The invention relates to a method for obtaining an aqueous extract enriched with small RNA having a maximum length of 150 nucleotides, from plant material. The invention is characterized in that it comprises the following steps according to which: a) the plant material is put in contact with water； b) tetrasodium ethylenediaminetetraacetic acid (EDTA) is added to the mixture obtained in a) at a pH between 10.5 and 11； c) then, the pH of the mixture obtained in b) is adjusted to a value between 6 and 8； d) the mixture obtained in c) is purified in such a manner as to eliminate the plant material and to recover an aqueous raw extract； and e) the pH is checked and readjusted if necessary to a value between 6 and 8. The invention also relates to an aqueous extract of plant material, enriched with small RNAs having a maximum length of 150 nucleotides, which can be obtained by such a method, as well as to the compositions comprising such an extract and to their cosmetic uses for combating the signs of skin aging and for improving the hydration of the skin.
