How is bisabolol obtained?

It is also possible to obtain bisabolol through laboratory synthesisfollowing several successive chemical reactions.

1. Preparation of Precursors : The precursors used for the synthesis of bisabolol are typically petrochemical compounds. These precursors are purified before they are made to react with each other.

2. Diels-Alder Reaction : The key reaction for the synthesis of bisabolol is the Diels-Alder reaction, which involves the cyclo-addition of a diene, a compound with two double bonds, with an alkene, a molecule having a double bond. This allows for the production of a compound referred to as a bisabolol precursor.

3. Hydrogenation : The cyclic precursor obtained from the Diels-Alder reaction undergoes a hydrogenation step, where double bonds are reduced to single bonds. This leads to the formation of bisabolol alcohol.

4. Purification and Refinement : The synthetic bisabolol obtained is then subjected to stages of purification and refinement to remove impurities and achieve a pure form of bisabolol.

This chemical synthesis typically allows for the acquisition of a more pure form of bisabolol than that obtained through plant extraction. However, it is more polluting.

Still under development, the third method of obtaining bisabolol utilises advanced biotechnologies. It is achieved through bacterial fermentation, meaning that it is bacteria, often of the Escherichia coli type, that produce the bisabolol. Here are the main steps followed:

1. Bacterial strain selection : a strain of bacteria, often E. coli, is selected for its ability to express α-synthase, the gene responsible for the synthesis of bisabolol. This gene can notably be obtained from the German chamomile flower.

2. Construction of the Expression Vector : The α-synthase is inserted into an expression vector, which is then introduced into the cells ofE. coli. This vector allows the bacterial cells to produce the enzymes necessary for the conversion of metabolic precursors into bisabolol.

3. Cell Culture and Fermentation : The E. coli cells containing the expression vector are cultivated in a suitable culture medium. The culture conditions, such as temperature, pH, and medium composition, are optimised to promote the production of bisabolol. Fermentation typically lasts several days.

4. Bisabolol Extraction : once the fermentation process is complete, bacterial cells are harvested and bisabolol is extracted from the culture medium. Various extraction methods can be employed, such as solvent extraction or distillation extraction.

5. Purification : The extracted bisabolol is then subjected to purification stages to remove impurities and obtain a purer form of the compound. Purification may involve techniques such as chromatography or crystallisation.

This method of obtaining bisabolol allows for reducing production costs and is environmentally friendly. However, it requires advanced knowledge in genetic engineering and specialised facilities.