In Vitro and In Vivo Antiviral Studies of New Heteroannulated 1,2,3-Triazole Glycosides Targeting the Neuraminidase of Influenza A Viruses.

There is an urgent need to develop and synthesize new anti-influenza drugs with activity against different strains, resistance to mutations, and suitability for various populations. Herein, we tested in vitro and in vivo the antiviral activity of new 1,2,3-triazole glycosides incorporating benzimidazole, benzooxazole, or benzotriazole cores synthesized by using a click approach. The Cu-catalyzation strategy consisted of 1,3-dipolar cycloaddition of the azidoalkyl derivative of the respective heterocyclic and different glycosyl acetylenes with five or six carbon sugar moieties. The antiviral activity of the synthesized glycosides against wild-type and neuraminidase inhibitor resistant strains of the avian influenza H5N1 and human influenza H1N1 viruses was high in vitro and in mice. Structure-activity relationship studies showed that varying the glycosyl moiety in the synthesized glycosides enhanced antiviral activity. The compound (2R,3R,4S,5R)-2-((1-(Benzo[d]thiazol-2-ylmethyl)-1H-1,2,3-triazol-4-yl)methoxy)tetrahydro-2H-pyran-3,4,5-triyl triacetate (Compound 9c) had a 50% inhibitory concentration (IC50) = 2.280 µM and a ligand lipophilic efficiency (LLE) of 6.84. The compound (2R,3R,4S,5R)-2-((1-((1H-Benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methoxy)tetrahydro-2H-pyran-3,4,5-triyl triacetate had IC50 = 2.75 µM and LLE = 7.3 after docking analysis with the H5N1 virus neuraminidase. Compound 9c achieved full protection from H1N1 infection and 80% protection from H5N1 in addition to a high binding energy with neuraminidase and was safe in vitro and in vivo. This compound is suitable for further clinical studies as a new neuraminidase inhibitor.

Synthesis, anticancer activity and molecular docking of new triazolo[4,5-d]pyrimidines based thienopyrimidine system and their derived N-glycosides and thioglycosides.

A series of new substituted triazolo[4,5-d]pyrimidine derivatives linked to thienopyrimidine ring system were prepared as a hybrid heterocyclic systems, as possible nucleobases analogs, starting from the key carboxamide derivative 2 and its azide precursor via heterocyclization reactions and their structures were characterized. Glycosylation of the prepared triazolopyrimidine derivatives was performed and afforded, regioselctively, the corresponding thienopyrimidine-triazolopyrimidine hybrid N1-glycosides and their thioglycoside analogues in good yields. The synthesized glycosyl heterocycles were studied for their cytotoxic activity against HepG-2 and MCF-7 human cancer cells and significant results were obtained. Compounds 7a, 8 b, 9 b, 9a and 7 b demonstrated promising activities comparable to the activity of the doxorubicin for (HepG-2) cell line. Furthermore, a number of the afforded triazolopyrimidine glycosides were found potent against cancer cells (MCF-7). Furthermore, docking simulation the promising thienopyrimidine analogues 7-13 was done against EGFR kinase to provide a binding model that could serve in discovery of further anticancer agents.

Synthesis and anti-H5N1 virus activity of triazole- and oxadiazole-pyrimidine hybrids and their nucleoside analogs.

New 1,2,3-triazole glycosides and 1,2,4-thioglycosides incorporating a substituted pyrimidinedione ring system were synthesized via click dipolar cycloaddition and heterocyclization of hydrazine-1-carbodithioate derivatives, respectively. The sugar hydrazine derivatives linked aminodimethyluracil were also prepared. In addition, the oxadiazoline substituted with acyclic sugar moieties linked to the pyrimidinedione as acyclic nucleoside analogs were synthesized. The antiviral activity of the synthesized compounds against avian influenza H5N1 virus was investigated and compounds 18, 13 and 19 showed good activities against the virus strains.

Synthesis and anti-HSV-1 evaluation of some pyrazoles and fused pyrazolopyrimidines.

