Design and development of raw clay-based formulations emulsions loaded with ascorbyl glucoside, in vitro evaluations on topical delivery and cell viability

Clays are layered materials with several unique features, which lead to many useful applications for natural products. In particular, raw clay has been increasingly utilized in skin care products and major advances have been achieved in the research and innovation related to these materials. This scientific manuscript addresses topical applications that include the development of O/W emulsions containing two types of raw clay such as kaolinite and sodium smectite associated with ascorbyl glucoside. The topical formulations were submitted to in vitro assays such as release, permeability using human cadaver skin as well as a skin retention study. The results of the release study showed that ascorbyl glucoside was delivered by the five formulations of this study. However, the skin permeation study of ascorbil glucoside showed that the formulation with smectite clay had a higher permeation and retention of AA2G in the skin layers suggesting that the smectitic clay (W4) acts as a promising permeation enhancer for this cosmetic active. Additionally, no cytotoxicity was detected in HaCaT and HDF cell lines, highlighting the safe character of the formulations, at least at short-term.