Ligand lipophilicity efficiency

A recently reported tool for hit evaluation and prioritization is ligand lipophilicity efficiency (LLE).21 LLE is calculated as the difference between the negative logarithm of a hit s binding affinity, such as —log /C50 or —log KD, and the logarithm of a hit s partition coefficient, such as log P or clog P (Equation 10.2). 

Edwards, M. P., Price, D. A. Role of Physiochemical Properties and Ligand Lipophilicity Efficiency in Addressing Drug Safety Risks. Annu. Rep. Med. Chem. 2010, 45, 381-391. 

Mortenson PN, Murray CW (2009) Ligand lipophilicity efficiency - assessing lipophilicity of fragments and early hits. Presented at RSC Fragments 2009, Astra Zeneca Alderley Park, UK, 4—5 March 2009, Poster 9... 

Select appropriate metrics for multidimensional optimization use ligand efficiency and lipophilic efficiency metrics in hit-to-lead optimization and change to more complex metrics emphasizing dosage to support lead optimization. 

Recent data indicate that SR-BI is a nonspecific receptor for many lipophilic molecules (Lorenzi et al., 2008 Reboul et al., 2007b). Apart from HDLs, rodent SR-BI also binds to LDL, VLDL, acetylated LDL, oxidized LDL, and maleylated bovine serum albumin. SR-BII has a similar ligand specificity and function to that of SR-BI (Webb et al., 1998). However, it has been shown that vitamin E (which like carotenoids is carried in the bloodstream mainly by LDL and HDL) is transported more efficiently into the endothelial cells from HDLs than from LDLs (Balazs et al., 2004 Kaempf-Rotzoll et al., 2003 Mardones and Rigotti, 2004). This is in striking contrast to cholesterol, which is taken up much more efficiently from LDLs than HDLs by the RPE to the retina (Tserentsoodol et al., 2006b). It remains to be shown which lipoproteins are the main carriers for carotenoids transported from blood into the RPE. 

This chapter will summarize recent developments regarding the role of physicochemical properties in safety liability and the emerging use of physicochemical property-based lead optimization using lipophilic ligand efficiency (LLE or LipE). 

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