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.
- Keywords
- Ricin inhibitors, chemical warfare, drug design, medicinal chemistry, ribosome-inactivating protein., ricin A chain,
- MeSH
- Antidotes * chemistry pharmacology MeSH
- Chemical Warfare Agents chemistry MeSH
- Humans MeSH
- Ricin * antagonists & inhibitors chemistry MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
- Names of Substances
- Antidotes * MeSH
- Chemical Warfare Agents MeSH
- Ricin * MeSH
Ricin is a very toxic RIP II type lectin. As no effective antidote is known, its toxicity could be misused in terrorist actions. The mechanism of the toxic action is currently studied for the preparation of selective immunotoxins, which could be used in the therapy of various cancer diseases or HIV infection. There are promising in vitro results, but some adverse in vivo effects limit the use of these preparations in real therapy.
- MeSH
- Immunotoxins MeSH
- Humans MeSH
- Ricin chemistry pharmacology therapeutic use toxicity MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- English Abstract MeSH
- Journal Article MeSH
- Review MeSH
- Names of Substances
- Immunotoxins MeSH
- Ricin MeSH
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.
- Keywords
- CBRN defense, MALDI-TOF MS, biological weapons, chemical weapons, ricin,
- MeSH
- Acetone chemistry MeSH
- Electrophoresis, Polyacrylamide Gel MeSH
- Hexanes chemistry MeSH
- Peptides analysis chemistry MeSH
- Ricin analysis chemistry MeSH
- Solvents chemistry MeSH
- Amino Acid Sequence MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization MeSH
- Tandem Mass Spectrometry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Acetone MeSH
- Hexanes MeSH
- n-hexane MeSH Browser
- Peptides MeSH
- Ricin MeSH
- Solvents MeSH
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.
- Keywords
- Ricin inhibitors, biological warfare agents, drug repurposing, ricin, virtual screening,
- MeSH
- Antidotes MeSH
- Drug Repositioning MeSH
- Ricin * chemistry metabolism pharmacology MeSH
- Molecular Dynamics Simulation MeSH
- Molecular Docking Simulation MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Antidotes MeSH
- Ricin * MeSH
Ricin is a toxin found in the castor seeds and listed as a chemical weapon by the Chemical Weapons Convention (CWC) due to its high toxicity combined with the easiness of obtention and lack of available antidotes. The relatively frequent episodes of usage or attempting to use ricin in terrorist attacks reinforce the urge to develop an antidote for this toxin. In this sense, we selected in this work the current RTA (ricin catalytic subunit) inhibitor with the best experimental performance, as a reference molecule for virtual screening in the PubChem database. The selected molecules were then evaluated through docking studies, followed by drug-likeness investigation, molecular dynamics simulations and Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) calculations. In every step, the selection of molecules was mainly based on their ability to occupy both the active and secondary sites of RTA, which are located right next to each other, but are not simultaneously occupied by the current RTA inhibitors. Results show that the three PubChem compounds 18309602, 18498053, and 136023163 presented better overall results than the reference molecule itself, showing up as new hits for the RTA inhibition, and encouraging further experimental evaluation.
