BackgroundThe front line molecules from filarial worms and other nematodes or helminthes are their Excretory-Secretory (ES) products. Their interaction with the host cells, proteins and immune system accounts for the skin and eye pathology or hyposensitivity observed in human onchocerciasis. ES products and adult worms’ crude extracts from Onchocerca ochengi, a filarial nematode that infects the African zebu cattle, were utilized in the present study as a model for studying Onchocerca volvulus that causes river blindness in man.MethodsThe ES products were generated from adult male and female worms in vitro and analyzed with poly acrylamide gel electrophoresis (PAGE) and enzyme-linked immunosorbent assay (ELISA) using sera from Onchocerca-infected cattle and humans. The cattle sera were collected from a herd that had been exposed for six years to natural transmission of Onchocerca spp. The expressed reactivity was evaluated and differences analyzed statistically using Kruskal-Wallis rank and Chi-square tests.ResultsThe gel electrophoretic analyses of 156 ES products from O. ochengi female and male worms and of two somatic extracts from three females and 25 males revealed differences in the protein pattern showing pronounced bands at 15, 30–50 and 75 kDa for male ES proteins and 15, 25 and 40–75 kDa for somatic extracts, respectively and less than 100 kDa for female worms. Proteins in the ES products and somatic extracts from female and male Onchocerca ochengi worms were recognized by IgG in sera from both Onchocerca-exposed cattle and humans. Bovine serum antibodies reacted more strongly with proteins in the somatic extracts than with those in the ES products. Interestingly, the reaction was higher with male ES products than with ES products from female worms, suggesting that the males which migrate from one nodule to another are more exposed to the host immune system than the females which remain encapsulated in intradermal nodules.ConclusionsThis study demonstrates that O. ochengi ES products and, in particular, extracts from male filariae may represent a good source of immunogenic proteins and potential vaccine candidates.

Acacia nilotica fruits with high tannin content are used in the northern parts of Cameroon as anti-filarial remedies by traditional healers. In this study, the hydro-alcoholic fruit extract (crude extract (CE)) and, one of the main constituents in its most active fractions, (+)-catechin-3-O-gallate (CG), as well as four related proanthocyanidins, (−)-epicatechin-3-O-gallate (ECG), (+)-gallocatechin (GC), (−)-epigallocatechin (EGC) and (−)-epigallocatechin-3-O-gallate (EGCG), were assessed for their potential in vitro anthelmintic properties against the free-living model organism Caenorhabditis elegans and against the cattle filarial parasite Onchocerca ochengi. Worms were incubated in the presence of different concentrations of fruit extract, fractions and pure compounds. The effects on mortality were monitored after 48 h. The plant extract and all of the pure tested compounds were active against O. ochengi (LC50 ranging from 1.2 to 11.5 µg/mL on males) and C. elegans (LC50 ranging from 33.8 to 350 µg/mL on wild type). While high LC50 were required for the effects of the compounds on C. elegans, very low LC50 were required against O. ochengi. Importantly, tests for acute oral toxicity (lowest dose: 10 mg/kg) in Wistar rats demonstrated that crude extract and pure compounds were non-toxic and safe to use. Additionally, the results of cytotoxicity tests with the Caco-2 cell line (CC50 ranging from 47.1 to 93.2 µg/mL) confirmed the absence of significant toxicity of the crude extract and pure compounds. These results are in good accordance with the use of A. nilotica against nematode infections by traditional healers, herdsmen and pastoralists in Cameroon.

