Ultrasound assisted regioselective synthesis of novel adamantyl-pyrazolo[1,5-a]pyrimidines in aqueous media and molecular docking and drug likeness studies

Multi-step synthesis of adamantyl-pyrazolo[1,5-a]pyrimidine derivatives under ultrasound irradiation has been described adopting the technique of molecular hybridization, whereby two core bioactive units- adamantanamine and pyrazolo[1,5-a]pyrimidine templates have been brought together into a new chemical entity. Ultrasound irradiation of N-(adamantan-1-yl)-3-amino-1H-pyrazole-4-carboxamide with formylated active proton compounds yields the desired hybrids in good to excellent yields. The N-(adamantan-1-yl)-3-amino pyrazolo[1,5-a]pyrimidine carboxamide derivatives were successfully identified with the help of spectral and analytical data. X-ray crystallography of ethyl 3-(adamantan-1-ylcarbamoyl)-7-methylpyrazolo[1,5-a]pyrimidine-6-carboxylate (14c) unambiguously confirmed the formation of the desired hybrid. The results and the findings of the docking scores indicate that the active ligands 7a and 11b exhibited highest binding energies with a score of –7.33 Kcal/mol and – 8.73 Kcal/mol, respectively. The inhibition constant (KI) for ligands 7a and 11b were found to be 4.24 µM and 396.32 µM, respectively which are comparatively lower than the control favipiravir thereby conforming to the drug-likeness prediction. These compounds as such become favorable for screening as drug candidates compared to the control favipiravir with lower binding energy, lower lipophilicity range and very high KI constant. The active ligands have promising functions to inhibit and interfere with the replication and maturation of Chymotrypsin-like protease (3CLpro) of SARS-Coronavirus 2. The lower KI, high binding energy and drug-likeness efficiency of the compounds can be further developed into a potent drug molecule against the uncontrollable SARS-COV-2.

Naphtho[2,1-b]furan derived triazole-pyrimidines as highly potential InhA and Cytochrome c peroxidase inhibitors: Synthesis, DFT calculations, drug-likeness profile, molecular docking and dynamic studies

Napthofuran and its fused heterocyclic derivatives evaluated with varied biological activity functional groups comprise an important class of compounds for new chemical entities. We here in reporting synthesis of new 3-(4-substituted phenyl)naphtho[1′,2′:4,5]furo[2,3-e][1,2,4]triazolo[4,3-c]pyrimidines 6(a-f). Structures of the newly synthesized compounds were confirmed by making use of spectroscopic techniques like IR, NMR and Mass. The DFT calculations were taken for the selected molecules using B3LYP hybrid functional with a 6–31+G (d, p) all-electron basis set using the Gaussian 09 package. The bioactivity predictions were evaluated for the synthesized compounds. The In vitro biological activities were reported for the all compounds 6(a-f). The compound 6a showed high activity of anti-TB and antioxidant activity with at MIC 1.6 μg/ml and at percentage of inhibition (72.54±0.21) at 10μg/ml respectively. The compound 6f (73.21±0.11) showed antioxidant activity better than standard drug BHA (71.32±0.13) at 10 μg/ml. Furthermore, the docking studies for the newly synthesized molecules were carried out by Auto dock software with proteins InhA (4TZK),Cytochrome c peroxidase (2 × 08) and protease (Mpro) of SARS-CoV-2 Omicron (PDB ID: 7TOB). All the compounds showed a strong binding affinity for the docked proteins. The outcome of docking results showed that compound 6ahad excellent binding energies -10.8, -9.4, and -9.0 kcal/mol with 4TZK, 2 × 08, and 7TOB respectively. Lastly, the protein stability, fluctuations of APO-Protein, protein-ligand complexes were investigated through Molecular Dynamics (MD) simulations studies using Desmond Maestro 11.3 and potential lead molecules were identified. © 2023

Design of novel pyrimidine based remdesivir analogues with dual target specificity for SARS CoV-2: A computational approach.

