ABSTRACT
The aim of this study was to investigate the transdermal penetration enhancement effect of wintergreen oil and its action mechanisms. The in vitro transdermal tests were carried out to study the transdermal penetration enhancement effect of wintergreen oil by using osthole and geniposide as the lipophilic and hydriphilic model drugs. Fourier-transform infrared spectroscopy was used to investigate the effect of wintergreen oil on the molecular structure of rat stratum corneum, and the scanning electron microscope was employed to observe the change of rat skin surface after treatment by the oil. The wintergreen oil at proper concentrations could effectively promote the transdermal permeation of osthole and geniposide, and exhibited better penetration-enhancing activity for the lipophilic osthole, close to the commonly used classical penetration enhancer azone. The infrared spectroscopy study and scanning electron microscope showed that wintergreen oil mainly acted on the stratum corneum lipids, reduced dense stratum corneum, and reduced the skin barrier function. Thus, the wintergreen oil could effectively facilitate the transdermal absorption of the lipophilic and hydrophilic drugs, resulting from the lowed skin barrier function.