The invention relates to a mixture to be included in a composition or its semi-finished product, which composition or its semi-finished product contains at least one anti-micro-organistic agent； a possible solvent system with either hydrophobic or hydrophilic nature, selected according to the target of usage； as well as 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 the following group: lignans, stilbenes, juvabiones and flavonoids； said mixture further containing oligomers of said polyphenolic compounds, so that the mixture also must have the following properties: the mixture has an anti-micro-organistic effect in the composition or in the semi-finished product； the cytotoxicity of the polyphenols contained in the mixture is at least 10 times lower with respect to BHT； the mixture does not irritate the skin in a so-called single patch test with contents of 0.1 wt%.
