Effect of Ginsenoside-Rh2 and Curcurbitacin-B on Cryptosporidium parvum in vitro.

Ginsenoside-Rh2 and cucurbitacin-B (CuB) are secondary metabolites of Ginseng (Panax ginseng) and Cucurbitaceae plants respectively. We assessed the anticryptosporidial activity of these two functional compounds in a cell culture model of cryptosporidiosis. The highest concentration of each compound that was not toxic to the host cells was used to assess the activity against C. parvum during infection/invasion and growth in HCT-8 cell monolayers. Monolayers were infected with pre-excysted C. parvum oocysts. Infected monolayers were incubated at 37 °C for 24 h and 48 h in the presence of different concentrations of each test compound. A growth resumption assay was performed by incubating infected monolayers in the presence of compounds for 24 h followed by a second 24-h incubation in the absence of compound. To screen for invasion inhibiting activity, freshly excysted C. parvum sporozoites were pre-treated with different concentrations of compounds prior to adding them to the cell monolayers. Paromomycin, a known inhibitor of C. parvum, and DMSO were used as positive and negative control, respectively. The level of infection was initially assessed using an immunofluorescent assay and quantified by real-time PCR. Both compounds were found to strongly inhibit C. parvum intracellular development in a dose-dependent manner. IC50 values of 25 µM for a 24 h development period and 5.52 µM after 48 h development were measured for Rh2, whereas for CuB an IC50 value of 0.169 µg/ml and 0.118 µg/ml were obtained for the same incubation periods. CuB also effectively inhibited resumption of growth, an activity that was not observed with Rh2. CuB was more effective at inhibiting excystation and/or host cell invasion, indicating that this compound also targets extracellular stages of the parasite.

Curcumin: A promising treatment for Cryptosporidium parvum infection in immunosuppressed BALB/c mice.

Members of the genus Cryptosporidium are frequent protozoan pathogens in humans and a wide range of animals. There is no consistently effective treatment against cryptosporidiosis, especially in immunodeficient patients. The present study was carried out to study the therapeutic effects of curcumin against cryptosporidiosis in immunosuppressed BALB/c mice. Mice were divided into five groups and immunosuppressed by dexamethasone. Three groups were inoculated with C. parvum oocysts, administered with curcumin, paromomycin, and without treatment. The reminders were regarded as controls. The oocysts in the fecal smear were counted daily. At days 0, 3, 7, and 11 post-treatment, the mice were sacrificed, and the efficacy of drugs was evaluated by comparing the histopathological alterations in jejunum and ileum, measuring the total antioxidant capacity, and malondialdehyde in the affected tissues. The infection was completely eliminated in the curcumin-treated group, and oocyst shedding stopped with no recurrence after drug withdrawal. On the contrary, paromomycin was unable to eliminate C. parvum infection completely, and oocyst shedding continued even 10 days after the drug withdrawal. Based on these findings, curcumin can be a trustworthy compound for the elimination of infection in immunosuppressed hosts. Further evaluation to find its accurate mechanism of action should be considered.

Comparative efficacy of curcumin and paromomycin against Cryptosporidium parvum infection in a BALB/c model.

Cryptosporidium is a ubiquitous protozoan parasite causing gastrointestinal disorder in various hosts worldwide. The disease is self-limiting in the immunocompetent but life-threatening in immunodeficient individuals. Investigations to find an effective drug for the complete elimination of the Cryptosporidium infection are ongoing and urgently needed. The current study was undertaken to examine the anti-cryptosporidial efficacy of curcumin in experimentally infected mice compared with that of paromomycin. Oocysts were isolated from a pre-weaned dairy calf and identified as Cryptosporidium parvum using a nested- polymerase chain reaction (PCR) on Small subunit ribosomal ribonucleic acid (SSU rRNA) gene and sequencing analysis. One hundred and ten female BALB/c mice were divided into five groups. Group 1 was infected and treated with curcumin; Group 2 infected and treated with paromomycin; Group 3 infected without treatment; Group 4 included uninfected mice treated with curcumin, and Group 5 included uninfected mice treated with distilled water for 11 successive days, starting on the first day of oocyst shedding. The oocyst shedding was recorded daily. At days 0, 3, 7, and 11 of post treatments, five mice from each group were killed humanly; jejunum and ileum tissue samples were processed for histopathological evaluation and counting of oocyst on villi, simultaneously. Furthermore, total antioxidant capacity (TAC) and malondialdehyde (MDA) concentrations in affected tissues were also measured in different groups. By treatments, tissue lesions and the number of oocyst on villi of both jejunum and ileum were decreased with a time-dependent manner. In comparison with Group 3, oocyst shedding was stopped at the end of treatment period in both groups 1 and 2 without recurrence at 10days after drug withdrawal. Also, TAC was increased and the MDA concentrations were decreased in Group 1. Moreover, paromomycin showed acceptable treatment outcomes during experiment and its anti-cryptosporidial activity was faster than curcumin. The results confirmed the anti-cryptosporidial and antioxidant activity of curcumin against C. parvum and further evaluation of immunosuppressed animal models needs to be carried out.

