The invention relates to a mixture to be included in a composition or its semifinished product that is administered to a mammal or gets into contact with a mammal, said composition or its semifinished product containing at least one first effective agent； as well as a possible solvent system with either hydrophobic or hydrophilic nature, selected according to the target of usage； and a possible surface active agent. The mixture is obtained by pulverizing wood or plant material and/or by extracting the possibly pulverized wood or plant material, so that said mixture contains at least two different polyphenolic compounds, selected from among the group: lignans, stilbenes, juvabiones and flavonoids, said mixture also containing oligomers of said polyphenolic compounds； the mixture does not irritate the skin in a so-called single patch test； the cytotoxicity of the polyphenols contained in the mixture is at least 10 times lower with respect to BHT； the mixture has the same effective properties as the effective agent contained in the composition or its semifinished product； and the mixture also has effects for modifying the properties of the first effective agent, or effects for increasing the safety of usage of the first effective agent.
