants. Its use as a nutritional component and/or supplement in a number of diseases, disorders, and syndromes such as chronic diseases of the central nervous system, cancer, inflammatory diseases, diabetes, and
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Resveratrol is a naturally occurring compound contributing to cellular defense mechanisms in plants. Its use as a nutritional component and/or supplement in a number of diseases, disorders, and syndromes such as chronic diseases of the central nervous system, cancer, inflammatory diseases, diabetes, and cardiovascular diseases has prompted great interest in the underlying molecular mechanisms of action. The present review focuses on resveratrol, specifically its isomer trans-resveratrol, and its effects on intracellular calcium signaling mechanisms. As resveratrol’s mechanisms of action are likely pleiotropic, its effects and interactions with key signaling proteins controlling cellular calcium homeostasis are reviewed and discussed. The clinical relevance of resveratrol’s actions on excitable cells, transformed or cancer cells, immune cells and retinal pigment epithelial cells are contrasted with a review of the molecular mechanisms affecting calcium signaling proteins on the plasma membrane, cytoplasm, endoplasmic reticulum, and mitochondria. The present review emphasizes the correlation between molecular mechanisms of action that have recently been identified for resveratrol and their clinical implications. Full article
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Open AccessArticle Camalexin-Induced Apoptosis in Prostate Cancer Cells Involves Alterations of Expression and Activity of Lysosomal Protease Cathepsin D
Molecules 2014, 19(4), 3988-4005; https://doi.org/10.3390/molecules19043988
Received: 7 January 2014 / Revised: 5 March 2014 / Accepted: 5 March 2014 / Published: 2 April 2014
Cited by 12 | PDF Full-text (2117 KB) | HTML Full-text | XML Full-text
Abstract
Camalexin, the phytoalexin produced in the model plant Arabidopsis thaliana, possesses antiproliferative and cancer chemopreventive effects. We have demonstrated that the cytostatic/cytotoxic effects of camalexin on several prostate cancer (PCa) cells are due to oxidative stress. Lysosomes are vulnerable organelles to Reactive
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Camalexin, the phytoalexin produced in the model plant Arabidopsis thaliana, possesses antiproliferative and cancer chemopreventive effects. We have demonstrated that the cytostatic/cytotoxic effects of camalexin on several prostate cancer (PCa) cells are due to oxidative stress. Lysosomes are vulnerable organelles to Reactive Oxygen Species (ROS)-induced injuries, with the potential to initiate and or facilitate apoptosis subsequent to release of proteases such as cathepsin D (CD) into the cytosol. We therefore hypothesized that camalexin reduces cell viability in PCa cells via alterations in expression and activity of CD. Cell viability was evaluated by MTS cell proliferation assay in LNCaP and ARCaP Epithelial (E) cells, and their respective aggressive sublines C4-2 and ARCaP Mesenchymal (M) cells, whereby the more aggressive PCa cells (C4-2 and ARCaPM) displayed greater sensitivity to camalexin treatments than the lesser aggressive cells (LNCaP and ARCaPE). Immunocytochemical analysis revealed CD relocalization from the lysosome to the cytosol subsequent to camalexin treatments, which was associated with increased protein expression of mature CD; p53, a transcriptional activator of CD; BAX, a downstream effector of CD, and cleaved PARP, a hallmark for apoptosis. Therefore, camalexin reduces cell viability via CD and may present as a novel therapeutic agent for treatment of metastatic prostate cancer cells. Full article
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Open AccessReview Natural Products from the Genus Tephrosia
Molecules 2014, 19(2), 1432-1458; https://doi.org/10.3390/molecules19021432
Received: 10 December 2013 / Revised: 2 January 2014 / Accepted: 13 January 2014 / Published: 27 January 2014
Cited by 18 | PDF Full-text (541 KB) | HTML Full-text | XML Full-text
Abstract
The genus Tephrosia, belonging to the Leguminosae family, is a large pantropical genus of more than 350 species, many of which have important traditional uses in agriculture. This review not only outlines the source, chemistry and biological evaluations of natural products from
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The genus Tephrosia, belonging to the Leguminosae family, is a large pantropical genus of more than 350 species, many of which have important traditional uses in agriculture. This review not only outlines the source, chemistry and biological evaluations of natural products from the genus Tephrosia worldwide that have appeared in literature from 1910 to December 2013, but also covers work related to proposed biosynthetic pathways and synthesis of some natural products from the genus Tephrosia, with 105 citations and 168 new compounds. Full article
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