Effect of in-feed paromomycin supplementation on antimicrobial resistance of enteric bacteria in turkeys.

Histomoniasis in turkeys can be prevented by administering paromomycin sulfate, an aminoglycoside antimicrobial agent, in feed. The aim of this study was to evaluate the impact of in-feed paromomycin sulfate supplementation on the antimicrobial resistance of intestinal bacteria in turkeys. Twelve flocks of breeder turkeys were administered 100 ppm paromomycin sulfate from hatching to day 120; 12 flocks not supplemented with paromomycin were used as controls. Faecal samples were collected monthly from days 0 to 180. The resistance of Escherichia coli, Enterococcus faecium and Staphylococcus aureus to paramomycin and other antimicrobial agents was compared in paromomycin supplemented (PS) and unsupplemented (PNS) flocks. E. coli from PS birds had a significantly higher frequency of resistance to paromomycin, neomycin and kanamycin until 1 month after the end of supplementation compared to PNS birds. Resistance to amoxicillin or trimethoprim-sulfamethoxazole was also more frequent in PS turkeys. Resistance was mainly due to the presence of aph genes, which could be transmitted by conjugation, sometimes with streptomycin, tetracycline, amoxicillin, trimethoprim or sulfonamide resistance genes. Resistance to kanamycin and streptomycin in E. faecium was significantly different in PS and PNS breeders on days 60 and 90. Significantly higher frequencies of resistance to paromomycin, kanamycin, neomycin and tobramycin were observed in S. aureus isolates from PS birds. Paromomycin supplementation resulted in resistance to aminoglycosides in bacteria of PS turkeys. Co-selection for resistance to other antimicrobial agents was observed in E. coli isolates.

Antileishmanial activity in Israeli plants.

Leishmaniasis is a vector-borne disease caused by flagellated protozoan parasites of the genus Leishmania, which affects both humans and other mammals. Most of the available drugs against the disease are toxic and parasite resistance to some of the drugs has already developed. In the present study, the leishmanicidal activities of methanolic extracts of some Israeli plants have been evaluated in vitro, against the free-living promastigotes and intracellular amastigotes of Leishmania major. Of the 41 extracts examined, those of two plants (Nuphar lutea>Withania somnifera) were highly effective (with a maximum inhibitory effect of >50%), those of three other species (Pteris vittata>Smyrnium olusatrum>Trifolium clypeatum) were moderately effective (25%-50%) and another four extracts (Erodium malacoides>Hyparrhenia hirta>Thymelaea hirsuta>Pulicaria crispa) showed a marginal effect (15%-22%) against the parasites. Extracts of nine plant species therefore showed antileishmanial activity but only the extract of N. lutea, used at 1.25 microg/ml, eliminated all the intracellular parasites within 3 days of treatment, with no detectable toxicity to the host macrophages. The mean (S.D.) values recorded for the median inhibitory concentrations of this extract (IC50) against the promastigotes [2.0 (0.12) microg/ml] and amastigotes [0.65 (0.023) microg/ml] and the median lethal concentration (LD50) against macrophages [2.1 (0.096) microg/ml] were encouraging, giving a therapeutic selectivity index [LD50/IC50 for amastigotes)] of 3.23. The extract of N. lutea was, in fact, generally as effective as the paromomycin that was used as the 'gold standard' drug. These results indicate that N. lutea and probably also Withania somnifera might be potential sources of clinically useful, antileishmanial compounds.

Nuphar lutea: in vitro anti-leishmanial activity against Leishmania major promastigotes and amastigotes.

