The Role of Pyrazolopyridine Derivatives on Different Steps of Herpes Simplex Virus Type-1 In Vitro Replicative Cycle

Abstract

Herpes simplex virus type-1 (HSV-1) infection causes several disorders, and acyclovir is used as a reference compound. However, resistant strains are commonly observed. Herein, we investigate the effects of N-heterocyclic compounds (pyrazolopyridine derivatives), named ARA-04, ARA-05, and AM-57, on HSV-1 in vitro replication. We show that the 50% effective concentration (EC50) values of the compounds ARA-04, ARA-05, and AM-57 were 1.00 ± 0.10, 1.00 ± 0.05, and 0.70 ± 0.10 µM, respectively. These compounds presented high 50% cytotoxic concentration (CC50) values, which resulted in a selective index (SI) of 1000, 1000, and 857.1 for ARA-04, ARA-05, and AM-57, respectively. To gain insight into which step of the HSV-1 replication cycle these molecules would impair, we performed adsorption and penetration inhibition assays and time-of-addition experiments. Our results indicated that ARA-04 and ARA-05 affected viral adsorption, while AM-57 interfered with the virus replication during its α- and γ-phases and decreased ICP27 content during initial and late events of HSV-1 replication. In addition, we also observed that AM-57 caused a strong decrease in viral gD content, which was reinforced by in silico calculations that suggested AM-57 interacts preferentially with the viral complex between a general transcription factor and virion protein (TFIIBc-VP16). In contrast, ARA-04 and ARA-05 interact preferentially in the proteins responsible for the viral adsorption process (nectin-1 and glycoprotein). Thus, our results suggest that the 1H-pyrazolo[3,4-b]pyridine derivatives inhibit the HSV-1 replicative cycle with a novel mechanism of action, and its scaffold can be used as a template for the synthesis of promising new molecules with antiviral effects, including to reinforce the presented data herein for a limited number of molecules.

Anti-BVDV Activity of Traditional Chinese Medicine Monomers Targeting NS5B (RNA-Dependent RNA Polymerase) In Vitro and In Vivo

“…Samples were collected for RNA and protein isolations at 48 h and 72 h, respectively, for RT-qPCR and Western blotting assays. [41,42] To conduct the viral replication cycle test, we selected the compound concentrations based on the results of BVDV replication. Specifically, we used daidzein at 3 µmol/L, artemisinine at 100 µmol/L, apigenin at 5 µmol/L, and curcumin at 7.5 µmol/L.…”

Discovery of New 1,4,6-Trisubstituted-1H-pyrazolo[3,4-b]pyridines with Anti-Tumor Efficacy in Mouse Model of Breast Cancer

“…Several pyrazolo[3,4- b ]pyridine-based derivatives that bear diverse substitutions were reported to exhibit potent antiviral [ 1 , 2 ] and antibacterial [ 3 , 4 ] properties; to inhibit important enzymes, such as phosphodiesterase-4 [ 5 ], or neutrophil elastase [ 6 ]; and to serve as ligands for A1-adenosine [ 7 ] or prostaglandin E2 receptor 1 [ 8 ]. The anti-cancer potential of this class of compounds is of particular interest as they show antiproliferative activity, apoptosis induction, and angiogenesis inhibition [ 9 , 10 , 11 ], albeit through diverse molecular targets and mechanisms of action, such as targeting tubulin polymerization [ 12 ] and protein kinase signal transduction in cancer cells [ 10 , 13 , 14 , 15 ].…”