Stereoselective synthesis and biological evaluation as inhibitors of hepatitis C virus RNA polymerase of GSK3082 analogues with structural diversity at the 5-position

Total synthesis of antiviral drug, nirmatrelvir (PF-07321332)

The emergence and rapid spread of coronavirus disease 2019 (COVID-19), a potentially fatal disease, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has swiftly led to public health crisis worldwide. Hence vaccines and antiviral therapeutics are an important part of the healthcare response to combat the ongoing threat by COVID-19. Here, we report an efficient synthesis of nirmatrelvir (PF-07321332), an orally active SARS-CoV-2 main protease inhibitor.

Tandem construction of biological relevant aliphatic 5-membered N-heterocycles

Nature often uses cascade reactions in a highly stereocontrolled manner for assembly structurally diverse nitrogen-containing heterocyclic scaffolds, i.e. secondary metabolites, important for medicinal chemistry and pharmacy. Five-membered nitrogen-containing heterocycles as standalone rings, as well as spiro and polycyclic systems are pharmacophores of drugs approved in various therapies, i.a. antibacterial or antiviral, antifungal, anticancer, antidiabetic, as they target many key enzymes. Furthermore, a large number of pyrrolidine derivatives are currently considered as drug candidates. Cascade transformations, also known as domino or tandem reactions, offer straightforward methods to build N-heterocyclic libraries of the great structural variety desired for drawing SAR conclusions. The tandem transformations are often atom economic and time-saving because they are performed as the one-pot, so no need for purification after each 'virtual' step and the limited necessity of protective groups are characteristic for these processes. Thus, the same results as in classical multistep synthesis can be achieved at markedly lower costs and shorter time, which is in line with modern green chemistry rules. Great advantage of cascade reactions is often reflected in their high regio- and stereoselectivities, enabling the preparing of the heterocyclic compound better fitted to the expected target in cells. This review reveals the biological relevance of N-heterocyclic scaffolds based on saturated 5-membered rings since we showed a number of examples of approved drugs together with the recent biologically attractive leading structures of drug candidates. Next, novel cascade synthetic procedures, taking into account the structure of the reactants and reaction mechanisms, enabling to obtain biological-relevant heterocyclic frameworks with good yields and relatively high stereoselectivity, were reviewed and compared. The review covers the advances of designing biological active N-heterocycles mainly from 2018 to 2021, whereas the synthetic part is focused on the last 7 years.

In Vitro Antiviral Activity of Tyrosinase from Mushroom Agaricus bisporus against Hepatitis C Virus

Tyrosinases from a commercial Agaricus bisporus protein extract and directly isolated from white mushrooms were purified in order to obtaining the well-known tyrosinase from A. bisporus (TyrAB) of 45 kDa and a newly discovered 50 kDa tyrosinase isoform (Tyr50 kDa), and tested showing high antiviral activity against the hepatitis C virus for the first time. Cell toxicity and antiviral activity of tyrosinases were determined in cultured Huh 5-2 liver tumor cells transfected with a replicon system (a plasmid that includes all non-structural hepatitis C virus proteins and replicates autonomously). TyrAB was able to inhibit the replication of the hepatitis C virus without inducing toxicity in liver cells. In addition, the post-translational isoform Tyr50 kDa showed higher antiviral capacity than the former (up to 10 times greater), also exhibiting 10 times higher activity than the commercial drug Ribavirin^®. This antiviral activity was directly proportional to the enzymatic activity of tyrosinases, as no antiviral capacity was observed in the inactive form of the enzymes. The tyrosinases approach could represent a new antiviral inhibition mechanism, through a plausible catalytic mechanism of selective hydroxylation of the key role of tyrosine residues in viral proteases.

Amino Acid and Peptide-Based Antiviral Agents

A significant number of antiviral agents used in clinical practice are amino acids, short peptides, or peptidomimetics. Among them, several HIV protease inhibitors (e. g. lopinavir, atazanavir), HCV protease inhibitors (e. g. grazoprevir, glecaprevir), and HCV NS5A protein inhibitors have contributed to a significant decrease in mortality from AIDS and hepatitis. However, there is an ongoing need for the discovery of new antiviral agents and the development of existing drugs; amino acids, both proteinogenic and non-proteinogenic in nature, serve as convenient building blocks for this purpose. The synthesis of non-proteinogenic amino acid components of antiviral agents could be challenging due to the need for enantiomerically or diastereomerically pure products. Herein, we present a concise review of antiviral agents whose structures are based on amino acids of both natural and unnatural origin. Special attention is paid to the synthetic aspects of non-proteinogenic amino acid components of those agents.

Serum inducible protein-10 chemokine as a biomarker for clearance of HCV with and without treatment in Egyptian patients

BACKGROUND AND AIMS

Assessment of the potential predictive value of serum inducible protein-10 chemokine (IP-10) in the clearance of HCV in Egyptian patients with and without treatment.

MATERIALS AND METHODS

Ninety Egyptian individuals were involved in the current study where, 20 patients (23%) were chronic HCV (positive HCV antibodies and positive HCV RNA without treatment, 20 (22%) were healthy individuals (negative for both HCV antibodies and HCV RNA, 20 (22%) were natural clearance (positive HCV antibodies and negative for HCV RNA without treatment), 20 (22%) were achieved SVR after treatment (responders group, HCV positive and negative for HCV RNA after treatment) and 10 (11%) were non responders (positive HCV antibodies and still positive HCV RNA after treatment). HCV RNA was quantitated by real time PCR and serum IP10 level was measured by commercial ELISA kit. All biochemical and hematological examinations included liver function, CBC and alphefeto protein were assessed.

RESULTS

The mean serum levels of IP-10 were significantly higher (p< 0.001) in CHC patients (345.4 ± 100) pg/ml compared with healthy control group (101.5 ± 31.4) and natural clearance group (103.2 ± 40.7). Also serum levels of IP-10 was significantly elevated in non-responders group (257.4 ± 52.5) compared with each of SVR group (103.5 ± 43.5) (p< 0.001) and healthy group (101.5 ± 31.4), (p< 0.001). Prediction of a clinical response based on a IP10 chemokine revealed high sensitivity (93%), specificity (96%), negative predictive value (96%), and area under curve is (1.00). Moreover, there is no correlation ((R= 0.05), P value p< 0.795) between serum level of IP-10 and HCV viral load.

CONCLUSION

IP10 is a useful non-invasive biomarker for viral clearance and might be used to apply patients according to the predictable treatment outcome. Accordingly, patients who are unlikely to respond to treatment would avoid unnecessary exposure to medication that is related with high morbidity.