Determination of lipophilic descriptors of antihelmintic 6,7-diaryl-pteridine derivatives useful for bioactivity predictions.

The liquid chromatographic retention factors extrapolated to pure water, k'(w), for several 6,7-diaryl-pteridine derivatives in both an octadecylsilane (ODS) and an immobilized artificial membrane column (IAM.PC.DD2), using acetonitrile-aqueous buffer pH = 7.45 as mobile phase, were obtained. The logarithms of the k'(w) values in the IAM.PC.DD2 column, log k'(w) (IAM), show good correlation with the calculated values of the octanol-water partition coefficients, log P(o/w), showing that the chromatographic parameter can be used as lipophilicity descriptor for the studied pteridines. However, interactions other than the lipophilic ones seem to be involved in the ODS column. Previous studies have shown that pteridines have antihelmintic properties. In spite of the complexity of the studied biological system as compared with the chromatographic one, good correlation between the descriptors obtained in the IAM column and biological activity (expressed as the log of the inhibitory concentration required to obtain up to 50% in the reduction of population growth of nematodes, log IC(50)) was observed.