Leveraging off higher plant phylogenetic insights for antiplasmodial drug discovery.

The antimalarial drug-resistance conundrum which threatens to reverse the great strides taken to curb the malaria scourge warrants an urgent need to find novel chemical scaffolds to serve as templates for the development of new antimalarial drugs. Plants represent a viable alternative source for the discovery of unique potential antiplasmodial chemical scaffolds. To expedite the discovery of new antiplasmodial compounds from plants, the aim of this study was to use phylogenetic analysis to identify higher plant orders and families that can be rationally prioritised for antimalarial drug discovery.

Interrogating alkyl and arylalkylpolyamino (bis)urea and (bis)thiourea isosteres as potent antimalarial chemotypes against multiple lifecycle forms of Plasmodium falciparum parasites.

A new series of potent potent aryl/alkylated (bis)urea- and (bis)thiourea polyamine analogues were synthesized and evaluated in vitro for their antiplasmodial activity. Altering the carbon backbone and terminal substituents increased the potency of analogues in the compound library 3-fold, with the most active compounds, 15 and 16, showing half-maximal inhibitory concentrations (IC50 values) of 28 and 30 nM, respectively, against various Plasmodium falciparum parasite strains without any cross-resistance. In vitro evaluation of the cytotoxicity of these analogues revealed marked selectivity towards targeting malaria parasites compared to mammalian HepG2 cells (>5000-fold lower IC50 against the parasite).

Kojic acid derived hydroxypyridinone-chloroquine hybrids: synthesis, crystal structure, antiplasmodial activity and β-haematin inhibition.

Aminochloroquinoline-kojic acid hybrids were synthesized and evaluated for β-haematin inhibition and antiplasmodial activity against drug resistant (K1) and sensitive (3D7) strains of Plasmodium falciparum. Compound 7j was the most potent compound in both strains (IC50(3D7)=0.004 μM; IC50(K1)=0.

Synthesis, Antiplasmodial Activity, and β-Hematin Inhibition of Hydroxypyridone-Chloroquine Hybrids.

A series of noncytotoxic 4-aminoquinoline-3-hydroxypyridin-4-one hybrids were synthesized on the basis of a synergistic in vitro combination of a precursor N-alkyl-3-hydroxypyridin-4-one with chloroquine (CQ) and tested in vitro against CQ resistant (K1 and W2) and sensitive (3D7) strains of Plasmodium falciparum. In vitro antiplasmodial activity of the precursors was negated by blocking the chelator moiety via complexation with gallium(III) or benzyl protection. None of the precursors inhibited β-hematin formation.