Antiretroviral drug activity and potential for pre-exposure prophylaxis against COVID-19 and HIV infection

Synthesis, evaluation of biological activity and SAR of new thioalkyl derivatives of pyridine

BACKGROUND

Pyridine and its derivatives play a vital role in medicinal chemistry, serving as key scaffolds for drugs. The ability to bind to biological targets makes pyridine compounds significant, sparking interest in creating new pyridine-based drugs. Thus, the purpose of the research is to synthesize new thioalkyl derivatives of pyridine, predict their biological spectrum, study their psychotropic properties, and based on these findings, perform structure-activity relationships to assess pharmacophore functional groups.

METHODS

Classical organic methods were employed for synthesizing new thioalkyl derivatives of pyridine, with a multifaceted pharmacological profiles. Various software packages and methods were employed to evaluate the biological spectrum of the newly synthesized compounds. For the evaluation of neurotropic activity of new synthesized compounds, some biological methods were used according to indicators characterizing anticonvulsant, sedative and antianxiety activity as well as side effects.

RESULTS

Effective synthetic methods for 6-amino-4-phenyl-2-thio-2H-thiopyran-5-carboxylic acid ethyl ester, 2-amino substituted thiopyridine derivatives and 6-cycloamino-2-thioalkyl-4-phenylnicotinate derivatives were obtained in high yield. Predicted biological spectra and pharmacokinetic data indicated high gastrointestinal absorption and low blood-brain barrier passage for most compounds and demonstrated potential various biological effects, particularly psychotropic properties. Studied compounds demonstrated high anticonvulsant activity through antagonism with pentylenetetrazole. They exhibited low toxicity without inducing muscle relaxation in the studied doses. In psychotropic studies, the compounds displayed activating, sedative, and anxiolytic effects. Notably, the 6-amino-2-thioalkyl-4-phenylnicotinate derivatives demonstrated significant anxiolytic activity (about four times more compared to diazepam). They also exhibited pronounced sedative effects. Ethyl 2-({2-[(diphenylmethyl)amino]-2-oxoethyl}thio)-4-phenyl-6-pyrrolidin-1-ylnicotinate exhibited anxiolytic activity even two times greater than diazepam. Moreover, all studied compounds showed statistically significant antidepressant effects. Noteworthy ethyl 2-({2-oxo-2-[(tetrahydrofuran-2-ylmethyl)amino]ethyl}thio)-4-phenyl-6-pyrrolidin-1-ylnicotinate showcasing its unique psychotropic effect.

CONCLUSIONS

The selected compounds demonstrate anticonvulsant properties, activating behavior, and anxiolytic effects, while simultaneously exhibiting antidepressant effects and these compounds as promising candidates for further exploration in the development of therapeutics with a broad spectrum of neuropsychiatric applications.

Antiviral Effect of 5'-Arylchalcogeno-3-aminothymidine Derivatives in SARS-CoV-2 Infection

The understanding that zidovudine (ZDV or azidothymidine, AZT) inhibits the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 and that chalcogen atoms can increase the bioactivity and reduce the toxicity of AZT has directed our search for the discovery of novel potential anti-coronavirus compounds. Here, the antiviral activity of selenium and tellurium containing AZT derivatives in human type II pneumocytes cell model (Calu-3) and monkey kidney cells (Vero E6) infected with SARS-CoV-2, and their toxic effects on these cells, was evaluated. Cell viability analysis revealed that organoselenium (R3a-R3e) showed lower cytotoxicity than organotellurium (R3f, R3n-R3q), with CC50 ≥ 100 µM. The R3b and R3e were particularly noteworthy for inhibiting viral replication in both cell models and showed better selectivity index. In Vero E6, the EC50 values for R3b and R3e were 2.97 ± 0.62 µM and 1.99 ± 0.42 µM, respectively, while in Calu-3, concentrations of 3.82 ± 1.42 µM and 1.92 ± 0.43 µM (24 h treatment) and 1.33 ± 0.35 µM and 2.31 ± 0.54 µM (48 h) were observed, respectively. The molecular docking calculations were carried out to main protease (Mpro), papain-like protease (PLpro), and RdRp following non-competitive, competitive, and allosteric inhibitory approaches. The in silico results suggested that the organoselenium is a potential non-competitive inhibitor of RdRp, interacting in the allosteric cavity located in the palm region. Overall, the cell-based results indicated that the chalcogen-zidovudine derivatives were more potent than AZT in inhibiting SARS-CoV-2 replication and that the compounds R3b and R3e play an important inhibitory role, expanding the knowledge about the promising therapeutic capacity of organoselenium against COVID-19.

