Coronavirus disease 2019 (COVID-19) is a new global pandemic with high morbidity and mortality caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). N-Hydroxycytidine derivatives show promise for combating COVID-19 and other viral diseases; in particular, molnupiravir has recently been approved for emergency prophylaxis in the early stages after infection with SARS-CoV-2. In the present work, a scheme for the synthesis of 5-halo-2ʹ-azido-substituted cytidine and N-hydroxycytidine derivatives was proposed. The synthesized compounds were tested against a panel of six RNA viruses, including SARS-CoV-2, enteroviruses, CHIKV, and HIV-1. A number of compounds showed ability to inhibit the reproduction of SARS-CoV-2 and CHIKV viruses in the micromolar range without noticeable cytotoxicity. The structures of the leader compounds can be used as a starting point for further design of antiviral agents.

In order to increase the bioavailability of water-insoluble pyropheophorbide-a (PPP-a) methyl ester, its liposomal form is prepared and the physicochemical and photochemical properties of this form are studied. The quantum yield of 1O2 is found to have a bell-shaped dependence on the concentration of PPP-a in the lipid phase of liposomes with the maximum at 31.6 µmol/g of lipids. The IR spectroscopy shows the photoinduced formation of aldehyde groups in the lipid phase of liposomes. The intracellular accumulation of PPP-a is confirmed by confocal microscopy.

Silver reduction from its nitrate has been studied in the media of DGEBA-based and aliphatic epoxy resins. It has been found that, under the experimental conditions that were employed, silver ions can be reduced without chemical interaction with the medium only due to photochemical processes. The reduction rate is determined by the rate of dissolution of the initial silver salt in an organic medium and the possibility of the formation of solvates by the system components. Refractometry has been proposed for use in monitoring the kinetics of silver nitrate dissolution in epoxy resins and the formation of silver nanoparticles. Stable dispersions of silver nanoparticles in epoxy resins have been obtained.