Effect of rifamycin and tilorone derivatives on Friend virus leukemia in mice.
Several derivatives of rifamycin, and analogs of the tilorone-fluoranthene group were tested for inhibition of splenic enlargement in Friend virus leukemia. At least three members of the rifamycin group caused significant inhibition (31-49%) as did at least three members of the tilorone group (32-48%). These six compounds are among those found by others (6, 7) to be most inhibitory in vitro to the RNA-directed DNA polymerase of oncornaviruses. However our studies do not furnish direct evidence for or against a role of inhibition of the viral enzyme in the suppression of splenomegaly. None of the agents was as effective as methotrexate, which caused 90-92% inhibition. The activity of five of the agents was reduced, rather than enhanced by the injection of adjuvants (M. butyricum and pertussis vaccine). Three of the agents had a subtractive, rather than an additive effect on the inhibition caused by methotrexate alone.
D000277:Adjuvants, Pharmaceutic; D000818:Animals; D005449:Fluorenes / Q000627:therapeutic use*; D005622:Friend murine leukemia virus / Q000187:drug effects* / Q000254:growth & development; D007942:Leukemia, Experimental / Q000517:prevention & control*; D008727:Methotrexate / Q000494:pharmacology; D051379:Mice; D009929:Organ Size; D012294:Rifamycins / Q000494:pharmacology / Q000627:therapeutic use*; D013154:Spleen / Q000033:anatomy & histology; D013994:Tilorone / Q000031:analogs & derivatives / Q000494:pharmacology / Q000627:therapeutic use*
D000277:Adjuvants, Pharmaceutic; D005449:Fluorenes; D012294:Rifamycins; D013994:Tilorone; D008727:Methotrexate