In Vitro Antiproliferative Effects and Mechanism of Action of the New Triazole Derivative UR-9825 against the Protozoan ParasiteTrypanosoma(Schizotrypanum)cruzi

Abstract

We describe the in vitro antiproliferative effects of the new triazole derivative UR-9825 against the protozoan parasite Trypanosoma (Schizotrypanum) cruzi, the causative agent of Chagas' disease in Latin America. The compound was found to be extremely active against the cultured (epimastigote) form of the parasite, equivalent to that present in the reduviid vector, with a MIC of 30 nM, a concentration 33-fold lower than that required with the reference compound ketoconazole. At that MIC, growth arrest coincided with depletion of the parasite's 4,14-desmethyl endogenous sterols (ergosterol, 24-ethylcholesta-5,7,22-trien-3b-ol, and precursors) and their replacement by methylated sterols (lanosterol, 24-methylenedihydrolanosterol, and obtusifoliol), as revealed by high-resolution gas chromatography coupled with mass spectrometry. This indicated that the primary mechanism of action of UR-9825 was inhibition of the parasite's sterol C14␣ demethylase, as seen with other azole derivatives. The phospholipid composition of growth-arrested epimastigotes was also altered, when compared to controls, with a significant increase in the content of phosphatidylethanolamine and phosphatidylserine and a concomitant reduction of the content of phosphatidylcholine. The clinically relevant intracellular amastigote form, grown in cultured Vero cells at 37°C, was even more sensitive to UR-9825, with a MIC of 10 nM, comparable to that for ketoconazole. The results showed that UR-9825 is among the most potent azole derivatives tested against this parasite and support in vivo studies with this compound.The largest parasitic disease burden on the American continent is Chagas' disease, caused by the kinetoplastid protozoon Trypanosoma (Schizotrypanum) cruzi, with 16 to 18 million people infected and an estimated annual loss of 2.7 disability-adjusted years (41). The parasite develops intracellularly in its mammalian hosts, leading to severe tissue damage, particularly in the heart and gastrointestinal tract, which, coupled with intense inflammatory reactions, underlies the pathogenesis of the disease (1, 5). Although Ͼ90% of those infected survive the initial acute phase, 30 to 40% of individuals with chronic T. cruzi infection will develop, over years or decades, irreversible heart and gastrointestinal lesions which are frequently lethal (1,6,23,25). Current chemotherapeutic approaches for the treatment of this condition, based on nitrofurans and nitroimidazoles, are unsatisfactory due to limited efficacy, particularly for the prevalent chronic form of the disease, and frequent toxic side effects (8,10,23,25). Recently, great advances have been made in the control of both vectorial and transfusional transmission of the disease, particularly through the Southern Cone and Andean Initiatives (41). However, transmission continues in other parts of the continent and the problem of those already infected, most of them in the undetermined chronic phase, remains a challenge (8,28,29).Sterol biosynthesis inhibitors (SBI) are currently the most ad...

Ergosterol biosynthesis and drug development for Chagas disease

“…1), such as TAK-187 (Takeda Chemical Company) (Urbina et al 2003c, Corrales et al 2005, UR-9825 (Uriach & Company) (Urbina et al 2000, Guedes et al 2004) and ravuconazole (ER-30346, Eisai Co.; BMS 207,147; Bristol-Myers Squibb) (Urbina et al 2003b) also exhibit trypanocidal activity in vitro and in vivo. TAK-187 is a long-lasting triazole derivative with broad-spectrum antifungal activity, which also possesses very potent anti-T. cruzi activity in vitro and is capable of curing both acute and chronic infections in murine hosts even when the infecting strain is resistant to nitrofuran and nitroimidazole (Urbina et al 2003c).…”

“…More recent work has shown that this compound is superior to BZN in preventing cardiac damage in a murine Chagas disease model (Corrales et al 2005). UR-9825 is another potent fungal and protozoan CYP51 inhibitor with remarkable in vitro anti-T. cruzi activity (Urbina et al 2000). However, its very short half-life in the mouse (< 0.5 h) precluded in vivo studies in this animal model, but work in a canine model has demonstrated that the compound exhibits curative activity against established infections of the virulent Y strain of T. cruzi with very low toxicity, although drug resistance was encountered with the Berenice-78 strain (Guedes et al 2004).…”

Chagas disease: What is known and what should be improved: a systemic review

“…Among these are allopurinol, an antiuricemic hypoxanthine that is used to treat gout, and antifungals that inhibit ergosterol, such as ketoconazole, itraconazole and fluconazole [42][43][44][45][46] . These have not been shown to be effective in vivo, including during the acute phase of the disease.…”

Activity of the New Triazole Derivative Albaconazole against Trypanosoma ( Schizotrypanum ) cruzi in Dog Hosts

“…1) displays in vitro activities against T. cruzi comparable to those of the most potent EBIs tested against this organism, and detailed biochemical studies indicated that its mechanism of action is due to a specific interference of the parasite's sterol C-14␣-demethylase (29). However, in vivo efficacy against T. cruzi requires both potent intrinsic antiparasitic activities and special pharmacokinetic properties (long terminal half-lives and large volumes of distribution) (28,33).…”