As the world undergone unpreceded time of tragedy with the corona virus, many researchers have raised to showcase their scientific contributions in terms of novel configured anti-viral drugs until now. Herein, we designed pyrimidine based nucleotides and assessed for the binding capability with SARS-CoV-2 viral replication targets of nsp12 RNA-dependent RNA polymerase and Mpro main protease. Molecular docking studies showed all the designed compounds to possess good binding affinity, with a few compounds which outperforms the control drug remdesivir GS-5743 and its active form GS-441524. Further molecular dynamics simulation studies confirmed their stability and preservation of the non-covalent interactions. Based on the present findings Ligand2-BzV_0Tyr, ligand3-BzV_0Ura, and ligand5-EeV_0Tyr showed good binding affinity with Mpro, whereas, ligand1-BzV_0Cys and Ligand2-BzV_0Tyr showed good binding affinity with RdRp, thus could act as potential lead compounds against SARS-CoV-2, which needs further validation studies. In particular, Ligand2-BzV_0Tyr could be more beneficial candidate with the dual target specificity for Mpro and RdRp.

Novel pyrimidines as COX-2 selective inhibitors: synthesis, DFT analysis, molecular docking and dynamic simulation studies.

Pyrimidine and its derivatives are associated with varieties of biological properties. Therefore, we herein reported the synthesis of four novel pyrimidines (2, 3, and 4a, b) derivatives. The structure of these molecules is confirmed by spectroscopic methods such as IR, NMR, and Mass analysis. The electronic behavior of synthesized compounds 4a, b and in silico drug design 4 c, d was explained by Density Functional Theory estimations at the DFT/B3LYP level via 6-31 G++ (d, p) replicates the structure and geometry. All the synthesized compounds were screened for their in vitro COX-1 and COX-2 inhibitory activity compared to standards Celecoxib and Ibuprofen. Compounds 3 and 4a afforded excellent COX-1 and COX-2 inhibitory activities at IC50 = 5.50 and 5.05 µM against COX-1, 0.85 and 0.65 µM against COX-2, respectively. The standard drugs Celecoxib and Ibuprofen showed inhibitory activity at IC50 = 6.34 and 3.1 µM against COX-1, 0.56 and 1.2 µM against COX-2, respectively. Further, these compounds showed high potential docking with SARS-CoV-2 Omicron protease & COX-2 and predicted drug-likeness for the pyrimidine analogs by using Molinspiration. The protein stability, fluctuations of APO-protein, protein-ligand complexes were investigated through Molecular Dynamics simulations studies using Desmond Maestro 11.3 and potential lead molecules were identified.Communicated by Ramaswamy H. Sarma.

Production of Modified Nucleosides in a Continuous Enzyme Membrane Reactor.

Nucleoside analogues are important compounds for the treatment of viral infections or cancers. While (chemo-)enzymatic synthesis is a valuable alternative to traditional chemical methods, the feasibility of such processes is lowered by the high production cost of the biocatalyst. As continuous enzyme membrane reactors (EMR) allow the use of biocatalysts until their full inactivation, they offer a valuable alternative to batch enzymatic reactions with freely dissolved enzymes. In EMRs, the enzymes are retained in the reactor by a suitable membrane. Immobilization on carrier materials, and the associated losses in enzyme activity, can thus be avoided. Therefore, we validated the applicability of EMRs for the synthesis of natural and dihalogenated nucleosides, using one-pot transglycosylation reactions. Over a period of 55 days, 2'-deoxyadenosine was produced continuously, with a product yield >90%. The dihalogenated nucleoside analogues 2,6-dichloropurine-2'-deoxyribonucleoside and 6-chloro-2-fluoro-2'-deoxyribonucleoside were also produced, with high conversion, but for shorter operation times, of 14 and 5.5 days, respectively. The EMR performed with specific productivities comparable to batch reactions. However, in the EMR, 220, 40, and 9 times more product per enzymatic unit was produced, for 2'-deoxyadenosine, 2,6-dichloropurine-2'-deoxyribonucleoside, and 6-chloro-2-fluoro-2'-deoxyribonucleoside, respectively. The application of the EMR using freely dissolved enzymes, facilitates a continuous process with integrated biocatalyst separation, which reduces the overall cost of the biocatalyst and enhances the downstream processing of nucleoside production.

