Influence of some plant extracts on the transdermal absorption and penetration of marker penetrants

Abstract

Context: Plant extracts are commonly used in a number of cosmetics and topical pharmaceuticals. The effects on such extracts on the subsequent dermal absorption and penetration of other cosmetic ingredients needs to be evaluated.Objective: This study demonstrates the effect of some natural extracts routinely found in cosmetics on the dermal absorption and penetration of marker penetrants.Methods: Aqueous ethanolic extracts of Gingko biloba, Lavendula angustifolia, Rosmarinus officinale, Mentha piperita, Matricaria recutita, Persea Americana, Avena sativa, Zingiber officinale were prepared. 14C-caffeine and 14C-salicylic acid were topically dosed with either 10% solutions of natural extracts or ethanol (control) using a flow through in vitro porcine skin diffusion system. Samples were analyzed with liquid scintillation counter. The parameters of flux, permeability, and percent dose absorbed/retained were calculated and compared.Results: The dermal absorption of 14C-caffeine was significantly higher (p ≥ 0.05) with avocado, chamomile, ginger and peppermint extract as compared to the control ethanol; while dermal absorption of 14C-salicylic acid was significantly greater with ginkgo and chamomile extract as compared to ethanol. Over four fold increase in flux and permeability of caffeine with avocado extract was observed while chamomile and peppermint extracts increased the flux and permeability of caffeine over three fold. Gingko and chamomile extracts increased salicylic acid’s flux and permeability by two fold. Sum of %dose skin residue + %absorption in receptor fluid for different extracts exhibited the similar trend as shown by flux and permeability. The other natural extracts tested did not produce statistically significant effects on dermal penetration parameters for both caffeine and salicylic acid (p ≥ 0.05).Conclusion: These results emphasize the influence of natural plant extracts on the transdermal penetration of hydrophilic (caffeine) and hydrophobic (salicylic acid) penetrants and thus warrants the consideration as to their safety in cosmetics and topical pharmaceuticals containing natural extracts.