- Keywords
- chemical/biological warfare agents, ligand-based virtual screening, molecular dynamics, ricin, ricin inhibitors,
- MeSH
- Algorithms MeSH
- Chemical Warfare Agents chemistry MeSH
- Ligands MeSH
- Molecular Conformation MeSH
- Molecular Structure MeSH
- Drug Discovery MeSH
- Ricin antagonists & inhibitors chemistry MeSH
- Molecular Dynamics Simulation MeSH
- Molecular Docking Simulation MeSH
- Binding Sites MeSH
- Hydrogen Bonding MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Chemical Warfare Agents MeSH
- Ligands MeSH
- Ricin MeSH
Explicit solvent molecular dynamics (MD) simulations were carried out for sarcin-ricin domain (SRD) motifs from 23S (Escherichia coli) and 28S (rat) rRNAs. The SRD motif consists of GAGA tetraloop, G-bulged cross-strand A-stack, flexible region and duplex part. Detailed analysis of the overall dynamics, base pairing, hydration, cation binding and other SRD features is presented. The SRD is surprisingly static in multiple 25 ns long simulations and lacks any non-local motions, with root mean square deviation (r.m.s.d.) values between averaged MD and high-resolution X-ray structures of 1-1.4 A. Modest dynamics is observed in the tetraloop, namely, rotation of adenine in its apex and subtle reversible shift of the tetraloop with respect to the adjacent base pair. The deformed flexible region in low-resolution rat X-ray structure is repaired by simulations. The simulations reveal few backbone flips, which do not affect positions of bases and do not indicate a force field imbalance. Non-Watson-Crick base pairs are rigid and mediated by long-residency water molecules while there are several modest cation-binding sites around SRD. In summary, SRD is an unusually stiff rRNA building block. Its intrinsic structural and dynamical signatures seen in simulations are strikingly distinct from other rRNA motifs such as Loop E and Kink-turns.
- MeSH
- Endoribonucleases metabolism MeSH
- Escherichia coli genetics MeSH
- Fungal Proteins metabolism MeSH
- Cations chemistry MeSH
- Nucleic Acid Conformation MeSH
- Rats MeSH
- Crystallography, X-Ray MeSH
- Models, Molecular * MeSH
- Base Pairing MeSH
- Computer Simulation MeSH
- Ricin metabolism MeSH
- RNA, Ribosomal, 23S chemistry metabolism MeSH
- RNA, Ribosomal, 28S chemistry metabolism MeSH
- Carbohydrates chemistry MeSH
- Binding Sites MeSH
- Water chemistry MeSH
- Hydrogen Bonding MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Names of Substances
- alpha-sarcin MeSH Browser
- Endoribonucleases MeSH
- Fungal Proteins MeSH
- Cations MeSH
- Ricin MeSH
- RNA, Ribosomal, 23S MeSH
- RNA, Ribosomal, 28S MeSH
- Carbohydrates MeSH
- Water MeSH
Sample preparation involving the cleavage of proteins into peptides is the first critical step for successful bottom-up proteomics and protein analyses. Time- and labor-intensiveness are among the bottlenecks of the commonly used methods for protein sample preparation. Here, we report a fast online method for postinjection acid cleavage of proteins directly in the mobile phase typically used for LC-MS analyses in proteomics. The chemical cleavage is achieved in 0.1% formic acid within 35 s in a capillary heated to 195 °C installed upstream of the analytical column, enabling the generated peptides to be separated. The peptides generated by the optimized method covered the entire sequence except for one amino acid of trastuzumab used for the method development. The qualitative results are extraordinarily stable, even over a long period of time. Moreover, the method is also suitable for accurate and repeatable quantification. The procedure requires only one manual step, significantly decreasing sample transfer losses. To demonstrate its practical utility, we tested the method for the fast detection of ricin. Ricin can be unambiguously identified from an injection of 10 ng, and the results can be obtained within 7-8 min after receiving a suspicious sample. Because no sophisticated accessories and no additional reagents are needed, the method can be seamlessly transferred to any laboratory for high-throughput proteomic workflows.