Design, synthesis, and computational studies of novel imidazo[1,2-a]pyrimidine derivatives as potential dual inhibitors of hACE2 and spike protein for blocking SARS-CoV-2 cell entry.

In the present work, a new series of imidazo[1,2-a]pyrimidine Schiff base derivatives have been obtained using an easy and conventional synthetic route. The synthesized compounds were spectroscopically characterized using 1H, 13C NMR, LC-MS(ESI), and FT-IR techniques. Green metric calculations indicate adherence to several green chemistry principles. The energy of Frontier Molecular Orbitals (FMO), Molecular Electrostatic Potential (MEP), Quantum Theory of Atoms in Molecules (QTAIM), and Reduced Density Gradient (RDG) were determined by the Density Functional Theory (DFT) method at B3LYP/6-31 G (d, p) as the basis set. Moreover, molecular docking studies targeting the human ACE2 and the spike, key entrance proteins of the severe acute respiratory syndrome coronavirus-2 were carried out along with hACE2 natural ligand Angiotensin II, the MLN-4760 inhibitor as well as the Cannabidiolic Acid CBDA which has been demonstrated to bind to the spike protein and block cell entry. The molecular modeling results showed auspicious results in terms of binding affinity as the top-scoring compound exhibited a remarkable affinity (-9.1 and -7.3 kcal/mol) to the ACE2 and spike protein respectively compared to CBDA (-5.7 kcal/mol), the MLN-4760 inhibitor (-7.3 kcal/mol), and angiotensin II (-9.2 kcal/mol). These findings suggest that the synthesized compounds may potentially act as effective entrance inhibitors, preventing the SARS-CoV-2 infection of human cells. Furthermore, in silico, ADMET, and drug-likeness prediction expressed promising drug-like characteristics.

A Sonochemical Access to 5-Aryl Substituted Pyrazolo[1,5-a]Pyrimidines as Potential Inhibitors of TNF-α

In spite of various and extensive studies known for pyrazolo[1,5-a]pyrimidines the synthesis, in silico studies and biological evaluation of their 5-(het)aryl analogs remained underexplored. The TNF-α inhibitors on the other hand has considerable therapeutic potential for autoimmune and inflammatory diseases in addition to cancer, diabetes and possibly COVID-19. In the current study 5-aryl pyrazolo[1,5-a]pyrimidines were explored as potential inhibitors of TNF-α that was supported by the in silico studies. This class of compounds was accessed via a sonochemical synthesis involving the acid catalyzed cyclocondensation reaction of aminopyrazoles with acrylophenones in the presence of aerial oxygen. The study indicated that the overall rate of the reaction was enhanced by ultrasound in the absence of which a longer duration and higher temperature was necessary. The current catalyst/promoter/ligand free and scalable method afforded a range of compounds. Some of these compounds showed good inhibition of TNF-α in vitro where ester/amide moiety at the C-3 position played a key role in interacting with the protein dimer as suggested by the in silico studies. Indeed, these groups formed H-bonds with A: GLY121 and B: TYR151 residues of TNF-α dimer in silico. A brief SAR within the series and in silico ADME/toxicity prediction for best active compounds is presented. Compounds 3a-c were identified as initial hits for further pharmacological evaluations. A sonochemical method has been developed for the facile synthesis of pyrazolo[1,5-a]pyrimidines that were evaluated as potential inhibitors of TNF-α. [ABSTRACT FROM AUTHOR] Copyright of Polycyclic Aromatic Compounds is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nucleoside Analogs That Inhibit SARS-CoV-2 Replication by Blocking Interaction of Virus Polymerase with RNA.

