Targeting Plasmodium PI(4)K to eliminate malaria.

Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria.

Total synthesis and biological evaluation of the resveratrol-derived polyphenol natural products hopeanol and hopeahainol A.

The total synthesis and biological evaluation of the resveratrol-derived natural products hopeanol (2) and hopeahainol A (3) in their racemic and antipodal forms are described. The Friedel-Crafts-based synthetic strategy employed was developed from model studies that established the feasibility of constructing the C(7b) quaternary center through an intramolecular Friedel-Crafts reaction and a Grob-type fragmentation to introduce an obligatory olefinic bond in the growing molecule. The final stages of the synthesis involved an epoxide substrate and an intramolecular Friedel-Crafts reaction, followed by oxidation to afford, upon global deprotection, hopeahainol A (3). The latter was converted under basic conditions to hopeanol (2), whereas the reverse transformation, previously suggested as a step in the biosynthesis of hopeahainol A (3), was not observed under a variety of conditions. Biological evaluation of the synthesized compounds confirmed the reported acetylcholinesterase inhibitory activity of hopeahainol A (3) but not the reported cytotoxic potencies of hopeanol (2).

Total synthesis and biological evaluation of cortistatins A and J and analogues thereof.

Total syntheses of the highly selective antiproliferative natural products cortistatins A (1) and J (5) in their naturally occurring enantiomeric forms are described. The modular and convergent strategy employed relies on an intramolecular oxa-Michael addition/aldol/dehydration cascade reaction to cast the ABCD ring framework of the molecule and both Sonogashira and Suzuki-Miyaura coupling reactions to assemble the necessary building blocks into the required heptacyclic skeleton. A divergent approach from a late-stage epoxy ketone leads to both target molecules in a stereoselective manner. The developed synthetic technologies were applied to the construction of several analogues of the cortistatins which were biologically evaluated and compared to the natural products with regards to their antiproliferative activities against a variety of cancer cells. Analogues 8 and 81, lacking both the dimethylamino and hydroxyl groups of cortistatin A, were found to exhibit comparable biological activity as the parent compound, leading to the conclusion that such functionalities are not essential for biological activity.

Chemical synthesis and biological evaluation of palmerolide A analogues.

Molecular design and chemical synthesis of several palmerolide A analogues allowed the first structure activity relationships (SARs) of this newly discovered marine antitumor agent. From several analogues synthesized and tested (ent- 1, 5- 14, 21- 26, 50, 51), compounds 25 (with a phenyl substituent on the side chain) and 51 (lacking the C-7 hydroxyl group) were the most interesting, exhibiting approximately a 10-fold increase in potency and equipotency, respectively, to the natural product. These findings point the way to more focused structure activity relationship studies.