Toward Developing Therapies against Corona Virus: Synthesis and Anti-Avian Influenza Virus Activity of Novel Cytosine Thioglycoside Analogues

Naphthyl cyanoketene N,S-acetals in glycoside synthesis: a new preparative route to a new class of N-naphthylcyanoacrylamide thioglycosides and their conversions to naphthyl-pyrazole hybrids

The novel N-naphthylcyanoacrylamide thioglycosides 4 were readily prepared by the reaction of N-napthylcyanoacetamide 1 with aryl isothiocyanates in the presence of potassium hydroxide, followed by coupling of the produced salts 2 with 2,3,4,6-tetra-O-acetyl-α-d-gluco- and galacto-pyranosyl bromides 3. The N-naphthyl acrylamide thioglycoside 12 was prepared by the reaction of N-napthylcyanoacetamide 1 with glucose isothiocyante 10 in the presence of potassium hydroxide, followed by alkylation of the produced salt 11 with methyl iodide. The reaction of thioglycoside compounds 4 with hydrazines afforded the corresponding naphthyl-pyrazole hybrids.

Synthesis and Biological Evaluation of Benzothiazolyl-pyridine Hybrids as New Antiviral Agents against H5N1 Bird Flu and SARS-COV-2 Viruses

A novel series of benzothiazolyl-pyridine hybrids 8a-h and 14a-e were produced from the reaction of enamine derivative 4 with each of the arylcyanoacetamides 5a-h and cyanoacetohydrazides 9a-e. The new products were characterized by spectral techniques (IR, 1H NMR, 13C NMR, and MS). Biological evaluation of 8a-h and 14a-e in vitro against H5N1 and SARS-COV-2 viruses showed that several compounds had significant activity. Compounds 8f-h, which contain fluorine atoms, have better activity against H5N1 and anti-SARS-CoV-2 viruses than the other compounds included in this study. Compound 8h has a trifluoromethyl group at position-3 of the phenyl ring and exhibits a high activity against H5N1 virus with 93 and 60% inhibition at concentrations of 0.5 and 0.25 μmol/μL, respectively, among the tested compounds, and it also showed anti-SARS-CoV-2 virus with a half-maximum inhibition rate of 3.669 μM, among the remaining compounds. The mechanism of action of 8f-h, which is expected to be repurposed against COVID-19, was investigated. The results showed that the compounds have virucidal effects at different stages of the three mechanisms of action. Furthermore, compounds 8f-h were found to possess CoV-3CL protease inhibitory activities with IC50 values of 544.6, 868.2, and 240.6 μg/mL, respectively, compared to IC50 = 129.8 μg/mL of the standard drug lopinavir. Interestingly, compounds 8f-h also showed high inhibitory activity against the H5N1 virus as well as the SARS-CoV-2 virus. Moreover, compounds 8f-h fit admirably into the active site of the SARS-CoV-2 main protease (PDB ID: 6LU7) using the molecular docking Moe software 2015.10.

New syntheses of thiosaccharides utilizing substitution reactions

Novel synthetic methods published since 2005 affording carbohydrates containing sulfur atom(s) are reviewed. The review is divided to subchapters based on the position of sulfur atom(s) in the sugar molecule. Only those methods that take advantage of substitution are discussed.

Novel Thiophene Thioglycosides Substituted with the Benzothiazole Moiety: Synthesis, Characterization, Antiviral and Anticancer Evaluations, and NS3/4A and USP7 Enzyme Inhibitions

Novel derivatives of benzothiazole-2-thiophene S-glycoside were synthesized and tested for their antiviral and anticancer potency and NS3/4A and USP7 enzyme inhibitions. The ring system was formed by first synthesizing new derivatives of 5-mercaptothiophene substituted with the benzothiazole moiety, followed by coupling with various halo sugar derivatives. New compounds were tested in vitro for the cytotoxic effect on five types of normal cell lines and for antiviral activity using a plaque reduction assay against CBV4, HSV-1, HCVcc genotype 4 viruses, HAV HM 175, and HAdV7. Notably, three compounds demonstrated substantial IC₅₀, CC₅₀, and SI values against HSV-1 with a viral reduction of 80% or more. Two substances have demonstrated a reduction of more than 50% in CBV4 and HCVcc viruses. The effectiveness of the compounds against HSV-1 and HCVcc was tested for their capability to inhibit NS3/4A protease and USP7 enzyme. Additionally, a panel of 60 human cancer cells was used to investigate the ability of the newly synthesized compounds to inhibit the in vitro tumor growth. The results revealed that two compounds, 6a and 6c, have an inhibitory effect on most cancer types, whereas 6d and 6f inhibited only three and two cell lines, respectively.

Synthesis of Pyrimidine Conjugates with 4-(6-Amino-hexanoyl)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine and Evaluation of Their Antiviral Activity

A series of pyrimidine conjugates containing a fragment of racemic 7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine and its (S)-enantiomer attached via a 6-aminohexanoyl fragment were synthesized by the reaction of nucleophilic substitution of chlorine in various chloropyrimidines. The structures of the synthesized compounds were confirmed by ¹H, ¹⁹F, and ¹³C NMR spectral data. Enantiomeric purity of optically active derivatives was confirmed by chiral HPLC. Antiviral evaluation of the synthesized compounds has shown that the replacement of purine with a pyrimidine fragment leads to a decrease in the anti-herpesvirus activity compared to the lead compound, purine conjugate. The studied compounds did not exhibit significant activity against influenza A (H1N1) virus.

