Adenosine Analogues as Selective Inhibitors of Glyceraldehyde-3-phosphate Dehydrogenase of Trypanosomatidae via Structure-Based Drug Design

Abstract

In our continuation of the structure-based design of anti-trypanosomatid drugs, parasite-selective adenosine analogues were identified as low micromolar inhibitors of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Crystal structures of Trypanosoma brucei, Trypanosoma cruzi, Leishmania mexicana, and human GAPDH's provided details of how the adenosyl moiety of NAD + interacts with the proteins, and this facilitated the understanding of the relative affinities of a series of adenosine analogues for the various GAPDH's. From exploration of modifications of the naphthalenemethyl and benzamide substituents of a lead compound, N 6 -(1-naphthalenemethyl)-2′-deoxy-2′-(3-methoxybenzamido)adenosine (6e), N 6 -(substituted-naphthalenemethyl)-2′-deoxy-2′-(substituted-benzamido)adenosine analogues were investigated. N 6 -(1-Naphthalenemethyl)-2′-deoxy-2′-(3,5-dimethoxybenzamido)adenosine (6m), N 6 -[1-(3-hydroxy-naphthalene)methyl]-2′-deoxy-2′-(3,5-dimethoxybenzamido)adenosine (7m), N 6 -[1-(3-methoxy-naphthalene)methyl]-2′-deoxy-2′-(3,5-dimethoxybenzamido)adenosine (9m), N 6 -(2-naphthalene-methyl)-2′-deoxy-2′-(3-methoxybenzamido)adenosine (11e), and N 6 -(2-naphthalenemethyl)-2′-deoxy-2′-(3,5-dimethoxybenzamido)adenosine (11m) demonstrated a 2-to 3-fold improvement over 6e and a 7100-to 25000-fold improvement over the adenosine template. IC 50 's of these compounds were in the range 2-12 μM for T. brucei, T. cruzi, and L. mexicana GAPDH's, and these compounds did not inhibit mammalian GAPDH when tested at their solubility limit. To explore more thoroughly the structure-activity relationships of this class of compounds, a library of 240 N 6 -(substituted)-2′-deoxy-2′-(amido)adenosine analogues was generated using parallel solution-phase synthesis with N 6 and C2′ substituents chosen on the basis of computational docking scores. This resulted in the identification of 40 additional compounds that inhibit parasite GAPDH's in the low micromolar range. We also explored adenosine analogues containing 5′-amido substituents and found that 2′,5′-

Hydrolysis products of cAMP analogs cause transformation ofTrypanosoma bruceifrom slender to stumpy-like forms

“…Although it currently is not possible to completely rule out any role for cAMP in this differentiation process, the present data throw into question whether the slender-tostumpy conversion is initiated by cAMP at all. The molecular mechanisms by which different adenosine analogs alter differentiation and proliferation are more difficult to interpret because adenosine analogs are known to cause such effects as triggering of cell-cycle arrest (39), inhibition of glycolysis (40,41), and alteration of purine transport or salvage (42). Similarly, AMP kinases are known targets in mammals but are as-yet-unknown in trypanosomes (43).…”

2,N 6 -Disubstituted Adenosine Analogs with Antitrypanosomal and Antimalarial Activities

“…Nevertheless, there is the possibility that these two molecules exert their antiprotozoal activities in their unmetabolized forms, for instance, by inhibiting certain ATP-or NAD(P)H-dependent enzymes, such as the kinases or enzymes involved in glycolysis. Over the past few years several studies that described the rational targeting of glycolytic enzymes by adenosine derivatives have appeared (6). Although various inhibitors of T. brucei and T. cruzi glyceraldehyde-3-phosphate dehydrogenase (6) and T. brucei phosphoglycerate kinase (5) have been identified, these compounds displayed antitrypanosomal activities only in the low micromolar range; i.e., they were 1 to 2 orders of magnitude less effective than compounds NA42 and NA134.…”

A Critical Review on Chagas Disease Chemotherapy

“…Crystal structure of trypanosomatids and human GAPDHs provided details about the interaction of adenosyl moiety of NAD + with proteins. Although adenosine is a very poor inhibitor, addition of substituents to the 2' position of ribose and the N6-position of adenosine led to a series of disubstituted nucleosides, and [N6-(1-naphthalenemethyl)-2'-(3-chlorobenzamido) adenosine] inhibited the proliferation of amastigotes without effect on the corresponding human enzyme (Bressi et al 2001). …”