11 Mar Chinese Licorice May Enhance Skin Protection From Sun Exposure
MedicalResearch.com interview with:
J. Kühnl, D. Roggenkamp, G. Neufang.
Research & Development, Beiersdorf AG, Hamburg
MedicalResearch:What is the background for this study? What are the main findings?
Response: The skin is constantly challenged by environmental stressors that induce inflammatory processes, resulting in skin damage and –in the long term- consequently aging processes. UV-irradiation is an important exogeneous stressor. Even the best filter systems do not completely abolish the impact of UV radiation. For example, after application of a SPF50+ sun lotion, about 2% of UV-rays still reach the skin. However, the skin developed strategies to cope with exogenous stressors: Intracellular thiols quench harmful UV-derived free radicals and a multitude of detoxifying enzymes convert noxious compounds and metabolites into harmless species.
We strived to specifically stimulate these cytoprotective cellular systems in order to tip the balance in favor of more robust skin cells.
Previous studies showed that the root extract of the plant Glycyrrhiza inflata (Chinese Licorice) exhibits anti-inflammatory and anti-microbial effects. The major phenolic constituent of the licorice extract is Licochalcone A (LicA) and this compound is largely responsible for the beneficial effects. This was explained by LicA´s inhibitory effect on the pro-inflammatory transcription factor NFkB and its antioxidant properties.
However, in this study, we could add another facet of LicA´s efficacy: by activating the transcription factor Nrf2, LicA stimulates the expression of cytoprotective enzymes such as heme oxygenase I and the key enzyme of glutathione synthesis, resulting in increased intracellular thiols concentrations. Consequently, when pre-incubated with LicA, isolated human skin cells were more robust against solar simulated light-induced cellular damage, indicated by a significantly decrease in the generation of free radicals in vitro. In a translational approach, we conducted a study with healthy volunteers demonstrating that the application of a lotion containing LicA-rich root extract on the inner forearms for two weeks protected the skin from UV-provoked oxidative stress.
Thus the cellular effects of licorice are able to provide a protective shield from sun exposure, supporting and going beyond the action of sunscreens regarding sun protection.
MedicalResearch: What should clinicians and patients take away from your report?
Response: Our findings clearly indicate that skin´s own protection systems can be enhanced by the application of licorice extract. In combination with UV filters, this approach might provide superior sun protection by not only mediating physical but also biological sun protection. Specific activation of cellular antioxidant-generating enzymes may be superior to topical application of “passive” antioxidants (i.e. radical scavenger) because the latter are rapidly depleted while the cellular-derived are constantly regenerated.
We think that the concept of stimulation of cellular defense systems against inflammatory stimuli and oxidative stress could also be relevant for other dermatological issues. For instance, the skin of patients suffering from atopic dermatitis or acne displays enhanced oxidative stress due to inflammatory processes. Also polymorphic light eruption (PLE, also known as sun allergy or Mallorca acne) is related to an increased oxidative burden. Fortifying skin cells against the detrimental effects of reactive oxygen species may therefore alleviate several skin conditions.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Response: We think that the outcome of our study helps to further improve the effectiveness of sunscreens by combining UV-filters with the favorable activation of cell´s own defense systems, protecting from harmful aspects of sun exposure. Furthermore, our study indicates that licorice extract improves inflammatory skin diseases and therefore might enable a better quality of life for patients with atopic dermatitis and acne. Future research should compare the profiles of plant extracts with regard to their ability to strengthen skin´s own defense in order to provide tailor-made solutions for different dermatological indications.
Citation:
Kühnl J1, Roggenkamp D, Gehrke SA, Stäb F, Wenck H, Kolbe L, Neufang G.
Exp Dermatol. 2015 Jan;24(1):42-7. doi: 10.1111/exd.12588. Epub 2014 Dec 8
MedicalResearch.com interview with: J. Kühnl, D. Roggenkamp, G. Neufang. (2015). Chinese Licorice May Enhance Skin Protection From Sun Exposure
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Last Updated on March 11, 2015 by Marie Benz MD FAAD