The origins of ricin as a biowarfare agent in ancient India

Ricin, a highly potent toxin derived from Ricinus communis, has been recognized as both a therapeutic agent and a bioweapon throughout history. Its toxic mechanism, involving ribosomal inhibition, makes it lethal even in minuscule amounts. Historical references, including the book Arthashastra by Kauṭilya in ancient India (4th century BC), describe its strategic use in warfare, particularly resembling modern day gas attacks. Kauṭilya's text details methods of ricin-based poisoning through inhalation and ingestion, highlighting its early role as a bioweapon. The inclusion of other toxic plants and substances in these formulations reflects a sophisticated understanding of toxicology in antiquity. The use of ricin in modern bioterrorism attempts, along with its potential medical applications in targeted cancer therapies, underscores its dual nature. The persistence of ricin as a potential threat reinforces the need for continued vigilance and historical analysis to inform contemporary biosecurity measures.

The use of adeno-associated vírus-based gene therapy to achieve long-term expression of recombinant neutralizing antibody against ricin

Ricin is a highly toxic plant protein for which there are no specific antidotes. Current prophylactic and emergency treatments for ricin intoxication are limited by the need for prior vaccination and the short half-life of antibody drugs in the circulation. To address these limitations, we developed a novel immunotherapeutic strategy using adeno-associated virus (AAV) gene transfer to achieve prolonged systemic serum levels of immunoglobulins to ricin. In this study, a single administration of rAAV was used to deliver protein immunotherapeutics, and its efficacy in protecting mice against lethal doses of ricin was investigated. The results revealed that the single administration of rAAV three days prior to ricin exposure effectively protected mice from lethal doses of ricin. Remarkably, this protection was sustained for up to 90 days after AAV injection, demonstrating long-term efficacy. Overall, our findings suggest that the rAAV-mediated approach holds promise for both early and long-term prevention of ricin intoxication. The favorable safety profile of this system and its potential for the development of novel ricin antibody therapeutics make it a noteworthy candidate for further exploration and development in the field.

Evaluation of an Electrochemiluminescence Assay for the Rapid Detection of Ricin Toxin

In this article, we detail a comprehensive laboratory evaluation of an immunoassay for the rapid detection of ricin using the Meso Scale Diagnostics Sector PR2 Model 1800. For the assay evaluation, we used inclusivity, exclusivity, and informational panels comprised of extracts of 35 near-neighbor plant cultivar-extracts, 66 lectins, 26 white powders, 16 closely related toxins and proteins/toxoids, and a pool of 30 BioWatch filter extracts. The results show that the Meso Scale Diagnostics ricin detection assay exhibits good sensitivity and specificity with a limit of detection of 1.2 ng/mL. However, the dynamic range of the assay for the quantitation of ricin was limited. We observed a hook effect at higher ricin concentrations, which can lead to potential false negative results. A modification of the assay protocol that incorporates extra wash steps can decrease the hook effect and the potential for false negative results.

Emerging global trends and development in forensic toxicology: A review

This study conducts a comprehensive analysis of forensic toxicology research trends, publication patterns, author's contributions, and collaboration. Utilizing the Scopus database, we scrutinized 3259 articles across 348 journals spanning from 1975 to 2023. Analysis employed diverse software tools such as VOSviewer, RStudio, MS Excel, and MS Access to dissect various publication aspects. We observed a notable surge in publications post-2007, indicating heightened research interest. Leading contributors included the United States, Germany, and Italy, with Logan B.K. emerging as the most prolific author. Forensic Science International stood out as the primary journal, publishing 888 articles and accruing significant citations. Keyword co-occurrences such as "forensic toxicology," "forensic science," and "toxicology" underscored core thematic areas in the field. Moreover, extensive research collaboration, especially among Western nations in Europe, was evident. This study underscores the imperative for enhanced collaboration between developing and developed nations to foster further advancements in forensic science. Strengthened partnerships can catalyze innovation, facilitate knowledge dissemination, and address emerging challenges, thereby propelling the field of forensic toxicology toward new frontiers of discovery and application.

The Search for Antidotes Against Ricin

The castor plant (Ricinus communis) is primarily known for its seeds, which contain a unique fatty acid called ricinoleic acid with several industrial and commercial applications. Castor seeds also contain ricin, a toxin considered a chemical and biological warfare agent. Despite years of investigation, there is still no effective antidote or vaccine available. However, some progress has been made, and the development of an effective treatment may be on the horizon. To provide an updated overview of this issue, we have conducted a comprehensive review of the literature on the current state of research in the fight against ricin. This review is based on the reported research and aims to address the challenges faced by researchers, as well as highlight the most successful cases achieved thus far. Our goal is to encourage the scientific community to continue their efforts in this critical search.