BACKGROUND: Graft-versus-host disease (GVHD) is a severe complication of allogeneic transplantation of hematopoietic stem cells. Donor T cells play a major role in GVHD leading to the host tissue damage, mainly the skin, liver, and gastrointestinal tract. A selective depletion using an anti-CD25 immunotoxin can eliminate harmful alloreactive T cells while preserving other donor T cells with antileukemic and antiinfectious reactivity. PATIENTS AND METHODS: We performed 15 mixed lymphocyte reactions with clinical specimens from 12 patients with various types of leukemia (7x AML, 3x ALL, 1x CML, 1x CLL) and PBMC from 15 healthy volunteers from Transfusive station FN Brno Bohunice. RESULTS: In our experiments we have demonstrated, that antileukemic (GVL) effect of donor, especially CD4+ T cells was well preserved (7.46%), while unfavourable alloreactive (GVH) reaction of donor T cells was completely removed. The graft-versus-host (GVH) reactivation of donor cells was negligible ever after repeated stimulation with irradiated patient's PBMC. CONCLUSION: We have shown that anti-CD25 immunotoxin (IT), RFT5-SMPT-dgA, launched against alpha chain for human interleukin 2 (IL-2), led to long-term selective depletion of alloreactive donor T cell clones while their antileukemic activity was well preserved. Base on our results the clinical phase I/II study was designed. This study was initiated in year 2007 in three clinical centers in Czech Republic.
- MeSH
- Clone Cells MeSH
- Child MeSH
- Adult MeSH
- Immunoconjugates MeSH
- Leukemia immunology MeSH
- Middle Aged MeSH
- Humans MeSH
- Lymphocyte Depletion * MeSH
- Adolescent MeSH
- Young Adult MeSH
- Antibodies, Monoclonal MeSH
- Graft vs Host Disease immunology prevention & control MeSH
- Interleukin-2 Receptor alpha Subunit immunology MeSH
- Ricin MeSH
- T-Lymphocytes immunology MeSH
- Lymphocyte Culture Test, Mixed MeSH
- Lymphocyte Transfusion MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Publication type
- English Abstract MeSH
- Journal Article MeSH
- Names of Substances
- Immunoconjugates MeSH
- Antibodies, Monoclonal MeSH
- Interleukin-2 Receptor alpha Subunit MeSH
- RFT5-SMPT-dgA immunotoxin MeSH Browser
- Ricin MeSH
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.
- Publication type
- Journal Article MeSH
The sarcin-ricin RNA motif (SR motif) is one of the most prominent recurrent RNA building blocks that occurs in many different RNA contexts and folds autonomously, that is, in a context-independent manner. In this study, we combined bioinformatics analysis with explicit-solvent molecular dynamics (MD) simulations to better understand the relation between the RNA sequence and the evolutionary patterns of the SR motif. A SHAPE probing experiment was also performed to confirm the fidelity of the MD simulations. We identified 57 instances of the SR motif in a nonredundant subset of the RNA X-ray structure database and analyzed their base pairing, base-phosphate, and backbone-backbone interactions. We extracted sequences aligned to these instances from large rRNA alignments to determine the frequency of occurrence for different sequence variants. We then used a simple scoring scheme based on isostericity to suggest 10 sequence variants with a highly variable expected degree of compatibility with the SR motif 3D structure. We carried out MD simulations of SR motifs with these base substitutions. Nonisosteric base substitutions led to unstable structures, but so did isosteric substitutions which were unable to make key base-phosphate interactions. The MD technique explains why some potentially isosteric SR motifs are not realized during evolution. We also found that the inability to form stable cWW geometry is an important factor in the case of the first base pair of the flexible region of the SR motif. A comparison of structural, bioinformatics, SHAPE probing, and MD simulation data reveals that explicit solvent MD simulations neatly reflect the viability of different sequence variants of the SR motif. Thus, MD simulations can efficiently complement bioinformatics tools in studies of conservation patterns of RNA motifs and provide atomistic insight into the role of their different signature interactions.
- MeSH
- Nucleic Acid Conformation MeSH
- Nucleotide Motifs MeSH
- Base Pairing MeSH
- RNA, Ribosomal chemistry metabolism MeSH
- RNA chemistry metabolism MeSH
- Solvents chemistry MeSH
- Molecular Dynamics Simulation MeSH
- Hydrogen Bonding MeSH
- Computational Biology MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
- Names of Substances
- RNA, Ribosomal MeSH
- RNA MeSH
- Solvents MeSH
