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Unraveling the properties of plant substances

Researchers from the Institute of Analytical Chemistry at the Mannheim University of Applied Sciences are focusing on sensors in their effort to increase the yields of bioreactors and reduce the number of animals used for toxicity testing of pharmaceuticals. In addition, the chemists from Mannheim are aiming to investigate the activity of plant substances in the Bioactive Plant Foods Network, a transnational network for the promotion of bioactive plant ingredients.

Mannheim University of Applied Sciences campus © Mannheim University of Applied Sciences

Living organisms use sensory organs such as the eye to perceive what is going on around them. It becomes soon clear that perception is also extremely important in technical terms, especially when it comes to the large number of sensors that have become part of our daily life: modern sensors check the carbon dioxide content of food packages or are part of park distance controls in cars. The Institute of Analytical Chemistry at the Mannheim University of Applied Sciences led by Prof. Dr. Tobias Werner and Prof. Dr. Siegfried Weber is mainly focused on sensor systems. The two chemists’ main aim is to investigate processes that are difficult to access, for example when no samples can be taken. “We are developing the sensors ourselves and try to find materials that provide us with selective signals,” said Prof. Tobias Werner who has been professor at the Mannheim University of Applied Sciences since 2006. 

One of the researchers’ current projects focuses on glucose and oxygen sensors. The probes, which are only a few millimetres in size, are glued into a test tube or inside a reactor where the sensors are in contact with the medium. Due to their optical characteristics, the sensors are able to measure the analyte concentration in the test tube or reactor. This enables oxygen or glucose concentrations in solutions to be determined without having to open the vial. “This is of course of great interest in processes where vials must not be opened for process reasons, for example in breweries or bioreactors,” explained Prof. Werner.


Cost reductions as one of many improvements

Sensors in a cell culture dish © Mannheim University of Applied Sciences

In their ongoing project, the researchers hope to obtain as much information as possible on the processes in a bioreactor. They hope to find ways to change the conditions in bioreactors by measuring the glucose concentration and improving the growth conditions of cells that synthesize proteins used in drugs. The control of the processes also makes it possible to reduce the cost of substances used in drugs.

In another project being carried out in cooperation with researchers from the University of Heidelberg, the Mannheim chemists are working on tests that they hope will lead to the development of drugs for cancer treatment. An oxygen sensor controls the respiration of the cells, thereby providing information as to whether a substance that has been added to the culture has a cystostatic, i.e. growth-inhibiting, or cytotoxic effect. “We hope that the use of sensors in drug testing will help to reduce the use of experimental animals significantly,” said Werner. Pharmacology seeks to find answers to questions such as: does the substance kill the correct tissue? Can adverse effects be expected? The oxygen sensors can be used to develop a selective test that will contribute to reducing the number of animals sacrificed in the testing of pharmaceuticals.

Quality control of food

Institute employee operating a fluorescence spectrometer © Mannheim University of Applied Sciences

The sensors can also be used for investigations into secondary plant substances, which are plant substances that are not directly involved in the plant metabolism, and into bioactive food ingredients. “For example, we plan to investigate whether certain substances prolong the life of cells,” said Werner, going on to add that his team will also be investigating whether resveratrol, a substance contained in red wine, has a protective effect on cells. This is one of many approaches related to the investigation of plant foods being pursued by Werner and his team.

Another research project involves the measurement of the optical properties of plant oils in order to glean information on the origin, quality and age of the oils. This would be a new and simple method to assess the quality of foods. Since the fluorescence of chlorophyll reacts to very small changes in the ingredients in oil, this parameter would enable simple measurements to be carried out at oil production sites.

Daily laboratory work © Mannheim University of Applied Sciences

In addition to the aforementioned projects, the institute is also active in Prof. Werner’s former specialist area, i.e. the analysis of metals. Atom absorption spectrometry can be used to determine the different proportions of copper and iron in individual cellular organelles. A few nanograms/litre of copper and iron provide information about the different ion concentrations in the cytoplasm and the mitochondria, for example.

In cooperation with the University of Heidelberg, the chemists from Mannheim are investigating the ability of plants to accumulate metal. The plant alyssum, for example, accumulates up to 1% zinc, 0.1% nickel, cobalt, lead and 0.01% cadmium, as a proportion of the dry mass. The weed cress Arabidopsis thaliana is able to take up arsenic from soil. Soils that are contaminated with arsenic can thus be returned to normal by growing Arabidopsis on them. At present, the Institute of Analytical Chemistry is focusing particularly on investigating the role of the tri-peptide glutathione in the accumulation of heavy metals in plants. “This process is known as phytomining. It will be increasingly applied in the future because rapid technical development in the communication and automotive industries increases the demand for special elements, including soil metals such as terbium, cerium and neodyme,” said Prof. Werner.

Tasty and healthy nutrition

In the Bioactive Plant Foods Network, Prof. Werner is in charge of the “Analytics” working group which focuses on identifying an amaranth genotype that corresponds to the network’s requirements. “The Universities of Hohenheim and Heidelberg are particularly active in this area,” said Werner. “We plan to investigate and understand the highly interesting plant ingredients and their mechanisms of action on the cellular level,” said the chemist who is also an enthusiastic cook.

His “Mannheim cooking lecture” is part of the annual Open Campus series of lectures and workshops at the Mannheim University of Applied Sciences, where Werner explains what happens on the molecular level when food is cooked. He also shows his audience how it is possible to eat a tasty and, more importantly, healthy diet. This year’s lecture entitled “Eating like the Incas and Aztecs” was about the practical application of the two pseudo-crops amaranth and quinoa and showed how these valuable foods can be integrated into everyday cooking.


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