science

Neothramycin

Neothramycin 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 Neothramycin rather than just read about it. In short: Neothramycin A and B are stereoisomeric antibiotics with anticancer activity. The stereoisomers are interchangeable in aqueous solution and the antibiotic, Neothramycin, contains both in approximately equal amounts.

Key takeaways

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

Reference excerpt

Neothramycin A and B are stereoisomeric antibiotics with anticancer activity. The stereoisomers are interchangeable in aqueous solution and the antibiotic, Neothramycin, contains both in approximately equal amounts. They belong to the pyrrolo(1,4)benzodiazepine, or anthramycin, group which includes other antibiotics such as anthramycin, tomaymycin, and sibiromycin. Neothramycin was originally isolated from Streptomyces No. MC916-C4, a cycloheximide-producing strain, by Umezawa et al. Subsequent testing has shown its capabilities as an anticancer drug, antiprotozoal drug, and even possible uses in DNA fluorescence based assays. Its activities against cancer warranted phase I testing of the drug. More recently, in 1991, anthramycin derivatives, which are very similar to neothramycin, have been investigated for their ability to link DNA when dimerized. These compounds were tested using a fluorescence based assay. These compounds showed an ability to bind dG-containing DNA duplexes with high specificity. This specificity of a DNA crosslinking agent is highly sought after since most are electrophiles and bind indiscriminately. The data collected also showed that pyrrolo(1,4)benzodiazepines can also be used to measure the fluorescence polarization anisotropy on the 0.1-100 ns time scale.

Activity Neothramycin shows weak antimicrobial activity compared to other pyrrolo(1,4)benzodiazepines. It also shows lower toxicity in mice. Neothramycin has been shown to exhibit activity against Yoshida sarcoma in rats, leukemia P388, sarcoma 180, Ehrlich Ascites carcinoma, Walker carcinosarcoma-256, and light activity against leukemia L-1210 in mice. These activities against cancer are typical to the activities seen in the other pyrrolo(1,4)benzodiazepine compounds. Neothramycin has also been tested, alongside other compounds, against malaria and for antiprotozoal activity. It showed moderate activity towards malaria with an IC50 value of about 1 μg/mL. Neothramycin also showed high cytotoxicity towards MRC-5 cells with and IC50 of 390 ng/mL. Butylneothramycin A, a derivative of neothramycin, showed 6-7 fold lower antiprotozoal activity than neothramycin.

Mechanism Neothramycin’s mode of action is widely known to be through the inhibition of DNA-dependent RNA and DNA polymerase. The antibiotic activity of neothramycin was determined to be directly binding DNA by UV-Vis absorption measurements with differing concentrations of DNA and neothramycin. The first studies of neothramycin began thinking that DNA was the chemoreceptor due to the inhibition of DNA and RNA polymerase that they observed when neothramycin was added. The antibiotic activity, since these first studies, has been determined to be due to its direct binding of DNA. More specifically, the neothramycin binds the NH2 of guanine in the minor groove. This binding was shown to only occur when the DNA is in duplex. This type of binding is observed in the other pyrrolo(1,4)benzodiazepines as well. However, the binding of neothramycin to DNA is much slower than the other compounds in the group. This binding of neothramycin to DNA does not significantly change the melting temperature of the DNA.

Clinical Testing Neothramycin went through phase I testing between June 1979 and June 1981. They determined the maximum tolerable dose to be 60 mg/m2 per single injection. Approximately half of the patients experienced nausea and vomiting, the most severe toxicity observed. Some hepatotoxic and nephrotoxic effects were observed but were reversible. The phase I clinical trial determined that 30–40 mg/m2 would be the optimal dose for phase II.

References

External links The treatment of bladder cancer by neothramycin

Illustrations

Worked examples

Example 1 — a first encounter with Neothramycin

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

In research: Neothramycin 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 Neothramycin 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: Neothramycin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Antibiotics, so understanding it makes those chapters shorter.
In everyday life: Look for Neothramycin 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 Neothramycin in 20 minutes

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

Frequently asked questions

What is Neothramycin in simple terms?

Why does Neothramycin 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 Neothramycin?

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 Neothramycin.