Ribavirin shows antiviral activity against SARS-CoV-2 and downregulates the activity of TMPRSS2 and the expression of ACE2 in vitro.

Ribavirin is a guanosine analog with broad-spectrum antiviral activity against RNA viruses. Based on this, we aimed to show the anti-SARS-CoV-2 activity of this drug molecule via in vitro, in silico, and molecular techniques. Ribavirin showed antiviral activity in Vero E6 cells following SARS-CoV-2 infection, whereas the drug itself did not show any toxic effect over the concentration range tested. In silico analysis suggested that ribavirin has a broad-spectrum impact on SARS-CoV-2, acting at different viral proteins. According to the detailed molecular techniques, ribavirin was shown to decrease the expression of TMPRSS2 at both mRNA and protein levels 48 h after treatment. The suppressive effect of ribavirin in ACE2 protein expression was shown to be dependent on cell types. Finally, proteolytic activity assays showed that ribavirin also showed an inhibitory effect on the TMPRSS2 enzyme. Based on these results, we hypothesized that ribavirin may inhibit the expression of TMPRSS2 by modulating the formation of inhibitory G-quadruplex structures at the TMPRSS2 promoter. As a conclusion, ribavirin is a potential antiviral drug for the treatment against SARS-CoV-2, and it interferes with the effects of TMPRSS2 and ACE2 expression.

Optimization of Immobilized Aldose Reductase Isolated from Bovine Liver.

OBJECTIVES: Isolation of enzymes and experiments on them require great effort and cost and are time-consuming. Therefore, it is important to extend the usability of the enzymes by immobilizing them. In this study our purpose was to immobilize the enzyme aldose reductase (AR) and to optimize the experimental conditions of the immobilized AR and compare them to those of free AR. MATERIALS AND METHODS: AR was isolated from bovine liver and the enzyme immobilized in photographic gelatin by cross-linking with glutaraldehyde. Then the optimum conditions for free and immobilized AR in terms of pH, temperature, and storage were characterized by determining the enzyme activity. RESULTS: Following immobilization, the optimum pH and temperature levels for free AR, which were pH 7.0 and 60°C, slightly altered to pH 7.5 and 50°C. The enzyme activity of the immobilized AR was maintained at about 65% after reusing 15 times. Moreover, immobilized AR maintained 95% of its original activity after 20 days of storage at 4°C, while the retained activity of the free AR was 85% of the original. CONCLUSION: Our experiments indicated that the conditions that affect enzyme activity might alter following immobilization. Once the optimum experimental conditions are fixed, the immobilized AR can be stored and reused with efficiency higher than that of free AR. Moreover, this study provides an insight into the advantages of using immobilized AR in enzyme assays rather than free AR.