How is bakuchiol obtained?

This is a terpenic phenol isolated in 1966 and derived from the seeds of Psoralea corylifolia (bakuchi or babki), which belongs to a significant group of natural compounds called meroterpenoids. P. corylifolia is widely used in traditional Indian (Ayurvedic) and Chinese medicine to treat numerous diseases such as psoriasis, leucoderma, leprosy, acne, and inflammatory skin diseases.

In skincare, bakuchiol is recognised as a natural and risk-free alternative to retinol (a derivative of vitamin A). However, bakuchiol does not share the structural similarity of retinol. Its association with this active ingredient is made through functional analogy, meaning it mimics its dermo-cosmetic properties.

Gentle and suitable for sensitive skin or skin prone to blemishes, it does not causeunpleasant side effects unlike retinol. Furthermore, there are no contraindications or dangers associated with its use by pregnant women or before sun exposure (bakuchiol is photostable). But how is it obtained?

Theextraction by solvent is a separation operation of a compound present within a solid raw material through the use of a solvent liquid in which the compound to extract and isolate is soluble. This process follows several stages:

1. The solvent (typically, hexane) and the P. corylifolia L. seed powder are mixed together within a tank

2. The solution is filtered.

3. The solvent is evaporated using a rotary vacuum evaporator to obtain a sticky, brownish dried extract.

Even though this method allows for a high extraction yield, n-hexane remains a polluting solvent and dangerous due to its high flammability. New extraction methods are currently being developed within the cosmetics industry.

In order to liberate ourselves from polluting solvents such as hexane or methanol, researchers have been working on the extraction of babchi seed oil using supercritical carbon dioxide, followed by further enrichment in bakuchiol through the technique of molecular distillation.

The extraction of compounds using supercritical CO2 dates back to the 1970s. It was then an ecological alternative to the use of traditional extraction solvents, which are often polluting and harmful. CO2 is a gas well-suited for the extraction of plant matter due to its purity and non-volatile, non-toxic, and non-polluting properties. Even though this extraction method is very costly, it provides a high-quality babchi seed vegetable oil (its biochemical composition is almost identical to that of the original seeds). The principle is simple: the plant material is passed through a flow of carbon dioxide (CO2), which is subjected to low temperature and high pressure. The active molecules of babchi, such as bakuchiol, are then naturally extracted before moving into another chamber. In this new chamber, the temperature and pressure are controlled to separate the babchi actives from the CO2.

The extract obtained by the method described above then undergoes a molecular distillation for the enrichment of bakuchiol. This is a distillationprocess under high vacuum which allows the isolation of molecules and therefore bakuchiol.

• SANKAR U. & al. Enhancement of bakuchiol in supercritical carbon dioxide extracts of chiba seed (Psoralea corylifolia L.) utilising molecular distillation–response surface methodology. Biotechnology and Bioprocess Engineering (2009).

• MUJEEB M. & al. Extraction, quantification, and cytokine inhibitory response of bakuchiol in Psoralea coryfolia Linn. Separations (2020).