Special Issue "Identification and Functional Characterization of Plant Toxins"

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Plant Toxins".

Deadline for manuscript submissions: closed (31 December 2020).

Special Issue Editors

Prof. Dr. Sabino Aurelio Bufo
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Guest Editor
Department of Science, University of Basilicata, Potenza, Italy
Interests: pharmaceuticals from plants and microorganisms; chemistry of natural substances in vegetables and soil; plant secondary metabolites; mass spectrometry
Special Issues and Collections in MDPI journals
Prof. Dr. Zbigniew Adamski
E-Mail Website
Guest Editor
Department of Animal Physiology and Development / Electron and Confocal Microscope Laboratory, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
Interests: lethal and sub-lethal effects of plant-derived substances and their possible application as insecticides and nematicides; effects of alkaloids at cell and tissue level; alkaloid-procured lethality, altered fecundity and fertility, and morphological malformations of tested organisms
Special Issues and Collections in MDPI journals
Dr. Luigi Milella
E-Mail Website1 Website2 Website3
Guest Editor
Department of Science, University of Basilicata, Potenza, Italy
Interests: secondary metabolite isolation; structural determination; oxidative stress; nutraceuticals; bioactive molecules; cholinesterase inhibitory activity; Alzheimer’s disease; cytotoxic effects
Special Issues and Collections in MDPI journals
Prof. Dr. Laura Scrano
E-Mail Website
Guest Editor
Dipartimento delle Culture Europee e del Mediterraneo, Università degli Studi della Basilicata, Potenza, Italy
Interests: pharmaceuticals from plants and microorganisms; chemistry of natural substances in vegetables and soil; plant secondary metabolites; mass spectrometry
Special Issues and Collections in MDPI journals

Special Issue Information

Given their primordial origin, plants have learned to implement biochemical strategies that allow them to produce defence substances that they have been refined over millions of years of evolution. Unable to move, the strategy that plants have chosen to defend themselves from their herbivorous predators is to produce poisonous substances and store them in their own tissues. Some have an unpleasant taste or smell, with a repellent effect on the animals that eat them. Others are irritating or toxic at high concentrations, but some can be lethal to large animals—such as humans, even in small doses. There are plants that have entered history for their ability to kill, and others that we have learned to manage and to obtain substances to be used as medicines. This Special issue Invites you to report on the identification and functional characterization of the toxic substances produced by plants. Methodological studies, functional investigations, and insights are welcome, as are reviews providing highlights of the most significant research results of the last 5–10 years.

Prof. Dr. Sabino Aurelio Bufo
Prof. Dr. Zbigniew Adamski
Dr. Luigi Milella
Dr. Laura Scrano
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a double-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • plant toxins
  • analytical methods
  • identification
  • functional characterisation
  • evolution
  • plant defence
  • plant medicine
  • herbivorous
  • poisonous substances

Published Papers (9 papers)

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Editorial

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Editorial
Identification and Functional Characterization of Plant Toxins
Toxins 2021, 13(3), 228; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13030228 - 22 Mar 2021
Viewed by 537
Abstract
The evolutionary arms race between plants and herbivores has led, over millions of years, to the production of many substances that prevent plants from being over-eaten by plant-feeding animals [...] Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)

