Inhibition of the Replication of Different Strains of Chikungunya Virus by 3-Aryl-[1,2,3]triazolo[4,5- d]pyrimidin-7(6 H)-ones.

The re-emergence of chikungunya virus (CHIKV) is a serious global health threat. CHIKV is an alphavirus that is transmitted to humans by Aedes mosquitoes; therefore, their wide distribution significantly contributes to the globalization of the disease. Unfortunately, no effective antiviral drugs are available. We have identified a series of 3-aryl-[1,2,3]triazolo[4,5- d]pyrimidin-7(6 H)-ones as selective inhibitors of CHIKV replication. New series of compounds have now been synthesized with the aim to improve their physicochemical properties and to potentiate the inhibitory activity against different CHIKV strains. Among these newly synthesized compounds modified at position 3 of the aryl ring, tetrahydropyranyl and N- t-butylpiperidine carboxamide derivatives have shown to elicit potent antiviral activity against different clinically relevant CHIKV isolates with 50% effective concentration (EC50) values ranging from 0.30 to 4.5 µM in Vero cells, as well as anti-CHIKV activity in human skin fibroblasts (EC50 = 0.1 µM), a clinically relevant cell system for CHIKV infection.

Improved proteolytic stability and potent activity against Leishmania infantum trypanothione reductase of α/ß-peptide foldamers conjugated to cell-penetrating peptides.

The objective of the current study was to enhance the proteolytic stability of peptide-based inhibitors that target critical protein-protein interactions at the dimerization interface of Leishmania infantum trypanothione reductase (Li-TryR) using a backbone modification strategy. To achieve this goal we carried out the synthesis, proteolytic stability studies and biological evaluation of a small library of α/ß3-peptide foldamers of different length (from 9-mers to 13-mers) and different αâ†’ß substitution patterns related to prototype linear α-peptides. We show that several 13-residue α/ß3-peptide foldamers retain inhibitory potency against the enzyme (in both activity and dimerization assays) while they are far less susceptible to proteolytic degradation than an analogous α-peptide. The strong dependence of the binding affinities for Li-TryR on the length of the α,ß-peptides is supported by theoretical calculations on conformational ensembles of the resulting complexes. The conjugation of the most proteolytically stable α/ß-peptide with oligoarginines results in a molecule with potent activity against L. infantum promastigotes and amastigotes.

Antiviral activity of [1,2,3]triazolo[4,5-d]pyrimidin-7(6H)-ones against chikungunya virus targeting the viral capping nsP1.

Chikungunya virus (CHIKV) is a re-emerging alphavirus transmitted to humans by Aedes mosquitoes. Since 2005, CHIKV has been spreading worldwide resulting in epidemics in Africa, the Indian Ocean islands, Asia and more recently in the Americas. CHIKV is thus considered as a global health concern. There is no specific vaccine or drug available for the treatment of this incapacitating viral infection. We previously identified 3-aryl-[1,2,3]triazolo[4,5-d]pyrimidin-7(6H)-ones as selective inhibitors of CHIKV replication and proposed the viral capping enzyme nsP1 as a target. This work describes the synthesis of novel series of related compounds carrying at the aryl moiety a methylketone and related oximes combined with an ethyl or an ethyl-mimic at 5-position of the triazolopyrimidinone. These compounds have shown antiviral activity against different CHIKV isolates in the very low µM range based on both virus yield reduction and virus-induced cell-killing inhibition assays. Moreover, these antivirals inhibit the in vitro guanylylation of alphavirus nsP1, as determined by Western blot using an anti-cap antibody. Thus, the data obtained seem to indicate that the anti-CHIKV activity might be related to the inhibition of this crucial step in the viral RNA capping machinery.