Using plants in forensics: State-of-the-art and prospects

The increasing use of plant evidence in forensic investigations gave rise to a powerful new discipline - Forensic Botany - that analyses micro- or macroscopic plant materials, such as the totality or fragments of an organ (i.e., leaves, stems, seeds, fruits, roots) and tissue (i.e., pollen grains, spores, fibers, cork) or its chemical composition (i. e., secondary metabolites, isotopes, DNA, starch grains). Forensic botanists frequently use microscopy, chemical analysis, and botanical expertise to identify and interpret evidence crucial to solving civil and criminal issues, collaborating in enforcing laws or regulations, and ensuring public health safeguards. The present work comprehensively examines the current state and future potential of Forensic Botany. The first section conveys the critical steps of plant evidence collection, documentation, and preservation, emphasizing the importance of these initial steps in maintaining the integrity of the items. It explores the different molecular analyses, covering the identification of plant species and varieties or cultivars, and discusses the limitations and challenges of these techniques in forensics. The subsequent section covers the diversity of Forensic Botany approaches, examining how plant evidence exposes food and pharmaceutical frauds, uncovers insufficient or erroneous labeling, traces illegal drug trafficking routes, and combats the illegal collection or trade of protected species and derivatives. National and global security issues, including the implications of biological warfare, bioterrorism, and biocrime are addressed, and a review of the contributions of plant evidence in crime scene investigations is provided, synthesizing a comprehensive overview of the diverse facets of Forensic Botany.

Human plasma ricinine quantification by LC-HRMS after micro-solid-phase elution

A rapid, sensitive and specific method for ricinine identification and quantification in plasma has been developed by LC-HRMS. Deuterated ricinine was used as the internal standard. From 100 μL of plasma, ricinine was extracted using micro-solid-phase elution, which allows a reduced extraction time, by eliminating the evaporation step. Eluate is directly injected into the LC-HRMS system. Chromatographic separation was performed using a reverse-phase C₁₈ column with a 4.5 min gradient elution. The method was validated according to European Medicines Agency guidelines. Linearity was verified between 0.25 and 500.0 ng/mL; the maximum precision calculated was 19.9% for the lower limit of quantitation and 9.6% for quality control, and accuracy was within ± 5.6% of the nominal concentrations. Selectivity, carryover, matrix effect and stability were also verified according to European Medicines Agency guidelines. The method allows the rapid and reliable identification of ricin-exposed victims in case of terrorist attacks or poisonings: three intoxication cases are reported.

Theoretical Investigation of Repurposed Drugs Potentially Capable of Binding to the Catalytic Site and the Secondary Binding Pocket of Subunit A of Ricin

Recently, we reported a library of 82 compounds, selected from different databanks through virtual screening and docking studies, and pointed to 6 among them as potential repurposed dual binders to both the catalytic site and the secondary binding pockets of subunit A of ricin (RTA). Here, we report additional molecular modeling studies of an extended list of compounds from the original library. Rounds of flexible docking followed by molecular dynamics simulations and further rounds of MM-PBSA calculations using a more robust protocol, enabled a better investigation of the interactions of these compounds inside RTA, the elucidation of their dynamical behaviors, and updating the list of the most important residues for the ligand binding. Four compounds were pointed as potential repurposed ricin inhibitors that are worth being experimentally investigated.

Non-Lethal Intoxication by Ingestion of 50 Castor Beans: Serial Measurement of Ricinine in Blood, Plasma and Urine

A 30-year-old woman presented to the emergency department 2 days after ingestion of 50 castor beans. Her symptoms on admission were vomiting, diarrhea, abdominal cramps, agitation and anxiety. Initial laboratory tests showed a slightly elevated C-reactive protein and mild liver and kidney dysfunction. The patient was transferred to the medium care unit of our hospital where she was observed for possible organ failure. During the next days, the kidney function improved and liver function started to recover. Four days after admission, the patient was transferred to the psychiatric ward. Urine, serum, plasma and whole-blood samples were analyzed for ricinine using a quantitative LC-MS-MS method. Initial values on admission (serum and urine) were very high in comparison with previously reported cases. Based on these values, the patient was monitored closely in the following days. The patient made a full recovery, and during the course of hospitalization, concentrations of ricinine in plasma/serum, blood and urine gradually declined. The presence of ricinine in a patient's blood or plasma is a proof of castor bean and, hence, ricin exposure. However, based on this case and previously reported cases in literature, we can conclude that no clear correlation can be established between ricinine blood, plasma or urine levels and the severity of the intoxication. Clinicians should be aware of the potential danger of a ricin intoxication, and patients should be monitored closely for several days due to the unpredictable outcome of the intoxication.