5-Amino-1-substituted-1H-pyrazole-4-carbonitrile derivative 1 was used as a precursor for preparation of some novel substituted pyrazole and pyrazolo[3,4-d]pyrimidine derivatives 2-10. Furthermore, the preparation of sugar hydrazone derivatives 11a,b, 12a,b and their annelated C-nucleosides 13a,b was described. Some of the prepared products revealed promising antiviral activity against herpes simplex virus type-1 (HSV-1) in comparison to Acyclovir as a control.

Synthesis and antiviral evaluation of some new pyrazole and fused pyrazolopyrimidine derivatives.

Some novel substituted pyrazole and pyrazolo[3,4-d]pyrimidine derivatives 2, 4, 8, and 9 were synthesized. Also, some acyclic S-nucleosides of pyrazolo[3,4-d]pyrimidine derivatives 10-13 were prepared via reaction of pyrazolo[3,4-d]pyrimidine-4(3H)-thione derivative 9 with some acyclic sugars. Moreover, the N-nucleoside derivative 14 was prepared via reaction of compound 8 with glucosamine hydrochloride. The antiviral evaluation of some selected new products showed that they have promising antiviral activity against hepatitis-A virus (HAV) and herpes simplex virus type-1 (HSV-1).

Synthesis, isomerization, and antimicrobial evaluation of some pyrazolopyranotriazolopyrimidine derivatives.

6-Amino-5-imino-pyrazolo[4',3':5,6]pyrano[2,3-d]pyrimidine derivative 4 and pyrazolo-[4',3':5,6]pyrano[2,3-d]pyrimidin-5-ylhydrazine derivative 5 were prepared starting from 6-amino-3-methyl-4-(p-nitrophenyl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile 1. The synthesis and structure characterization of 9,11-dihydropyrazolo[4',3':5,6]pyrano[3,2-e][1,2,4]triazolo[4,3-c]pyrimidine derivatives 7 and 9 and their isomerization to 9,11-dihydropyrazolo[4',3':5,6]pyrano[3,2-e] [1,2,4]triazolo[1,5-c]pyrimidine derivatives 6 and 8, respectively, under different suitable reaction conditions are reported. Moreover, the synthesis of 9,11-dihydropyrazolo[4',3':5,6]pyrano[3,2-e] tetrazolo[1,5-c]pyrimidine derivative 14 and N(9)-acyclic nucleoside 15 are described. Some of the prepared products showed potent antimicrobial activity.

Synthesis and antimicrobial activity of some cyclic and acyclic nucleosides of thieno[2,3-d]pyrimidines.

The reaction of compounds 1, 2, 3, 4, or 13 with 2-chloroethyl methyl ether or 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide, afforded some acyclic and cyclic nucleosides of thieno[2,3-d]pyrimidine derivatives. Furthermore, cyclic C-nucleosides 24 and 25 were prepared from the reaction of 20, 21 or from 26, 27 with D-glucose. The antimicrobial evaluation of some prepared products showed promising antimicrobial activity.

Synthesis of pyrazolo[4',3':5,6]pyrano[2,3-d]pyrimidine derivatives for antiviral evaluation.

6-Amino-3-methyl-4-(4-nitrophenyl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (1) was used as a precursor for preparation of some novel 3,7-dimethyl-4-(4-nitrophenyl)-2,4-dihydropyrazolo[4',3':5,6]pyrano[2,3-d]pyrimidine derivatives 3-6, and some of their corresponding N(2)- and C(5)-S-acyclic nucleosides 7 and 8. Furthermore, the preparation of 5-amino-1-[3,7-dimethyl-4-(4-nitrophenyl)-2,4-dihydropyrazolo[4',3':5,6]pyrano[2,3-d]pyrimidin-5-yl]-1H-pyrazole derivatives 10-16 were described. Some of the prepared products were selected and tested for antiviral activity against Herpes Simplex Virus type-1 (HSV-1).