Published: 11 May 2020, 17:00 | By: Ute Schönfelder
A research team from the University of Jena and Louisiana State University (USA) has clarified the molecular mechanism behind the anti-inflammatory effect of a natural product from frankincense resin. The enzyme 5-lipoxygenase plays a key role here: the natural product reprograms the normally pro-inflammatory enzyme into an anti-inflammatory protein.
Once upon a time, the Three Kings brought precious gifts to the new-born baby Jesus: as well as gold and myrrh, they also had frankincense in their bags. “Even today, frankincense is a valuable gift,” says Prof. Oliver Werz of Friedrich Schiller University – although he is not really thinking about the biblical meaning of frankincense. “The resin extracted from the bark of the frankincense tree contains anti-inflammatory substances, which make it suitable for the treatment of diseases such as asthma, rheumatoid arthritis or neurodermatitis, among others,” he explains.
Pharmacist Werz and his team have been investigating the anti-inflammatory effect of frankincense resin and its components for several years. Now, together with colleagues in the US, the Jena University researchers have succeeded in uncovering the molecular mechanism of boswellic acid, a substance which is responsible for the anti-inflammatory effect of frankincense. They present their results in the current issue of the specialist journal “Natural Chemical Biology” (DOI: 10.1038/s41589-020-0544-7).
The enzyme 5-lipoxygenase plays a key role in the effect of frankincense. “It has been known for more than 40 years that this enzyme promotes the formation of leukotrienes, an important group of inflammatory mediators in the human body,” explains Werz. However, in its current paper, the research team has for the first time been able to clarify and image the crystal structure of this central inflammatory enzyme with bound inhibitors. The images of the crystal structure allow detailed studies of the enzyme and its interaction with active substances, as well as the development of new anti-inflammatory drugs.
And that is exactly what Werz and his colleagues have done. In addition to zileuton, an anti-inflammatory drug already on the market, which is a synthetic preparation used to treat asthma, the researchers have combined the enzyme with various natural products and analysed the crystal structures of the resulting complexes. The result initially surprised the researchers: while other natural products, in a similar way to zileuton, dock directly to the active site of the enzyme and thus inhibit its function, boswellic acid binds to another site of the enzyme molecule, far from the active site. “However, this binding leads to structural changes in the active site and this also inhibits the enzyme activity,” says Werz.
Gilbert NC et al. Structural and mechanistic insights into 5-lipoxygenase inhibition by natural products, Nature Chemical Biology (2020), https://www.nature.com/articles/s41589-020-0544-7
These studies were carried out and funded within the collaborative research centres SFB1127 ChemBioSys and SFB1278 Polytarget, and the Free State of Thuringia and the European Social Fund.