In vitro and in vivo activities of formycin B against Trypanosoma cruzi

Abstract

The inosine analog formycin B was examined for in vitro and in vivo activities against Trypanosoma cruzi. A concentration of formycin B as low as 0.1 ,ug/ml markedly inhibited intracellular multiplication of T. cruzi strains both in macrophages and in L929 cells. Mice infected with 105 blood form trypomastigotes of the highly virulent strain Y of T. cruzi were completely protected against death by treatment with 11.8 or 5.9 mg of formycin B per kg administered intraperitoneally each day for 19 days. Four different strains of T. cruzi were used, and each was susceptible to formycin B administered either intraperitoneally or orally. Parasitological cure, however, was not achieved with any of the treatments used, including prolonged treatment for up to 10 weeks. Formycin B has a remarkable capacity for inhibiting the in vitro intracellular replication of T. cruzi and protecting mice against death due to the acute infection with the organism. It does not appear, however, to be able to completely eliminate T. cruzi from infected mice. Recent reviews on the chemotherapy of Chagas' disease have emphasized the deficiencies of presently available therapeutic agents and the need for new ones (10, 13).Allopurinol (4-hydroxypyrazolo[3,4-d]pyrimidine) has recently been shown to be active against Trypanosoma cruzi both in vitro and in vivo (1)(2)(3)17). A related compound, formycin B (7-hydroxypyrazolo[4,3-d]pyrimidine), an inosine analog, has been shown to inhibit replication of epimastigotes of T. cruzi (16,20) and to inhibit the in vivo and in vitro replication of Leishmania donovani and Leishmania mexicana in vitro and in vivo (4-6, 11, 16).We examined the in vitro and in vivo effects of formycin B against T. cruzi. In vitro the drug significantly inhibited the replication of intracellular amastigotes. In vivo formycin B completely protected mice against death when a lethal inoculum of any of four different strains of T. cruzi was administered. Parasitological cure of the infected mice, however, was not achieved even after treatment regimens that lasted for 10 weeks.MATERIALS AND METHODS In vitro experiments. The epimastigote and the intracellular amastigote stages of the Y strain of T. cruzi (9) were used. Epimastigotes were from cultures in brain heart infusion medium supplemented with 5% newborn bovine serum and hemoglobin; amastigotes were isolated from spleens of mice infected 7 days earlier as previously described (18,19). Epimastigotes were cultured at 28°C in brain heart infusion medium containing 0.2 to 60 ,ug of formycin B per ml. Isolated amastigotes were suspended in RPMI 1640 medium (GIBCO Laboratories, Grand Island, N.Y.) supplemented with 10% fetal calf serum and used to infect monolayers of either normal mouse peritoneal macrophages or L929 cells at a ratio of 1 amastigote per cell. Infection was carried out for 10 h in an incubator at 37°C under an atmosphere of 5% CO2. Thereafter, the extracellular organisms were removed by several washes with medium. Fresh medium without formycin B or containing 0.1, 1,...

Novobiocin antagonism of amastigotes of Trypanosoma cruzi growing in cell-free medium

“…Differences in the ability of a drug to antagonize insect stages as compared with intracellular stages of T. cruzi and Leishmania species have been previously observed (1,30,31), but it was difficult to determine whether the differences related to. differences in stages or in environments (extracellular versus intracellular).…”

Discovery of Novel 7-Aryl 7-Deazapurine 3′-Deoxy-ribofuranosyl Nucleosides with Potent Activity against Trypanosoma cruzi

“…Trypanosoma cruzi parasites, like their related Trypanosoma brucei counterparts, are purine auxotrophs (i.e., they rely on salvaging preformed purine analogues from the host as they are unable to synthesize the purine ring themselves). − Hence, focused purine (nucleoside) libraries are a promising source for discovering new antitrypanosomal agents. Natural antibiotics such as tubercidin, formycin A and formycin B, − cordycepin, − stylomycin aminonucleoside (also known as puromycin aminonucleoside), , and allopurinol , as well as certain other inosine analogues ,, have been found to possess activity against T. cruzi (Figure ). Allopurinol, although not a nucleoside analogue sensu stricto (its active metabolite is generated by phosphoribosylation in the parasite), has been evaluated in clinical trials …”

“…[11][12][13][14] Hence, focused purine (nucleoside) libraries are a promising source for discovering new antitrypanosomal agents. Natural antibiotics such as tubercidin, 15 Formycin A 16 and Formycin B, [17][18][19] cordycepin, [19][20][21][22][23] stylomycin aminonucleoside (also known as puromycin aminonucleoside) [24][25] as well as allopurinol [26][27] and certain other inosine analogs 20,[28][29] have been found to possess activity against T. cruzi (Figure 1). Allopurinol, although not a nucleoside analog sensu stricto (its active metabolite is generated by phosphoribosylation in the parasite 26 ), has been evaluated in clinical trials.…”

Rate-of-Kill (RoK) assays to triage large compound sets for Chagas disease drug discovery: Application to GSK Chagas Box

“…• Similar profile is shared by TCMDC-143083, Formycin B, a inosine analog with activity against T. cruzi [38]. It is cidal in the RoK assay, has ME positive for all times.…”