chemistry

Precoccinelline

Precoccinelline 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 Precoccinelline rather than just read about it. In short: Precoccinelline is an alkaloid produced by the Coccinella septempunctata, also known as the seven-spot ladybird. The alkaloid is released from the joints in C. septempunctata legs when it is provoked to deter predators such as ants or birds.

Key takeaways

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

Reference excerpt

Precoccinelline is an alkaloid produced by the Coccinella septempunctata, also known as the seven-spot ladybird. The alkaloid is released from the joints in C. septempunctata legs when it is provoked to deter predators such as ants or birds. It binds to both insect and mammalian nicotinic acetylcholine receptors, giving it use as an insecticide or as a therapy to treat drug dependence.

Biosynthesis It was determined that precoccinelline is produced de novo in the C. septempunctata as their diet, which is composed of aphids, does not contain this alkaloid. While the exact biosynthesis has not been fleshed out, precoccinelline is thought to be of polyketide origin. The hypothesized biosynthesis involves condensation of six acetates and methyl addition.

Chemical synthesis

2,6-lutidine (1) is used as starting material, and its treatment with β-bromo-propionaldehyde dimethyl acetal in ether produces a monolithium derivative. In the presence of 2,6-lutidine in excess, the monolithium derivative becomes an acetal (2). Treatment of the acetal with phenyl-lithium and then adding an ethereal solution of acetonitrile produces the crude ketone (3), followed by immediate transformation into the diacetal (4). Using sodium-isoamyl alcohol, the diacetal can be reduced to give the cis piperidine (5). The trans-isomer of the cis piperidine can be isolated and hydrolyzed using aqueous hydrochloric acid to yield the ketol (6). The ketol can then be cyclized with the use of acetic acid and pyrrolidine in refluxing tetrahydrofuran which gives a mixture of ketones. Separation of structure 7 from the mixture and then treatment with methyllithium in ether to produce a carbinol (8). Dehydrating the carbinol with thionyl chloride in methylene chloride gives olefin which can be hydrogenated to produce precoccinelline.

Mechanism of action Precoccinelline is an alkaloid which acts as an inhibitor of nicotinic acetylcholine receptors (nAChRs). It binds to an allosteric site on nAChRs― a site separate from the ACh recognition site. Of the secreted ladybird alkaloids, precoccinelline was the most potent inhibitor, acting via a non-competitive mechanism. Targeting nAChRs has several implications including developing insecticides and modulating drug dependence relating to the reward pathway in the brain.

References

Illustrations

Worked examples

Example 1 — a first encounter with Precoccinelline

Start with the simplest possible case. Write down what Precoccinelline 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 Precoccinelline 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 Precoccinelline 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 Precoccinelline

In research: Precoccinelline 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 Precoccinelline 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: Precoccinelline is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acetylcholinesterase inhibitors, Alkaloids, Heterocyclic compounds with 3 rings, so understanding it makes those chapters shorter.
In everyday life: Look for Precoccinelline 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 Precoccinelline in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Precoccinelline 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 Precoccinelline out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Precoccinelline in simple terms?

Why does Precoccinelline 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 Precoccinelline?

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 Precoccinelline.