In Vitro Activities of Two Antimitotic Compounds, Pancratistatin and 7-Deoxynarciclasine, against Encephalitozoon intestinalis , a Microsporidium Causing Infections in Humans

Abstract

The antiparasitic effect of a collection of compounds with antimitotic activity has been tested on a mammalian cell line infected with Encephalitozoon intestinalis, a microsporidian causing intestinal and systemic infection in immunocompromised patients. The antiparasitic effect was evaluated by counting the number of parasitophorous vacuoles detected by immunofluorescence. Out of 526 compounds tested, 2 (pancratistatin and 7-deoxynarciclasine) inhibited the infection without affecting the host cell. The 50% inhibitory concentrations (IC 50 s) of pancratistatin and 7-deoxynarciclasine for E. intestinalis were 0.18 M and 0.2 M, respectively, approximately eightfold lower than the IC 50 s of these same compounds against the host cells. Electron microscopy confirmed the gradual decrease in the number of parasitophorous vacuoles and showed that of the two life cycle phases, sporogony was more sensitive to the inhibitors than merogony. Furthermore, the persistence of meronts in some cells apparently devoid of sporonts and spores indicated that the inhibitors block development rather than entry of the parasite into the host cell. The occurrence of binucleate sporoblasts and spores suggests that these inhibitors blocked a specific phase of cell division.Microsporidia are widespread obligatory intracellular parasites, apparently able to invade any cell in animals and humans (4, 16). These unicellular parasites have been increasingly recognized as opportunistic pathogens of immunodeficient patients (24). Two species cause diarrhea, malabsorption, and weight loss in AIDS patients (6). Enterocytozoon bieneusi is the most prevalent cause of these symptoms and is occasionally associated with hepatobiliary disease or infection of the upper respiratory tract (24). The second prevalent species, Encephalitozoon (Septata) intestinalis, is responsible for nephritis, bronchitis, and lytic mandibular lesions (11,16). Rational strategies for the development of chemotherapeutic agents against microsporidia require a better understanding of the mechanisms controlling the proliferation of these parasites.The life cycle of Encephalitozoon intestinalis (Fig. 1) consists of two successive developmental sequences, merogony and sporogony, both of which occur in a parasitophorous vacuole (PV) within host cells. During merogony, proliferative stages known as meronts are produced. After multiple divisions, meronts are transformed into sporonts. During sporogony, each sporont divides into two sporoblasts, which mature into spores which are approximately 2.0 by 1.2 m. They contain a complex extrusion apparatus which ensures inoculation of the infective sporoplasm into a host cell. Meronts and sporonts are mononucleate cells which replicate by binary fission. Sometimes, the karyokinetic process is repeated before cytokinesis occurs, resulting in a ribbon-like cell containing two to four nuclei. The production of tetranucleate meronts and sporonts suggests some variability in the timing of cytokinetic cycles in E. intestinalis (3). Sporoblasts and ...

In vitro amoebicidal activity of ethanol extracts of Arachis hypogaea L., Curcuma longa L. and Pancratium maritimum L. on Acanthamoeba castellanii cysts

“…Because of the importance of cyclin-dependent kinase and their regulators in the multiplication and development of eukaryotes, these enzymes represent attractive potential targets for antiparasitic chemotherapy. It was found that pancratistatin and 7-deoxynarciclasine are cyclin kinase inhibitors (Ouarzane-Amara et al 2001). The previous effect may be responsible for the obtained cysticidal activity of P. maritimum in this study.…”

“…Alkaloids are the main active constituents in this plant (Berkov et al 2004) which exhibited anti-fungal, anti-malarial, and cytotoxic activities (Sür-Altiner et al 1999;Sener et al 2003;Kaya et al 2010). Pancratistatin, which is the most important metabolite responsible for the therapeutic benefits of this plant, has been shown to have anti-viral, anti-neoplastic (Pandey et al 2005), and antiparasitic effect against Encephalitozoon intestinalis, a microsporidium causing intestinal and systemic infection in immunocompromised patients (Ouarzane-Amara et al 2001).…”

Total Syntheses of Pancratistatin. A Review

“…12,14 Powerful antiviral 18 and antiparasitic 19 activities of pancratistatin constitute a related area of promise. Importantly, it has been noted that pancratistatin and 7-deoxypancratistatin are the only known agents (other than an interferon inducer) to show a significant chemotherapeutic efficacy in a Japanese encephalitis virus-infected mouse model.…”

Chemistry and Synthesis of Highly Oxygenated Alkaloids from Amaryllidaceae: Lycoricidine, Narciclasine, Pancratistatin and Analogs

“…The antiparasitic effect of these compounds has been tested on a mammalian cell line infected with Encephalitozoon intestinalis, a microsporidian causing intestinal and systemic infection in immunocompromised patients. Pancratistatin and lycoricidine inhibited the infection without affecting the host cell with IC 50 values of 0.18 and 0.2 mM, respectively [67].…”