purvalanol-b and olomoucine

Topics: Adenine; Cell Division; Cyclin-Dependent Kinases; Drug Design; Drug Evaluation, Preclinical; Enzyme Inhibitors; Genomics; Humans; Kinetin; Ligands; Microarray Analysis; Small Molecule Libraries; Tumor Cells, Cultured

The development of novel chemotherapeutic agents has become an urgent task due to the development and rapid spread of drug resistance in Plasmodium falciparum, the protozoan parasite responsible for cerebral malaria. Cyclin-dependent kinases (CDKs) are essential for the regulation of the eukaryotic cell cycle, and several enzymes of this family have been identified in P. falciparum. In recent years, a number of purine-derived kinase inhibitors have been synthesised, some of which display selective activity against CDKs. This report describes a study in which various purine derivatives were screened for in vitro antimalarial activity. The erythrocytic asexual stages of the chloroquine-resistant P. falciparum strain (FCR-3) were cultivated in vitro in the presence of the various purines, and their effect on parasite proliferation was determined by the [3H]hypoxanthine incorporation assay. Our results show considerable variation in the sensitivity of P. falciparum to the different purines, as well as a general independence from their effect on purified starfish CDK1/cyclin B activity, which has been the standard assay used to identify CDK-specific inhibitors. Two subfamilies of purines with moderate to poor activity against CDK1/cyclin B activity showed submicromolar activity against P. falciparum. Structure-activity analysis indicates that certain structural features are associated with increased activity against P. falciparum. These features can be exploited to synthesise compounds with higher activity and specificity towards P. falciparum.

Topics: Adenine; Animals; Antimalarials; Cell Cycle; Dose-Response Relationship, Drug; Isopentenyladenosine; Kinetin; Parasitic Sensitivity Tests; Phosphotransferases; Plasmodium falciparum; Purines; Roscovitine; Structure-Activity Relationship

Although iterative development can be uncoupled from morphogenesis in plant organs, the relationship between the cell cycle and developmental events is not well established in embryos. Zygotes of fucoid algae, including Fucus and Pelvetia are particularly well suited for studying the interaction(s) between cell cycle progression and the early morphogenetic events, as the establishment of polarity and its morphogenetic expression, i.e. germination, and the first cell cycle are concomitant. We have previously demonstrated that, in Fucus zygotes, various aspects of cell cycle progression are tightly controlled by cyclin-dependent kinase (CDK)-like proteins, including two PSTAIRE CDK-like proteins, p34 and p32, which are synthesised after fertilisation. We show that specific inhibition of CDK-like proteins, either with purine derivatives such as olomoucine and amino-purvalanol or by microinjection of the CDK inhibitor p21(cip1), prevents germination and cell division. Whereas direct inhibition of DNA replication by aphidicolin did not affect polarised development, olomoucine, which has previously been shown to prevent entry in S phase, and other purine derivatives also inhibited photopolarisation. Early microinjection of a monoclonal anti-PSTAIRE antibody also prevented germination and cell division. Only p34 had affinity for amino-purvalanol, suggesting that among PSTAIRE CDKs, this protein is the main target of purine derivatives. Models to account for the simultaneous control of early cell cycle progression and polarisation are proposed.

Topics: Adenine; Algal Proteins; Aphidicolin; Cell Cycle; Cell Polarity; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinases; Cyclins; Enzyme Inhibitors; Kinetin; Microinjections; Phaeophyceae; Purines; Zygote