Development of a Photo-Cross-Linkable Diaminoquinazoline Inhibitor for Target Identification in Plasmodium falciparum

Abstract

Diaminoquinazolines represent a privileged scaffold for antimalarial discovery, including use as putative Plasmodium histone lysine methyltransferase inhibitors. Despite this, robust evidence for their molecular targets is lacking. Here we report the design and development of a small-molecule photo-cross-linkable probe to investigate the targets of our diaminoquinazoline series. We demonstrate the effectiveness of our designed probe for photoaffinity labeling of Plasmodium lysates and identify similarities between the target profiles of the probe and the representative diaminoquinazoline BIX-01294. Initial pull-down proteomics experiments identified 104 proteins from different classes, many of which are essential, highlighting the suitability of the developed probe as a valuable tool for target identification in Plasmodium falciparum.

Unpacking the Pathogen Box—An Open Source Tool for Fighting Neglected Tropical Disease

“…Furthermore, these compounds have been found to be orally efficacious in murine malaria models, inhibiting the blood stage of the disease including transmission . The scaffold of 498 was recently exploited to generate a photoaffinity probe, identifying 104 proteins as potential targets of off‐target binding sites of this class . Verma et al.…”

Evaluation of 4-Amino 2-Anilinoquinazolines against Plasmodium and Other Apicomplexan Parasites In Vitro and in a P. falciparum Humanized NOD- scid IL2Rγ null Mouse Model of Malaria

“…However, the degree of resistance to compounds 2 and 4 indicates that broad resistance mechanisms, such as Pfmdr1 amplifications, could be playing a role (28,29). Previous studies of a related 2,4-diamino quinazoline series indicated that histone lysine methyltransferases could be the target of these compounds; however, recent use of photo-cross-linkable probes indicated that the compounds bound to many targets, including redox and nucleosome proteins, as well as chaperones (31)(32)(33). In vitro activity of 2-anilinoquinazolines in other apicomplexan parasites.…”

The antimalarial resistome – finding new drug targets and their modes of action

“…Interacting proteins, now enriched, are prepared for liquid chromatography followed by mass spectrometry (LC/MS—MS) so they can be identified. Recently, an alkyne tag on a photoactivatable group-diaminoquinazoline compound probe was used to bind its molecular target via UV-activated click chemistry; LC/MS—MS identified 104 candidate target genes [ 27 ]. Because pull-downs can yield false positives through non-specific binding, they should also be used in competition assays.…”