Anticancer agents suppressive for adult parasites of filariasis in Mongolian jirds

Apoptotic impact on Brugia malayi by sulphonamido-quinoxaline: search for a novel therapeutic rationale

Human lymphatic filariasis although not fatal but poses serious socioeconomic burden due to associated disability. This is reflected by the huge magnitude of the estimated disability-adjusted life years of about 5.09 million. Therefore, following WHO mandate, our earlier studies on antifilarial drug development revealed the significance of apoptosis. Apoptotic impact has been implicated in anticancer rationale of several drugs. In this study, we explored the antifilarial potential of sulphonamido-quinoxaline compounds, shown to be specific inhibitor for c-Met kinase in human cancer cells. Out of studied compounds, Q4, showing favorable drug-likeness and medicinal chemistry properties on bioinformatics platform along with subsequently recorded lowest IC₁₀₀ value, was considered as a suitable antifilarial candidate. Significant apoptosis due to mitochondrial involvement was recorded in drug-treated parasite unlike untreated control. In spite of homology between human c-Met kinase and Brugia malayi counterpart, comparative docking result of this compound showed more favorable binding parameters with the parasitic target. The wide gap between IC₁₀₀ and LD₅₀ values further confirmed the therapeutic safety. We propose sulphonamido-quinoxaline derivative as a lead candidate for antifilarial drug development. Further study is warranted to authenticate parasitic c-Met kinase as a novel therapeutic target reminiscent of anticancer rationale implicating inhibition of proliferation.

Efficient synthesis and first regioselective C-3 direct arylation of imidazo[1,2-b]pyrazoles

Highly regioselective: An efficient synthesis of the imidazo[1,2-b]pyrazole core has been developed, and the first regioselective palladium-catalyzed direct arylation of the C-3 position is described (see scheme). Good to excellent yields were obtained for a wide range of aryl partners with electron-rich and electron-poor substituents. This methodology allows rapid access to a large variety of imidazo[1,2-b]pyrazole products and could open the way to the design of new biologically active compounds.

Ivermectin for onchocercal eye disease (river blindness)

BACKGROUND

It is believed that ivermectin (a microfilaricide) could prevent blindness due to onchocerciasis. However, when given to everyone in communities where onchocerciasis is common, the effects of ivermectin on lesions affecting the eye are uncertain and data on whether the drug prevents visual loss are unclear.

OBJECTIVES

The aim of this review was to assess the effectiveness of ivermectin in preventing visual impairment and visual field loss in onchocercal eye disease. The secondary aim was to assess the effects of ivermectin on lesions affecting the eye in onchocerciasis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 3), MEDLINE (January 1950 to April 2012), EMBASE (January 1980 to April 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 2 April 2012.

SELECTION CRITERIA

We included randomised controlled trials with at least one year of follow-up comparing ivermectin with placebo or no treatment. Participants in the trials were people normally resident in endemic onchocercal communities with or without one or more characteristic signs of ocular onchocerciasis.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality. We contacted study authors for additional information. As trials varied in design and setting, we were unable to perform a meta-analysis.

MAIN RESULTS

The review included four trials: two small studies (n = 398) in which people with onchocercal infection were given one dose of ivermectin or placebo and followed up for one year; and two larger community-based studies (n = 4941) whereby all individuals in selected communities were treated every six or 12 months with ivermectin or placebo, whether or not they were infected, and followed for two to three years. The studies provide evidence that treating people who have onchocerciasis with ivermectin reduces the number of microfilariae in their skin and eye(s) and reduces the number of punctate opacities. There was weaker evidence that ivermectin reduced the risk of chorioretinitis. The studies were too small and of too short a duration to provide evidence for an effect on sclerosing keratitis, iridocyclitis, optic nerve disease or visual loss. One community-based study in communities mesoendemic for the savannah strain of O.volvulus provided evidence that annual mass treatment with ivermectin reduces the risk of new cases of optic nerve disease and visual field loss. The other community-based study of mass biannual treatment of ivermectin in communities affected by the forest strain of O.volvulus demonstrated reductions in microfilarial load, punctate keratitis and iridocyclitis but not sclerosing keratitis, chorioretinitis, optic atrophy or visual impairment. The study was underpowered to estimate the effect of ivermectin on visual impairment and other less frequent clinical signs. The studies included in this review reported some adverse effects, in particular an increased risk of postural hypotension in people treated with ivermectin.

