**4.3 Data analysis**

In order to provide a general and fast procedure to perform the PCA on the conformational data sets, the next strategy was followed: *1)* In the Cartesian referential, all conformers were oriented, in such a way that the structurally rigid fragment of arbutin (the glucopyranoside ring) was placed as close as possible to the axes origin; *2)* All Cartesian coordinates of the 130 conformers of arbutin were then used to perform the PCA. The table of data (data matrix) was built as follows: each row corresponds to a conformer and the columns to the Cartesian coordinates: the first 35 columns, to the x- coordinates of the 35 atoms of arbutin, the second 35 columns, to the y coordinates, and the last 35 columns, to the z coordinates.
