RESUMO
The widespread emergence of Plasmodium falciparum (Pf) strains resistant to frontline agents has fuelled the search for fast-acting agents with novel mechanism of action. Here, we report the discovery and optimization of novel antimalarial compounds, the triaminopyrimidines (TAPs), which emerged from a phenotypic screen against the blood stages of Pf. The clinical candidate (compound 12) is efficacious in a mouse model of Pf malaria with an ED99 <30 mg kg(-1) and displays good in vivo safety margins in guinea pigs and rats. With a predicted half-life of 36 h in humans, a single dose of 260 mg might be sufficient to maintain therapeutic blood concentration for 4-5 days. Whole-genome sequencing of resistant mutants implicates the vacuolar ATP synthase as a genetic determinant of resistance to TAPs. Our studies highlight the potential of TAPs for single-dose treatment of Pf malaria in combination with other agents in clinical development.
Assuntos
Antimaláricos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Pirimidinas/farmacologia , Aminas/farmacologia , Animais , Avaliação Pré-Clínica de Medicamentos , Resistência Microbiana a Medicamentos , Cobaias , Meia-Vida , RatosRESUMO
A whole cell based screening effort on a focused library from corporate collection resulted in the identification of biarylmethoxy nicotinamides as novel inhibitors of M. tuberculosis (Mtu) H37Rv. The series exhibited tangible structure-activity relationships, and during hit to lead exploration, a cellular potency of 100 nM was achieved, which is an improvement of >200-fold from the starting point. The series is very specific to Mtu and noncytotoxic up to 250 µM as measured in the mammalian cell line THP-1 based cytotoxicity assay. This compound class retains its potency on several drug sensitive and single drug resistant clinical isolates, which indicate that the compounds could be acting through a novel mode of action.
RESUMO
NDH-2 is an essential respiratory enzyme in Mycobacterium tuberculosis (Mtb), which plays an important role in the physiology of Mtb. Herein, we present a target-based effort to identify a new structural class of inhibitors for NDH-2. High-throughput screening of the AstraZeneca corporate collection resulted in the identification of quinolinyl pyrimidines as the most promising class of NDH-2 inhibitors. Structure-activity relationship studies showed improved enzyme inhibition (IC50) against the NDH-2 target, which in turn translated into cellular activity against Mtb. Thus, the compounds in this class show a good correlation between enzyme inhibition and cellular potency. Furthermore, early ADME profiling of the best compounds showed promising results and highlighted the quinolinyl pyrimidine class as a potential lead for further development.
