NATURALS


85


Brasenia schreberi: ancient epidermal biomimetic


Alain Thibodeau, André Pichette, Jessica Fortin-Mimeault, François Simard, Jean Legault – Boréaceutique Daniel Grenier, Roxane Pouliot - Université Laval, Quebec City, Canada


Being located at the body-environment interface, the skin must play dual roles. The barrier function preventing uncontrolled water loss has been well characterized. It mainly resides within the outermost layer of the epidermis, the stratum corneum, the final step of the keratinocyte terminal differentiation programme. During their upward migration,


keratinocytes will initiate an orchestrated synthesis of specialized proteins that ultimately will become key components of the skin barrier function. The fully differentiated keratinocytes together with intercellular lipids such as cholesterol, ceramides and fatty acids will act as a permissive shield preventing excessive trans-epidermal water loss. Another important task of the skin is


to act as a first line of defence against the surroundings. Volatile chemicals, particulate matters, radiation and climate impacts can influence skin biological processes, more often than not in a negative way. Such impacts can trigger pro-oxidative and


pro-inflammatory responses. If not properly controlled, these reactions can be deleterious for the skin and translated into visible signs of aging. The climate changes we are facing these years are likely to put more pressure on the physiological skin defence armoury. The skin barrier must then fight on


two fronts to maintain skin homeostasis. Despite the presence of an intricate array of antioxidant, detoxification and communication pathways, the topical application of key active molecules may help skin cells to better cope with their challenging daily tasks. Also facing two different elements, the


leaves of Brasenia schreberi - commonly known as watershield - lie on the surface of water while exposing the top side to the dry environment. The underside of the leaf, constantly immersed, is covered by a polysaccharide-rich mucilage with alleged anti-herbivore and drought-protecting actions. In a way, B. schreberi leaf is reminiscent


of the epidermis that also act as a frontier between the underneath hydrated layers of the skin and the external environment often source of harmful ingresses. This aquatic plant takes its origin during


the Tertiary geologic period that began approximately 65 million years ago in the aftermath of the mass extinction that ended the reign of dinosaurs. B. schreberi


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accompanied the growth of glaciers in the northern hemisphere and the appearance of the first hominid relatives of humans. Fossils dating of more than 50 million years ago is a proof that Brasenia has witnessed a gigantic portion of the earth evolution timetable.1 We developed the ingredient Barrier &


Beyond derived from the immersed and aerial portions of B. schreberi. The plant is manually harvested in Canadian boreal forest lakes where its overgrowth can become a nuisance for the aquatic ecosystem. Thin layer chromatography led to the


identification of the flavonoids gossypin and quercimeritrin (quercetin-7-O-b-D- glucopyranoside) in the extract. Various biological activities have been demonstrated


for both components.2,3 We tested the extract


for its efficacy in supporting keratinocytes in synthesizing epidermal barrier building blocks as well as counteracting environmental radiation and chemical aggressions.


Material and methods Brasenia schreberi aerial parts were extracted in water/ethanol conditions.


Radiation and heavy metal-induced oxidative damage Exposition to UVB or heavy metals (Fe3+


) elicits


pro-oxidative reactions within cells forming reactive oxygen species (ROS). WS1 human skin fibroblasts were grown in 96-well plates in an appropriate culture medium. The Brasenia extract was added at a


concentration of 50 µg/ml into the culture medium, and cells were then exposed to UVB (12 min, 80 mJ/cm2


) or to Fe3+ (900 µg/ml) as a heavy


metal. The medium was replaced by a buffered saline solution containing the probe DH-RHO 123 (dihydrorhodamine 123). Once inside the cell, DH- RHO 123 will react with ROS forming the oxidized fluorescent product RHO 123 (green).


Pro-inflammatory markers U937 human macrophages were exposed to lipopolysaccharides to induce a pro- inflammatory state. The production of the cytokines IL-1b, IL-6, IL-8 and TNFa was quantified using specific immuno-detection assays.


NF-kB activation was assessed using U937 macrophages transfected with a luciferase


March 2024 PERSONAL CARE


Credit: Stephen J. Davies


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