The SARS-CoV-2 betacoronavirus pandemic has claimed more than 6.5 million lives and, despite the development and use of COVID-19 vaccines, remains a major global public health problem. The development of specific drugs for the treatment of this disease remains a very urgent task. In the context of a repurposing strategy, we previously screened a library of nucleoside analogs showing different types of biological activity against the SARS-CoV-2 virus. The screening revealed compounds capable of inhibiting the reproduction of SARS-CoV-2 with EC50 values in the range of 20-50 µM. Here we present the design and synthesis of various analogs of the leader compounds, the evaluation of their cytotoxicity and antiviral activity against SARS-CoV-2 in cell cultures, as well as experimental data on RNA-dependent RNA polymerase inhibition. Several compounds have been shown to prevent the interaction between the SARS-CoV-2 RNA-dependent RNA polymerase and the RNA substrate, likely inhibiting virus replication. Three of the synthesized compounds have also been shown to inhibit influenza virus. The structures of these compounds can be used for further optimization in order to develop an antiviral drug.

Green and efficient one-pot three-component synthesis of novel drug-like furo[2,3-d]pyrimidines as potential active site inhibitors and putative allosteric hotspots modulators of both SARS-CoV-2 MPro and PLPro.

In this paper, an environmentally benign, convenient, and efficient one-pot three-component reaction has been developed for the regioselective synthesis of novel 5-aroyl(or heteroaroyl)-6-(alkylamino)-1,3-dimethylfuro[2,3-d]pyrimidine-2,4(1H,3H)-diones (4a‒n) through the sequential condensation of aryl(or heteroaryl)glyoxal monohydrates (1a‒g), 1,3-dimethylbarbituric acid (2), and alkyl(viz. cyclohexyl or tert-butyl)isocyanides (3a or 3b) catalyzed by ultra-low loading ZrOCl2•8H2O (just 2 mol%) in water at 50 ˚C. After synthesis and characterization of the mentioned furo[2,3-d]pyrimidines (4a‒n), their multi-targeting inhibitory properties were investigated against the active site and putative allosteric hotspots of both SARS-CoV-2 main protease (MPro) and papain-like protease (PLPro) based on molecular docking studies and compare the attained results with various medicinal compounds which approximately in three past years were used, introduced, and or repurposed to fight against COVID-19. Furthermore, drug-likeness properties of the mentioned small heterocyclic frameworks (4a‒n) have been explored using in silico ADMET analyses. Interestingly, the molecular docking studies and ADMET-related data revealed that the novel series of furo[2,3-d]pyrimidines (4a‒n), especially 5-(3,4-methylendioxybenzoyl)-6-(cyclohexylamino)-1,3-dimethylfuro[2,3-d]pyrimidine-2,4(1H,3H)-dione (4g) as hit one is potential COVID-19 drug candidate, can subject to further in vitro and in vivo studies. It is worthwhile to note that the protein-ligand-type molecular docking studies on the human body temperature-dependent MPro protein that surprisingly contains zincII (ZnII) ion between His41/Cys145 catalytic dyad in the active site, which undoubtedly can make new plans for designing novel SARS-CoV-2 MPro inhibitors, is performed for the first time in this paper, to the best of our knowledge.

Synthesis of novel indolo[3,2-c]isoquinoline derivatives bearing pyrimidine, piperazine rings and their biological evaluation and docking studies against COVID-19 virus main protease.

A series of hybrid indolo[3,2-c]isoquinoline (δ-carboline) analogs incorporating two pyrimidine and piperizine ring frameworks were synthesized. Intending biological activities and SAR we propose replacements of fluorine, methyl and methoxy of synthetic compounds for noteworthy antimicrobial, antioxidant, anticancer and anti-tuberculosis activities. Among these compounds 3a, 4a and 5e were progressively strong against E. coli and K. pneumonia. Whereas, compounds 4a, 5a and 6a with addition of various functional groups (OCH3, CH3) were excellent against S. aureus and B. subtilis. Compound 5c exhibited strong RSA and dynamic ferrous ion (Fe2+) metal chelating impact with IC50 of 7.88 ± 0.93 and 4.06 ± 0.31 µg/mL, respectively. Compound 5e was considerably cytotoxic against all cancer cells displaying activity better than the standard drug. Compounds 6b and 6e inhibited M. tuberculosis (MIC 1.0 mg/L) considerably. Molecular docking studies indicate that compounds 4d, 5a, 5b, 6b and 6f exhibited good interactions with 6LZE (COVID-19) and 6XFN (SARS-CoV-2) at active sites. The structure of the synthesized compounds were elementally analyzed using IR, 1H, 13C NMR and mass spectral information.

