A novel method for synthesizing 1,2,4-triazole- and tetrazole-containing 4H-thiopyrano[2,3-b]quinolines using a new combination of the thio-Michael and aza-Morita–Baylis–Hillman reactions was developed. Target compounds were evaluated for their cytotoxicities and antiviral activities against influenza A/Puerto Rico/8/34 virus in MDCK cells. The compounds showed low toxicity and some exhibited moderate antiviral activity. Molecular docking identified the M2 channel and polymerase basic protein 2 as potential targets. We observed that the antiviral activity of thiopyrano[2,3-b]quinolines is notably affected by both the nature and position of the substituent within the tetrazole ring, as well as the substituent within the benzene moiety of quinoline. These findings contribute to the further search for new antiviral agents against influenza A viruses among derivatives of thiopyrano[2,3-b]quinoline.

An antiviral effect of extracts prepared from aerial parts of nine species and from leaves of two species of the genus Spiraea L. was investigated for potential antiviral activity toward influenza A (H1N1) virus. The toxicity of dry extracts was analyzed, and the most selective extract was identified in vitro. The study’s material was collected in the Asian part of Russia. The plant extracts were prepared via three-stage countercurrent repercolation involving a complete cycle. All 40%-ethanolic extracts from Spiraea manifested antiviral activity against influenza A (H1N1) virus, with a selectivity index (SI) ranging from 1 to 10. IC₅₀ values indicated that the S. salicifolia L. S15 leaf extract (5.9 µg/mL) has the most pronounced antiviral effect and the lowest toxicity (CC₅₀ = 57.6 µg/mL) among the studied samples. The SI of this extract was 10, which exceeded that of the antiviral agent rimantadine (SI = 6). Biologically active compounds in the extract with the highest antiviral activity were identified using UV spectrometry and high-performance liquid chromatography. The S. salicifolia leaf extract was found to contain phenolic acids (chlorogenic, gentisic, caffeic, ferulic, and cinnamic acids), flavonols (quercetin, quercetin-3-glucuronoside, hyperoside, isoquercitrin, rutin, spiraeoside, avicularin, quercitrin, kaempferol, nicotiflorin, astragalin, and isorhamnetin-3-rutinoside), flavones (orientin, luteolin-7-glucoside, and vitexin), and coumarin. Predominant biologically active compounds in the S. salicifolia S15 leaf extract were such flavonols as rutin (19.3 mg/g), isoquercitrin (16.6 mg/g), isorhamnetin-3-rutinoside (10.6 mg/g), and astragalin (9.5 mg/g). Extraction of S. salicifolia leaves by repercolation is a more suitable method for extracting active ingredients with an antiviral effect.

Background. Modern clinical practice often excludes the possibility of differential diagnostics for acute respiratory viral infection pathogens and identification of a specific viral pathogen. In this regard, it is important to search for drugs with a broad spectrum of activity against pathogens of acute respiratory viral infections. The aim of the study was to assess the antiviral activity of the drug Cytovir®-3 in vitro against the cytopathogenic effect of human adenovirus. Material and methods. The antiviral effect of the drug Cytovir®-3 in comparison with the drug Umifenovir against human adenovirus type 5 was studied on Vero cell culture. The drugs were administered 1 hour before (prophylactic regimen) and 1 hour after (therapeutic regimen) infection of the cell culture with the virus. The working concentration range for the studied drugs was determined based on the 50% cytotoxic concentration values, calculated based on the results of the microtetrazolium (MTT) assay. Results and discussion . The drug Cytovir®-3 in two application regimens (therapeutic or prophylactic) demonstrated antiviral efficacy in vitro against human adenovirus in the non-toxic range (0-631 µg/ml) regardless of the application scheme (therapeutic or prophylactic ). Conclusion . The in vitro antiviral activity of the drug Cytovir®-3 against human adenovirus has been proven. Moreover, in all series of experiments, Cytovir®-3 had a selectivity index comparable to that of the reference drug Umifenovir.