AUTHORS' CONCLUSIONS

The lack of evidence for prevention of visual impairment and blindness should not be interpreted to mean that ivermectin is not effective, however, clearly this is a key question that remains unanswered. The main evidence for a protective effect of mass treatment with ivermectin on visual field loss and optic nerve disease comes from communities mesoendemic for the savannah strain of O.volvulus. Whether these findings can be applied to communities with different endemicity and affected by the forest strain is unclear. Serious adverse effects were rarely reported. None of the studies, however, were conducted in areas where people are infected with Loa loa (loiasis).

In Vitro Activity of Geldanamycin Derivatives against Schistosoma japonicum and Brugia malayi

Geldanamycin (GA) is a benzoquinone-containing ansamycin that inhibits heat shock protein 90. GA derivatives are being evaluated as anti-neoplastic agents, but their utility against parasites whose heat shock proteins (Hsps) have homology with human Hsp90 is unknown. The activities of four synthetic GA derivatives were tested in vitro using adult Brugia malayi and Schistosoma japonicum. Two of the derivatives, 17-N-allyl-17-demethoxygeldanamycin (17-AAG) and 17-N-(2-dimethylaminoethylamino)-17-demethoxygeldanamycin (DMAG), are currently in human clinical trials as anticancer drugs. Using concentrations considered safe peak plasma concentrations for these two derivatives, all four derivatives were active against both parasites. The less toxic derivative 17-AAG was as effective as GA in killing S. japonicum, and both DMAG and 5′-bromogeldanoxazinone were more active than 17-AAG against B. malayi. This work supports continued evaluation of ansamycin derivatives as broad spectrum antiparasitic agents.

Ethyl 6-methylsulfanyl-2-phenyl-1H-imidazo[1,2-b]pyrazole-7-carboxylate monohydrate

The title compound, C₁₅H₁₅N₃O₂S·H₂O, has been obtained in a search for new imidazo[1,2-b]pyrazole derivatives with better biological activity. The 1H-imidazo[1,2-b]pyrazole plane forms a dihedral angle of 16.90 (3)° with the benzene ring. π–π inter­actions are indicated by the short distance of 3.643 (2) Å between the centroids of the benzene and imidazole rings. The crystal structure also involves inter­molecular O—H⋯N hydrogen bonds.

Lymphatic filariasis: new insights and prospects for control

Although lymphatic filariasis remains among the major causes of disability among the tropical infectious diseases, dramatic advances have been made in the approach to its diagnosis, epidemiology and treatment, in our understanding of the molecular composition of the parasites that cause these infections, and in the factors underlying the pathology seen. Superimposing the tools of modern epidemiology, immunology, and molecular biology on field-based clinical trials has allowed the emergence of the concept of elimination of lymphatic filariasis. Much of the important new research emphasizes parasite development in the context of the host response, the importance of both the adult worm and other factors in the pathogenesis of lymphatic filarial disease, the role the Wolbachia endosymbiont holds as both a target for drug treatment and in inducing post-treatment reactions, and the various principles underlying the implementation of control programs.

Ivermectin for onchocercal eye disease (river blindness)

BACKGROUND

It is believed that ivermectin (a microfilaricide) could prevent blindness due to onchocerciasis. However, when given to everyone in communities where onchocerciasis is common, the effects of ivermectin on lesions affecting the eye are uncertain and data on whether the drug prevents visual loss is unclear.

OBJECTIVES

The aim of this review is to assess the effectiveness of ivermectin in preventing visual acuity and visual field loss in onchocercal eye disease. The secondary aim is to assess the effects of ivermectin on lesions affecting the eye in onchocerciasis.

SEARCH STRATEGY

We searched the Cochrane Eyes and Vision Group specialised register, the Cochrane Controlled Trials Register - CENTRAL, MEDLINE, EMBASE, the reference lists of identified trials, the Science Citation Index and we contacted investigators, experts and pharmaceutical companies to identify additional trials.

SELECTION CRITERIA

We included randomised controlled trials with at least one year follow up, comparing ivermectin at a dose of 150 micrograms per kilogram of body weight with either placebo or no treatment. Participants were people normally resident in endemic onchocercal communities with or without one or more characteristic signs of ocular onchocerciasis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed trial quality. Study authors were contacted for additional information. Trials varied in design and setting, so no meta-analysis was done.

MAIN RESULTS

This review includes five trials with data from 3810 participants. All the trials compared ivermectin with placebo and were judged to be of moderate risk of bias in terms of methodological quality. No statistically significant difference was observed in any trial (reporting visual acuity outcome) between ivermectin and placebo groups for visual acuity loss.

REVIEWER'S CONCLUSIONS

Questions about the effectiveness of ivermectin in preventing visual acuity loss have not been answered by best available evidence.