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Rifamycins: modulation of specific anti-poxviral activity by small substitutions on the piperazinyliminomethyl side
Abstract:
Rifamycin derivatives differing in the substitutent at the 4 position of the piperazinyliminomethyl side chain were tested for anti-poxviral activity. The effects of each derivative on wild-type vaccinia virus and on a mutant selected for resistance to rifampin were determined. Antiviral activity was measured in tissue culture by plaque inhibition, reduction in virus yield, and specific interruption of virus morphogenesis. Rifamycin derivatives containing H, ethyl, or propyl groups at the 4 position of the piperazinyliminomethyl side chain were much less active than rifampin, which has a methyl group at this position. Thus, minimal shortening or lengthening of the methyl piperazinyliminomethyl side chain of rifampin led to loss of specific antiviral activity. In contrast, the derivative containing an amino group at the 4 position of the piperazinyliminomethyl side chain had enhanced anti-poxviral activity.
Insights
Rifamycin derivatives were tested for anti-poxviral activity. Modifications to the piperazinyliminomethyl side chain significantly altered efficacy, with an amino group enhancing activity against vaccinia virus.
Area of Science:
- Microbiology
- Virology
- Medicinal Chemistry
Background:
- Poxviruses, such as vaccinia virus, remain a public health concern.
- Rifamycin derivatives are known for their antimicrobial properties.
- Understanding structure-activity relationships is crucial for developing novel antiviral agents.
Purpose of the Study:
- To evaluate the anti-poxviral activity of novel rifamycin derivatives.
- To investigate the impact of substitutions at the 4-position of the piperazinyliminomethyl side chain on antiviral efficacy.
- To compare the activity of these derivatives against wild-type vaccinia virus and a rifampin-resistant mutant.
Main Methods:
- Synthesis and characterization of rifamycin derivatives with varying substituents at the piperazinyliminomethyl side chain.
- In vitro antiviral assays including plaque inhibition, virus yield reduction, and assessment of virus morphogenesis.
- Testing against wild-type vaccinia virus and a rifampin-resistant mutant strain.
Main Results:
- Rifamycin derivatives with hydrogen, ethyl, or propyl groups at the 4-position showed significantly reduced anti-poxviral activity compared to rifampin.
- Rifampin, possessing a methyl group at this position, demonstrated notable activity.
- The derivative with an amino group at the 4-position exhibited enhanced anti-poxviral activity.
Conclusions:
- The specific substituent at the 4-position of the piperazinyliminomethyl side chain is critical for anti-poxviral activity.
- Minimal alterations (shortening or lengthening) of the methyl group in rifampin lead to a loss of efficacy.
- Introducing an amino group at this position can enhance the anti-poxviral potency of rifamycin derivatives.