UNLABELLED: Several anti-leishmanial drugs of choice are of plant origin. Many of the available drugs against the disease are toxic and in certain cases parasite drug resistance is developed. The development of new compounds is urgently required. AIMS OF THE STUDY: To determine the leishmanicidal activity of the Nuphar lutea plant extract against Leishmania major in vitro. MATERIALS AND METHODS: The leishmanicidal activity of methanolic plant extract against L. major free living promastigotes and intracellular amastigotes was evaluated, using microscopic examinations and the enzymatic XTT assay. RESULTS: Methanolic extract of N. lutea was highly effective against both Leishmania promastigotes and L. amastigotes (IC(50)=2+/-0.12 microg/ml; ID(50)=0.65+/-0.02 3 microg/ml; LD(50)=2.1+/-0.096 microg/ml, STI=3.23). The extract at 1.25 microg/ml totally eliminated the intracellular parasites within 3 days of treatment. Also, a synergistic anti-leishmanial activity was demonstrated with N. lutea extract combined with the anti-leishmanial drug--paromomycin. The partially purified N. lutea active component was found to be a thermo-stable alkaloid(s) with no electrical charge and is resistant to boiling and to methanol, dichloromethane and xylene treatment. CONCLUSIONS: The present study suggests that N. lutea might be a potential source of anti-leishmanial compounds.

Translational bypass of nonsense mutations in zebrafish rep1, pax2.1 and lamb1 highlights a viable therapeutic option for untreatable genetic eye disease.

The extensive molecular genetic heterogeneity seen with inherited eye disease is a major barrier to the development of gene-based therapeutics. The underlying molecular pathology in a considerable proportion of these diseases however are nonsense mutations leading to premature termination codons. A therapeutic intervention targeted at this abnormality would therefore potentially be relevant to a wide range of inherited eye diseases. We have taken advantage of the ability of aminoglycoside drugs to suppress such nonsense mutations and partially restore full-length, functional protein in a zebrafish model of choroideraemia (chm(ru848); juvenile chorio-retinal degeneration) and in two models of ocular coloboma (noi(tu29a) and gup(m189); congenital optic fissure closure defects). In vitro cell-based assays showed significant readthrough with two drugs, gentamicin and paromomycin, which was confirmed by western blot and in vitro prenylation assays. The presence of either aminoglycoside during zebrafish development in vivo showed remarkable prevention of mutant ocular phenotypes in each model and a reduction in multisystemic defects leading to a 1.5-1.7-fold increase in survival. We also identified a significant reduction in abnormal cell death shown by TUNEL assay. To test the hypothesis that optic fissure closure was apoptosis-dependent, the anti-apoptotic agents, curcumin and zVAD-fmk, were tested in gup(m189) embryos. Both drugs were found to reduce the size of the coloboma, providing molecular evidence that cell death is required for optic fissure remodelling. These findings draw attention to the value of zebrafish models of eye disease as useful preclinical drug screening tools in studies to identify molecular mechanisms amenable to therapeutic intervention.

Antigiardial drugs.

Giardia intestinalis is a world-wide cause of intestinal infection. Treatment of this debilitating disease is usually accomplished using one of several drugs. Metronidazole is the treatment of choice, but benzimidazoles are now being used more frequently. Other treatments include quinacrine, paromomycin and furazolidone. Even though these drugs are all used to treat the same disease, their modes of action differ in all cases. However, resistance is increasing and new alternatives are being sought. New wave antigiardials all appear to have their roots in natural herbal remedies. This mini-review looks at the current treatments available, their efficacy, side effects and different modes of action and addresses a possible way forward using natural products.

Comparison of the efficacy of free and non-ionic-surfactant vesicular formulations of paromomycin in a murine model of visceral leishmaniasis.

