Evaluation of skin permeability of sesquiterpenes of an innovative supercritical carbon dioxide Arnica extract by HPLC/DAD/MS

Recently, a supercritical carbon dioxide dried extract of Arnica flower, with a very high sesquiterpene content was developed. In view of using this extract in formulations for cutaneous application, the ability of sesquiterpenes to permeate the skin was evaluated by HPLC/DAD/MS using the following permeation enhancers: oleic acid (OA), dimethylsulfoxide (DMSO), lauroglycol, isopropyl myristate and Tween 80. A skin permeation study was performed using a modified Franz diffusion cell and the human stratum corneum and epidermis as membrane. Solutions of the enhancers were directly analysed after dilution with methanol or DMSO. A simple RP-HPLC-DAD-MS method for the quantification of the sesquiterpenes was developed and the method showed no interference with the other substances extracted from the skin and the permeation enhancers. The study evidenced that among the selected skin permeation enhancers, DMSO and OA can be considered as good candidates to be used in preparations for cutaneous application.