Synthesis and P2Y2 receptor agonist activities of uridine 5'-phosphonate analogues.

We explored the influence of modifications of uridine 5'-methylenephosphonate on biological activity at the human P2Y(2) receptor. Key steps in the synthesis of a series of 5-substituted uridine 5'-methylenephosphonates were the reaction of a suitably protected uridine 5'-aldehyde with [(diethoxyphosphinyl)methylidene]triphenylphosphorane, C-5 bromination and a Suzuki-Miyaura coupling. These analogues behaved as selective agonists at the P2Y(2) receptor, with three analogues exhibiting potencies in the submicromolar range. Although maximal activities observed with the phosphonate analogues were much less than observed with UTP, high concentrations of the phosphonates had no effect on the stimulatory effect of UTP. These results suggest that these phosphonates bind to an allosteric site of the P2Y(2) receptor.

Synthesis, modeling and evaluation of 3'-(1-aryl-1H-tetrazol-5-ylamino)-substituted 3'-deoxythymidine derivatives as potent and selective human mitochondrial thymidine kinase inhibitors.

Based on the presumed binding mode of an earlier identified inhibitor, we herein report new 3'-modified nucleosides as potent and selective inhibitors of mitochondrial thymidine kinase (TK2). A series of thirteen 3'-amino-, 3'-guanidino- and 3'-tetrazole-containing nucleosides were synthesized and evaluated for their TK2 inhibitory activity. Within the tetrazole series, compounds with nanomolar inhibitory activity were identified. A homology model of TK2 allowed to elucidate the observed activities. Introduction of a 2-bromovinyl group on C-5 of the pyrimidine base of the most promising 3'-derivative further improved the inhibitory activity, and caused a significant increase in the selectivity for TK2 versus TK1. Interestingly, for the current series of analogues, a strong correlation was observed between TK2 and Drosophila melanogaster dNK inhibition, further substantiating the phylogenetic relationship between these two nucleoside kinases.

Synthesis and inhibitory activity of thymidine analogues targeting Mycobacterium tuberculosis thymidine monophosphate kinase.

We report on Mycobacterium tuberculosis thymidine monophosphate kinase (TMPKmt) inhibitory activities of a series of new 3'- and 5'-modified thymidine analogues including α- and ß-derivatives. In addition, several analogues were synthesized in which the 4-oxygen was replaced by a more lipophilic sulfur atom to probe the influence of this modification on TMPKmt inhibitory activity. Several compounds showed an inhibitory potency in the low micromolar range, with the 5'-arylthiourea 4-thio-α-thymidine analogue being the most active one (K(i)=0.17 µM). This compound was capable of inhibiting mycobacteria growth at a concentration of 25 µg/mL.

3'-[4-Aryl-(1,2,3-triazol-1-yl)]-3'-deoxythymidine analogues as potent and selective inhibitors of human mitochondrial thymidine kinase.

In an effort to increase the potency and selectivity of earlier identified substrate-based inhibitors of mitochondrial thymidine kinase 2 (TK-2), we now describe the synthesis of new thymidine analogues containing a 4- or 5-substituted 1,2,3-triazol-1-yl substituent at the 3'-position of the 2'-deoxyribofuranosyl ring. These analogues were prepared by Cu- and Ru-catalyzed cycloadditions of 3'-azido-3'-deoxythymidine and the appropriate alkynes, which produced the 1,4- and 1,5-triazoles, respectively. Selected analogues showed nanomolar inhibitory activity for TK-2, while virtually not affecting the TK-1 counterpart. Enzyme kinetics indicated a competitive and uncompetitive inhibition profile against thymidine and the cosubstrate ATP, respectively. This behavior is rationalized by suggesting that the inhibitors occupy the substrate-binding site in a TK-2-ATP complex that maintains the enzyme's active site in a closed conformation through the stabilization of a small lid domain.

Synthesis of alpha-substituted fosmidomycin analogues as highly potent Plasmodium falciparum growth inhibitors.

In view of the promising antimalarial activity of fosmidomycin or its N-acetyl homologue FR900098, the objective of this work was to investigate the influence of aromatic substituents in the alpha-position of the phosphonate moiety. The envisaged analogues were prepared using a linear route involving a 3-aryl-3-phosphoryl propanal intermediate. The activities of all compounds were evaluated on Eschericia coli 1-deoxy-d-xylulose 5-phosphate reductoisomerase and against two Plasmodium falciparum strains. Compared with fosmidomycin, several analogues displayed enhanced activity towards the P. falciparum strains. Compound 1e with a 3,4-dichlorophenyl substitution in the alpha-position of fosmidomycin emerged as the most potent analogue of this series. It is approximately three times more potent in inhibiting the growth of P. falciparum than FR900098, the most potent representative of this class reported so far.