Besides the 4,366 compounds (cf. Table 1 under the title of Group-I) with known metabolic pathway classes, there are 11,661 compounds without known metabolic pathway classes in KEGG. Among these compounds, 5,549 compounds that have annotated interactions with the compounds of the 4,366 compounds in STITCH were collected. Such 5,549 compounds are to form an independent dataset, being used to test our prediction method in hopes to acquire useful information for further investigation.