Amentoflavone: A safe and novel penetration enhancer for transdermal applications

Most of existing chemical penetration enhancers are along with obvious toxicity and skin irritation, new penetration enhancer is still to be developed yet. Amentoflavone is a flavonoid compound extracted from plant Selaginella tamariscina with high biocompatibility. However, its efficacy of penetration enhancers has not been studied. For the first time, the influence of amentoflavone to the skin penetration of caffeine was investigated by the Franz diffusion cells. The interactions of amentoflavone with the skin lipid and keratin were determined to identify the underlying mechanisms by the Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), etc. Results showed that the penetration enhancement ratio (ER) of amentoflavone to model compound caffeine is nearly three times. The major mechanism was identified to be contributed to that, amentoflavone can not only change the keratin structure in stratum corneum (SC), but also undergo hydration interactions with intradermal components, therefore dissolving the lipid, loosening and reducing the barrier function of SC. These results give new evidence to the potential of amentoflavone as the novel effective chemical enhancer for the skin meditated delivery of external molecules, and it can exert the dual effects of traditional Chinese medicine activity and penetration enhancement.