Drug Design and Analytical Chemistry


Selective active agents and application systems for the treatment of bacterial infectious diseases of the periodontium

Periodontitis, commonly referred to as gum disease, is an inflammatory disease of the periodontium that affects almost every second adult in Germany. It is caused by a local infection involving specific oral microorganisms and the subsequent local immune response. Left untreated, periodontitis leads to tooth loss and bone loss in the jaw. Studies also show that chronic periodontitis drastically increases the risk of developing diabetes, cardiovascular diseases and rheumatoid arthritis.

All of the preparations used to date come with the serious drawback that their active agent is a broad-spectrum antibiotic and/or antiseptic. They therefore kill all the bacteria found in dental plaque, including those in the oral microbiome that are commensally desired, which often leads to the treated areas being recolonized by the germs that cause the disease.

The ParoStop project aims to develop a pathogen-specific form of treatment. This is based on an agent that selectively kills off the bacteria that cause periodontitis by inhibiting an essential enzyme: Bacterial glutaminyl cyclase.

Besides developing the active agent, the project is also looking at developing a suitable route of administration that is as straightforward and pain-free as possible. Maintaining the concentration of the agent at the target location presents a particular challenge here as agents are usually washed out quickly due to mechanical influences and the constant flow of liquid in the mouth and especially around the gum pockets.

Alternative metal binding groups in drugs for the treatment of periodontitis

In the context of drug development, despite enormous progress in computer-aided prediction of various parameters of drug candidates, one still has to rely on investigating as wide a variety of chemically diverse molecules as possible. This usually involves adding different substituents to a constant basic structure in order to investigate their influence on the activity of the compounds, but also their toxicity or pharmacokinetics. This requires a relatively large number of different derivatives, since even small chemical differences can have a major impact on the properties mentioned. Such compound libraries typically contain several dozen compounds, but can also grow to several hundred derivatives on an industrial scale. In order to enable a broad chemical variability, the so-called flow-chemistry is to be established within the scope of the project. This will make it possible to produce a large number of compounds simply and quickly in flow-through microreactors. This state-of-the-art technology will be established in a joint project with PerioTrap Pharmaceuticals GmbH. Basic scaffolds developed there will be further derivatized at the Fraunhofer IZI Department of Drug Design and Target Validation in order to advance the development of drug candidates.

The project, which started on December 7, 2020, will run until July 31, 2022, and is funded by the German Federal State of Saxony-Anhalt with money from the European Regional Development Fund (ERDF).

Project coordination: Kathrin Tan.

Mikro and nanoparticle applikation systems of drugs for dental cosmetic and therapeutic Applications

Applying medical or cosmetic active ingredients in just the right place inside the oral cavity continues to present a major challenge. This is partly because many medications do not remain in the mouth for long enough due to salivation. As a result, medications for some symptoms must be used systemically, i.e. to the whole body, instead of locally. This is particularly true for periodontitis – one of the world’s most common infections, which not only leads to the destruction of the periodontium, but also increases the risk of rheumatoid arthritis, diabetes, and cardiovascular disease. Alongside mechanical removal of the microbial covering for periodontitis, broad-spectrum antibiotics must also be administered in tablet form as a supportive treatment. The high doses required here cause side effects, such as a change in and decimation of the intestinal flora as well as promoting the development of resistance, which represent an ever greater problem in everyday clinical practice in industrialized and newly industrialized countries.

Researchers at the Fraunhofer Institute for Microstructure of Materials and Systems IMWS are thus working together with the .Department of Drug Design and Target Validation of the Fraunhofer Institute for Cell Therapy and Immunology IZI on a form of application that is intended to avoid this kind of systemic approach. The aim is to develop a corresponding antibiotic or antiseptic that can be placed locally as easily and pain-free as possible. At the same time, the required effective level of the medication must be maintained over a long period of time.

First of all, a new formulation platform is being developed and tested with the help of an active ingredient that is already known and used for periodontitis. It is a kind of mode of transport for the active ingredient that enables long-lasting local release. This platform is intended to then be expanded to a wide range of substances and purposes later on. Subsequent use in preventative or selective antiseptic oral care products is being considered.


