Prymnesin-2 is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

that is

secreted 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...

by the

haptophyte The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for ''Prymnesium''), are a clade of algae. The names Haptophyceae or Prymnesiophyceae are sometimes used instead. This ending implies classification at t ...

Prymnesium parvum ''Prymnesium parvum'' is a species of haptophytes (also collectively called Prymnesiophyta). The species is of concern because of its ability to produce the phycotoxin prymnesin. It is a flagellated alga that is normally found suspended in the ...

''. It belongs to the

prymnesin Prymnesin may refer to: * Prymnesin-1 * Prymnesin-2 Prymnesin-2 is an organic compound that is secretion, secreted by the haptophyte ''Prymnesium parvum''. It belongs to the prymnesin family and has potent Hemolysis, hemolytic and Ichthyotoxin, i ...

family and has potent

hemolytic Hemolysis or haemolysis (), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo o ...

and

ichthyotoxic Ichthyotoxins are compounds which are either toxic to fish, or are toxins produced by fish. The former include the algae-produced euglenophycin and prymnesins, which can cause large-scale fish deaths. The latter includes ostracitoxin, produced by bo ...

properties. In a purified form it appears as a pale yellow solid. ''P. parvum'' is responsible for red

harmful algal bloom A harmful algal bloom (HAB) (or excessive algae growth) is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes ...

s 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 Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estua ...

, as the compound can reach critical concentrations more easily.

Structure and reactivity

The structural formula of prymnesin-2 is: C₉₆H₁₃₆Cl₃NO₃₅. The compound exhibits multiple

chiral Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from ...

centers. The molecule is

amphoteric In chemistry, an amphoteric compound () is a molecule or ion that can react both as an acid and as a base. What exactly this can mean depends on which definitions of acids and bases are being used. One type of amphoteric species are amphiproti ...

, 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 moiety at C77. This might lead to interaction with biomembranes, which is thought to be the basis of its toxicity. The difference between

prymnesin-1 Prymnesin-1 is a chemical with the molecular formula . It is a member of the prymnesins, a class of hemolytic phycotoxins made by the alga ''Prymnesium parvum''. It is known to be toxic to fish, causing mass fish deaths around the world, including ...

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.

Synthesis

There is not much known about the synthesis of prymnesin-1 and prymnesin-2 ''in vivo.'' However, it is likely that both are derived from acetate-related 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

Mechanism of action

The mechanism of action of prymnesin-2 remains to be determined. Prymnesin-2 and prymnesin-1 show comparable activities. Prymnesin-2 has shown multiple functionalities, such as potent

activity and diverse biological activities, such as mouse lethality, ichthyotoxicity and activity inducing Ca2+ influx into cultured cells. The hemolytic potency of prymnesin-2 exceeds that of plant

saponin Saponins (Latin "sapon", soap + "-in", one of), also selectively referred to as triterpene glycosides, are bitter-tasting usually toxic plant-derived organic chemicals that have a foamy quality when agitated in water. They are widely distributed ...

by 50.000 times. 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.

Toxicity

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

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). 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.

References