Daily tenofovir disoproxil fumarate/emtricitabine and hydroxychloroquine for pre-exposure prophylaxis of COVID-19: a double-blind placebo-controlled randomized trial in healthcare workers

OBJECTIVES

To assess the effect of hydroxychloroquine (HCQ) and Tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) as pre-exposure prophylaxis on COVID-19 risk.

METHODS

EPICOS is a double-blind, placebo-controlled randomized trial conducted in Spain, Bolivia, and Venezuela. Healthcare workers with negative SARS-CoV-2 IgM/IgG test were randomly assigned to the following: daily TDF/FTC plus HCQ for 12 weeks, TDF/FTC plus HCQ placebo, HCQ plus TDF/FTC placebo, and TDF/FTC placebo plus HCQ placebo. Randomization was performed in groups of four. Primary outcome was laboratory-confirmed, symptomatic COVID-19. We also studied any (symptomatic or asymptomatic) COVID-19. We compared group-specific 14-week risks via differences and ratios with 95% CIs.

RESULTS

Of 1002 individuals screened, 926 (92.4%) were eligible and there were 14 cases of symptomatic COVID-19: 220 were assigned to the TDF/FTC plus HCQ group (3 cases), 231 to the TDF/FTC placebo plus HCQ group (3 cases), 233 to the TDF/FTC plus HCQ placebo group (3 cases), and 223 to the double placebo group (5 cases). Compared with the double placebo group, 14-week risk ratios (95% CI) of symptomatic COVID-19 were 0.39 (0.00-1.98) for TDF + HCQ, 0.34 (0.00-2.06) for TDF, and 0.49 (0.00-2.29) for HCQ. Corresponding risk ratios of any COVID-19 were 0.51 (0.21-1.00) for TDF + HCQ, 0.81 (0.44-1.49) for TDF, and 0.73 (0.41-1.38) for HCQ. Adverse events were generally mild.

DISCUSSION

The target sample size was not met. Our findings are compatible with both benefit and harm of pre-exposure prophylaxis with TDF/FTC and HCQ, alone or in combination, compared with placebo.

Finding a prospective dual-target drug for the treatment of coronavirus disease by theoretical study

Spike protein of coronavirus is a key protein in binding and entrance of virus to the human cell via binding to the receptor-binding domain (RBD) domain of S1 subunit to peptidase domain region of ACE2 receptor. In this study, the possible effect of 24 antiviral drugs on the RBD domain of spike protein was investigated via docking and molecular dynamics simulation for finding a dual-target drug. At first, all drugs were docked to the RBD domain of spike protein, and then all complexes and free RBD domains were separately used for molecular dynamics simulation for 50 ns via amber18 software. The simulation results showed that 10 ligands from 28 ligands were separated from the RBD domain, and among 18 remained ligands, baloxavir marboxil, and danoprevir drugs, besides endonuclease activity and protease inhibitory, can bind to key residues of the RBD domain. Then these drugs have a dual target and should be more effective than current drugs, and experimental studies should be done on baloxavir marboxil and danoprevir as more potential drugs for coronavirus disease Communicated by Ramaswamy H. Sarma.

The Nucleoside/Nucleotide Analogs Tenofovir and Emtricitabine Are Inactive against SARS-CoV-2

The urgent response to the COVID-19 pandemic required accelerated evaluation of many approved drugs as potential antiviral agents against the causative pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Using cell-based, biochemical, and modeling approaches, we studied the approved HIV-1 nucleoside/tide reverse transcriptase inhibitors (NRTIs) tenofovir (TFV) and emtricitabine (FTC), as well as prodrugs tenofovir alafenamide (TAF) and tenofovir disoproxilfumarate (TDF) for their antiviral effect against SARS-CoV-2. A comprehensive set of in vitro data indicates that TFV, TAF, TDF, and FTC are inactive against SARS-CoV-2. None of the NRTIs showed antiviral activity in SARS-CoV-2 infected A549-hACE2 cells or in primary normal human lung bronchial epithelial (NHBE) cells at concentrations up to 50 µM TAF, TDF, FTC, or 500 µM TFV. These results are corroborated by the low incorporation efficiency of respective NTP analogs by the SARS-CoV-2 RNA-dependent-RNA polymerase (RdRp), and lack of the RdRp inhibition. Structural modeling further demonstrated poor fitting of these NRTI active metabolites at the SARS-CoV-2 RdRp active site. Our data indicate that the HIV-1 NRTIs are unlikely direct-antivirals against SARS-CoV-2, and clinicians and researchers should exercise caution when exploring ideas of using these and other NRTIs to treat or prevent COVID-19.

