Synthesis of methylerythritol phosphate analogues and their evaluation as alternate substrates for IspDF and IspE from Agrobacterium tumefaciens

Highly diastereo- and enantioselective organocatalytic synthesis of trifluoromethylated erythritols based on the in situ generation of unstable trifluoroacetaldehyde

Thus far, only a few methods for the asymmetric synthesis of erythritols bearing a trifluoromethyl group have been developed, and these methods present serious disadvantages such as the requirement of multiple steps for the preparation of their starting materials, low stereoselectivity, and the use of highly toxic reagents. Herein, we have developed a highly diastereo- and enantioselective organocatalytic method to synthesise erythritols bearing a trifluoromethyl group using (1) a commercially available organocatalyst to produce unstable trifluoroacetaldehyde in situ from its corresponding hemiacetal, followed by the simultaneous asymmetric carbon-carbon bond-forming reaction of the organocatalyst with an in situ-generated chiral enamine derived from 2,2-dimethyl-1,3-dioxane-5-one to obtain the corresponding aldol product in good yield (65-80%) with high diastereoselectivity (up to 94% de) and excellent enantioselectivity (up to >98% ee), (2) the highly diastereoselective reduction of the ketone moiety in the aldol product (up to 98% de), and (3) the deprotection of the acetal moiety.

Antibacterial activity of 2-amino-4-hydroxypyrimidine-5-carboxylates and binding to Burkholderia pseudomallei 2-C-methyl-d-erythritol-2,4-cyclodiphosphate synthase

Enzymes in the methylerythritol phosphate pathway make attractive targets for antibacterial activity due to their importance in isoprenoid biosynthesis and the absence of the pathway in mammals. The fifth enzyme in the pathway, 2-C-methyl-d-erythritol-2,4-cyclodiphosphate synthase (IspF), contains a catalytically important zinc ion in the active site. A series of de novo designed compounds containing a zinc binding group was synthesized and evaluated for antibacterial activity and interaction with IspF from Burkholderia pseudomallei, the causative agent of Whitmore's disease. The series demonstrated antibacterial activity as well as protein stabilization in fluorescence-based thermal shift assays. Finally, the binding of one compound to Burkholderia pseudomallei IspF was evaluated through group epitope mapping by saturation transfer difference NMR.

Synthesis and Kinetic evaluation of an azido analogue of methylerythritol phosphate: a Novel Inhibitor of E. coli YgbP/IspD

As multidrug resistant pathogenic microorganisms are a serious health menace, it is crucial to continuously develop novel medicines in order to overcome the emerging resistance. The methylerythritol phosphate pathway (MEP) is an ideal target for antimicrobial development as it is absent in humans but present in most bacteria and in the parasite Plasmodium falciparum. Here, we report the synthesis and the steady-state kinetics of a novel potent inhibitor (MEPN₃) of Escherichia coli YgbP/IspD, the third enzyme of the MEP pathway. MEPN₃ inhibits E. coli YgbP/IspD in mixed type mode regarding both substrates. Interestingly, MEPN₃ shows the highest inhibitory activity when compared to known inhibitors of E. coli YgbP/IspD. The mechanism of this enzyme was also studied by steady-state kinetic analysis and it was found that the substrates add to the enzyme in sequential manner.

Synthesis and Evaluation of Fluoroalkyl Phosphonyl Analogues of 2- C-Methylerythritol Phosphate as Substrates and Inhibitors of IspD from Human Pathogens

Targeting essential bacterial processes beyond cell wall, protein, nucleotide, and folate syntheses holds promise to reveal new antimicrobial agents and expand the potential drugs available for combination therapies. The synthesis of isoprenoid precursors, isopentenyl diphosphate (IDP) and dimethylallyl diphosphate (DMADP), is vital for all organisms; however, humans use the mevalonate pathway for production of IDP/DMADP while many pathogens, including Plasmodium falciparum and Mycobacterium tuberculosis, use the orthogonal methylerythritol phosphate (MEP) pathway. Toward developing novel antimicrobial agents, we have designed and synthesized a series of phosphonyl analogues of MEP and evaluated their abilities to interact with IspD, both as inhibitors of the natural reaction and as antimetabolite alternative substrates that could be processed enzymatically to form stable phosphonyl analogues as potential inhibitors of downstream MEP pathway intermediates. In this compound series, the S-monofluoro MEP analogue displays the most potent inhibitory activity against Escherichia coli IspD and is the best substrate for both the E. coli and P. falciparum IspD orthologues with a K_m approaching that of the natural substrate for the E. coli enzyme. This work represents a first step toward the development of phosphonyl MEP antimetabolites to modulate early isoprenoid biosynthesis in human pathogens.