Ricin poisoning: A review on contamination source, diagnosis, treatment, prevention and reporting of ricin poisoning

INTRODUCTION

Ricin, a toxic glycoprotein derived from the castor bean plant, is one of the most potent poisons known in the world. Ricin intoxication is a fatal and uncommon medical condition and recently its use as a potential bioterrorism agent has also been reported. This study aims to identify the main characteristics of diagnosed ricin poisoning cases worldwide in order to raise awareness of this toxin among the population and clinicians.

METHODS

A collection of human case studies of ricin intoxication in the world was produced. The databases Pubmed, Sciencedirect and Google Scholar were used to extract articles from January 1980 to June 2020.

RESULTS

Fifty ricin-intoxicated patients worldwide described in the literature have been identified. Most cases were found in Asia (19 cases), Europe (12 cases) and America (15 cases). Intoxication was mostly accidental (37 cases). Intoxication by castor bean is characterized by acute gastroenteritis-like disease as primary manifestations leading to severe fluid and electrolyte imbalance. The mechanism of death was peripheral vascular collapse and progressing multiple organ failure occurring 10h-72h after intoxication. The questioning of patients and family made it possible to retrieve an history of castor seeds or castor oil ingestion Patients received symptomatic treatment consisting mostly to rehydration with intravenous fluids and digestive decontamination performed with activated charcoal and/or gastric lavage within one day after the ingestion, to reduce gastrointestinal absorption of ricin. This decontamination treatment administered early has been very effective. Only six deaths were observed.

DISCUSSION

Currently, no antidote, vaccine, or other specific effective treatment is available for ricin poisoning or prevention. Prompt treatment with supportive care was necessary to limit morbidity and mortality. To date, patient education is essential to prevent this accidental poisoning.

CONCLUSION

Clinicians and health care professionals should have a high level of suspicion when faced with an outbreak of serious respiratory or gastrointestinal illness.

Near-fatal poisoning after ricin injection

OBJECTIVE

To report a near-fatal poisoning after intentional injection of ricin from a castor bean (Ricinus communis) extract.

CASE REPORT

A 21 year-old man self-injected ∼3 mL of a castor bean extract intramuscularly and subcutaneously in the left antecubital fossa. Upon admission to our ED (1 h post-exposure; day 1, D1) he was awake and alert, but complained of mild local pain and showed slight local edema and erythema. He evolved to refractory shock (∼24 h post-exposure) that required the administration of a large volume of fluids and high doses of norepinephrine and vasopressin, mainly from D2 to D4. During this period, he developed clinical and laboratory features compatible with systemic inflammatory response syndrome, multiple organ dysfunction, capillary leak syndrome, rhabdomyolysis, necrotizing fasciitis and possible compartment syndrome. The patient underwent forearm fasciotomy on D4 and there was progressive improvement of the hemodynamic status from D7 onwards. Wound management involved several debridements, broad-spectrum antibiotics and two skin grafts. Major laboratory findings within 12 days post-exposure revealed hypoalbuminemia, proteinuria, thrombocytopenia, leukocytosis and increases in cytokines (IL-6, IL-10 and TNF-α), troponin and creatine kinase. Ricin A-chain (ELISA) was detected in serum up to D3 (peak at 24 h post-exposure), with ∼79% being excreted in the urine within 64 h post-exposure. Ricinine was detected in serum and urine by LC-MS up to D5. A ricin A-chain concentration of 246 µg/mL was found in the seed extract, corresponding to the injection of ∼738 µg of ricin A-chain (∼10.5 µg/kg). The patient was discharged on D71, with limited range of motion and function of the left forearm and hand.

CONCLUSION

Ricin injection resulted in a near-fatal poisoning that evolved with septic shock-like syndrome, multiple organ dysfunction and necrotizing fasciitis, all of which were successfully treated with supportive care.

Identification of novel potential ricin inhibitors by virtual screening, molecular docking, molecular dynamics and MM-PBSA calculations: a drug repurposing approach

Ricin is a potent cytotoxin with no available antidote. Its catalytic subunit, RTA, damages the ribosomal RNA (rRNA) of eukaryotic cells, preventing protein synthesis and eventually leading to cell death. The combination between easiness of obtention and high toxicity turns ricin into a potential weapon for terrorist attacks, urging the need of discovering effective antidotes. On this context, we used computational techniques, in order to identify potential ricin inhibitors among approved drugs. Two libraries were screened by two different docking algorithms, followed by molecular dynamics simulations and MM-PBSA calculations in order to corroborate the docking results. Three drugs were identified as potential ricin inhibitors: deferoxamine, leucovorin and plazomicin. Our calculations showed that these compounds were able to, simultaneously, form hydrogen bonds with residues of the catalytic site and the secondary binding site of RTA, qualifying as potential antidotes against intoxication by ricin.Communicated by Ramaswamy H. Sarma.

Ricin poisoning after oral ingestion of castor beans: A case report and literature review

Introduction

>1000 ricin poisoning cases secondary to intentional castor bean consumption have been reported in the literature since the late 1800s. The lethality of ricin poisoning after oral ingestion is determined by a few factors.

