Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sweet Poison - Star fruit neurotoxin identified

21.11.2013
Patients with kidney disease have to watch what they eat: bananas, oranges, tomatoes, nuts, broccoli, and beans are all off-limits. Putting star fruit or carambola on the menu would be downright dangerous.

This fruit contains a substance that is a deadly neurotoxin for people with kidney disease. Brazilian researchers have now isolated and identified this neurotoxin. As they report in the journal Angewandte Chemie, it is an amino acid similar to phenylalanine.



People suffering from chronic kidney disease have to avoid eating star fruit if they value their lives. Around the world, many cases have been documented in which ingestion of the yellow star-shaped fruit led to poisoning of dialysis patients and people with kidney disease.

There are a variety of symptoms: from intractable hiccups, vomiting, weakness, mental confusion, and psychomotor agitation, to unusually long-lasting epileptic seizures, coma, and death. In acute cases, only hemodialysis can save the patient.

It is clear that star fruit contains an unidentified neurotoxin that healthy people clear out through the kidneys without problems. In those with kidney disease, however, the toxin accumulates and can eventually enter the brain. A team at the University of São Paulo (Brazil) has now been able to unmask the culprit.

To do this, scientists led by Norberto Garcia-Cairasco and Norberto P. Lopes modeled star fruit poisoning in animals. They gave either crude extracts of star fruit to animals with experimental kidney disease (to mimic the patient´s ingestion) or injected extracts of star fruit into the brains of healthy rats, inducing the behavioral and electrographical seizures typical of star fruit poisoning.

The extracts were fractionated by means of chromatographic procedures and each individual fraction tested for activity. Active fractions were then chromatographically separated and tested again. This process was repeated until a single substance responsible for the seizures was isolated. The researchers named it caramboxin.

By using a variety of spectroscopic techniques, the scientists were able to determine the structure of caramboxin. The main structure of the neurotoxin resembles that of the amino acid phenylalanine. In contrast to the natural amino acid, the phenol ring of the toxin is also bound to extra ether, alcohol, and acid groups.

Further tests revealed that caramboxin acts on AMPA and kainate receptors, two important glutamate-controlled neurotransmitter receptors of the central nervous system. This causes hyperexcitability in the brain, resulting in the typically observed seizures, which showed neurodegenerative effects in the study.

About the Author
Dr. Norberto P. Lopes is Professor of Organic Chemistry at Faculdade de Ciências Farmacêuticas de Ribeirão Preto at the University of São Paulo (FCFRP-USP), is the Task Leader for the Research Support Center in Natural and Synthetic Products (NPPNS/USP), and has been working in natural product chemistry and mass spectrometry for over 15 years. He is currently Head of the Physics and Chemistry Department of the FCFRP and board member of the Brazilian Chemical Society and Brazilian Mass Spectrometry Society.

Author: Norberto P. Lopes, University of São Paulo (Brazil), mailto:npelopes@fcfrp.usp.br

Title: Elucidating the Neurotoxicity of the Star Fruit
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201305382

Norberto P. Lopes | GDCh
Further information:
http://pressroom.angewandte.org.

More articles from Life Sciences:

nachricht Antimicrobial substances identified in Komodo dragon blood
23.02.2017 | American Chemical Society

nachricht New Mechanisms of Gene Inactivation may prevent Aging and Cancer
23.02.2017 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>