Research

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Article
Rapid, Sensitive and Reliable Ricin Identification in Serum Samples Using LC–MS/MS
Toxins 2021, 13(2), 79; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13020079 - 22 Jan 2021
Cited by 6 | Viewed by 772
Abstract
Ricin, a protein derived from the seeds of the castor bean plant (Ricinus communis), is a highly lethal toxin that inhibits protein synthesis, resulting in cell death. The widespread availability of ricin, its ease of extraction and its extreme toxicity make [...] Read more.
Ricin, a protein derived from the seeds of the castor bean plant (Ricinus communis), is a highly lethal toxin that inhibits protein synthesis, resulting in cell death. The widespread availability of ricin, its ease of extraction and its extreme toxicity make it an ideal agent for bioterrorism and self-poisoning. Thus, a rapid, sensitive and reliable method for ricin identification in clinical samples is required for applying appropriate and timely medical intervention. However, this goal is challenging due to the low predicted toxin concentrations in bio-fluids, accompanied by significantly high matrix interferences. Here we report the applicability of a sensitive, selective, rapid, simple and antibody-independent assay for the identification of ricin in body fluids using mass spectrometry (MS). The assay involves lectin affinity capturing of ricin by easy-to-use commercial lactose–agarose (LA) beads, following by tryptic digestion and selected marker identification using targeted LC–MS/MS (Multiple Reaction Monitoring) analysis. This enables ricin identification down to 5 ng/mL in serum samples in 2.5 h. To validate the assay, twenty-four diverse naive- or ricin-spiked serum samples were evaluated, and both precision and accuracy were determined. A real-life test of the assay was successfully executed in a challenging clinical scenario, where the toxin was identified in an abdominal fluid sample taken 72 h post self-injection of castor beans extraction in an eventual suicide case. This demonstrates both the high sensitivity of this assay and the extended identification time window, compared to similar events that were previously documented. This method developed for ricin identification in clinical samples has the potential to be applied to the identification of other lectin toxins. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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Article
Solanum nigrum Fruit Extract Increases Toxicity of Fenitrothion—A Synthetic Insecticide, in the Mealworm Beetle Tenebrio molitor Larvae
Toxins 2020, 12(10), 612; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12100612 - 24 Sep 2020
Cited by 3 | Viewed by 862
Abstract
Synthetic insecticides are widely used for crop protection both in the fields and in the food stored facilities. Due to their toxicity, and assumptions of Integrated Pest Management, we conducted two independent experiments, where we studied the influence of Solanum nigrum unripe fruit [...] Read more.
Synthetic insecticides are widely used for crop protection both in the fields and in the food stored facilities. Due to their toxicity, and assumptions of Integrated Pest Management, we conducted two independent experiments, where we studied the influence of Solanum nigrum unripe fruit extract on the toxicity of an organophosphorus insecticide fenitrothion. In the first variant of the experiment, Tenebrio molitor larvae were fed with blended fenitrothion (LC50) and the extract in four concentrations (0.01, 0.1, 1 and 10%) in ratio 1:1 for 3 days. In the second variant, a two-day application of fenitrothion (LC40) was preceded by a one-day extract treatment. The first variant did not show any increase in lethality compared to fenitrothion; however, ultrastructure observations exhibited swollen endoplasmic reticulum (ER) membranes in the midgut and nuclear and cellular membranes in the fat body, after application of blended fenitrothion and extract. An increased amount of heterochromatin in the fat body was observed, too. In the second variant, pre-treatment of the extract increased the lethality of larvae, decreased the level of glycogen and lipids in the fat body and disrupted integrity of midgut cellular membranes. S. nigrum extract, applied prior to fenitrothion treatment can be a factor increasing fenitrothion toxicity in T. molitor larvae. Thus, this strategy may lead to decreased emission of synthetic insecticides to the environment. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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Article
Determination of Cytisine and N-Methylcytisine from Selected Plant Extracts by High-Performance Liquid Chromatography and Comparison of Their Cytotoxic Activity
Toxins 2020, 12(9), 557; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12090557 - 29 Aug 2020
Cited by 1 | Viewed by 1148
Abstract
Quinolizidine alkaloids exhibit various forms of biological activity. A lot of them were found in the Leguminosae family, including Laburnum and Genista. The aim of the study was the optimization of a chromatographic system for the analysis of cytisine and N-methylcytisine in [...] Read more.
Quinolizidine alkaloids exhibit various forms of biological activity. A lot of them were found in the Leguminosae family, including Laburnum and Genista. The aim of the study was the optimization of a chromatographic system for the analysis of cytisine and N-methylcytisine in various plant extracts as well as an investigation of the cytotoxic activities of selected alkaloids and plant extracts obtained from Laburnum anagyroides, Laburnum anagyroides L. quercifolium, Laburnum alpinum, Laburnum watereri, Genista germanica, and Genista tinctoria against various cancer cell lines. The determination of investigated compounds was performed by High Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD), while High Performance Liquid Chromatography coupled with Quadrupole Time-of-Flight–Mass Spectrometry (HPLC-QTOF-MS) was applied for the qualitative analysis of plant extracts. The retention, separation selectivity, peaks shape, and systems efficiency obtained for cytisine and N-methylcytisine in different chromatographic systems were compared. The application of columns with alkylbonded and phenyl stationary phases led to a very weak retention of cytisine and N-methylcytisine, even when the mobile phases containing only 5% of organic modifiers were used. The strongest retention was observed when hydrophilic interaction chromatography (HILIC) or especially when ion exchange chromatography (IEC) were applied. The most optimal system in terms of alkaloid retention, peak shape, and system efficiency containing an strong cation exchange (SCX) stationary phase and a mobile phase consisted of 25% acetonitrile and formic buffer at pH 4.0 was applied for investigating alkaloids analysis in plant extracts. Cytotoxic properties of the investigated plant extracts as well as cytisine and N-methylcytisine were examined using human tongue squamous carcinoma cells (SCC-25), human pharyngeal squamous carcinoma cells (FaDu), human triple-negative breast adenocarcinoma cell line (MDA-MB-231), and human breast adenocarcinoma cell line (MCF-7). The highest cytotoxic activity against FaDu, MCF-7, and MDA-MB cancer cell lines was observed after applying the Genista germanica leaves extract. In contrast, the highest cytotoxic activity against SCC-25 cell line was obtained after treating with the seed extract of Laburnum watereri. The investigated plant extracts exhibit significant cytotoxicity against the tested human cancer cell lines and seem to be promising for further research on its anticancer activity. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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Article
