Anthelminthic properties of Methylene chloride-methanol (1:1) extracts of two Cameroonians medicinal plants on Heligmosomoides bakeri (Nematoda: Heligmosomatidea).

BACKGROUND: The resistance of some medico-veterinary parasite strains as well as the unavailability and toxicity of synthetic anthelminthics on humans, animals and the impacts of their residues in the environment have pushed scientists to turn to plants with anthelminthic properties. Hence, the aim of this work was to contribute to the fight against helminths of medical and veterinary importance in general, and also to clear the environment of their free living stages. METHODS: Fresh eggs of Heligmosomoides bakeri were obtained from the faeces of experimentally infected mice. L1 and L2 larval stages were obtained after 48 and 72 h of coproculture respectively. Methylene Chloride-Methanol (1:1) extracts of Annona senegalensis and Nauclea latifolia were diluted in DMSO or Tween 80 to prepare the following concentrations: 625, 1250, 2500, 3750 and 5000 µg/ml. The effects of extract solutions were evaluated on the embryonation of eggs, egg hatching and on L1 and L2 survival after 48, 10 and 24 h of incubation. Negative controls were 1.5% DMSO, 4% Tween 80 and a mixture of these solvents. The TLC was carried out and the profiles of secondary metabolites were made. RESULTS: Negative controls had no effect on the embryonation, eggs hatching and on larval mortality. However, it was found that, the extracts affected the free living stages of H. bakeri in a concentration-dependant manner. At the highest concentration (5000 µg/ml), the rate of inhibition of embryonation obtained were 20.80%, 38.15% and 84.83% for Methylene Chloride-Methanol of Annona senegalensis (MCM As), Nauclea latifolia (MCM Nl) extracts and mixture of Annona senegalensis and Nauclea latifolia (MCM As-Nl) extract respectively. For egg hatch, the inhibition rate was 16.10%, 46.24% and 87.07% for the above three extracts respectively at the same concentration of 5000 µg/ml. On L1 and L2 larval stages after 24 h of exposure to extracts, the mortality rates of 100%, 54.76% and 96.77% against 98%, 51.44% and 100% were obtained for MCM As, MCM Nl and MCM As-Nl respectively at the highest concentration. The Methylene Chloride-Methanol of A.senegalensis, N. latifolia extracts showed the presence of alkaloids except in N. latifolia extract, flavonoids, sterols, triterpens, tanins, polyphenols, anthraquinons, saponins and terpenoids. CONCLUSION: These findings suggest that, the mixture of the two plant extracts showed an additive (synergetic effect) ovicidal effect and a slight larval mortality on L1 as compared to the effect of MCM As extract alone. These effects were due to the presence ao secondary metabolites identifies in the plant extracts. Thus, they may be used as possible «disinfectants¼ for soil transmitted nematodes.

In vitro anthelminthic efficacy of Dichrocephala integrifolia (Asteraceae) extracts on the gastro-intestinal nematode parasite of mice: Heligmosomoides bakeri (Nematoda, Heligmosomatidae).

OBJECTIVE: To evaluate the ovicidal and larvicidal activities of aqueous and ethanolic extracts of leaves of Dichrocephala integrifolia (D. integrifolia) against the eggs (fresh and embryonnated), the first and second larval stages of Heligmosomoides bakeri. In order to verify if this medicinal plant possesses active compounds capable of inhibiting the embryonation and hatching of eggs or to induce the mortality of larvae (L1 and L2). METHODS: dried extracts were diluted in distilled FIV water to obtain five different concentrations: 625, 1,250, 2,500, 3,750 and 5,000 µg/mL. Fresh eggs obtained from artificially infected mice feces were exposed to these different concentrations for 48 h. Time of contact for embryonated eggs was 6 h while L1 and L2 larvae were exposed for 24 h. Distilled water (placebo) and 1.5% DMSO were used as negative controls. RESULTS: Distilled water, and 1.5% DMSO had no effect on embryonation, hatching and larval survival. Aqueous extracts of D. integrifolia showed a weak activity against all stages of the parasite at all concentrations tested. On the contrary, the ethanolic extract of D. integrifolia inhibited the embryonation of 87.5% of fresh eggs, the hatching of 81.1% of embryonated eggs and induced the mortality of 98.1% and 98% of L1 and L2 larvae respectively at 5,000 µg/mL. CONCLUSIONS: The results of the present study indicate that the ethanolic extracts of D. integrifolia contained compounds with ovicidal and larvicidal properties. In spite of these results, in vivo tests, studies on toxicity and mechanism of action of active compounds are also needed to validate the utilisation of this medicinal plant by population of Dschang-Cameroon to treat gastro-intestinal parasites.

The In Vitro Effects of Aqueous and Ethanolic Extracts of the Leaves of Ageratum conyzoides (Asteraceae) on Three Life Cycle Stages of the Parasitic Nematode Heligmosomoides bakeri (Nematoda: Heligmosomatidae).

A comparative in vitro study was carried out to determine the ovicidal and larvicidal activity of aqueous and ethanolic extracts of Ageratum conyzoides (Asteraceae) leaves on the eggs (unembryonated and embryonated), first and second larval stages of Heligmosomoides bakeri. Four different concentrations (0.625, 1.25, 2.5, and 3.75 mg·mL(-1)) of both aqueous and ethanolic extracts were tested. Distilled water and 5% tween were used as negative controls in the bioassay. In fact, they did not affect development of eggs, hatching, and larval survival. The extract activities were dose dependent. The ethanolic extract was more potent against embryonation (39.6 ± 2.9%) than the aqueous extract (53.3 ± 10.9%) at the highest concentration (3.75 mg·ml(-1)). Both types of extracts killed larvae. Mebendazole proved more lethal (EC(50) of 0.745 and 0.323 mg·mL(-1), resp., for L(1) and L(2) larvae). The aqueous extracts were the least lethal (EC(50) of 4.76 and 2.29 mg·mL(-1), resp., for L(1) and L(2) larvae). The ethanolic extracts showed intermediate activity (EC(50) of 1.323 and 1.511 mg·mL(-1), resp., for L(1) and L(2) larvae). It is concluded that the ovicidal and larvicidal properties of aqueous and ethanolic extracts of Ageratum conyzoides leaves are demonstrated in this work.