**4.2 Theoretical data set and pre-treatment**

The group of Cartesian coordinates corresponding to the 35 atoms of arbutin (see Fig. 9), for each of the 130 conformers found after the conformational analysis was used as data set in this study. In other words, our data set consisted of a matrix of 130 x 105 elements, corresponding to the arbutin conformers and the x, y, z coordinates of each atom of the molecule, respectively. Data were mean centred prior PCA.