INADEQUATE IMMUNE RESPONSE TO COVID-19 VACCINES IN THE PRESENCE OF DISEASE-MODIFYING ANTIRHEUMATIC DRUGS (DMARDS)

SESSION TITLE: Issues After COVID-19 Vaccination Case Posters SESSION TYPE: Case Report Posters PRESENTED ON: 10/19/2022 12:45 pm - 01:45 pm INTRODUCTION: Since the onset of the COVID-19 pandemic, vaccines were introduced to mitigate the spread of the virus. Depending on the COVID-19 vaccine, regimens consist of one dose (ie, J&J) or two doses (ie, Pfizer and Moderna) and is followed by a third dose/booster (for immunocompromised/immunocompetent individuals). Here, we present a case of COVID-19 infection in a triple vaccinated patient with concurrent rheumatoid arthritis (RA) receiving disease modifying antirheumatic drugs (DMARDs) who was unable to mount an adequate immune response to the vaccine. CASE PRESENTATION: Patient is a 67 year old male with PMH of RA (on DMARDs) presented to the ED with complaints of shortness of breath. He was on treatment for RA with leflunomide, rituximab and prednisone. He was COVID-19 triple vaccinated. In ED, the patient was found to be hypoxic, saturating at 87% on room air with a respiratory rate of 18. Physical examination was significant for coarse breath sounds bilaterally and remaining vitals were unremarkable. Patient was initially placed on 3 L oxygen via NC but due to persistent hypoxia, was transitioned to high-flow nasal cannula. Further investigations revealed that the patient was COVID-19 positive. He was treated with remdesivir and dexamethasone. His oxygen requirements continued to escalate and he was ultimately intubated. While in the ICU, the patient's hypoxia continued to worsen despite optimal medical and ventilatory management and he subsequently died. DISCUSSION: DMARDs are a group of medications used to slow the progression of rheumatoid arthritis. They work by reducing the immune response of B cells, T cells and cytokines. Our patient was on two commonly prescribed medications for rheumatoid arthritis, leflunomide and rituximab. The former acts by inhibiting the pyrimidine synthesis pathway, thereby decreasing T lymphocyte production and the latter depletes CD-20 positive B cells. While there is limited data on COVID-19 vaccine, it has been established that patients on DMARDs have reduced antibody titres after immunization against influenza and pneumonia vaccinations [1, 2]. A study assessing the effectiveness of a third vaccine dose in patients taking rituximab vs placebo found a significant difference in seroconversion (78.8% vs 18.2%, p=<0.0001) and neutralizing activity (80.0% vs 21.9%, p=<0.0001) [3]. In our case, the patient was on two immunosuppressive drugs which suppressed both the humoral and cell mediated immunity, resulting in an inadequate immune response and subsequently developing COVID. CONCLUSIONS: This case highlights patients on immunosuppressant therapy failing to mount an adequate immune response to the COVID-19 vaccine, warranting more booster doses in patients on DMARDs. Reference #1: Adler S, Krivine A, Weix J et al. Protective effect of A/ H1N1 vaccination in immune-mediated disease–a prospectively controlled vaccination study. Rheumatology 2012;51:695–700. Reference #2: Franca ILA, Ribeiro ACM, Aikawa NE et al. TNF blockers show distinct patterns of immune response to the pandemic influenza A H1N1 vaccine in inflammatory arthritis patients. Rheumatology 2012;51:2091–8. Reference #3: David S, Koray T, Filippo F et al. Efficacy and safety of SARS-CoV-2 revaccination in non-responders with immune-mediated inflammatory disease. http://dx.doi.org/10.1136/annrheumdis-2021-221554 DISCLOSURES: No relevant relationships by Gursharan Kaur No relevant relationships by Aishwarya Krishnaiah No relevant relationships by sandeep mandal