Case report

We present a case that highlights the erratic absorption of ricin after accidental oral ingestion. On admission, the physical examination found a somnolent patient, with miosis, and a generalized abdominal tenderness. Her blood tests showed metabolic acidosis. Thanks to her early management, the discharge was possible three days later.

Discussion

The toxicity of ricin is dependent on the dose delivered and the route of the exposure. Supportive care is the mainstay of treatment. As shown in our case, early management is crucial for a good outcome.

Another umbrella murder? - A rare case of Minamata disease

We report a rare case of fatal intoxication in a 40-year-old man caused by injection of a fluid containing organic mercury, allegedly in an attack with a syringe fixed to the tip of an umbrella. The man suffered from severe neurological symptoms and progressive multiorgan failure and died 10 months later in refractory status epilepticus. Autopsy revealed severe brain atrophy and non-specific kidney damage. Neuropathological examination showed neuronal loss especially in the occipital lobe, distinct granule cell necrosis in the cerebellum and Wallerian degeneration in the brainstem. Postmortem toxicological analysis revealed extremely increased levels of mercury in liver and kidney tissue as well as methylmercury levels in peripheral blood.

A Proof-of-Concept, Two-Tiered Approach for Ricin Detection Using Ambient Mass Spectrometry

Ricin is a naturally occurring, highly potent toxin native to castor bean plants that has recently been used as a biological weapon in cases of bioterrorism and suicide attempts. Difficulties with direct detection arise from large heterogeneities in ricin glycosylation, which leads to markedly different bioactivity, and the fact that carefully developed and laborious sample preparation steps are required to maintain the activity of the protein during analysis. Herein, we present an alternative, two-tiered approach to identify the presence of ricin by detecting ricinoleic acid and ricinine, which are co-extracted with the protein. This direct mass spectrometric-based technique takes as little as 2 minutes, and we determined its sensitivity to be in the parts-per-trillion range. Our method is applicable to paper substrates from suspected contaminated envelopes and biofluids from at-risk patients. The fact that prior sample preparations are not needed in this procedure means that analysis can be performed in the field for emergency cases.

Ricin is a naturally occurring, highly potent toxin native to castor bean plants that has recently been used as a biological weapon in cases of bioterrorism and suicide attempts.

Terrorismo químico: proposta de modelagem de risco envolvendo ricina em eventos de grande visibilidade no Brasil

RESUMO Grandes eventos estão no centro de estratégias terroristas e vem-se repetindo com frequência no âmbito internacional. Durante os últimos anos, o Brasil é palco de megaeventos esportivos; e este ano sediará a Copa do Mundo Fifa Sub-17. Assume-se que a maior exposição, nesses contextos, aumenta a vulnerabilidade ante as ameaças não convencionais, assim, é necessário que o planejamento da segurança brasileira seja apoiado em estudos sobre gestão de risco. Considera-se que um maior conhecimento sobre o tema é o primeiro passo para um sistema de defesa eficiente. A literatura apresenta relatos de episódios de emprego da ricina como arma química. Assim, este estudo objetivou avaliar a probabilidade de risco de um ataque terrorista com ricina, em um modelo matemático. Para isso, foi utilizada a teoria dos jogos e a equação de probabilidade de Major para análise de risco de terrorismo. A escolha da ricina justifica-se pelo fato de se tratar de uma biotoxina de extração relativamente simples, proveniente da mamona, que é uma planta endêmica no território brasileiro. Os parâmetros analisados foram os recursos de ataque, defesa e valor do alvo. A equação de probabilidade foi otimizada para defesa.

Uniformly 15N-Labeled Recombinant Ricin A-Chain as an Internal Retention Time Standard for Increased Confidence in Forensic Identification of Ricin by Untargeted Nanoflow Liquid Chromatography-Tandem Mass Spectrometry

Ricin, a toxic protein from the castor plant, is of forensic and biosecurity interest because of its high toxicity and common occurrence in crimes and attempted crimes. Qualitative methods to detect ricin are therefore needed. Untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics methods are well suited because of their high specificity. Specificity in LC-MS/MS comes from both the LC and MS components. However, modern untargeted proteomics methods often use nanoflow LC, which has less reproducible retention times than standard-flow LC, making it challenging to use retention time as a point of identification in a forensic assay. We address this challenge by using retention times relative to a standard, namely, the uniformly ¹⁵N-labeled ricin A-chain produced recombinantly in a bacterial expression system. This material, added as an internal standard prior to trypsin digestion, produces a stable-isotope-labeled standard for every ricin tryptic peptide in the sample. We show that the MS signals for ¹⁵N and natural isotopic abundance ricin peptides are distinct, with mass shifts that correspond to the numbers of nitrogen atoms in each peptide or fragment. We also show that, as expected, labeled and unlabeled peptides coelute, with relative retention time differences of less than 0.2%.

