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Efficient mosquito repellent: with grapefruits against malaria infections


Research on active grapefruit as a mosquito repellent
Can grapefruits be used as a mosquito repellent? A team of students from the Heinrich Heine University Düsseldorf (HHU) and the University of Cologne is looking for a mosquito repellent that is affordable for people in poorer countries. An active ingredient from grapefruit is the focus of research.

As part of the international iGEM competition, the students are looking for an effective mosquito repellent that can be manufactured inexpensively and has as few harmful side effects as possible. This could also help prevent malaria and other mosquito-borne diseases. Their approach is based on the use of an active ingredient from the grapefruit skin.

Contribution to curbing malaria infections?
For the iGEM competition, the participants must independently initiate a project in the field of synthetic biology, whereby the projects should be based on current topics. "The overall aim of the competition is to educate the world about the possibilities of synthetic biology and to improve it with the projects," reports the HHU. In their research project, the students of the Universities of Cologne and Düsseldorf are devoted to developing a mosquito repellent, also against the background that this could help to contain malaria infections.

Infected billions of people
"Malaria and other mosquito-borne diseases affect well over three billion people worldwide," the HHU explains the scope of the project. A large proportion of deaths from a malaria infection are recorded in Africa, according to the WHO (90 percent of the cases in 2015). Malaria is also a problem in Southeast Asia (7 percent of deaths) and the Eastern Mediterranean region (2 percent of deaths). Some progress has already been made in reducing malaria, "so far, chemical measures used to protect people from stings have either been too expensive or are associated with considerable health risks," said the HHU.

Active ingredient from the grapefruit bowl
In the fight against malaria, according to the HHU, a molecule has been gaining more and more attention for some time, which is very effective in repelling mosquitoes and ticks, and is environmentally friendly and, above all, harmless to humans. This so-called nootkatone is found in the skin of the grapefruit and is responsible for the characteristic smell of the fruit, reports the university. So far, however, the mass production of "the fragrant mosquito repellent" has been blocked by the enormous production costs.

Cost-effective production of the active ingredient is the goal
According to the HHU, nootkatone still has to be obtained from the fruit peel of grapefruit, which is only found in very small quantities, and biotechnological production is currently not possible. Because the substance damages the microorganisms used for the synthesis in the biotechnological production and kills them before significant amounts of nootkatone can be produced, reports the university. In the current project, the team of students is trying to "integrate an artificial compartment into microorganisms in which the production of nootcatone can take place without affecting the life cycle of the cells."

Can other active ingredients also be better manufactured in the future?
If the students are successful, this could not only help in the development of a new mosquito repellent. Because "the production of many other fabrics faces the same problems as nootkatone," emphasizes René Inckemann, a student at HHU and head of the team. Here, researchers see great potential for the use of their artificial compartment in other areas, such as the production of taxol, which is used in cancer therapy.

The participating teams were able to plan and implement their idea for the iGEM competition for a total of one year. They had to organize the scientific part in the laboratory as well as sponsoring themselves. The researchers still have until November 2017 to work on their project before the results are presented at the large gathering of all iGEM teams in Boston (USA). (fp)

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