AND KIDNEY OF MALE ALBINO RATS

As a result of the scale of the Covid 19 pandemic that launched from China in December 2019 and to limit its spread, several treatments were used to control this virus, including, hydroxychloroquine, favipiravir, lopinavir, remidesivir, tocilizumab, and anakinra. Favipiravir is an antiviral drug that works by inhibiting RNA-dependent RNA polymerase, favipiravir inhibited viral genome replication, which was most noticeable in the middle of the viral proliferation period. Favipiravir was found to have antiviral activity, Purine nucleosides or purine bases inhibit favipiravir, meaning that it competes with purine nucleosides rather than pyrimidine nucleosides, In a time-of-drugaddition test, to treat a variety of RNA viruses (influenza, West Nile, yellow fever, flaviviruses, arenaviruses, bunyaviruses and alphaviruses). Here, we show for the first time the histologycal effect of favipiravir on the liver and kidneys using albino rats, using light microscopy, where the optical microscopic revealed that normal doses in liver showed hepatic cords arranged, normal central vein and mild sinusoildal infiltration of mono nuclear leukocytes mainly lymphocytes, the hepatocytes showed mild granular cytoplasm while double doses showed little hemorrhagic foci and disarrangement of hepatic cords. The magnified sections revealed few of hepatocytes showed mild cloudy swelling associated with little figures of cellular necrosis. As for kidneys, the optical microscopic observations showed multiple foci of hemorrhage, the magnified section revealed congestion of glomerular capillary tuft and few of renal tubules showed mild granular or vacular degeneration. On the other hand, sections of renal medulla revealed normal appearance for normal doses while renal cortex and medulla were showed marked interstitial nephritis, which characterized by interstitial thickening due to infiltration of mono nuclear leukocytes and the renal tubules showed sever vacular degeneration and necrosis for double doses. These results can guide the safe use of favipiravir and reduce the risks to tissue the liver and kidney by using double doses.

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.

Could pyrimidine derivative be effective against Omicron of SARS-CoV-2?

BACKGROUND: A pyrimidine based Schiff base was examined in this report. Structural and spectral characterizations were done with Gaussian software. Active sites of the compound were determined using molecular electrostatic potential (MEP) maps. AIM: We focused to determine whether pyrimidine based Schiff base would be an inhibitor against Omicron of SARS-CoV-2 in silico. RESULTS AND CONCLUSION: As one of the perils the world has seen lately, omicron of SARS-CoV-2, is a complication to be solved. For the sake of that, anti-viral properties of studied pyrimidine based Schiff base compound were investigated with molecular docking calculations. It was found that the quantitative values of the calculated parameters were in the applicable ranges. In accordance with these results, it will be an important guide for future in vitro and in vivo analysis (Tab. 3, Fig. 7, Ref. 70).

Synthesis of novel pyridine and pyrimidine thioglycoside phosphoramidates for the treatment of COVID-19 and influenza A viruses.

A novel series of pyridine, cytosine, and uracil thioglycoside analogs (4a-i, 9a,b, and 13a,b, respectively) and their corresponding phosphoramidates (6a-I, 10a,b, and 14a,b, respectively) were synthesized and assessed for their antiviral inhibitory activities in a dual-pathogen screening protocol against SARS-CoV-2 and influenza A virus (IAV). MTT cytotoxicity (TC50) and plaque reduction assays were used to explore inhibition and cytotoxicity percentage values for H5N1 influenza virus strain and the half-maximal cytotoxic concentration (CC50) and inhibitory concentration (IC50) for SARS-CoV-2 virus. Most of the tested compounds demonstrated dose-dependent inhibition behavior. Both cytosine thioglycoside phosphoramidates 10a and 10b exhibited the most potent profiles with 83% and 86% inhibition at 0.25 µM concentration against H5N1 and IC50 values of 12.16 µM, 14.9 µM against SARS-CoV-2, respectively. Moreover, compounds 10a and 10b have been shown to have the highest selectivity index (SI) among all the tested compounds against SARS-CoV-2 with 28.2 and 26.9 values, respectively.