First Discovery of Novel Cytosine Derivatives Containing a Sulfonamide Moiety as Potential Antiviral Agents

A series of cytosine derivatives containing a sulfonamide moiety were designed and synthesized, and their antiviral activities against pepper mild mottle virus (PMMoV) were systematically evaluated. Then, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model was constructed to study the structure-activity relationship according to the pEC₅₀ of the compounds' protective activities. Next, compound A32 with preferable antiviral activity on PMMoV was obtained based on the CoMSIA and CoMFA models, with an EC₅₀ of 19.5 μg/mL, which was superior to the template molecule A25 (21.3 μg/mL) and ningnanmycin (214.0 μg/mL). In addition, further studies showed that the antiviral activity of compound A32 against PMMoV was in accord with the up-regulation of proteins expressed in the defense response and carbon fixation in photosynthetic organisms. These results indicated that cytosine derivatives containing a sulfonamide moiety could be used as novel potential antiviral agents for further research and development.

An Overview of Synthesis and Biological Activity of Dihydropyrimidine Derivatives

Dihydropyrimidine derivatives are most important scaffolds due to structure similarities with natural products it is a hetrocyclic compound. The chemistry of Dihydropyrimidine is a blossoming field. Various reaction schemes for the preparation of Dihydropyrimidines and produce different biological effect and offer vast scope in the field of medicinal chemistry. This article goal to analysis the work reported the recent chemistry and pharmacological activities of dihydropyrimidine derivatives.

Synthesis of novel calcium channel blockers with ACE2 inhibition and dual antihypertensive/anti-inflammatory effects: A possible therapeutic tool for COVID-19

Hypertension has been recognized as one of the most frequent comorbidities and risk factors for the seriousness and adverse consequences in COVID-19 patients. 3,4-dihydropyrimidin-2(1H) ones have attracted researchers to be synthesized via Beginilli reaction and evaluate their antihypertensive activities as bioisosteres of nifedipine a well-known calcium channel blocker. In this study, we report synthesis of some bioisosteres of pyrimidines as novel CCBs with potential ACE2 inhibitory effect as antihypertensive agents with protective effect against COVID-19 infection by suppression of ACE2 binding to SARS-CoV-2 Spike RBD. All compounds were evaluated for their antihypertensive and calcium channel blocking activities using nifedipine as a reference standard. Furthermore, they were screened for their ACE2 inhibition potential in addition to their anti‐inflammatory effects on LPS-stimulated THP‐1 cells. Most of the tested compounds exhibited significant antihypertensive activity, where compounds 7a, 8a and 9a exhibited the highest activity compared to nifedipine. Moreover, compounds 4a,b, 5a,b, 7a,b, 8a,c and 9a showed promising ACE2:SARS-CoV-2 Spike RBD inhibitory effect. Finally, compounds 5a, 7b and 9a exerted a promising anti-inflammatory effect by inhibition of CRP and IL-6 production. Ultimately, compound 9a may be a promising antihypertensive candidate with anti-inflammatory and potential efficacy against COVID-19 via ACE2 receptor inhibition.

Crystal structures of (E)-2-amino-4-methyl-sulfanyl-6-oxo-1-(1-phenyl-ethyl-idene-amino)-1,6-di-hydro-pyrimidine-5-carbo-nitrile and (E)-2-amino-4-methyl-sulfanyl-6-oxo-1-[1-(pyridin-2-yl)ethyl-idene-amino]-1,6-di-hydro-pyrimidine-5-carbo-nitrile

The title compounds 3a, C14H13N5OS, and 3b, C13H12N6OS, both show an E configuration about the N=C bond and a planar NH2 group. The mol-ecules, which only differ in the presence of a phenyl (in 3a) or pyridyl (in 3b) substituent, are closely similar except for the different orientations of these groups. The amino hydrogen atoms form classical hydrogen bonds; in 3a the acceptors are the oxygen atom and the cyano nitro-gen atom, leading to ribbons of mol-ecules parallel to the b axis, whereas in 3b the acceptors are the oxygen atom and the pyridyl nitro-gen, leading to a layer structure perpendicular to (01).

New Route to the Synthesis of Benzamide-Based 5-Aminopyrazoles and Their Fused Heterocycles Showing Remarkable Antiavian Influenza Virus Activity

This study describes a new route to the synthesis of novel benzamide-based 5-aminopyrazoles and their corresponding pyrazolo[1,5-a]pyrimidine and pyrazolo[5,1-c][1,2,4]triazine derivatives. Benzamide-based 5-aminopyrazoles were prepared through a reaction of benzoyl isothiocyanate with malononitrile in KOH-EtOH followed by alkylation with alkyl halides and then a reaction with hydrazine. In an attempt to react benzoyl isothiocyanate with ethyl cyanoacetate in KOH-EtOH followed by alkylation with methyl iodide at room temperature and then a reaction with hydrazine has resulted in the formation of 3-ethoxy-5-phenyl-1H-1,2,4-triazole. The structures of the new compounds were characterized by mass spectroscopy, ¹H nuclear magnetic resonance (¹H NMR) spectroscopy, infrared spectroscopy (IR), and X-ray analysis. The new compounds were tested in vitro for their anti-influenza A virus (subtype H5N1) activity. Among the synthesized compounds, eight compounds 3b, 4, 10b, 10c, 12a, 19, 21a, and 21b were found to possess significant antiviral activities against bird flu influenza (H5N1) with viral reduction in the range of 85-65%.