# Prymnesin-2

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**Prymnesin-2** is an [organic compound](/source/Organic_compound) that is [secreted](/source/Secretion) by the [haptophyte](/source/Haptophyte) *[Prymnesium parvum](/source/Prymnesium_parvum)*. It belongs to the [prymnesin](/source/Prymnesin) family and has potent [hemolytic](/source/Hemolysis) and [ichthyotoxic](/source/Ichthyotoxin) properties. In a purified form it appears as a pale yellow solid.[2] *P. parvum* is responsible for red [harmful algal blooms](/source/Harmful_algal_bloom) worldwide, causing massive fish killings. When these algal blooms occur, this compound poses a threat to the local fishing industry. This is especially true for [brackish water](/source/Brackish_water), as the compound can reach critical concentrations more easily.[2]

## Structure and reactivity

The structural formula of prymnesin-2 is: C96H136Cl3NO35. The compound exhibits multiple [chiral](/source/Chirality_(chemistry)) centers. The molecule is [amphoteric](/source/Amphoterism), which means that it can act both as base and an acid. This is because all 16 hydroxyls, except for one at C32, are concentrated on carbons C48-84, and there [α-L-xylofuranose](/source/Xylose) moiety at C77.[1] This might lead to interaction with biomembranes, which is thought to be the basis of its toxicity.[2] The difference between [prymnesin-1](/source/Prymnesin) and prymnesin-2 is the glycosidic residues: L-arabinose, D-galactose and D-ribose, yet prymnesin-2 and prymnesin-1 show comparable activities. Prymnesins also have unique features: The possession of only one methyl, but three chlorine atoms, four C-C triple bonds, sugars and an amino group.[3]

### Biosynthesis

Prymnesin-1 and prymnesin-2 are both are derived from acetate-related (i.e. polyketide) metabolism, based on knowledge about the structure of the prymnesins. In general primary and secondary metabolites such as fatty acids, polyketides and non-ribosomal peptides are synthesised by the [acetate pathway](/source/Acetyl%E2%80%94CoA_synthetase).[4] In 2024 the backbone of A-type prymnesins like prymnesin-2 was reported to be made by giant polyketide synthase enzymes dubbed the "PKZILLAs".[5]

## Mechanism of action

The mechanism of action of prymnesin-2 remains to be determined.[3] Prymnesin-2 and prymnesin-1 show comparable activities. Prymnesin-2 has shown multiple functionalities, such as potent [hemolytic](/source/Hemolysis) activity and diverse biological activities, such as mouse lethality, [ichthyotoxicity](/source/Ichthyotoxicity) and activity inducing Ca2+ influx into cultured cells. The hemolytic potency of prymnesin-2 exceeds that of plant [saponin](/source/Saponin) by 50,000 times.[6]

Prymnesin-2 causes hemolysis by direct interaction between toxin and cell surface. Partly due to interaction with cellular lipids, mainly to interaction with a specific binding site on the blood cell surface. This is supported by the observation of competitive inhibition by the prymnesin-2 analogues, which assume the presence of a specific binding site on the blood cell surface. Also the process of toxin molecule aggregation may be involved in the main mechanism of the haemolytic activity.[6]

## Toxicity

Prymnesin-2 is an ichthyotoxic compound with the ability to hemolyze blood. 2.5nM is needed for a 50% hemolysis rate of a 1% rat blood cell suspension, and 9nM is enough for killing freshwater fish. The hemolytic and ichthyotoxic properties increase when the pH of the solution rises from 7 to 8.[7] Prymnesin-2 causes calcium ion influx into C6 rat glioma cells at a concentration of 70nM.[8]

Besides the lytic effect on blood cells, hepatocytes, Hela cells and artificial liposomes are affected by prymnesin-2.

As seen in the table below, prymnesin-2 is highly hemolytic for blood cells of different animal species, even when compared to the already highly hemolytic toxin saponin.

