Cytotoxicity reduction by O-nicotinoylation of antiviral 6-benzylaminopurine ribonucleosides

Synthesis of O-Nicotinoyl-Substituted Depot Forms of Biologically Active N6-Benzyladenosine Analogs

This unit describes an effective method for the preparation of N6-benzyl-2',3',5'-tri-O-nicotinoyl adenosine and N6-(3-fluorobenzyl)-2',3',5'-tri-O-nicotinoyl adenosine. These compounds are depot forms of biologically active N6-benzyladenosine (BAR) and its fluorinated analog N6-(3-fluorobenzyl)adenosine (FBAR), which had previously shown pronounced antiviral activity against human enterovirus EV-A71. BAR and FBAR bearing biodegradable O-nicotinoyl ester moieties were obtained by a three-step synthesis starting from inosine. An attractive feature of this strategy is the possibility of obtaining biodegradable depot forms of various biologically active ribonucleoside derivatives, particularly N6-substituted adenosine derivatives. © 2025 Wiley Periodicals LLC. Basic Protocol: Preparation of N6-benzyl-2',3',5'-tri-O-nicotinoyl adenosine (4a). Alternate Protocol: Preparation of N6-(3-fluorobenzyl)-2',3',5'-tri-O-nicotinoyl adenosine (4b).

Hydrophobic Rose Bengal Derivatives Exhibit Submicromolar-to-Subnanomolar Activity against Enveloped Viruses

Rose Bengal (RB) is an anionic xanthene dye with multiple useful biological features, including photosensitization properties. RB was studied extensively as a photosensitizer, mostly for antibacterial and antitumor photodynamic therapy (PDT). The application of RB to virus inactivation is rather understudied, and no RB derivatives have been developed as antivirals. In this work, we used a synthetic approach based on a successful design of photosensitizing antivirals to produce RB derivatives for virus photoinactivation. A series of n-alkyl-substituted RB derivatives was synthesized and evaluated as antiviral photosensitizers. The compounds exhibited similar 1O2 generation rate and efficiency, but drastically different activities against SARS-CoV-2, CHIKV, and HIV; with comparable cytotoxicity for different cell lines. Submicromolar-to-subnanomolar activities and high selectivity indices were detected for compounds with C4-6 alkyl (SARS-CoV-2) and C6-8 alkyl (CHIKV) chains. Spectrophotometric assessment demonstrates low aqueous solubility for C8-10 congeners and a significant aggregation tendency for the C12 derivative, possibly influencing its antiviral efficacy. Initial evaluation of the synthesized compounds makes them promising for further study as viral inactivators for vaccine preparations.