A Broad Antiviral Strategy: Inhibitors of Human DHODH Pave the Way for Host-Targeting Antivirals against Emerging and Re-Emerging Viruses.

New strategies to rapidly develop broad-spectrum antiviral therapies are urgently required for emerging and re-emerging viruses. Host-targeting antivirals (HTAs) that target the universal host factors necessary for viral replication are the most promising approach, with broad-spectrum, foresighted function, and low resistance. We and others recently identified that host dihydroorotate dehydrogenase (DHODH) is one of the universal host factors essential for the replication of many acute-infectious viruses. DHODH is a rate-limiting enzyme catalyzing the fourth step in de novo pyrimidine synthesis. Therefore, it has also been developed as a therapeutic target for many diseases relying on cellular pyrimidine resources, such as cancers, autoimmune diseases, and viral or bacterial infections. Significantly, the successful use of DHODH inhibitors (DHODHi) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection further supports the application prospects. This review focuses on the advantages of HTAs and the antiviral effects of DHODHi with clinical applications. The multiple functions of DHODHi in inhibiting viral replication, stimulating ISGs expression, and suppressing cytokine storms make DHODHi a potent strategy against viral infection.

The time-dependency of the cyclobutane pyrimidine dimer-evoked cellular damages using a CPD-specific photolyase-encoding mRNA-based model system

UVB damages DNA predominantly by the formation of cyclobutane pyrimidine dimers (CPDs) that are repaired by nucleotide excision repair system in humans. Organisms more primitive than placental mammals remove CPDs by photolyase in a process of photoreactivation that uses the energy of visible light. Our previously established model system based on transient transfection of human keratinocytes with in vitro transcribed CPD-photolyase mRNA containing 1-methylpseudouridine modifications (CPD-PL mRNA). The RNA composition is similar to that used in the BioNTech COVID-19 vaccine. Immediately, 6, 8, 12 and 24 hours after UVB irradiation, CPD-PL mRNA- transfected HaCaT and NHEK keratinocytes were either exposed to photoreactivating light or kept in the dark. Keratinocytes express functional photolyase upon transfection of CPD-PL mRNA. CPDs were effectively removed by photoreactivation immediately as well as 6 hour after transfection relieving the negative effects of UVB on cell viability and prevented the loss of cell proliferation and G2/M cell cycle block. Using our model system, it has been proved that CPDs are responsible for production of mitochondrial reactive oxygen species followed by the activation of several energy sensor enzymes, and compensatory metabolic changes in keratinocytes exposed to UVB. CPDs could be removed not only from nuclear genome but from mitochondrial genome as well and restored mitochondrial DNA copy number suggesting that damage to mitochondria can also be repaired by photolyase activation. UVB-induced mutagenesis was completely abrogated by photoreactivation emphasizing the key role of CPDs in mediating DNA damage and carcinogenesis. These results suggest that activation of a non-human photolyase encoded by nucleoside-modified mRNA is able to prevent UVB-induced cellular damage even hours after UVB exposure.

New Insights into the Interaction of Class II Dihydroorotate Dehydrogenases with Ubiquinone in Lipid Bilayers as a Function of Lipid Composition.

