science

Pumiliotoxin 251D

Pumiliotoxin 251D is a science 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 Pumiliotoxin 251D rather than just read about it. In short: Pumiliotoxin 251D is a toxic organic compound. It is found in the skin of poison frogs from the genera Dendrobates, Epipedobates, Minyobates, and Phyllobates and toads from the genus Melanophryniscus.

Key takeaways

Pumiliotoxin 251D belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Pumiliotoxin 251D to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Pumiliotoxin 251D from memory before moving on to harder problems.

Reference excerpt

Pumiliotoxin 251D is a toxic organic compound. It is found in the skin of poison frogs from the genera Dendrobates, Epipedobates, Minyobates, and Phyllobates and toads from the genus Melanophryniscus. Its name comes from the pumiliotoxin family (PTXs) and its molecular mass of 251 daltons. When the toxin enters the bloodstream through cuts in the skin or by ingestion, it can cause hyperactivity, convulsions, cardiac arrest and ultimately death. It is especially toxic to arthropods (e.g. mosquitoes), even at low (naturally occurring) concentrations.

Chemical properties

Structure The chiral centers in pumiliotoxin 251D can give several stereoisomers of the compound. Only one form of the toxin is present in nature and has toxic properties.

Two enantiomers of pumiliotoxin 251D. On the left the plus enantiomer is shown which is toxic. On the right side the minus enantiomer, which is not toxic, is shown. The side chain conformation of substituents at the C-2’ position plays an important role in the toxicity of the compound.

Synthesis The synthesis of pumiliotoxin 251D is quite complex and contains multiple steps. It can be achieved starting from the N-Boc derivative of L-proline methyl ester.

Pumiliotoxin (−)-251D can be synthesized in a similar way with minor alterations to the overall synthesis.

Toxicity

Mechanism of action In general, pumiliotoxins are known as positive modulators of voltage-gated sodium channels (VGSCs, membrane proteins). Pumiliotoxin 251D is not such a poison. However, it does block the influx of Na+ ions in mammalian VGSCs. Pumiliotoxin 251D is able to shift the V1/2. This is the potential at which the sodium open probability is half maximal. Both the steady-state activation and inactivation curves of each mammalian VGSCs are shifted to a more negative potential. PTX 251D shifts the V1/2 of insect VGSCs even further than the mammalian VSGCs. This explains why it is especially toxic to insects, like mosquitoes. Furthermore, the presence of PTX 251D results in a six time higher permeability of the VGSCs for K+ ions. This severely disturbs the delicate sodium-potassium equilibrium in the nerve system. The effect of pumiliotoxin 251D on the voltage-gated potassium channels (VGPCs) currents is quite small. The toxic has an effect on the deactivation kinetics of the potassium channel. It inhibits its inactivation. This effect is still under investigation. PTX 251D also completely inhibits the activity of Ca2+-stimulated ATPase. This results in a decreased reuptake of Ca2+ and thus a high concentration of free Ca2+ in the organism. This may be related to the potentiation and prolongation of muscle twitch caused by the inhibition. The mechanism of biotransformation of PTX 251D is still unknown.

Effects Pumiliotoxin is a toxin found in poison dart frogs (genus Dendrobates and Phyllobates). It affects the calcium channels, interfering with muscle contraction in the heart and skeletal muscle. PTX 251D has several effects. It rapidly induces convulsions and death to mice and insects (LD50 being, respectively, 10 mg/kg and 150 ng/larvae). These convulsions are the result of the uncontrollable distortion of the sodium-potassium equilibrium in the neurons. This is caused by the inhibition of the VGSCs. It also acts as cardiac depressor, causing cardiac arrest. This can be explained by its negative effect on the cardiac VGSC hNav1.5/β1. Although nothing is known of how well PTX 251D penetrates into the brain where convulsions are originated, the observation of convulsions can be explained through inhibition of VGPCs.

Treatment Symptomatic treatment of PTX 251D poisoning include reducing the convulsions using carbamazepine. This drug targets the affected VGSCs. Phenobarbital also shows positive effects by interacting with the affected Ca2+ channels. Ineffective drugs include diazepam and dizocilpine.

References

Illustrations

Worked examples

Example 1 — a first encounter with Pumiliotoxin 251D

Start with the simplest possible case. Write down what Pumiliotoxin 251D claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Pumiliotoxin 251D 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 Pumiliotoxin 251D 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 Pumiliotoxin 251D

In research: Pumiliotoxin 251D appears in science 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 Pumiliotoxin 251D 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: Pumiliotoxin 251D is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alkaloids, Amphibian toxins, Indolizidines, so understanding it makes those chapters shorter.
In everyday life: Look for Pumiliotoxin 251D 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 Pumiliotoxin 251D in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pumiliotoxin 251D 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 Pumiliotoxin 251D out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pumiliotoxin 251D in simple terms?

Why does Pumiliotoxin 251D matter?

Because it connects several science 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 Pumiliotoxin 251D?

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 Pumiliotoxin 251D.