Hydrosulfide group, hydrazide group, and several other
groups were defined as ZBG. Subsequently, the druglike database was screened by the defined ZBG criteria. As a
result, the database was subdivided into several small
databases. Obviously, these different sub-databases did not
contain the same number of molecules. If there are more
than 1,000 molecules in a sub-database, then this database
will be screened by a pharmacophore model featured by a
negative charge center and a hydrophobic point (Fig. 1a).
If the number of molecules is still more than 1,000, then the
refiltered database will be screened by a more restrict
pharmacophore model (Fig. 1b) which contains three features (a negative charge center, a hydrophobic point, and an
H-bond acceptor).