Lethal Injection of a Castor Bean Extract: Ricinine Quantification as a Marker for Ricin Exposure Using a Validated LC-MS/MS Method

Ricin is a highly toxic agent derived from the castor bean plant (Ricinus communis). Poisoning occurs commonly by oral ingestion of the beans. Injection of ricin is believed to be more lethal. Ricin is a large glycosylated protein difficult to detect in clinical samples. Instead, ricinine, a small alkaloid found in the same beans, is used as surrogate marker for ricin exposure. We describe a simple LC-MS/MS method for the detection of ricinine in serum, blood and urine, validated according to EMA guidelines and successfully applied to patient samples of a suicidal death after injection of a castor bean extract. A 26-year-old man self-presented to the emergency department with severe abdominal cramps and nausea after injection of a castor bean extract. Due to rapid deterioration of his hemodynamic function despite early aggressive fluid resuscitation, he was transferred to ICU. Abdominal cramps worsened and a fulminant diarrhea developed, resulting in hypovolemic shock and cardiorespiratory collapse. Despite full supportive therapy, the patient died approximately 10 hours after injection due to multiple organ failure. Ricinine was quantified by LC-MS/MS after LLE with diethyl ether using ricinine-D3 as internal standard. Six hours after injection, ricinine concentrations in serum and blood were 16.5 and 12.9 ng/mL, respectively, which decreased to 12.4 and 10.6 ng/mL, 4 hours later. The urinary concentration was 81.1 ng/mL 7 hours after injection, which amply exceeded the levels previously reported in similar cases with lethal outcome. Concentrations of ricinine, compatible with a lethal exposure to castor beans, were detected in serum, blood and urine. Ricinine was also found in bile and liver tissue.

A New Method for Extraction and Analysis of Ricin Samples through MALDI-TOF-MS/MS

We report for the first time the efficient use of accelerated solvent extraction (ASE) for extraction of ricin to analytical purposes, followed by the combined use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and MALDI-TOF MS/MS method. That has provided a fast and unambiguous method of ricin identification for in real cases of forensic investigation of suspected samples. Additionally, MALDI-TOF MS was applied to characterize the presence and the toxic activity of ricin in irradiated samples. Samples containing ricin were subjected to ASE, irradiated with different dosages of gamma radiation, and analyzed by MALDI-TOF MS/MS for verification of the intact protein signal. For identification purposes, samples were previously subjected to SDS-PAGE, for purification and separation of the chains, followed by digestion with trypsin, and analysis by MALDI-TOF MS/MS. The results were confirmed by verification of the amino acid sequences of some selected peptides by MALDI-TOF MS/MS. The samples residual toxic activity was evaluated through incubation with a DNA substrate, to simulate the attack by ricin, followed by MALDI-TOF MS/MS analyses.

Precise ricin A-chain delivery by Golgi-targeting carbon dots

The as-prepared CDs–RTA conjugates exhibit enhanced internalization, improved stability against enzymatic digestion and an increased location rate of RTA to the ER, and thus much more RTA could translocate to the cytosol and ribosome to exert toxic effects.

Chemical warfare agents. Classes and targets

Synthetic toxic chemicals (toxicants) and biological poisons (toxins) have been developed as chemical warfare agents in the last century. At the time of their initial consideration as chemical weapon, only restricted knowledge existed about their mechanisms of action. There exist two different types of acute toxic action: nonspecific cytotoxic mechanisms with multiple chemo-biological interactions versus specific mechanisms that tend to have just a single or a few target biomolecules. TRPV1- and TRPA-receptors are often involved as chemosensors that induce neurogenic inflammation. The present work briefly surveys classes and toxicologically relevant features of chemical warfare agents and describes mechanisms of toxic action.

Bio-detoxification of ricin in castor bean (Ricinus communis L.) seeds

Ricin is a highly toxic ribosome-inactivating lectin occurring in the seeds of castor bean (Ricinus communis L.). Castor bean grows throughout tropical and sub-tropical regions and is a very important crop due to its high seed content of ricinoleic acid, an unusual fatty acid, which has several industrial applications. However, due to the presence of the toxin, castor bean can cause death after the exposure of animals to low doses of ricin through skin contact, injection, inhalation or oral routes. Aiming to generate a detoxified genotype, we explored the RNAi concept in order to silence the ricin coding genes in the endosperm of castor bean seeds. Results indicated that ricin genes were effectively silenced in genetically modified (GM) plants, and ricin proteins were not detected by ELISA. Hemagglutination activity was not observed with proteins isolated from GM seeds. In addition, we demonstrated that seed proteins from GM plants were not toxic to rat intestine epithelial cells or to Swiss Webster mice. After oil extraction, bio-detoxified castor bean cake, which is very rich in valuable proteins, can be used for animal feeding. Gene silencing would make castor bean cultivation safer for farmers, industrial workers and society.

