The present invention relates to a process for obtaining an extract of a plant material having an ability to penetrate the skin and / or optimized skin assimilation, wherein: (a) the plant material is subject either (i) in the fresh state, or in the dried state, or in the frozen state, or (ii) in the freeze-dried state, respectively to a solventless pressure extraction for cases (i) or extraction with a solvent selected from glycerin, ethanol and water for the case (ii), (b) the plant biomass thus extracted is separated from the liquid phase by filtration and / or centrifugation, ( c) the product obtained in step (b) is kept away from light and / or oxygen, (d) the extract is obtained at the end of step (c) and present an ability to penetrate the skin and / or optimized skin assimilation (s). It also relates to an extract of a plant material having an ability to penetrate the skin and / or optimized skin assimilation, obtainable by the implementation of a method of the invention, as well as to a cosmetic or dermatological composition comprising the extract of a plant material, to the cosmetic use of the composition or of the extract, to the non-therapeutic cosmetic treatment process comprising the application to the skin or the mucous membranes of the cosmetic or dermatological composition or of the extract and a kit for the non-therapeutic cosmetic treatment of the skin or mucous membranes comprising a cosmetic or dermatological composition or the extract. La présente invention se rapporte à un procédé d'obtention d'un extrait d'un matériau végétal présentant une capacité de pénétration dans la peau et/ou d'assimilation par la peau optimisées, dans lequel: (a) le matériau végétal est soumis, soit (i) à l'état frais, ou à l'état séché, ou à l'état congelé, soit (ii) à l'état lyophilisé, respectivement à une extraction par pression sans solvant pour les cas (i) ou à une extraction au moyen d'un solvant choisi parmi la glycérine, l'éthanol et l'eau p
