Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (641 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
Cyclic heptapeptides found in microcystis and other cyanobacteria. Hepatotoxic and carcinogenic effects have been noted. They are sometimes called cyanotoxins, which should not be confused with chemicals containing a cyano group (CN) which are toxic.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Cyanoginosins.
Where it fits in the MeSH classification
- Broader topics
- Peptides, Cyclic; Cyanobacteria Toxins
Related concepts
- Microcystis
- Cyanobacteria
Research landscape
PubMed indexes 5,099 records tagged with the MeSH heading “Microcystins” (counts retrieved 2026-10-31). 1,653 of them (32.4%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 1,943 records.
Reviews account for 300 records (5.9%) and meta-analyses for 15. Randomized controlled trials number 1 (0.0%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 358 |
| 2000-2009 | 1,145 |
| 2010-2019 | 1,943 |
| 2020 onward | 1,653 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 300 | 5.9% |
| Meta-analyses | 15 | 0.3% |
| Randomized controlled trials | 1 | 0.0% |
Method: PubMed query "Microcystins"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in drugs and chemicals
Studies of a chemical or drug can answer very different questions: what it is and how it behaves in cells and animals, how the body handles it, and whether it changes outcomes in people. Laboratory and animal findings often do not carry over to patients, and observational studies of exposures are confounded by who uses a substance and why. Nothing on this page is a recommendation to use, avoid, start or stop any substance or medicine; talk to a qualified clinician or pharmacist about your own situation. Check the dose, the species, the comparison group and whether a patient-relevant outcome was measured.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
On the chemistry, toxicology and genetics of the cyanobacterial toxins, microcystin, nodularin, saxitoxin and cylindrospermopsin [1]
Abstract reading summary — source excerpts
- Opening excerpt
- The cyanobacteria or "blue-green algae", as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity.
- Closing excerpt
- This review provides an overview of these biosynthesis pathways and additionally summarizes the chemistry and toxicology of these remarkable secondary metabolites.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (124 words)
The cyanobacteria or "blue-green algae", as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity. Many aquatic, bloom-forming species of cyanobacteria are capable of producing biologically active secondary metabolites, which are highly toxic to humans and other animals. From a toxicological viewpoint, the cyanotoxins span four major classes: the neurotoxins, hepatotoxins, cytotoxins, and dermatoxins (irritant toxins). However, structurally they are quite diverse. Over the past decade, the biosynthesis pathways of the four major cyanotoxins: microcystin, nodularin, saxitoxin and cylindrospermopsin, have been genetically and biochemically elucidated. This review provides an overview of these biosynthesis pathways and additionally summarizes the chemistry and toxicology of these remarkable secondary metabolites.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 20559491 · DOI · PMC2885083
The cyanobacterial hepatotoxin microcystin binds to proteins and increases the fitness of microcystis under oxidative stress conditions [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Microcystins are cyanobacterial toxins that represent a serious threat to drinking water and recreational lakes worldwide.
- Closing excerpt
- Taken together, our data suggest a protein-modulating role for microcystin within the producing cell, which represents a new addition to the catalogue of functions that have been discussed for microbial secondary metabolites.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (200 words)
Microcystins are cyanobacterial toxins that represent a serious threat to drinking water and recreational lakes worldwide. Here, we show that microcystin fulfils an important function within cells of its natural producer Microcystis. The microcystin deficient mutant ΔmcyB showed significant changes in the accumulation of proteins, including several enzymes of the Calvin cycle, phycobiliproteins and two NADPH-dependent reductases. We have discovered that microcystin binds to a number of these proteins in vivo and that the binding is strongly enhanced under high light and oxidative stress conditions. The nature of this binding was studied using extracts of a microcystin-deficient mutant in vitro. The data obtained provided clear evidence for a covalent interaction of the toxin with cysteine residues of proteins. A detailed investigation of one of the binding partners, the large subunit of RubisCO showed a lower susceptibility to proteases in the presence of microcystin in the wild type. Finally, the mutant defective in microcystin production exhibited a clearly increased sensitivity under high light conditions and after hydrogen peroxide treatment. Taken together, our data suggest a protein-modulating role for microcystin within the producing cell, which represents a new addition to the catalogue of functions that have been discussed for microbial secondary metabolites.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 21445264 · DOI · PMC3060824
Microcystin-LR ameliorates pulmonary fibrosis via modulating CD206+ M2-like macrophage polarization [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Idiopathic pulmonary fibrosis (IPF) is a group of chronic interstitial pulmonary diseases characterized by myofibroblast proliferation and extracellular matrix deposition with limited treatment options.
- Closing excerpt
- Our results revealed a novel mechanism that may account for therapeutic effect of microcystin-LR on IPF.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (171 words)
Idiopathic pulmonary fibrosis (IPF) is a group of chronic interstitial pulmonary diseases characterized by myofibroblast proliferation and extracellular matrix deposition with limited treatment options. Based on our previous observation, we hypothesized microcystin-leucine arginine (LR), an environmental cyanobacterial toxin, could potentially suppress pulmonary fibrosis. In this study, we first demonstrated that chronic exposure of microcystin-LR by oral for weeks indeed attenuated the pulmonary fibrosis both on bleomycin-induced rat and fluorescein isothiocyanate-induced mouse models. Our data further indicated that treatment with microcystin-LR substantially reduced TGF-β1/Smad signaling in rat pulmonary tissues. The experiments in vitro found that microcystin-LR was capable of blocking epithelial-mesenchymal transition (EMT) and fibroblast-myofibroblast transition (FMT) through suppressing the differentiation of CD206+ macrophages. Mechanically, microcystin-LR was found to bind to glucose-regulated protein 78 kDa (GRP78) and suppress endoplasmic reticulum unfolded protein response (UPRER) signaling pathways. These events led to the modulation of M2 polarization of macrophages, which eventually contributed to the alleviation of pulmonary fibrosis. Our results revealed a novel mechanism that may account for therapeutic effect of microcystin-LR on IPF.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 32075954 · DOI · PMC7031231
Hepatocyte-Derived Extracellular Vesicles Deliver miR-328-3p to Trigger PP2A-B56δ-Mediated p-NLRP3S295-Dependent Metaflammation in Macrophages upon Microcystin-LR Exposure [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Microcystin-LR (MC-LR) exacerbates metabolic dysfunction-associated steatotic liver disease (MASLD) by inducing histopathological damage and lipid metabolism disorders.