BackgroundOnchocerciasis is one of the tropical neglected diseases (NTDs) caused by the nematode Onchocerca volvulus. Control strategies currently in use rely on mass administration of ivermectin, which has marked activity against microfilariae. Furthermore, the development of resistance to ivermectin was observed. Since vaccine and safe macrofilaricidal treatment against onchocerciasis are still lacking, there is an urgent need to discover novel drugs. This study was undertaken to investigate the anthelmintic activity of Lophira lanceolata on the cattle parasite Onchocerca ochengi and the anthelmintic drug resistant strains of the free living nematode Caenorhabditis elegans and to determine the phytochemical profiles of the extracts and fractions of the plants.MethodsPlant was extracted in ethanol or methanol-methylene chloride. O. ochengi, C. elegans wild-type and C. elegans drug resistant strains were cultured in RPMI-1640 and NGM-agar respectively. Drugs diluted in dimethylsulphoxide/RPMI or M9-Buffer were added in assays and monitored at 48 h and 72 h. Worm viability was determined by using the MTT/formazan colorimetric method. Polyphenol, tannin and flavonoid contents were determined by dosage of gallic acid and rutin. Acute oral toxicity was evaluated using Swiss albino mice.ResultsEthanolic and methanolic-methylene chloride extracts killed O. ochengi with LC50 values of 9.76, 8.05, 6.39 μg/mL and 9.45, 7.95, 6.39 μg/mL respectively for leaves, trunk bark and root bark after 72 h. The lowest concentrations required to kill 50% of the wild-type of C. elegans were 1200 and 1890 μg/mL with ethanolic crude extract, 1000 and 2030 μg/mL with MeOH-CH2Cl2 for root bark and trunk bark of L. lanceolata, respectively after 72 h. Leave extracts of L. lanceolata are lethal to albendazole and ivermectin resistant strains of C. elegans after 72 h. Methanol/methylene chloride extracted more metabolites. Additionally, extracts could be considered relatively safe.ConclusionEthanolic and methanolic-methylene chloride crude extracts and fractions of L. lanceolata showed in vitro anthelmintic activity. The extracts and fractions contained polyphenols, tannins, flavonoids and saponins. The mechanism of action of this plant could be different from that of albendazole and ivermectin. These results confirm the use of L. lanceolata by traditional healers for the treatment of worm infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-017-1904-z) contains supplementary material, which is available to authorized users.

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Background Human onchocerciasis caused by the filarial worm, Onchocerca volvulus is a parasitic that forms nodules under the skin. In the developing countries, it has been estimated that more than 80% of the population rely on traditional medicines for their primary healthcare needs. The aim of this work was to assess the nematicidal activities of Aloe vera on Onchocerca ochengi and Caenorahbditis elegans and to determine the phytochemical compounds. Methods Nodules were collected from the umbilical region of infected cattle, dissected and male worms were cultured in RPMI-1640. Worms were incubated for 48 h and 72 h with different concentrations of A. vera extracts in RPMI-1640 and M9-buffer. Polyphenol, tannin and flavonoid contents of extract were determined by using gallic acid and rutin as standards. The antioxidant activity was evaluated by DPPH radical scavenging method. Results The anthelmintic effect of A. vera extract against O. ochengi was concentration dependent with LC50 of 20.71 µg/mL and 11.75 µg/mL after 48 and 72h respectively. A. vera extract exerted concentration dependent lethal effects (LC50 = 2747 and LC50 = 1937 µg/mL) against C. elegans (WT). MeOH-CH2Cl2 of A. vera extract exhibited high DPPH activity with an IC50 value of 15 µg/mL and 9 µg/mL for ascorbic acid. The highest activity in adult worms was observed with the MeOH (100: 0) and AcOEtMeOH fractions with LC50 values of 12.82 and 15.50 µg/mL respectively. EcOEtMeOH (8:2 v/v) was more effective (LC50 = 250 µg/mL) on WT C. elegans. A. vera contains polyphenols (1015.05 and AcOEtMeOH = 893.60), flavonoids (25.35 and MeOH = 225.76) and tannins (401.37 and Hex = 788.89). Conclusions A. vera showed in vitro nematicidal activity against O. ochengi and C. elegans. Aloe vera could be used as alternative anthelmintic for onchocerciasis treatment.