The fourth enzymatic reaction in the de novo pyrimidine biosynthesis, the oxidation of dihydroorotate to orotate, is catalyzed by dihydroorotate dehydrogenase (DHODH). Enzymes belonging to the DHODH Class II are membrane-bound proteins that use ubiquinones as their electron acceptors. We have designed this study to understand the interaction of an N-terminally truncated human DHODH (HsΔ29DHODH) and the DHODH from Escherichia coli (EcDHODH) with ubiquinone (Q10) in supported lipid membranes using neutron reflectometry (NR). NR has allowed us to determine in situ, under solution conditions, how the enzymes bind to lipid membranes and to unambiguously resolve the location of Q10. Q10 is exclusively located at the center of all of the lipid bilayers investigated, and upon binding, both of the DHODHs penetrate into the hydrophobic region of the outer lipid leaflet towards the Q10. We therefore show that the interaction between the soluble enzymes and the membrane-embedded Q10 is mediated by enzyme penetration. We can also show that EcDHODH binds more efficiently to the surface of simple bilayers consisting of 1-palmitoyl, 2-oleoyl phosphatidylcholine, and tetraoleoyl cardiolipin than HsΔ29DHODH, but does not penetrate into the lipids to the same degree. Our results also highlight the importance of Q10, as well as lipid composition, on enzyme binding.

A Sonochemical Access to 5-Aryl Substituted Pyrazolo[1,5-a]Pyrimidines as Potential Inhibitors of TNF-α

In spite of various and extensive studies known for pyrazolo[1,5-a]pyrimidines the synthesis, in silico studies and biological evaluation of their 5-(het)aryl analogs remained underexplored. The TNF-α inhibitors on the other hand has considerable therapeutic potential for autoimmune and inflammatory diseases in addition to cancer, diabetes and possibly COVID-19. In the current study 5-aryl pyrazolo[1,5-a]pyrimidines were explored as potential inhibitors of TNF-α that was supported by the in silico studies. This class of compounds was accessed via a sonochemical synthesis involving the acid catalyzed cyclocondensation reaction of aminopyrazoles with acrylophenones in the presence of aerial oxygen. The study indicated that the overall rate of the reaction was enhanced by ultrasound in the absence of which a longer duration and higher temperature was necessary. The current catalyst/promoter/ligand free and scalable method afforded a range of compounds. Some of these compounds showed good inhibition of TNF-α in vitro where ester/amide moiety at the C-3 position played a key role in interacting with the protein dimer as suggested by the in silico studies. Indeed, these groups formed H-bonds with A: GLY121 and B: TYR151 residues of TNF-α dimer in silico. A brief SAR within the series and in silico ADME/toxicity prediction for best active compounds is presented. Compounds 3a-c were identified as initial hits for further pharmacological evaluations. A sonochemical method has been developed for the facile synthesis of pyrazolo[1,5-a]pyrimidines that were evaluated as potential inhibitors of TNF-α. A sonochemical method has been developed for the facile synthesis of pyrazolo[1,5-a]pyrimidines that were evaluated as potential inhibitors of TNF-α.

The New Generation hDHODH Inhibitor MEDS433 Hinders the In Vitro Replication of SARS-CoV-2 and Other Human Coronaviruses.

Although coronaviruses (CoVs) have long been predicted to cause zoonotic diseases and pandemics with high probability, the lack of effective anti-pan-CoVs drugs rapidly usable against the emerging SARS-CoV-2 actually prevented a promptly therapeutic intervention for COVID-19. Development of host-targeting antivirals could be an alternative strategy for the control of emerging CoVs infections, as they could be quickly repositioned from one pandemic event to another. To contribute to these pandemic preparedness efforts, here we report on the broad-spectrum CoVs antiviral activity of MEDS433, a new inhibitor of the human dihydroorotate dehydrogenase (hDHODH), a key cellular enzyme of the de novo pyrimidine biosynthesis pathway. MEDS433 inhibited the in vitro replication of hCoV-OC43 and hCoV-229E, as well as of SARS-CoV-2, at low nanomolar range. Notably, the anti-SARS-CoV-2 activity of MEDS433 against SARS-CoV-2 was also observed in kidney organoids generated from human embryonic stem cells. Then, the antiviral activity of MEDS433 was reversed by the addition of exogenous uridine or the product of hDHODH, the orotate, thus confirming hDHODH as the specific target of MEDS433 in hCoVs-infected cells. Taken together, these findings suggest MEDS433 as a potential candidate to develop novel drugs for COVID-19, as well as broad-spectrum antiviral agents exploitable for future CoVs threats.