chemistry

Nereistoxin

Nereistoxin is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nereistoxin rather than just read about it. In short: Nereistoxin is a natural product identified in 1962 as the toxic organic compound N,N-dimethyl-1,2-dithiolan-4-amine. It had first been isolated in 1934 from the marine annelid Lumbriconereis heteropoda and acts by blocking the nicotinic acetylcholine receptor.

Key takeaways

Nereistoxin belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nereistoxin to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nereistoxin from memory before moving on to harder problems.

Reference excerpt

Nereistoxin is a natural product identified in 1962 as the toxic organic compound N,N-dimethyl-1,2-dithiolan-4-amine. It had first been isolated in 1934 from the marine annelid Lumbriconereis heteropoda and acts by blocking the nicotinic acetylcholine receptor. Researchers at Takeda in Japan investigated it as a possible insecticide. They subsequently developed a number of derivatives that were commercialised, including those with the ISO common names bensultap, cartap, thiocyclam and thiosultap.

Structures and synthesis

Bensultap (R=SO2Ph) was made by the reaction of the sodium salt of benzenethiolsulfonate (PhSO2SNa) with N,N-dimethyl 1,3-dichloro-2-propylamine or N,N-dimethyl 2,3-dichloropropylamine in ethanol.

Bensultap can be converted to nereistoxin by treatment with alkali.

History Japanese fishermen used the annelid worm Lumbriconereis heteropoda as bait but after accidental human poisonings the chemical agent responsible was identified and named nereistoxin. In the 1960s, researchers at Takeda Chemical Industries synthesised the active material N,N-dimethyl-1,2-dithiolan-4-amine and derivatives in which the sulfur-sulfur bond of the 1,2-dithiolane ring was replaced by alternative sulfur-linked groups. The resulting compounds were in many cases less toxic to mammals than the natural product while retaining good activity on insects. It was subsequently shown that all the compounds which were commercialised acted by being propesticides — breaking down in the environment to nereistoxin or a toxic dithiol.

Mechanism of action Nereistoxin has chemical similarity to acetylcholine and its mode of action was suggested originally as being possibly by interference with acetylcholinesterase. Later electrophysiological studies using synapses from the cockroach Periplaneta americana showed that it acts by blocking the nicotinic acetylcholine receptor / ion channel complex in the insect central nervous system. This is also the mode of action of the related insecticides, all of which can produce the dithiol corresponding to cleavage of the 1,2-thiolane ring in the parent compound.

Usage None of the insecticidal analogues of nereistoxin became major products in agriculture and their use was mainly limited to Japanese and Chinese cultivation of rice, where their control of pests such as the rice stem borer Chilo suppressalis was significant. They were not licensed for use in Europe or the USA. The limited success of this group of chemicals was partly due to other compounds having similar modes of action but higher potency and mammalian safety becoming available.

References

Further reading Godfrey, C. R. A. (17 November 1994). Agrochemicals from Natural Products. CRC Press. ISBN 0824795539.

External links

Cartap in the Pesticide Properties DataBase (PPDB) Bensultap in the Pesticide Properties DataBase (PPDB) Thiosultap in the Pesticide Properties DataBase (PPDB) Thiocyclam in the Pesticide Properties DataBase (PPDB)

Illustrations

Worked examples

Example 1 — a first encounter with Nereistoxin

Start with the simplest possible case. Write down what Nereistoxin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nereistoxin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nereistoxin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nereistoxin

In research: Nereistoxin appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nereistoxin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nereistoxin is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1,2-Dithiolanes, Dimethylamino compounds, Insecticides, so understanding it makes those chapters shorter.
In everyday life: Look for Nereistoxin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Nereistoxin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nereistoxin means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nereistoxin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nereistoxin in simple terms?

Why does Nereistoxin matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nereistoxin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nereistoxin.