All fragments are oxygenated with hydroxyl, carbonyl, and carboxyl groups. The ring most common is a tetrahydropyran. The FDA fragments (Figure ) have a nitrogen function (amines and amides), distinguishing them as the only set with nitrogen structures. Additionally, three structures present sulfur with thiazolidine rings, another characteristic not found in the other common fragment sets. Six out of ten fragments also contain carbonyl, hydroxyl, and carboxyl groups. Analogous conclusions can be derived considering the number of heavy atoms. NPDBEjeCol has an average of 17 heavy atoms, while the reference databases are between 26 and 28 atoms. The count of oxygen and nitrogen atoms also shows significant differences. For NPDBEjeCol, there are, on average, 3 oxygen atoms, while for the other datasets, there are between 4 and 6. Regarding nitrogen atoms, there are closeness values between NPDBEjeCol and BIOFACQUIM, but generally, all databases except FDAapproved drugs have less than one nitrogen atom on average. FDA-approved drugs have, on average, 2 nitrogen atoms. For sp