Ricin Poisoning after Oral Ingestion of Castor Beans: A Case Report and Review of the Literature and Laboratory Testing

BACKGROUND

Ricin is a protein toxin derived from the castor bean plant Ricinus communis. Several cases secondary to its consumption have been published and, more recently, its use as a potential bioterrorism agent has also been reported. Oral absorption of ricin is highly erratic, leading to a wide spectrum of symptoms. In addition, conventional urine drug screening tests will not be able to detect this compound, posing a diagnostic challenge.

CASE REPORT

A male teenager intended to die by ingesting 200 castor beans after mixing and blending them with juice. Eight hours later, he presented with weakness, light-headedness, nausea, and vomiting and sought medical treatment. The patient was admitted and treated conservatively. An immune-based standard urine toxicology drug screen panel was reported as negative. A comprehensive untargeted urine drug screen test showed the presence of ricinine, a surrogate marker of ricin intoxication. He was transferred to the psychiatric service 3 days after admission. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case highlights the importance of knowing the peculiar pharmacokinetic properties of ricin after oral ingestion of castor beans and toxin release through mastication. Emergency physicians should be aware that oral absorption of ricin is dependent on several factors, such type and size of seeds and the geographic harvesting region, making it extremely difficult to estimate its lethality based solely on the number of ingested beans. Finally, comprehensive untargeted urine drug screening testing is highly valuable as a diagnostic tool in this context.

Plant Ribosome-Inactivating Proteins: Progesses, Challenges and Biotechnological Applications (and a Few Digressions)

Plant ribosome-inactivating protein (RIP) toxins are EC3.2.2.22 N-glycosidases, found among most plant species encoded as small gene families, distributed in several tissues being endowed with defensive functions against fungal or viral infections. The two main plant RIP classes include type I (monomeric) and type II (dimeric) as the prototype ricin holotoxin from Ricinus communis that is composed of a catalytic active A chain linked via a disulphide bridge to a B-lectin domain that mediates efficient endocytosis in eukaryotic cells. Plant RIPs can recognize a universally conserved stem-loop, known as the α-sarcin/ ricin loop or SRL structure in 23S/25S/28S rRNA. By depurinating a single adenine (A4324 in 28S rat rRNA), they can irreversibly arrest protein translation and trigger cell death in the intoxicated mammalian cell. Besides their useful application as potential weapons against infected/tumor cells, ricin was also used in bio-terroristic attacks and, as such, constitutes a major concern. In this review, we aim to summarize past studies and more recent progresses made studying plant RIPs and discuss successful approaches that might help overcoming some of the bottlenecks encountered during the development of their biomedical applications.

Poisoning by Herbs and Plants: Rapid Toxidromic Classification and Diagnosis

The American Association of Poison Control Centers has continued to report approximately 50,000 telephone calls or 8% of incoming calls annually related to plant exposures, mostly in children. Although the frequency of plant ingestions in children is related to the presence of popular species in households, adolescents may experiment with hallucinogenic plants; and trekkers and foragers may misidentify poisonous plants as edible. Since plant exposures have continued at a constant rate, the objectives of this review were (1) to review the epidemiology of plant poisonings; and (2) to propose a rapid toxidromic classification system for highly toxic plant ingestions for field use by first responders in comparison to current classification systems. Internet search engines were queried to identify and select peer-reviewed articles on plant poisonings using the key words in order to classify plant poisonings into four specific toxidromes: cardiotoxic, neurotoxic, cytotoxic, and gastrointestinal-hepatotoxic. A simple toxidromic classification system of plant poisonings may permit rapid diagnoses of highly toxic versus less toxic and nontoxic plant ingestions both in households and outdoors; direct earlier management of potentially serious poisonings; and reduce costly inpatient evaluations for inconsequential plant ingestions. The current textbook classification schemes for plant poisonings were complex in comparison to the rapid classification system; and were based on chemical nomenclatures and pharmacological effects, and not on clearly presenting toxidromes. Validation of the rapid toxidromic classification system as compared to existing chemical classification systems for plant poisonings will require future adoption and implementation of the toxidromic system by its intended users.

Recyclable SERS substrates based on Fe2O3–Ag hybrid hollow microspheres with crumpled surfaces

Fe₂O₃–Ag hybrid hollow microspheres with crumpled surfaces were prepared as SERS recyclable substrates for 4-aminobenzenethiol (4-ABT) and toxin protein ricin.

