This discovery allowed the plant researchers around Prof. Alain Tissier to produce the economically valuable plant material by biotechnological means in yeast cells. The project was published in the renowned journal Nature Communications.
Carnosic acid is a natural antioxidant that is found in the leaves of rosemary and sage. It is used worldwide as a preservative and flavor in meat products, oils, fats, sauces and animal feed. Carnosic acid, for which the demand is steadily increasing, is still extracted from rosemary plants, which grow slowly. Dried leaves of sage or rosemary contain at most 2.5 percent of carnosic acid, necessitating a large amount of plant material to ensure the production of the antioxidant on industrial scale. Furthermore, the complex structure of carnosic acid makes an industrial synthetic process unrealistic.
The biosynthesis of carnosic acid within the plant takes place in several reaction steps, which are catalyzed by different enzymes. The enzyme that catalyzes the last step of the reaction chain had not yet been discovered. This knowledge-gap has now been closed by the IPB researchers. They discovered an additional, previously unknown intermediate and also new enzymes, which were described and characterized by them. With the knowledge of all involved reaction partners, the scientists were able to introduce the genes coding for the corresponding enzymes into yeast cells and make them produce carnosic acid. This is the first step in the development of a biotechnological production process for the antioxidant.
Carnosic acid is also the starting material for the biosynthesis of many other phenolic diterpenes, which act as bioactive substances against inflammation, cancer and various neurodegenerative diseases. Also for this reason, it will be interesting to produce carnosic acid in the future with biotechnology-based processes and thus independently of climate fluctuations, soil quality and harvest yields.
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