Hydrolipophilic anomalies of some guanine derivatives

The hydrolipophilic properties of some guanine derivatives, acyclovir, deoxyacyclovir and their acetyl congeners, were studied. The partition coefficients n-octanol/water (P) were determined by the shake-flask method and compared with calculated values obtained by Rekker's method. Additionally, the hydrolipophilic properties were determined by RPLC (reversed-phase liquid chromatography) method. It was established that the RPLC method does not give reliable results for hydrolipophilic properties of the tested guanine derivatives compared with the experimentally determined logP value. The calculated logP values of investigated derivatives differ significantly from those determined by experiment. The observed differences were discussed in terms of a keto-enol equilibrium and the reduction of contact lipophilic surface area.