The human skin is the outer covering of the body. It is composed of multiple layers epidermis, dermis, and hypodermis. Because it interfaces with the environment, skin plays an important immunity role in protecting the body against pathogens and excessive water loss. Some other functions are temperature regulation, sensation, synthesis of vitamin D. On average humans have 20 square feet (1.9 m2) of skin although this figure varies from person to person.
The epidermis, the outermost layer, acts as a barrier against the external environment for example UV light through melanin secreted by melanocytes. However, excessive melanin accumulation causes the skin pigmentation disorders hyperpigmentation, melasma, and freckles. The next layer, dermis, provides strength and elasticity via activation of type I and III collagen fibrils, fibronectin, and elastin. Thus, enhancement of the structural matrix of the dermis is important in maintenance of healthy skin. The hypodermis is located beneath the skin and plays important roles in storage of excessive fat, maintenance of body temperature, and providing protective padding. However, a diminished dermis and excessive fat accumulation results in poor skin health. Inhibition of excessive accumulation of fat in the hypodermis is important for prevention of skin wrinkles and poor skin health.
The researchers evaluated the beneficial effects of fisetin for skin health in vitro using B16F10 melanoma cells (mouse cells), human skin fibroblasts and 3T3-L1 cells (mouse cells used in research on adipose (fat) tissue).
The researchers noted that recent reports have suggested that the connective tissue growth factor (CCN2) stimulates extracellular matrix (ECM) synthesis via activation of the transforming growth factor-β (TGF-β) pathway. Regulation of the CCN2/TGF-β signaling pathway may also reportedly exert beneficial effects on skin fibroblasts for production of ECM components and for wound healing. They hypothesized fisetin may influence this mechanism.
They found from the test results that induced melanosis in B16F10 melanoma cells was inhibited by fisetin treatment, which also enhanced mRNA expression levels of skin fibril-related genes via the CCN2/TGF-β signaling pathway. Decreased intracellular lipid accumulation via down-regulation of transcriptional factors through activation of the CCN2/TGF-β signaling pathway was also observed.
In summary a novel function of fisetin in skin health via down-regulation of melanosis and adipogenesis, and up-regulation of skin fibril-related genes was discovered by the researchers. Altogether this suggests that fisetin has potential to improve the skin and is a candidate for the development of nutri-cosmetics for skin health.
You can find the report here.