Bakuchiol, a naturally derived alternative to retinol?

The retinol is a derivative of vitamin A that has been widely used in dermatology and cosmetics since the 1970s, notably for its effects on signs of ageing and blemishes. It works by regulating keratinocyte differentiation, stimulating collagen production and accelerating cell turnover. The bakuchiol, by contrast, is a plant-derived compound isolated from the seeds of Psoralea corylifolia, a plant that is highly regarded in traditional Indian and Chinese medicine. It is only recently, since the 2010s, that it has begun to attract interest in cosmetics as a natural alternative to retinol, notably for sensitive skin.

If these two actives are so often compared, it is because their chemical structures are similar and because they share several properties. Indeed, the retinol and the bakuchiol have both demonstrated the ability to reduce the appearance of wrinkles, improve skin texture, reduce hyperpigmentation and attenuate imperfections. They also share certain common mechanisms of action, such as the capacity to stimulate fibroblast activity, thereby promoting the synthesis of collagen and elastin, or to reduce the expression of matrix metalloproteinases, which degrade the structural proteins of the dermal extracellular matrix.

While the cosmetic and dermatological benefits of retinol are well established and its action is no longer in doubt, several studies have compared its efficacy with that of bakuchiol to determine whether the latter can truly be classed as "retinol-like". Here are their conclusions.

Bakuchiol and retinol: comparable efficacy against skin imperfections?

The emergence of pimples is the result of several mechanisms: an excess of sebum and a buildup of dead cells leading to hair follicle blockage, a proliferation of the bacterium Cutibacterium acnes and local inflammation. Retinoids, such as retinol, are particularly useful for combating skin imperfections because they act at multiple levels. By promoting keratinocyte differentiation and stimulating epidermal renewal, they help to unclog pores and reduce comedone formation. Moreover, some studies in vitro suggest a sebum-regulating effect of retinol. With regard to its antibacterial action against C. acnes, this has not yet been demonstrated for retinol, unlike other retinoids such as adapalene. Finally, retinol exhibits anti-inflammatory properties by inhibiting the expression of certain cytokines, such as TNF-α and IL-6, which helps to reduce inflammatory lesions.

Bakuchiol possesses comparable properties. Studies in vitro have revealed its ability to inhibit the growth of C. acnes, helping to prevent inflammation of acne lesions. In parallel, bakuchiol reduces the expression of inflammatory markers such as NF-κB and COX-2, thereby diminishing the redness associated with certain lesions. Finally, work conducted in vitro suggests it may act on lipogenesis and reduce sebum production. One study even compared bakuchiol’s seboregulating effect with that of retinoic acid, a prescription-only retinoid, by examining their ability to inhibit 5α-reductase, whose activity is correlated with sebum production. The results indicate comparable efficacy.

Several clinical studies have demonstrated the potential of bakuchiol and retinol in managing skin imperfections, yet none have directly compared them, which limits the conclusions. One such study assessed the efficacy of a 1% bakuchiol formulation against a salicylic acid-based product in sixty subjects with mild to moderate acne. Participants applied one of the treatments twice daily for six weeks, and acne severity was measured using the tool Global Acne Grading System. Another study, undertaken in 2009 by Natakankitkul et al., evaluated a formulation containing 0.2% retinol against a cream with a vitamin C derivative. In this trial, 45 individuals with acne applied one of the products once daily for eight weeks. The results of both studies, presented below, shed light on retinol and bakuchiol, but a direct comparison remains difficult since their impact on skin imperfections was not assessed within the same protocol.

Bakuchiol, as effective as retinol against wrinkles?

If retinol is so popular in cosmetics, it is primarily due to its action on the signs of ageing. It works in several ways to target wrinkles, notably by stimulating keratinocyte proliferation and the production of collagen and elastin by fibroblasts. It also accelerates cell renewal and reduces the cohesion of corneocytes in the stratum corneum, refining skin texture and diminishing the appearance of fine lines. Bakuchiol possesses similar properties. Several studies in vitro have shown that it can stimulate the expression of genes involved in the synthesis of types I and III collagen, while inhibiting metalloproteinases responsible for the degradation of dermal fibres. Furthermore, it increases the production of fibronectin, a glycoprotein essential to the cohesion of the extracellular matrix.