The History of Biological Weapons Use: What We Know and What We Don't

This article critically reviews the literature on the history of biological warfare, bioterrorism, and biocrimes. The first serious effort to review this entire history, made in 1969, had numerous limitations. In recent decades, several authors have filled many of the gaps in our understanding of the past use of biological agents (including both pathogens and toxins), making it possible to reconstruct that history with greater fidelity than previously possible. Nevertheless, there are numerous remaining gaps, and closer inspection indicates that some supposed uses of biological weapons never took place or are poorly substantiated. Topics requiring additional research are identified.

Engineering plants for aphid resistance: current status and future perspectives

The current status of development of transgenic plants for improved aphid resistance, and the pros and cons of different strategies are reviewed and future perspectives are proposed. Aphids are major agricultural pests that cause significant yield losses of crop plants each year. Excessive dependence on insecticides for aphid control is undesirable because of the development of insecticide resistance, the potential negative effects on non-target organisms and environmental pollution. Transgenic plants engineered for resistance to aphids via a non-toxic mode of action could be an efficient alternative strategy. In this review, the distribution of major aphid species and their damages on crop plants, the so far isolated aphid-resistance genes and their applications in developments of transgenic plants for improved aphid resistance, and the pros and cons of these strategies are reviewed and future perspectives are proposed. Although the transgenic plants developed through expressing aphid-resistant genes, manipulating plant secondary metabolism and plant-mediated RNAi strategy have been demonstrated to confer improved aphid resistance to some degree. So far, no aphid-resistant transgenic crop plants have ever been commercialized. This commentary is intended to be a helpful insight into the generation and future commercialization of aphid-resistant transgenic crops in a global context.

Liquid chromatography-mass spectrometry and chemometric analysis of Ricinus communis extracts for cultivar identification

INTRODUCTION

Seeds of Ricinus communis contain the toxic protein ricin, a 64 kD heterodimeric type II ribosome-inactivating protein that has been used in several high-profile poisoning incidents. The ability to determine which cultivar the toxin was isolated from via an LC-MS method would be of significant use to law enforcement and forensic agencies.

OBJECTIVE

To analyse via LC-MS and chemometrics (principal components analysis (PCA), orthogonal partial-least-squares discriminant analysis (OPLS-DA)) extracts of R. communis to identify compounds specific to a particular cultivar.

METHODS

Seeds from eight specimens of six cultivars of R. communis ('carmencita', 'dehradun', 'gibsonii', 'impala', 'sanguineus' and 'zanzibariensis') were extracted using a standard methodology. These extracts were analysed by LC-MS then subjected to chemometric analysis (PCA and OPLS-DA). Identified compounds of importance were subjected to high-resolution Fourier transform (HRFT) MS and MS/MS to elucidate their structures.

RESULTS

This analysis identified 17 ions as potential cultivar determinators. Through accurate mass measurement and MS/MS, molecular formulae for 13 ions were determined, including two known and 11 new peptides.

CONCLUSION

Unique ions in extracts of 'carmencita', 'dehradun', 'gibsonii', 'impala' and 'zanzibariensis' were identified that would allow an individual cultivar to be distinguished from other cultivars in this study. Although 'sanguineus' extracts contained no unique compounds, a unique LC-MS profile would allow for cultivar assignment.

Targeting ricin to the ribosome

The plant toxin ricin is highly toxic for mammalian cells and is of concern for bioterrorism. Ricin belongs to a family of functionally related toxins, collectively referred to as ribosome inactivating proteins (RIPs), which disable ribosomes and halt protein synthesis. Currently there are no specific antidotes against ricin or related RIPs. The catalytic subunit of ricin is an N-glycosidase that depurinates a universally conserved adenine residue within the sarcin/ricin loop (SRL) of the 28S rRNA. This depurination activity inhibits translation and its biochemistry has been intensively studied. Yet, recent developments paint a more complex picture of toxicity, with ribosomal proteins and cellular signaling pathways contributing to the potency of ricin. In particular, several studies have now established the importance of the ribosomal stalk structure in facilitating the depurination activity and ribosome specificity of ricin and other RIPs. This review highlights recent developments defining toxin-ribosome interactions and examines the significance of these interactions for toxicity and therapeutic intervention.

Nucleic acid aptamers against biotoxins: a new paradigm toward the treatment and diagnostic approach

Nucleic acid aptamers are short single-stranded DNA or RNA oligonucleotides that can bind to their targets with very high affinity and specificity, and are generally selected by a process referred to as systematic evolution of ligands by exponential enrichment. Conventional antibody-based therapeutic and diagnostic approach currently employed against biotoxins pose major limitations such as the requirement of a live animal for the in vivo enrichment of the antibody species, decreased stability, high production cost, and side effects. Aptamer technology is a viable alternative that can be used to combat these problems. Fully sequestered in vitro, aptamers eliminate the need for a living host. Furthermore, one of the key advantages of using aptamers instead of antibodies is that they can be selected against very weakly immunogenic and cytotoxic substances. In this review, we focus on nucleic acid aptamers developed against various biotoxins of plant, microorganism, or animal origin and show how these can be used in diagnostics (e.g., biosensors) and therapy.

