Computation of the solvent-accessible surface area of monomer nonionic contrast media. Consequences for used probe radius in the study of hydrophilic characteristics.
OBJECTIVE
The solvent-accessible surface areas of different monomer nonionic contrast media were calculated for different probe radii. By correlating these areas with an experimental (octanol/water partition coefficient) and a calculated parameter (COMB-C), implications for the radius of the probe volume are pointed out.


METHODS
The solvent-accessible surface areas of seven monomer nonionic iodinated contrast media were calculated with GEPOL (a program able to calculate various molecular surfaces and volumes) for a wide range of probe radii of the solvent. These areas were correlated with the octanol/ water partition coefficient and COMB-C, a parameter describing the spatial distribution of the hydrophilic elements of a molecule.


RESULTS
The correlation coefficients of the solvent-accessible surface areas (determined with the different probe radii) with the octanol/water partition coefficient and of the solvent-accessible surface areas (determined with the same probe radii) with COMB-C were good. This correlation was better for probe raddi of 3 A or more.


CONCLUSIONS
COMB-C, a parameter designed earlier, correlated well with the hydrophilia of a monomer nonionic contrast molecule. It was shown that a probe radius of at least 3 A should be used when correlations with hydrophilic characteristics are studied, rather than a probe radius of 1.5 A, which is generally used in assessment of solubilities of molecules in biologic environment. Implications are discussed.
Violon
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D003199:Computer Systems; D003287:Contrast Media / Q000737:chemistry*; D015394:Molecular Structure; D012997:Solvents / Q000737:chemistry*
D003287:Contrast Media; D012997:Solvents