The skin is the largest organ of the human body and bioactive compounds like caffeine and catechins have been described for their skin beneficial effects. While caffeine is widely used as a model in skin permeation studies, the skin permeation of catechins is more challenging. Therefore, methods promoting skin absorption of catechins are of great interest.

In this work, we aim to compare the dermal permeation of bioactive compounds through ex vivo pig skin in two situations: 1) in normal condition, without applying any treatment; and 2) in a condition where the skin was pre-treated with a microneedle device.

Permeation assays were performed using ex vivo pig skin mounted on Franz cells. The microneedle device was previously applied to the skin for the treatment condition. Sampling at different time points was conducted for the skin permeation of bioactive compounds. Quantification was calculated using UV spectroscopy and corresponding calibration curves. Additionally, polyphenol content confirmed the results obtained for epicatechin.

Our results showed that higher quantities of the bioactive compounds permeate the skin when the microneedle device was previously applied. For caffeine, after 2h, the pre-treatment promoted a 26 ± 6% increase in the amount permeated compared to untreated skin. A similar increase in the permeation of epicatechin was also observed when the microneedle device was applied. For epicatechin, at 4h, the pre-treatment promoted an increase in the amount permeated superior to 20%, confirmed by UV spectroscopy and by the Folin-Ciocalteu reaction.

Our results show that the microneedle device enhanced the skin permeation of bioactive compounds in terms of quantity permeated, in a similar range for the two compounds tested. Finally, this work encourages further studies of the application of microneedle devices to promote dermal delivery of bioactive compounds.