Synthetic models of DNA complexes with antimalarial compounds. 2. The problem of guanine specificity in chloroquine binding

Stacking interactions between the aminoquinoline ring of the antimalarial chloroquine and the purine bases have been studied by preparing and examining models in which the quinoline is linked to the base by a trimethylene chain. The degree of stacking of the models which reflects the strength of the interaction was quantitatively determined in water at different temperatures by hypochromism measurement in the uv. Adenine and guanine exhibit equal affinity for the quinoline nucleus as reflected by very close hypochromism values observed for the two models at all temperatures studied.