A clinical study conducted with 44 volunteers aimed to compare the efficacy of retinol and bakuchiol on signs of skin ageing. Over twelve weeks, participants applied a cream containing 0.5% retinol or 0.5% bakuchiol. At the end of the study, both groups showed a significant decrease in wrinkle depth, slightly more pronounced in the group treated with retinol. However, adverse effects were more frequent in this group: 20% of participants experienced skin peeling, compared with only 10% in the bakuchiol group.

Is bakuchiol as effective as retinol for attenuating brown spots?

Bakuchiol and retinol both demonstrate significant properties for reducing pigmented spots. Bakuchiol operates at different stages of melanogenesis: it inhibits tyrosinase activity, the enzyme catalysing the conversion of tyrosine into melanin, and reduces the expression of TRP-1 and TRP-2 proteins, which are involved in the maturation and stabilisation of melanin within melanosomes. Meanwhile, retinol exerts an effect on hyperpigmentation via through both direct and indirect mechanisms. It can inhibit the expression of tyrosinase and TRP-1 and TRP-2 proteins, which slows melanin production, but also influences pigment distribution in the epidermis by promoting a more uniform dispersion of melanin granules within keratinocytes.

The aforementioned clinical study, conducted on 44 participants who applied a cream containing 0.5% retinol or 0.5% bakuchiol daily for twelve weeks, also evaluated the effect of these formulations on pigmentation. The results demonstrated a significant improvement in skin tone uniformity in both groups, slightly more pronounced in the retinol group.

Bakuchiol is indeed establishing itself as a plant-based alternative to retinol and appears capable of addressing the same concerns.

The bakuchiol is an overall gentler active ingredient than retinol.

Retinol, despite its recognised efficacy, is frequently associated with adverse effects, such as redness, tingling sensations, increased dryness and visible skin flaking. These effects are directly linked to its mechanism of action: by binding to nuclear RAR (Retinoic Acid Receptors) and RXR (Retinoid X Receptors), retinol triggers an intracellular signalling cascade that modulates keratinocyte proliferation, cell differentiation and collagen synthesis. However, this intense stimulation of epidermal renewal can temporarily disrupt the skin barrier and increase transepidermal water loss. This phenomenon is most commonly observed in sensitive skin, although it can affect all skin types.

In comparison, bakuchiol is generally better tolerated. Although the risk of irritation can never be entirely excluded, as with any cosmetic active ingredient, studies report a lower incidence of side effects. The bakuchiol can even be used by individuals prone to rosacea, who often have very sensitive skin. The previously mentioned clinical trial, comparing the efficacy of a 0.5% bakuchiol cream with that of a formulation containing 0.5% retinol, also examined the tolerance of both products and specifically assessed the occurrence of flaking and stinging sensations. The charts below, taken from the study, confirm the superior cutaneous tolerance of bakuchiol compared to retinol.

• NATAKANKITKUL S. & al. Comparison of clinical efficacies of sodium ascorbyl phosphate, retinol and their combination in acne treatment. International Journal of Cosmetic Science (2009).

• MARCHIO F. & al. Bakuchiol in the management of acne-affected skin. Cosmetics & Toiletries (2011).

• CHAUDHURI R. K. & al. Bakuchiol: a retinol-like functional compound revealed by gene expression profiling and clinically proven to have anti-aging effects. International Journal of Cosmetic Science (2014).

• SIVAMANI R. K. & al. Prospective, randomized, double‐blind assessment of topical bakuchiol and retinol for facial photoageing. British Journal of Dermatology (2019).

• KIM S. Y. & al. UP256 inhibits hyperpigmentation by tyrosinase expression/dendrite formation via rho-dependent signaling and by primary cilium formation in melanocytes. International Journal of Molecular Science (2020).

• SODHA P. & al. The use of bakuchiol in dermatology: a review of in vitro and in vivo evidence. Journal of Drugs in Dermatology (2022).