Table1. Sensitivities of blood cells from different animal species Prymnesin-2 (nM) Saponin (nM) Relative to saponin Mouse 2.5 17000 6800 Rabbit 1.7 15000 8800 Dog 0.5 25000 50000 Sheep 0.6 23000 38000 Chicken 1.9 17000 8900 Carp 1.6 11500 7200

## Effects on animals

In the US, the first recorded *P. parvum* bloom occurred in 1985 in a semi-arid region of the country (Pecos River, Texas).[9] Since then, the incidence of *P. parvum* blooms dramatically increased in the US, where the organism has invaded lakes and rivers throughout southern regions and most recently into northern regions. The magnitude of *P. parvum* blooms are also increasing over the past decade compared to 30 years ago, with massive fish killings as result.[10][11][12]

## See also

- [Prymnesin-1](/source/Prymnesin-1)
- [Prymnesin-B1](/source/Prymnesin-B1)

## References

1. Igarashi, Tomoji; Satake, Masayuki; Yasumoto, Takeshi (1999). "Structures and Partial Stereochemical Assignments for Prymnesin-1 and Prymnesin-2: Potent Hemolytic and Ichthyotoxic Glycosides Isolated from the Red Tide AlgaPrymnesium parvum". *Journal of the American Chemical Society*. **121** (37): 8499–8511. American Chemical Society (ACS). [Bibcode:1999JAChS.121.8499I](https://ui.adsabs.harvard.edu/abs/1999JAChS.121.8499I). [doi:10.1021/ja991740e](https://doi.org/10.1021/ja991740e). [ISSN 0002-7863](https://www.worldcat.org/issn/0002-7863)

1. Igarashi, Tomoji; Satake, Masayuki; Yasumoto, Takeshi (1996). "Prymnesin-2: A Potent Ichthyotoxic and Hemolytic Glycoside Isolated from the Red Tide Alga Prymnesium parvum". *Journal of the American Chemical Society*. **118** (2): 479–480. [Bibcode:1996JAChS.118..479I](https://ui.adsabs.harvard.edu/abs/1996JAChS.118..479I). [doi:10.1021/ja9534112](https://doi.org/10.1021/ja9534112)

1. Yasumoto, Takeshi (2001). "The chemistry and biological function of natural marine toxins". *The Chemical Record*. **1** (3): 228–242. [doi:10.1002/tcr.1010](https://doi.org/10.1002/tcr.1010). [ISSN 1528-0691](https://www.worldcat.org/issn/1528-0691). [PMID 11895121](https://pubmed.ncbi.nlm.nih.gov/11895121)

1. Manning, Schonna R. & La Claire, John W. (2010-03-16). "Prymnesins: Toxic Metabolites of the Golden Alga, Prymnesium parvum Carter (Haptophyta)". *Marine Drugs*. **8** (3): 678–704. [doi:10.3390/md8030678](https://doi.org/10.3390/md8030678). [PMC 2857367](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857367). [PMID 20411121](https://pubmed.ncbi.nlm.nih.gov/20411121)

1. Fallon, Timothy R.; Shende, Vikram V.; Wierzbicki, Igor H.; Pendleton, Amanda L.; Watervoort, Nathan F.; Auber, Robert P.; Gonzalez, David J.; Wisecaver, Jennifer H.; Moore, Bradley S. (2024-08-09). "Giant polyketide synthase enzymes in the biosynthesis of giant marine polyether toxins". *Science*. **385** (6709): 671–678. [Bibcode:2024Sci...385..671F](https://ui.adsabs.harvard.edu/abs/2024Sci...385..671F). [doi:10.1126/science.ado3290](https://doi.org/10.1126/science.ado3290). [ISSN 0036-8075](https://www.worldcat.org/issn/0036-8075). [PMC 11416037](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11416037). [PMID 39116217](https://pubmed.ncbi.nlm.nih.gov/39116217)

