Bakuchiol [(1E,3S)-3-ethenyl-3,7-dimethyl-1,6-octadien-1-yl]phenol, a prenylated phenolic monoterpene found in the seeds and leaves of various plants, particularly Psoralea corylifolia, has been used to treat a broad array of disorders, including skin conditions, in the traditional medical practices of China, Japan, and Korea, as well as Ayurvedic medicine in India.1-6 Specifically, the seeds of as well as cardiovascular diseases, nephritis, osteoporosis, and cancer.7-9
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This primary active ingredient is reputed to exert antioxidant, antibacterial, anti-inflammatory, antiaging, and estrogen-like functions, and recent data suggest anticancer activity, including activity against skin cancer. Its antiaging properties manifest via preservation of cutaneous collagen.4 The plant itself has displayed a wide range of biological functions, such as antibacterial, anticancer, cytotoxic, cardiac, diaphoretic, diuretic, stimulant, aphrodisiac, and tonifying activities.8,9 A 2016 quantitative analysis of Psoralea corylifolia and seven of its standard constituents (psoralen, angelicin, neobavaisoflavone, psoralidin, isobavachalcone, bavachinin, and bakuchiol) using high-performance liquid chromatography revealed that bakuchiol is the strongest phytochemical ingredient in the plant, which the investigators found also confers neuroprotective and antineuroinflammatory benefits.3
Other species contain bakuchiol, and its biological activities have been harnessed in other folk medical traditions. The monoterpene is an important constituent found in Ulmus davidiana var. japonica, which is used for its anti-inflammatory properties in traditional Korean medicine.10 Further, bakuchiol and 3-hydroxy-bakuchiol have been identified as key components isolated from Psoralea glandulosa, which is a shrub used in Chilean folk medicine to treat cutaneous disorders engendered by bacteria and fungus.11 Topical applications of bakuchiol have been demonstrated to confer antiaging benefits.12 This column briefly identifies some of the various uses emerging for this compelling botanical agent.
Antiaging activities
In 2014, Yu et al. found that bakuchiol may impart antiaging benefits by supporting the cellular activity of the expression level of human skin fibroblasts (ESF-1), as well as production of collagen types I and III, while reducing the matrix metalloproteinase-1 mRNA expression.13
The same year, Chaudhuri et al. compared the skin care–related activities of retinol and bakuchiol, finding their gene expression profiles very similar. In addition, they observed that bakuchiol up-regulated collagen types I and IV in a DNA microarray study and stimulated type III collagen production in a model of mature fibroblasts. Further, the investigators formulated bakuchiol into a skin care product and tested it clinically, with twice daily applications over 12 weeks yielding significant amelioration in lines and wrinkles, pigmentation, elasticity, and firmness, as well as overall diminished photodamage without provoking redness. They concluded that bakuchiol can act as an antiaging agent through regulation of gene expression comparable to retinol.1
Retinoids without reactions?
In 2017, Ma et al. set out to synthesize and test in psoriatic cytokine–treated cultures of keratinocytes and organotypic skin substitutes a new substance created by combining two skin-active compounds (bakuchiol and salicylic acid) into bakuchiol salicylate (bakusylan), with the intention of rendering a novel functional retinoid. The researchers reported that the gene expression profile showed elimination of various retinoid-like proinflammatory responses, without a loss of normalizing activity. They concluded that their work may result in a new class of functional retinoids.14