- Closing excerpt
- Collectively, the miR-328-3p/PP2A-B56δ/p-NLRP3S295 axis is identified as a crucial driver of metaflammation and establishes circulating EV-miR-328-3p as a novel biomarker and anti-p-NLRP3S295 mAbs as translational tools for MC-LR-associated MASLD.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (146 words)
Microcystin-LR (MC-LR) exacerbates metabolic dysfunction-associated steatotic liver disease (MASLD) by inducing histopathological damage and lipid metabolism disorders. Inducible hepatocyte-derived extracellular vesicles (iHD-EVs) released after xenobiotic exposure activate the macrophage NOD-like receptor protein 3 (NLRP3) inflammasome. Suppression of NLRP3 phosphorylation at serine 295 (p-NLRP3S295) is previously shown to alleviate MASLD progression. Here, it is demonstrated that microcystin-LR (MC-LR)-induced iHD-EVs reduced deliver of miR-328-3p to macrophages, thereby upregulating protein phosphatase 2A (PP2A)-B56δ. Consequent PP2A-B56δ activation disrupts inositol 1,4,5-triphosphate receptor and voltage-dependent anion channel 1 coupling, evokes mitochondria-associated endoplasmic reticulum membrane (MAM) calcium (Ca2+) overload, and recruits p-NLRP3S295 into the inflammasome. Neutralization of p-NLRP3S295 with a site-specific monoclonal antibody (anti-p-NLRP3S295 mAb) markedly attenuates liver inflammation and injury in MC-LR-exposed mice. Collectively, the miR-328-3p/PP2A-B56δ/p-NLRP3S295 axis is identified as a crucial driver of metaflammation and establishes circulating EV-miR-328-3p as a novel biomarker and anti-p-NLRP3S295 mAbs as translational tools for MC-LR-associated MASLD.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41255311 · DOI · PMC12866802
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Toxins of cyanobacteria [5]
- Research article Molecular mechanisms of microcystin toxicity in animal cells [6]
- Research article Structural Diversity, Characterization and Toxicology of Microcystins [7]
- Research article Human health risk assessment related to cyanotoxins exposure [8]
- Research article A review of reproductive toxicity of microcystins [9]
- Research article Cyanobacterial peptides beyond microcystins - A review on co-occurrence, toxicity, and challenges for risk assessment [10]
References
- Pearson L, Mihali T, Moffitt M, Kellmann R, Neilan B. On the chemistry, toxicology and genetics of the cyanobacterial toxins, microcystin, nodularin, saxitoxin and cylindrospermopsin. . 2010. PMID 20559491 · DOI · PMC2885083
- Zilliges Y, Kehr JC, Meissner S, Ishida K, Mikkat S, Hagemann M, et al.. The cyanobacterial hepatotoxin microcystin binds to proteins and increases the fitness of microcystis under oxidative stress conditions. . 2011. PMID 21445264 · DOI · PMC3060824
- Wang J, Xu L, Xiang Z, Ren Y, Zheng X, Zhao Q, et al.. Microcystin-LR ameliorates pulmonary fibrosis via modulating CD206+ M2-like macrophage polarization. . 2020. PMID 32075954 · DOI · PMC7031231
- Wu JS, Zhang XY, Ma XY, Wei YY, Wang LL, Du ZB, et al.. Hepatocyte-Derived Extracellular Vesicles Deliver miR-328-3p to Trigger PP2A-B56δ-Mediated p-NLRP3S295-Dependent Metaflammation in Macrophages upon Microcystin-LR Exposure. . 2026. PMID 41255311 · DOI · PMC12866802
- van Apeldoorn ME, van Egmond HP, Speijers GJ, Bakker GJ. Toxins of cyanobacteria. Mol Nutr Food Res. 2007. PMID 17195276 · DOI
- Campos A, Vasconcelos V. Molecular mechanisms of microcystin toxicity in animal cells. Int J Mol Sci. 2010. PMID 20162015 · DOI · PMC2821003
- Bouaïcha N, Miles CO, Beach DG, Labidi Z, Djabri A, Benayache NY, et al.. Structural Diversity, Characterization and Toxicology of Microcystins. Toxins (Basel). 2019. PMID 31817927 · DOI · PMC6950048
- Funari E, Testai E. Human health risk assessment related to cyanotoxins exposure. Crit Rev Toxicol. 2008. PMID 18259982 · DOI
- Chen L, Chen J, Zhang X, Xie P. A review of reproductive toxicity of microcystins. J Hazard Mater. 2016. PMID 26521084 · DOI
- Janssen EM. Cyanobacterial peptides beyond microcystins - A review on co-occurrence, toxicity, and challenges for risk assessment. Water Res. 2019. PMID 30641464 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
See how EvidenceLib is built. Spotted an error? Email support@evidencehelix.com.
Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.