1. Igarashi, T.; Aritake, S.; Yasumoto, T. (1998). "Biological activities of prymnesin-2 isolated from a red tide alga Prymnesium parvum". *Natural Toxins*. **6** (1): 35–41. [doi:10.1002/(SICI)1522-7189(199802)6:1<35::AID-NT7>3.0.CO;2-7](https://doi.org/10.1002/(SICI)1522-7189(199802)6:1%3C35::AID-NT7%3E3.0.CO;2-7). [ISSN 1056-9014](https://www.worldcat.org/issn/1056-9014). [PMID 9851510](https://pubmed.ncbi.nlm.nih.gov/9851510)

1. Granéli, Edna & Salomon, Paulo S. (1 February 2010). "Factors Influencing Allelopathy and Toxicity in Prymnesium parvum". *JAWRA Journal of the American Water Resources Association*. **46** (1): 108–120. [Bibcode:2010JAWRA..46..108G](https://ui.adsabs.harvard.edu/abs/2010JAWRA..46..108G). [doi:10.1111/j.1752-1688.2009.00395.x](https://doi.org/10.1111/j.1752-1688.2009.00395.x). [ISSN 1752-1688](https://www.worldcat.org/issn/1752-1688)

1. Morohashi, Akio; Satake, Masayuki; Oshima, Yasukatsu; Igarashi, Tomoji; Yasumoto, Takeshi (2001). "Absolute configuration at C14 and C85 in prymnesin-2, a potent hemolytic and ichthyotoxic glycoside isolated from the red tide alga Prymnesium parvum". *Chirality*. **13** (9): 601–605. [doi:10.1002/chir.1184](https://doi.org/10.1002/chir.1184). [ISSN 1520-636X](https://www.worldcat.org/issn/1520-636X). [PMID 11579456](https://pubmed.ncbi.nlm.nih.gov/11579456)

1. James T. L., De La Cruz A.. Prymnesium parvum Carter (Chrysophyceae) as a suspect of mass mortalities of fish and shellfish communities in western Texas, Texas Journal of Science, 1989, vol. 41 (pp. 429-430).

1. Roelke, Daniel; Augustine, Sarah; Buyukates, Yesim (2003-11-01). "Fundamental Predictability in Multispecies Competition: The Influence of Large Disturbance.". *The American Naturalist*. **162** (5): 615–623. [Bibcode:2003ANat..162..615R](https://ui.adsabs.harvard.edu/abs/2003ANat..162..615R). [doi:10.1086/378750](https://doi.org/10.1086/378750). [ISSN 0003-0147](https://www.worldcat.org/issn/0003-0147). [PMID 14618539](https://pubmed.ncbi.nlm.nih.gov/14618539). [S2CID 19980618](https://api.semanticscholar.org/CorpusID:19980618)

1. Buyukates, Yesim & Roelke, Daniel (2005-10-01). "Influence of Pulsed Inflows and Nutrient Loading on Zooplankton and Phytoplankton Community Structure and Biomass in Microcosm Experiments Using Estuarine Assemblages". *Hydrobiologia*. **548** (1): 233–249. [Bibcode:2005HyBio.548..233B](https://ui.adsabs.harvard.edu/abs/2005HyBio.548..233B). [doi:10.1007/s10750-005-5195-x](https://doi.org/10.1007/s10750-005-5195-x). [ISSN 0018-8158](https://www.worldcat.org/issn/0018-8158). [S2CID 40194710](https://api.semanticscholar.org/CorpusID:40194710)

1. Miller, Carrie J.; Roelke, Daniel L.; Davis, Stephen E.; Li, Hsiu-Ping; Gable, George (2008). "The role of inflow magnitude and frequency on plankton communities from the Guadalupe Estuary, Texas, USA: Findings from microcosm experiments". *Estuarine, Coastal and Shelf Science*. **80** (1): 67–73. [Bibcode:2008ECSS...80...67M](https://ui.adsabs.harvard.edu/abs/2008ECSS...80...67M). [doi:10.1016/j.ecss.2008.07.006](https://doi.org/10.1016/j.ecss.2008.07.006)

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