Lichtgedanken 03

S C HW E R P U N K T 31 03 | LICHT GEDANKEN relationships to determine their possible biological function. This enables the researchers to kill two birds with one stone: at the same time as finding new natural products, they gain a better un- derstanding of fundamental mechanis- ms in complex symbiotic systems. »We have already found a few new mo- lecules,« says Beemelmanns. One of the molecules formed by the actinobacteria in the termites’ gut is of particular in- terest to the researchers, because it has an as-yet-unknown structure. It is a hy- brid molecule that is composed of three different building blocks—a sugar, a polyketide and an amino acid—through the interaction between many different enzymes. »The final finished molecu- le is biologically inactive, as far as we have been able to assess that to date. However, some intermediate products show antimicrobial activities,« explains Beemelmanns. The natural product researcher and her team assume that these tropolone derivates, as they are called, along with a few other natural products that have been found, prevent the harmful fungus from infesting the termite mound. That is to say, they form a natural pesticide combination, which supports the termites in cultivating their food source. Active substances turn fungi into parasites and disarm hospital-acquired bacteria In further investigations, Christine Bee- melmanns and her research group ex- amined another parasitic fungus more closely. They observed that this fungus, of the genus Pseudoxylaria , acts like an invasive weed, overrunning the fungus that is essential to the termites. Beemel- manns explains how this works: »From this harmful fungus we were able to isolate cyclic tetrapeptides, which are probably in part responsible for its pa- rasitic lifestyle.« In further experiments, Contact Dr Christine Beemelmanns Leibniz Institute for Natural Product Research and Infection Biology – Hans Knöll Institute (HKI) Beutenbergstraße 11a 07745 Jena, Germany Phone: +49 36 41 53 21 525 Email: christine.beemelmanns@leibniz-hki.de www.leibniz-hki.de Original Publication Isolation, biosynthesis and chemical modifi- cations of rubterolones A–F, rare tropolone alkaloids from Actinomadura sp. 5 – 2 (2017) , DOI: 10.1002/chem.201701005 the researchers discovered that the- se active substances are also effective against the bacterium Pseudomonas ae- ruginosa . This is an interesting finding, in particular because Pseudomonas ae- ruginosa— a typical hospital-acquired bacterium—can trigger serious wound infections in patients. Such »gram-nega- tive« bacteria are difficult to tackle. The researchers in Jena therefore thought that they had a potential new substance for treating wound infections. However, the substance turned out to be toxic, so that it was unsuitable for use as an antibiotic for humans. »We have other substances in the pipeline, however, which we hope will show better phar- macological characteristics,« adds Bee- melmanns with confidence. The HKI, together with the University of Jena, is currently applying for a pa- tent for a new natural product, which could be used in developing a new drug for cancer therapy.. Termite queen and king of the species Macrotermes natalensis . The queen (left) can grow to a length of 15 centimetres. Clearly visible is her enlarged abdomen for egg produc- tion. The king (right) reaches a size of only two to three centimetres. The queen is surrounded by a number of »workers« and small »soldiers«. The workers cultivate the fungus gardens and supply the queen and king with food. The soldier termites protect the gardens and the royal couple.