In vitro anti-Onchocerca ochengi activities of extracts and chromatographic fractions of Craterispermum laurinum and Morinda lucida

Abstract

BackgroundOnchocerciasis caused by Onchocerca volvulus is the world’s second leading infectious cause of blindness. There is currently no cure for the disease. Ivermectin, the current drug of choice is only microfilaricidal and suboptimal response to it is increasingly being reported. Thus, in contributing to the search for a cure, crude extracts and chromatographic fractions of Craterispermum laurinum and Morinda lucida were screened in vitro, against the bovine and most popular model of the parasite, Onchocerca ochengi.MethodsExtracted parasites were cultured in RPMI-1640 based media for 05 days in the presence of control drugs, test drugs or drug diluents only. Microfilarial motility was scored using microscopy while adult worm viability was determined biochemically by MTT/formazan colorimetry. Cytotoxicity and acute toxicity of active fractions were tested on monkey kidney epithelial cells (LLCMK2) and in Balb/c mice, respectively.ResultsOut of the 18 extracts screened, the methanolic extracts of the leaves of both plants recorded the highest activities against both the microfilariae (IC100 of 125 μg/ml for both extracts) and adult worms (IC100 of 250 μg/ml and 500 μg/ml for M. lucida and C. laurinum respectively). The most active chromatographic fraction was obtained from M. lucida and had an IC50 of 7.8 μg/ml and 15.63 μg/ml on microfilariae and adult worms respectively, while the most active fraction from C. laurinum had an IC50 of 15.63 μg/ml and 46.8 μg/ml, respectively on microfilariae and adult worms. The 50% cytotoxic concentration (CC50s) on LLCMK2 cells ranged from 15.625 μg/ml to 125 μg/ml for the active fractions. No acute toxicity was recorded for the extracts from both plants. Phytochemical analysis of the most active fractions revealed the presence of sterols, alkaloids, triterpenes, saponins and flavonoids.ConclusionsThis study validates the use of these plants by traditional health practitioners in managing the disease, and also suggests a new source for isolation of potential lead compounds against Onchocerca volvulus.

Antifilarial Activity of Cucurbita pepo ovifera var ovifera (Cucurbitaceae) on Onchocerca ochengi Adult Worms

“…The antifilarial activities of some medicinal plants from Cameroon have been reported on Onchocerca ochengi [7,[9][10][11][12][13]. Both parasites O. volvulus and O. ochengi are evolutionary closely related and are transmitted to their human and bovine host by the same blackfly vector Simulium damnosum, their microfilariae being equally sensitive to ivermectin [14].…”

Targeting Human Onchocerciasis: Recent Advances Beyond Ivermectin

“…Following a similar approach, Samje et al 50 screened the chromatographic fractions of crude extracts from Craterispermum laurinum and Morinda lucida, plants which have traditionally been used to manage O. ochengi, against the disease in vitro. Of the 18 extracts screened, the methanolic extracts of the leaves of both plants recorded the highest activities against both the microfilariae and adult worms.…”

Evaluation of anti-onchocercal activity of pseudopalmatine, a quaternary protoberberine alkaloid of Enantia chlorantha (Syn. <i>Annickia chlorantha</i>)

“…While human onchocerciasis (river blindness) is not only a neglected tropical disease (NTD), it remains the world's second most leading infectious cause of blindness, with over 37 million patients and a risk population of over 120 million Samje et al (2014). Iver mectin (Mectizan®, Merck), the currently available drug of choice for the treatment of river blindness, is limited only on the juvenile form of the parasite (microfilariae), and there are now reports of its suboptimal effect on these worms Cupp et al (2011).…”