Quantitative Structure-Activity Relationships in Cytokinin Agonistic and Antagonistic Pyrido[2,3-d]pyrimidine Derivates: Insights into Receptor Topology
2-(Methylthio)pyrido[2,3-d]pyrimidines having various alkylamino and anilino substituents at the 4-position were prepared and tested for their cytokinin agonistic and antagonistic activities by the tobacco callus bioassay. The alkyl series of compounds showed anticytokininactivity, whereas the anilino derivatives exhibited both cytokinin and anticytokininactivities depending on the structure and