Identifying FDA-approved drugs with multimodal properties against COVID-19 using a data-driven approach and a lung organoid model of SARS-CoV-2 entry

BACKGROUND

Vaccination programs have been launched worldwide to halt the spread of COVID-19. However, the identification of existing, safe compounds with combined treatment and prophylactic properties would be beneficial to individuals who are waiting to be vaccinated, particularly in less economically developed countries, where vaccine availability may be initially limited.

METHODS

We used a data-driven approach, combining results from the screening of a large transcriptomic database (L1000) and molecular docking analyses, with in vitro tests using a lung organoid model of SARS-CoV-2 entry, to identify drugs with putative multimodal properties against COVID-19.

RESULTS

Out of thousands of FDA-approved drugs considered, we observed that atorvastatin was the most promising candidate, as its effects negatively correlated with the transcriptional changes associated with infection. Atorvastatin was further predicted to bind to SARS-CoV-2's main protease and RNA-dependent RNA polymerase, and was shown to inhibit viral entry in our lung organoid model.

CONCLUSIONS

Small clinical studies reported that general statin use, and specifically, atorvastatin use, are associated with protective effects against COVID-19. Our study corroborrates these findings and supports the investigation of atorvastatin in larger clinical studies. Ultimately, our framework demonstrates one promising way to fast-track the identification of compounds for COVID-19, which could similarly be applied when tackling future pandemics.

Current evidence for the risk of PR prolongation, QRS widening, QT prolongation, from lopinavir, ritonavir, atazanavir, and saquinavir: A systematic review

BACKGROUND

Lopinavir, ritonavir, atazanavir, and saquinavir had been reportedly used or suggested for coronavirus disease 2019 (COVID-19) treatment. They may cause electrocardiography changes. We aim to evaluate risk of PR prolongation, QRS widening, and QT prolongation from lopinavir, ritonavir, atazanavir, and saquinavir.

METHODS

In accordance with preferred reporting items for systematic reviews and meta-analyses guidelines, our search was conducted in PubMed Central, PubMed, EBSCOhost, and ProQuest from inception to June 25, 2020. Titles and abstracts were reviewed for relevance. Cochrane Risk of Bias Tool 2.0 and Downs and Black criteria was used to evaluate quality of studies.

RESULTS

We retrieved 9 articles. Most randomized controlled trials have low risk of biases while all quasi-experimental studies have a positive rating. Four studies reporting PR prolongation however only 2 studies with PR interval >200 ms. One of which, reported its association after treatment with ritonavir-boosted saquinavir treatment while another, during treatment with ritonavir-boosted atazanavir. No study reported QRS widening >120 ms with treatment. Four studies reporting QT prolongation, with only one study reaching QT interval >450 ms after ritonavir-boosted saquinavir treatment on healthy patients. There is only one study on COVID-19 patients reporting QT prolongation in 1 out of 95 patients after ritonavir-boosted lopinavir treatment.

CONCLUSION

Limited evidence suggests that lopinavir, ritonavir, atazanavir, and saquinavir could cause PR prolongation, QRS widening, and QT prolongation. Further trials with closer monitoring and assessment of electrocardiography are needed to ascertain usage safety of antivirals in COVID-19 era.

Tenofovir, Another Inexpensive, Well-Known and Widely Available Old Drug Repurposed for SARS-COV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is spreading worldwide with different clinical manifestations. Age and comorbidities may explain severity in critical cases and people living with human immunodeficiency virus (HIV) might be at particularly high risk for severe progression. Nonetheless, current data, although sometimes contradictory, do not confirm higher morbidity, risk of more severe COVID-19 or higher mortality in HIV-infected people with complete access to antiretroviral therapy (ART). A possible protective role of ART has been hypothesized to explain these observations. Anti-viral drugs used to treat HIV infection have been repurposed for COVID-19 treatment; this is also based on previous studies on severe acute respiratory syndrome virus (SARS-CoV) and Middle East respiratory syndrome virus (MERS-CoV). Among them, lopinavir/ritonavir, an inhibitor of viral protease, was extensively used early in the pandemic but it was soon abandoned due to lack of effectiveness in clinical trials. However, remdesivir, a nucleotide analog that acts as reverse-transcriptase inhibitor, which was tested early during the pandemic because of its wide range of antiviral activity against several RNA viruses and its safety profile, is currently the only antiviral medication approved for COVID-19. Tenofovir, another nucleotide analog used extensively for HIV treatment and pre-exposure prophylaxis (PrEP), has also been hypothesized as effective in COVID-19. No data on tenofovir's efficacy in coronavirus infections other than COVID-19 are currently available, although information relating to SARS-CoV-2 infection is starting to come out. Here, we review the currently available evidence on tenofovir's efficacy against SARS-CoV-2.