Cosmeceutical potential
Among the important bioactive ingredients present in C. japonica are phenolic compounds, terpenoids, and fatty acids, which are thought to account for the anti-inflammatory, antioxidant, antimicrobial, and anticancer activity associated with the plant.1 The high concentration of polyphenolic substances, in particular, is thought to at least partly account for the inclusion of C. japonica leaf extracts in antiaging cosmetics and cosmeceuticals.12 Specifically, some of the antioxidant substances found in C. japonica extracts include quercetin, quercetin-3-O-glucoside, quercitrin, and kaempferol.9
Wrinkle reduction and moisturization
In 2007, Jung and colleagues found that C. japonica oil activated collagen 1A2 promotion in human dermal fibroblast cells in a concentration-dependent fashion. The oil also suppressed MMP-1 functions and spurred the production of human type I procollagen. On human skin, C. japonica oil was tested on the upper back of 30 volunteers and failed to provoke any adverse reactions. The oil also diminished transepidermal water loss on the forearm. The researchers concluded that C. japonica oil merits consideration as an antiwrinkle ingredient in topical formulations.13
More recently, Choi and colleagues showed that ceramide nanoparticles developed through the use of natural oils derived from Korean traditional plants (including C. japonica, along with Panax ginseng, C. sinensis, Glycine max napjakong, and Glycine max seoritae) improve skin carrier functions and promote gene expressions needed for epidermal homeostasis. The expressions of the FLG, CASP14, and INV genes were notably enhanced by the tested formulation. The researchers observed from in vivo human studies that the application of the ceramide nanoparticles yielded more rapid recovery in impaired skin barriers than the control formulation. Amelioration of stratum corneum cohesion was also noted. The investigators concluded that this and other natural oil–derived ceramide nanoparticle formulations may represent the potential for developing better moisturizers for enhancing skin barrier function.14
Hair-growth promotion and skin-whitening activity
Early in 2021, Cho and colleagues demonstrated that C. japonica phytoplacenta extract spurred the up-regulation of the expression of hair growth–marker genes in human follicle dermal papilla cells in vitro. In clinical tests with 42 adult female volunteers, a solution with 0.5% C. japonica placenta extract raised moisture content of the scalp and reduced sebum levels, dead scalp keratin, and redness. The researchers concluded that C. japonica phytoplacenta extract displays promise as a scalp treatment and hair growth–promoting agent.2
Dr. Leslie S. Baumann
Later that year, Ha and colleagues reported on their findings regarding the tyrosinase inhibitory activity of the essential oil of C. japonica seeds. They identified hexamethylcyclotrisiloxane (42.36%) and octamethylcyclotetrasiloxane (23.28%) as the main constituents of the oil, which demonstrated comparable inhibitory activity to arbutin (positive control) against mushroom tyrosinase. Melanogenesis was also significantly suppressed by C. japonica seed essential oil in B16F10 melanoma cells. The investigators concluded that the essential oil of C. japonica seeds exhibits robust antityrosinase activity and, therefore, warrants consideration as a skin-whitening agent.15
Conclusion
C. japonica is not as popular or well researched as another Camellia species, C. sinensis (the primary tea plant consumed globally and highly touted and appreciated for its multitude of health benefits), but it has its own history of traditional uses for medical and cosmetic purposes and is a subject of increasing research interest along with popular applications. Its antioxidant and anti-inflammatory properties are thought to be central in conferring the ability to protect the skin from aging. Its effects on the skin barrier help skin hydration. More research is necessary to elucidate the apparently widespread potential of this botanical agent that is already found in some over-the-counter products.
Dr. Baumann is a private practice dermatologist, researcher, author, and entrepreneur in Miami. She founded the division of cosmetic dermatology at the University of Miami in 1997. The third edition of her bestselling textbook, “Cosmetic Dermatology,” was published in 2022. Dr. Baumann has received funding for advisory boards and/or clinical research trials from Allergan, Galderma, Johnson & Johnson, and Burt’s Bees. She is the CEO of Skin Type Solutions, a SaaS company used to generate skin care routines in office and as an ecommerce solution. Write to her at dermnews@mdedge.com.
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