OMEGA Release 2.5.1.4 OpenEye Scientific Software, Inc.

CHAPTER
ELEVEN
MOLECULAR PROPERTIES AND
PREDICTORS
FILTER provides a range of properties to predictors to be used as molecular filters. Molecular properties are distinct
physical properties that can be measured such as the following:
• Structural and Chemical Features
• Functional Groups
There have been several attempts at developing fast-approximate QSAR models for bioavailability that have been
published. The first of these was Lipinski’s work ([Lipinski-1997]) and it has been followed by work at Pharmacopia
[Egan-2000], Abbott [Martin-2005], and GSK [Veber-2002]. The simplest and probably most trusted is the work of
LogP and PSA used by Egan. The most recent work by Martin, the Abbott Bioavailability Score (ABS) appears to be a
refinement of the first generation models and is designed specifically to categorize a molecule’s probability of having
a bioavailability>10% in rats.
See Also:
The Pharmacokinetic Predictors section in the Filter Files chapter.
11.1 Structural and Chemical Features
There are a number of important structural and chemical features of molecules that it is desirable to limit for virtual
screening. The following simple measures are provided as filterable properties:
• Molecular weight
• Ring count
• Ring-system size
• Size of non-ring structures
• Length of unbranched chains
• Hetero-atom fraction
• Halide fraction
• Formal charges
• Rotatable bonds
It also includes slightly more complex algorithms for hydrogen-bond donors and acceptors as well as chiral centers.
See Also:
43