Leishmania donovani: Pilot Study for Evaluation of Therapeutic Effects of Inosine Analogs against Amastigotes in Vitro and in Vivo

Abstract

The inhibition of carbocyclic inosine (C-Ino), 3′-deoxyinosine (3′-dI), and 3′-deoxy-3′-fluoroinosine (3′-FI) to Leishmania donovani amastigotes was examined. J774.1 cells (a mouse macrophage line) were cultured in GIT medium with lipopolysaccharide and hemin and infected with the parasite. C-Ino (3 μM) completely inhibited and 3′-dI (30 μM) reduced to 40% the infection rate on Day 6 after infection. Pentostam (30 μM) resulted in a 38% infection rate. The therapeutic efficacies of nonentrapped free and liposome-entrapped inosine analogs were tested in mice infected with L. donovani. The mice were injected intravenously five times on alternate days, beginning 2 days after infection. Treatment with the nonentrapped free inosine analog of C-Ino (100 mg/kg), 3′-dI (100 mg/kg), or 3′-FI (50 mg/kg) resulted in an LDU that was 94, 68, or 73% lower, respectively, than the control values. Treatment with the corresponding entrapped inosine analog (10 mg/kg) caused decreases of 90, 69, or 68% LDU, respectively. The entrapped inosine analogs were inhibitory at doses one-fifth to one-tenth of the nonentrapped free inosine analogs. C-Ino had the strongest inhibitory effect among the three analogs tested in vitro and in vivo. Liposome-entrapped C-Ino had no severe side effects, although spleen weight increased, The agent may be useful as an anti-leishmanial drug.