The 27 neuraminidase inhibitors used, including 24 training set compounds and 3 test set compounds, were adapted from Zhang's study [102] . Compounds were drawn using ChemBioOffice 2008 (PerkinElmer Inc., Cambridge, MA) and modified to physiological ionization using the Prepare Ligand function in DS 2.5. Bioactivity values (IC 50 ) were also obtained from Zhang's study though the original sources were not clarified, and converted to pIC 50 (log(1/ IC 50 )). Molecular descriptors of the compounds were calculated using Calculate Molecular Properties in DS 2.5 and the GFA was used to select the best representative molecular descriptors [107] . Utilizing the best representative molecular descriptors identified through GFA, MLR and SVM models were constructed using MATLAB (The Mathworks Inc., Natick, MA) and LibSVM [108] , respectively, and used to predict the bioactivity of TCM de novo compounds.