Identification and Structure Elucidation of Epoxyjanthitrems from Lolium perenne Infected with the Endophytic Fungus Epichloë festucae var. lolii and Determination of the Tremorgenic and Anti-Insect Activity of Epoxyjanthitrem I
Toxins 2020, 12(8), 526; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12080526 - 17 Aug 2020
Cited by 5 | Viewed by 1098
Abstract
Epoxyjanthitrems I–IV (14) and epoxyjanthitriol (5) were isolated from seed of perennial ryegrass (Lolium perenne) infected with the endophytic fungus Epichloë festucae var. lolii. Although structures for epoxyjanthitrems I–IV have previously been proposed in the [...] Read more.
Epoxyjanthitrems I–IV (14) and epoxyjanthitriol (5) were isolated from seed of perennial ryegrass (Lolium perenne) infected with the endophytic fungus Epichloë festucae var. lolii. Although structures for epoxyjanthitrems I–IV have previously been proposed in the literature, this is the first report of a full structural elucidation yielding NMR (Nuclear magnetic resonance) assignments for all five epoxyjanthitrem compounds, and additionally, it is the first isolation of epoxyjanthitriol (5). Epoxyjanthitrem I induced tremors in mice and gave a dose dependent reduction in weight gain and feeding for porina (Wiseana cervinata), a common pasture pest in New Zealand. These data suggest that epoxyjanthitrems are involved in the observed effects of the AR37 endophyte on livestock and insect pests. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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Article
Toxic Potential and Metabolic Profiling of Two Australian Biotypes of the Invasive Plant Parthenium Weed (Parthenium hysterophorus L.)
Toxins 2020, 12(7), 447; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12070447 - 10 Jul 2020
Cited by 6 | Viewed by 1389
Abstract
Parthenium weed (Parthenium hysterophorus L.) is an invasive plant species in around 50 countries and a ‘Weed of National Significance’ in Australia. This study investigated the relative toxicity of the leaf, shoot and root extracts of two geographically separate and morphologically distinct [...] Read more.
Parthenium weed (Parthenium hysterophorus L.) is an invasive plant species in around 50 countries and a ‘Weed of National Significance’ in Australia. This study investigated the relative toxicity of the leaf, shoot and root extracts of two geographically separate and morphologically distinct biotypes of parthenium weed in Queensland, Australia. Parthenium weed exhibited higher phytotoxic, cytotoxic and photocytotoxic activity in leaf tissue extracts in contrast to shoot and root. The germination and seedling growth of a dicot species (garden cress) were inhibited more than those of a monocot species (annual ryegrass) using a phytotoxicity bioassay. The cytotoxicity of leaf extracts was assessed in a mouse fibroblast cell suspension assay and increased under high ultraviolet A(UV-A) radiation. A major secondary metabolite, parthenin, was found in abundance in leaf extracts and was positively correlated with cytotoxicity but not with photocytotoxicity or phytotoxicity. Ambrosin and chlorogenic acid were also detected and were positively correlated with germination inhibition and the inhibition of radicle elongation, respectively. In addition, other currently unidentified compounds in the leaf extracts were positively correlated with phytotoxicity, cytotoxicity and photocytotoxicity with two to three molecules strongly correlated in each case. Both parthenium weed biotypes investigated did not differ with respect to their relative toxicity, despite their reported differences in invasive potential in the field. This suggests that secondary chemistry plays a limited role in their invasion success. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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Article
Nematicidal Activity of Stevia rebaudiana (Bertoni) Assisted by Phytochemical Analysis
Toxins 2020, 12(5), 319; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12050319 - 12 May 2020
Cited by 3 | Viewed by 1297
Abstract
To date, there has been great demand for ecofriendly nematicides with beneficial properties to the nematode hosting plants. Great efforts are made towards the chemical characterization of botanical extracts exhibiting nematicidal activity against Meloidogyne spp., but only a small percentage of these [...] Read more.
To date, there has been great demand for ecofriendly nematicides with beneficial properties to the nematode hosting plants. Great efforts are made towards the chemical characterization of botanical extracts exhibiting nematicidal activity against Meloidogyne spp., but only a small percentage of these data are actually used by the chemical industry in order to develop new formulates. On the other hand, the ready to use farmer produced water extracts based on edible plants could be a sustainable and economic solution for low income countries. Herein, we evaluate the nematicidal potential of Stevia rebaudiana grown in Greece against Meloidogyne incognita and Meloidogyne javanica, two most notorious phytoparasitic nematode species causing great losses in tomato cultivation worldwide. In an effort to recycle the plant’s remnants, after leaves selection for commercial use, we use both leaves and wooden stems to test for activity. In vitro tests demonstrate significant paralysis activity of both plant parts’ water extracts against the second-stage juvenile (J2) of the parasites; while, in vivo bioassays demonstrated the substantial efficacy of leaves’ powder (95% at 1 g kg−1) followed by stems. Interestingly, the incorporation of up to 50 g powder/kg of soil is not phytotoxic, which demonstrates the ability to elevate the applied concentration of the nematicidal stevia powder under high inoculum level. Last but not least, the chemical composition analyses using cutting edge analytical methodologies, demonstrated amongst components molecules of already proven nematicidal activity, was exemplified by several flavonoids and essential oil components. Interestingly, and to our knowledge, for the flavonoids, morin and robinin, the anthocyanidin, keracyanin, and a napthalen-2-ol derivative is their first report in Stevia species. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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Review