TRIGGER: King of hearts, joints and lungs; periodontal pathogens as etiologic factor in RA, CVD and COPD and their impact on treatment strategy

Extensive clinical and epidemiological data clearly shows that chronic periodontal disease (PD), the most prevalent infectious inflammatory disease of mankind, is strongly linked to systemic inflammatory diseases such as cardiovascular diseases (CVD), rheumatoid arthritis (RA), and chronic obstructive pulmonary disease (COPD). Taking into account that up to 30% of the adult population worldwide suffers from severe periodontitis, the impact of this disease on human health is immense and has been recognized by World Health Organization. Nevertheless, in many EU countries PD is a neglected disease, both by the population in general and health-care personnel. Often this negligence comes to the point that, like a hair-loss, the tooth-loss due to periodontitis is still considered as a normal inevitable event associated with aging. To combat this misconception and conceive novel approaches to prevent and/or treat CVD, RA, and COPD we will explore highly innovative ideas that these non-communicable diseases are at least aggravated, if not initiated, by periodontal infection. Results emanating from our project will: i) elucidate a relationship between the presence of specific periodontal pathogens and severity of systemic diseases; ii) show that extensive periodontal treatment improves clinical parameters of investigated systemic diseases; iii) reveal the impact of eradication of specific periodontal pathogen on the level of inflammatory markers; iv) develop novel, periodontal-pathogen selective bactericidal compounds based on specific enzymes that are essential for these pathogens vitality. This will reduce mortality and ameliorate the quality of life of CVD, RA, and COPD patients.

Development of inhibitors for alternative beta-secretases as a new therapeutic approach for Alzheimer’s disease

© Fraunhofer IZI

The number of patients suffering from Alzheimer’s disease will increase dramatically, especially in the industrial nations. The major reason is the increasing lifespan, since age is the main risk factor for this disease. Thus, about 33 % of the whole population above 80 years is diagnosed with Alzheimer’s dementia.

In recent years pharma research was faced with a lot of failures in the development of novel drugs against Alzheimer’s disease that were based on the inhibition of an enzyme – beta secretase BACE-1 – being responsible for the release of a particular neurotoxic peptide (amyloid Abeta) as the main factor for the onset of the disease. The compounds exhibited a good efficacy in vitro, a good bioavailability and were well tolerated by the organism.

However, they failed in clinical trials due to a lack of efficacy in patients with spontaneous Alzheimer´s disease. Only in the case of a small sub population of 5 % of all patients that suffered from a genetically encoded variant of Alzheimer’s disease, the compounds showed promising effects in vivo.

This leads to the assumption of the existence of additional enzymes that might be able to release the neurotoxic amyloid peptide. Within this project we are investigating one of these alternative beta secretases. The aim is the computer aided and structure-based design and development of inhibitors of the isoenzymes Meprin alpha and beta. It was already possible to develop very specific acting compounds, exhibiting better activity than the known non-specific Meprin inhibitors. The IP is filed and we are now able to investigate the pathophysiological roles of Meprin alpha and beta more detailed.

The goal in this project will be the development of new therapeutic options for Alzheimer’s disease in close collaboration with the other units of the department.

Broadening the chemical space of metal binding groups

© Fraunhofer IZI

A lot of potential target enzymes with high medical interest contain a metal ion in their active site which is essential for the catalysis of the corresponding reaction. These metal ions are usually interesting pharmacophoric points for the development of new inhibitors because a binding to them leads very often to potent compounds. Unfortunately only a small amount of different potential metal binding groups are known, limiting the development of new drugs, because of their unselective binding not only to the target but also to other enzymes. One example for the discontinuation of the development of promising new drugs are matrix-metallo-protease inhibitors, where it was not possible to develop selective compounds among the enzyme class.

By the usage of a combination of semi-empirical, quantum chemical, ligand- and structure based approaches we are now able to overcome this limitations and to broaden the available chemical space for metallo enzyme inhibitors. In one example it was possible to extend the amount of the known 4 metal binding groups for a metal dependent acyltransferase by a number of 6, fully new and undescribed. This allows the development of a whole new world of active molecules.

MALDI-TOF mass spectrometry-based assays for the quantification of biomarkers

© Fraunhofer IZI

MALDI-TOF mass spectrometry is routinely used for the investigation of biomolecules of higher molecular weights, e.g. proteins. Examples are the sequencing of proteins and the investigation of different species of one protein or peptide. However, all of these tools are of a qualitative kind, because for a quantification of the proteins other mass spectrometry based tools are used. But these methods need more time for analysis and so the throughput is limited.

Nevertheless, for certain biomarkers the use of MALDI-TOF for quantification is a useful solution, because they need for the full ionization, and thereby quantification, more energy, than other methods are able to provide. As an example a MALDI-TOF based assay for the quantification of a relatively large protein of 4,8 kDa, used as a bio-marker was established. For this a sample preparation routine had to be developed that is easy to handle. For the determination of such critical parameter like LOD and LOQ an internal standard was synthesized (deuterated) and it was successfully used for the determination of a concentration range of 20 ng/µL to 100 ng/µL in human plasma that exactly represents the range, described for this biomarker in healthy persons and patients.