Non-ionic-surfactant vesicular (NIV) formulations of paromomycin have been tested in-vitro and in-vivo for their activity against Leishmania donovani. Production of NIV was dependent both on the surfactant used and on the concentration of paromomycin; only two of the surfactants studied formed vesicles at the highest paromomycin concentration (9 mg mL(-1)). At surfactant-lipid concentrations > or = 1.5 mM, suspensions of NIV (drug- or glucose-loaded) were cytotoxic to macrophages infected with L. donovani; high levels of nitrite were produced in cell supernatants. At surfactant-lipid concentrations < 1.5 mM, drug-loaded NIV were more effective than the same dose of free drug, in terms of the percentage of cells infected and the number of parasites/cell. At surfactant-lipid concentrations < or = 0.15 mM, drug-loaded NIV were ineffective in-vitro. In-vivo, treatment with decaethylene glycol mono n-hexadecyl ether paromomycin NIV was more effective than hexaethylene glycol mono n-hexadecyl ether paromomycin NIV, in terms of suppression of liver and spleen parasite burdens. Against liver parasites, both types of paromomycin-loaded NIV were more effective than free drug. Neither the NIV nor free forms of paromomycin caused significant suppression of bone-marrow parasites. The study shows that entrapment of paromomycin in NIV can be used to increase its antileishmanial activity in-vitro and in-vivo.

Evaluation of a two-phase scid mouse model preconditioned with anti-interferon-gamma monoclonal antibody for drug testing against Cryptosporidium parvum.

One 1-mg injection of anti-interferon-gamma monoclonal antibody (anti-IFN-gamma MAb) into newly weaned scid mice 2 h before challenge with Cryptosporidium parvum oocysts markedly exacerbated the course of the infection for > or = 47 days, compared with challenged mice that received an equivalent dose of irrelevant MAb. Oocyst excretion in feces started 4-6 days after challenge and continued at high levels for > or = 47 days. Loss of body weight was also apparent. The extent and distribution of mucosal infection were profound, involving the stomach and several segments of the small and large intestines. The acute phase, which involved infection of the gut, was during the first 25 days after challenge. The following chronic phase consistently involved, in addition, infection of the hepatobiliary tract. The acute phase is a useful model in which to test luminally active drugs, while the chronic phase may be used in the future to test drugs that are active against hepatobiliary tract infections as well.

Partial restoration of meiosis in an apomictic strain of Saccharomyces cerevisiae: a model system for investigation of nucleomitochondrial interactions during sporulation.

In an apomictic strain of Saccharomyces cerevisiae (ATCC 4117-H2) which undergoes a single nuclear division during sporulation and consequently forms asci containing two uninucleate diploid spores, a study was undertaken to investigate the effects of cultivation in three presporulation media (YPA; YNB; SMM) on nuclear division and ascosporogenesis in sporulation medium. Comparison of effects of presporulation culture in these media on the number of spores formed per ascus showed that a marked induction (30 +/- 4.3 per cent) of three- and four-spored asci could occur in sporulation medium following cultivation in a defined YNB medium supplemented with a 1 per cent solution of vitamins and containing decreased ammonium sulphate and increased glucose levels. Experiments in which the concentrations of glucose and of ammonium sulphate were varied simultaneously indicated that the initial presporulation carbon to nitrogen source ratio is an important factor in determining tetrad formation in sporulation medium. Nuclear staining demonstrated two classes of asci: binucleate (one- and two-spored) and tetranucleate (three- and four-spored). Genetic evidence and data concerning effects of inclusion in sporulation medium of a meiotic inhibitor (glucose) indicated spores in tetrads were haploid rather than diploid. This ability to condition a significant number of cells for meiotic rather than apomictic differentiation made possible investigation of effects of mitochondrial inhibitors on both developmental processes simultaneously. It was found possible to selectively inhibit meiotic development by inclusion in sporulation medium of appropriate concentrations of specific inhibitors. Moreover, the data suggest meiotic sporulation is more strictly dependent than apomictic sporulation on mitochondrial function.

The screening of four aminoglycosides in the selective decontamination of the digestive tract in mice.

The suppressive effect of amikacin, gentamicin, tobramycin and paromomycin on the aerobic endogenous flora and on the colonization resistance of the digestive tract was tested by administering one of the antibiotics orally at five different dose levels. At a certain dose level, all antibiotics suppressed the endogenous Enterobacteriaceae species. Amikacin was particularly effective in this respect. Low doses of amikacin rapidly destroyed the colonization resistance. This resistance only remained unaffected in animals treated with tobramycin in doses that were still adequate to completely suppress the endogenous Enterobacteriaceae species. We concluded that of all the antibiotics tested in this study, only tobramycin may have a future in (clinical) application for the selective decontamination of the digestive tract. Selective decontamination can be considered an effective method for infection prevention in leukopenic patients.