A computational perspective of molecular interactions through virtual screening, pharmacokinetic and dynamic prediction on ribosome toxin A chain and inhibitors of Ricinus communis

Background:

Ricin is considered to be one of the most deadly toxins and gained its favor as a bioweapon that has a serious social and biological impact, due to its widespread nature and abundant availability. The hazardous effects of this toxin in human being are seen in almost all parts of the organ system. The severe consequences of the toxin necessitate the need for developing potential inhibitors that can effectively block its interaction with the host system.

Materials and Methods:

In order to identify potential inhibitors that can effectively block ricin, we employed various computational approaches. In this work, we computationally screened and analyzed 66 analogs and further tested their ADME/T profiles. From the kinetic and toxicity studies we selected six analogs that possessed appropriate pharmacokinetic and dynamic property. We have also performed a computational docking of these analogs with the target.

Results:

On the basis of the dock scores and hydrogen bond interactions we have identified analog 64 to be the best interacting molecule. Molecule 64 seems to have stable interaction with the residues Tyr80, Arg180, and Val81. The pharmacophore feature that describes the key functional features of a molecule was also studied and presented.

Conclusion:

The pharmacophore features of the drugs provided suggests the key functional groups that can aid in the design and synthesis of more potential inhibitors.

High-resolution single-molecule recognition imaging of the molecular details of ricin-aptamer interaction

We studied the molecular details of DNA aptamer-ricin interactions. The toxic protein ricin molecules were immobilized on a Au(111) surface using a N-hydroxysuccinimide (NHS) ester to specifically react with lysine residues located on the ricin B chains. A single ricin molecule was visualized in situ using the AFM tip modified with an antiricin aptamer. Computer simulation was used to illustrate the protein and aptamer structures, the single-molecule ricin images on a Au(111) surface, and the binding conformations of ricin-aptamer and ricin-antibody complexes. The various ricin conformations on a Au(111) surface were caused by the different lysine residues reacting with the NHS ester. It was also observed that most of the binding sites for aptamer and antibody on the A chains of ricin molecules were not interfered by the immobilization reaction. The different locations of the ricin binding sites to aptamer and antibody were also distinguished by AFM recognition images and interpreted by simulations.

A novel xyloglucan film-based biosensor for toxicity assessment of ricin in castor seed meal

Oil from the seed of the castor plant (Ricinus communis L.) is an important commodity for a number of industries, ranging from pharmaceuticals to renewable energy resources. However, the seed and subsequent seed meal contain ricin (RCA60), a potent cytotoxin, making it an unusable product for animal feed. In order to investigate the efficiency of reducing the toxicity of the seed meal, a biosensor is proposed by exploring the lectin-carbohydrate binding. A gold electrode was assembled with a film of Xyloglucan (XG) extracted from Hymenaea courbaril L. The analytical response to RCA60 was obtained using a polyclonal antibody against RCA60 conjugated to peroxidase. The current responses were generated by reaction with H2O2 and amplified with hydroquinone as chemical mediator. Voltammetric studies showed that the XG film was tightly bound to the gold electrode. This biosensor allows discriminate lectins in native and denatured forms. The limit of detection of native RCA60 was 2.1 μg mL(-1). This proposed biosensor showed to be a potential and accurate method for toxicity assessment of the ricin in castor seed meal by simple polysaccharide film-electrode strategy.

Following aptamer-ricin specific binding by single molecule recognition and force spectroscopy measurements

Single molecule recognition imaging and dynamic force spectroscopy (DFS) analysis showed strong binding affinity between an aptamer and ricin, which was comparable with antibody-ricin interaction. Molecular simulation showed a ricin binding conformation with aptamers and gave different ricin conformations immobilizing on substrates that were consistent with AFM images.

Draft genome sequence of the oilseed species Ricinus communis

Castor bean (Ricinus communis) is an oilseed crop that belongs to the spurge (Euphorbiaceae) family, which comprises approximately 6,300 species that include cassava (Manihot esculenta), rubber tree (Hevea brasiliensis) and physic nut (Jatropha curcas). It is primarily of economic interest as a source of castor oil, used for the production of high-quality lubricants because of its high proportion of the unusual fatty acid ricinoleic acid. However, castor bean genomics is also relevant to biosecurity as the seeds contain high levels of ricin, a highly toxic, ribosome-inactivating protein. Here we report the draft genome sequence of castor bean (4.6-fold coverage), the first for a member of the Euphorbiaceae. Whereas most of the key genes involved in oil synthesis and turnover are single copy, the number of members of the ricin gene family is larger than previously thought. Comparative genomics analysis suggests the presence of an ancient hexaploidization event that is conserved across the dicotyledonous lineage.