Targeted biosynthesis of pharmaceutically relevant triterpenoids

Triterpenoids, with many thousands known compounds, represent one of the largest groups of secondary metabolites in the plant kingdom. These are natural compounds produced by plants not for primary metabolism in growth, but for special tasks such as defense against pests or attracting pollinators.
During biosynthesis, more than 100 different triterpene scaffolds are synthesized from six isoprene units, which undergo further modifications, leading to this enormous structural diversity. Cyclic triterpenoids are of particular interest - they exhibit very versatile bioactive functions. The potential includes antimicrobial, antioxidant, anticarcinogenic, and antiallergic effects, making them attractive for agricultural and pharmaceutical applications.

Project objectives and structure

This project forms part of the “Tailor-made bio-based ingredients for a competitive bioeconomy” funding programme of the Federal Ministry of Research, Technology and Space (BMBF), as well as the National Research Strategy Bioeconomy 2030.

The R&D consortium is coordinated by Fraunhofer IME and includes additional partners such as the Technical University of Munich (TUM), as well as the SMEs Phytowelt GreenTechnologies GmbH and VivaCell Biotechnology GmbH.

Research background

Triterpenoids are of great economic interest due to their diverse biological activities, such as anti-inflammatory and anti-tumour properties. The main objective of the 'Perspective' project is to develop pharmacologically relevant triterpenoids through targeted biological synthesis. This will be achieved through biocatalysis and fermentation on a yeast-based platform. The project aims to exploit the structure–activity relationships of these bioactive substances to enable applications in the fields of pharmaceuticals, cosmetics and agriculture.

Progress and results
As part of the “Perspective” project, we made significant progress in the application of triterpenoids and understanding their effects. In the areas of gene identification and expression, we developed a platform for the oxidation and glycosylation of triterpenoids. The optimization of yeast strains enabled the production of relevant quantities of oxidized triterpenes on a gram scale. We demonstrated the feasibility of glycosylation both in vivo and in vitro, which can now be scaled up. For downstream processing, we optimized chromatographic separation by fractional extraction of the triterpenoids, enabling us to isolate them with a purity of over 98 percent (NMR tested).
In biological tests, the isolated triterpenoids showed significant activity in pharmacologically relevant experiments, such as inflammation assays. They also demonstrated a positive effect on the digestive tract in model systems.
We compiled a priority list that ranks triterpenoids intended for further diversification strategies through enzymatic catalysis in yeast.  Through metabolic analysis, we identified additional ways to optimise yeast strains and modify fermentation conditions to boost triterpenoid production, employing 13C labelling and subsequent testing. We are currently conducting experiments to track the metabolism of applied triterpenoids in a cell model.

Outlook and future steps
The triterpenoids developed in this project will be evaluated in collaboration with industrial partners across various application areas, including animal feed, bioactives, cosmetics and pharmaceuticals. This will facilitate their timely integration into the approval process.

Conclusion
The project has achieved significant scientific progress while concurrently creating sustainable value in accordance with the national Bioeconomy 2030 research strategy, the German sustainability strategy, and the United Nations Sustainable Development Goals (UN SDGs). The results of the study indicate the potential for triterpenoids to be used industrially in the future.