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Review
Cannabis: A Toxin-Producing Plant with Potential Therapeutic Uses
Toxins 2021, 13(2), 117; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13020117 - 05 Feb 2021
Cited by 6 | Viewed by 1960
Abstract
For thousands of years, Cannabis sativa has been utilized as a medicine and for recreational and spiritual purposes. Phytocannabinoids are a family of compounds that are found in the cannabis plant, which is known for its psychotogenic and euphoric effects; the main psychotropic [...] Read more.
For thousands of years, Cannabis sativa has been utilized as a medicine and for recreational and spiritual purposes. Phytocannabinoids are a family of compounds that are found in the cannabis plant, which is known for its psychotogenic and euphoric effects; the main psychotropic constituent of cannabis is Δ9-tetrahydrocannabinol (Δ9-THC). The pharmacological effects of cannabinoids are a result of interactions between those compounds and cannabinoid receptors, CB1 and CB2, located in many parts of the human body. Cannabis is used as a therapeutic agent for treating pain and emesis. Some cannabinoids are clinically applied for treating chronic pain, particularly cancer and multiple sclerosis-associated pain, for appetite stimulation and anti-emesis in HIV/AIDS and cancer patients, and for spasticity treatment in multiple sclerosis and epilepsy patients. Medical cannabis varies from recreational cannabis in the chemical content of THC and cannabidiol (CBD), modes of administration, and safety. Despite the therapeutic effects of cannabis, exposure to high concentrations of THC, the main compound that is responsible for most of the intoxicating effects experienced by users, could lead to psychological events and adverse effects that affect almost all body systems, such as neurological (dizziness, drowsiness, seizures, coma, and others), ophthalmological (mydriasis and conjunctival hyperemia), cardiovascular (tachycardia and arterial hypertension), and gastrointestinal (nausea, vomiting, and thirst), mainly associated with recreational use. Cannabis toxicity in children is more concerning and can cause serious adverse effects such as acute neurological symptoms (stupor), lethargy, seizures, and even coma. More countries are legalizing the commercial production and sale of cannabis for medicinal use, and some for recreational use as well. Liberalization of cannabis laws has led to increased incidence of toxicity, hyperemesis syndrome, lung disease cardiovascular disease, reduced fertility, tolerance, and dependence with chronic prolonged use. This review focuses on the potential therapeutic effects of cannabis and cannabinoids, as well as the acute and chronic toxic effects of cannabis use on various body systems. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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Review
Biological Activity of Berberine—A Summary Update
Toxins 2020, 12(11), 713; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12110713 - 12 Nov 2020
Cited by 7 | Viewed by 1269
Abstract
Berberine is a plant metabolite belonging to the group of isoquinoline alkaloids with strong biological and pharmacological activity. Currently, berberine is receiving considerable interest due to its anticancer activity based on many biochemical pathways, especially its proapoptotic and anti-inflammatory activity. Therefore, the growing [...] Read more.
Berberine is a plant metabolite belonging to the group of isoquinoline alkaloids with strong biological and pharmacological activity. Currently, berberine is receiving considerable interest due to its anticancer activity based on many biochemical pathways, especially its proapoptotic and anti-inflammatory activity. Therefore, the growing number of papers on berberine demands summarizing the knowledge and research trends. The efficacy of berberine in breast and colon cancers seems to be the most promising aspect. Many papers focus on novel therapeutic strategies based on new formulations or search for new active derivatives. The activity of berberine is very important as regards sensitization and support of anticancer therapy in combination with well-known but in some cases inefficient therapeutics. Currently, the compound is being assessed in many important clinical trials and is one of the most promising and intensively examined natural agents. Full article
(This article belongs to the Special Issue Identification and Functional Characterization of Plant Toxins)
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