Antimalarial drugs have thus far been chiefly derived from two sources—natural products and synthetic drug-like compounds. Here we investigate whether antimalarial agents with novel mechanisms of action could be discovered using a diverse collection of synthetic compounds that have three-dimensional features reminiscent of natural products and are underrepresented in typical screening collections. We report the identification of such compounds with both previously reported and undescribed mechanisms of action, including a series of bicyclic azetidines that inhibit a new antimalarial target, phenylalanyl-tRNA synthetase. These molecules are curative in mice at a single, low dose and show activity against all parasite life stages in multiple in vivo efficacy models. Our findings identify bicyclic azetidines with the potential to both cure and prevent transmission of the disease as well as protect at-risk populations with a single oral dose, highlighting the strength of diversity-oriented synthesis in revealing promising therapeutic targets.

N-type voltage-dependent Ca 2؉ channels (VDCCs), predominantly localized in the nervous system, have been considered to play an essential role in a variety of neuronal functions, including neurotransmitter release at sympathetic nerve terminals. As a direct approach to elucidating the physiological significance of N-type VDCCs, we have generated mice genetically deficient in the ␣1B subunit (Cav 2.2). The ␣1B-deficient null mice, surprisingly, have a normal life span and are free from apparent behavioral defects. A complete and selective elimination of N-type currents, sensitive to -conotoxin GVIA, was observed without significant changes in the activity of other VDCC types in neuronal preparations of mutant mice. The baroreflex response, mediated by the sympathetic nervous system, was markedly reduced after bilateral carotid occlusion. In isolated left atria prepared from N-type-deficient mice, the positive inotropic responses to electrical sympathetic neuronal stimulation were dramatically decreased compared with those of normal mice. In contrast, parasympathetic nervous activity in the mutant mice was nearly identical to that of wild-type mice. Interestingly, the mutant mice showed sustained elevation of heart rate and blood pressure. These results provide direct evidence that N-type VDCCs are indispensable for the function of the sympathetic nervous system in circulatory regulation and indicate that N-type VDCC-deficient mice will be a useful model for studying disorders attributable to sympathetic nerve dysfunction. V oltage-dependent Ca 2ϩ channels (VDCCs) mediate calcium entry into cells, which is essential for a wide variety of physiological functions. Among three types of VDCCs, P͞Q-type, N-type, and R-type, predominantly expressed in neuronal cells (1, 2), N-type Ca 2ϩ channels have been recognized as high-voltage-activated Ca 2ϩ channels selectively sensitive to blockade by -conotoxin GVIA (-CTX), a 27-amino acid peptide isolated from the venom of the fish-hunting cone snail Conus geographus, but resistant to the L-type Ca 2ϩ channelspecific blockers such as dihydropyridines. Molecular studies have revealed that the ␣ 1B (Ca v 2.2) subunit gene encodes N-type Ca 2ϩ channels and is expressed widely in neuronal tissues (3-12). Experiments employing -CTX have demonstrated the physiological significance of the N-type Ca 2ϩ channels in the nervous system, where they have a specific developmental role in the migration of immature neurons before the establishment of their synaptic circuit (13). N-type Ca 2ϩ channels have been shown to be critically involved in the release of neurotransmitters, including glutamate (14-16), ␥-aminobutyric acid (14), acetylcholine (17), dopamine (18)(19)(20), and norepinephrine (21) in mammalian central neurons. For instance, in CA1 hippocampal neurons, the inhibitory GABAergic synaptic potentials are reduced by 85-90% by saturating concentrations of -CTX, whereas the excitatory glutaminergic transmission is blocked by 65-70% (16).In peripheral neurons such as autonomic neurons...

These results indicate that our torsadogenic risk assessment is reliable and has a potential to replace the hERG assay for torsadogenic risk prediction, however, this system needs to be improved for the accurate of prediction of clinical TdP risk. Here, we propose a novel drug induced torsadogenic risk categorising system using hiPSC-CMs and the MEA system.