Antiviral activity of 2,3-dihydro-1H-imidazo[1,2-b]pyrazole in herpes simplex virus type 1-infected mammalian cells

Redox-neutral zinc-catalyzed cascade [1,4]-H shift/annulation of diaziridines with donor-acceptor aziridines

The coupling of diaziridines with donor-acceptor aziridines (DAAs) has been achieved using Zn-catalysis to furnish imidazopyrazole-4,4-dicarboxylates via [1,4]-hydride shift. The use of Zn-catalysis, [1,4]-hydride shift, natural product modification and a late-stage molecular docking study are important practical features.

Fused Imidazopyrazoles: Synthetic Strategies and Medicinal Applications

The current review summarizes the known synthetic routes of fused imidazopyrazoles. This review is classified into two main categories based on the type of annulations, for example, annulation of the imidazole ring onto a pyrazole scaffold or annulation of the pyrazole ring onto an imidazole scaffold. Some medicinal applications of imidazopyrazoles are mentioned.

Ethanol, disulfiram, and pyrazole: effects on interferon production in mice

The effects of ethanol alone or combined with pyrazole or disulfiram were studied in reference to interferon production. Saline, ethanol (2 g/kg), pyrazole (2 mg/kg), or disulfiram (2 mg/kg) were injected, intraperitoneally, 3 hr after poly I:C, an interferon inducer. Drugs were administered either by a single injection, or twice daily for 7 days, and the mice were sacrificed 6 hr after poly I:C. Sera from mice were pooled, dialyzed, and assayed for interferon by the microplaque reduction method. Administration of ethanol alone reduced interferon production 76% and 66% after the single and the multiple injections, respectively. A similar inhibition of interferon occurred after either pyrazole or disulfiram, with a greater potency for pyrazole. Treatment with pyrazole prior to ethanol reduced interferon production further, but only after the 7-day schedule. All drugs tested affected cellular immunity as measured by interferon production. Moreover, reduced interferon production by these agents was associated with a loss of splenic lymphoid tissue, suggesting that ethanol, pyrazole, and disulfiram could affect susceptibility to viral infection.

The selective inhibition of viral DNA synthesis by chemotherapeutic agents: an indicator of clinical usefulness?

A cell culture system has been utilized to measure the effects of drugs on DNA synthesis in uninfected and HSV-(herpes simplex virus)-infected KB cells. DNA from HSV-infected cells was separated into viral and cellular components by isopycnic centrifugation in CsCl gradients. The amount of [3H]thymidine incorporated into acid-insoluble material was measured in the absence and presence of drugs. Dose-response relationships were established by linearly regressing the probit value of the percent inhibition DNA synthesis against the logarithm of drug concentration. Fifty percent inhibitory (I50) concentrations were interpolated from the corresponding regression lines for inhibition of the following: (i) DNA synthesis is uninfected KB cells, (ii) total DNA synthesis in HSV-infected KB cells (iii) cellular DNA synthesis in HSV-infected cells, and (iv) viral DNA synthesis in HSV-infected cells. We have derived an index (SI, selective index) that quantifies the preferential inhibition of viral or uninfected cellular DNA synthesis. This index can be expressed as SI = log10 I50 concentration for DNA synthesis in uninfected cells divided by I50 concentration for viral DNA synthesis in HSV-infected cells. The SI is positive if viral DNA synthesis is inhibited preferentially and negative if uninfected cellular DNA synthesis is more strongly inhibited. A positive SI value of 0.5 was obtained for the clinically useful antiviral drug arabinosyladenine (ara-A) and a value of 0.4 for its metabolite, arabinosylhypoxanthine (ara-H). Although the adenosine deaminase inhibitor coformycin greatly increased the potency of ara-A, the inhibitor did not increase the selectivity of the drug (SI = 0.3). Stallimycin (distimycin A) (SI = 0.3) and phosphonoacetic acid (SI = 0.3) were similarly effective in preferentially inhibiting the synthesis of HSV DNA. In contrast, arabinosylcytosine (ara-C) and ribavirin inhibited DNA synthesis in uninfected cells to a greater degree than viral DNA synthesis (SI = -0.5 and -1.9, respectively). An analysis of the advantages and limitations of this experimental procedure is made and the suggestion is offered that the in vitro determination of a drug's selective index may be a valid predictor of clinical usefulness.