In vitro efficacy of aqueous plants extracts in the control of gastrointestinal nematodes of cattle.

Background: Gastrointestinal helminthes in cattle had prejudge performance and productivity of animals. Affect beef cattle and dairy, generating huge economic losses. Commercial anthelmintics have been administered improperly, promoting the selection of resistant populations, in addition to increasing production costs and waste accumulate in animal products and the environment. It is therefore of great importance to find new alternatives as control. In this quest, was aimed with this study to evaluate the in vitro efficacy of plant aqueous extracts in the inhibition of larval development assay (ILDA) and inhibition of hatchability assay (IHA) of gastrointestinal nematodes of cattle. Materials, Methods & Results: The ILDA was performed by quantitative coproculture , with aqueous extracts of the leaves of Acrocomia aculeata, Anacardium occidentale, Caryocar brasiliense, Cymbopogon citratus, Mangifera indica var. Uba and Musa spp. cv. Prata-ana on the concentration of 100 mg/mL. In the IHA was evaluated the aqueous extracts of leaves and fruit peels of C. brasiliense, at the concentrations 15.00, 7.50, 3.75 and 1.88 mg/mL. The controls of assays were ivermectin (16 μg/mL) and levamisole phosphate solution (15 mg/ml), respectively, and water in both tests. Efficiencies were calculated and count data submitted to analysis of variance and the means were compared by Tukey test (P < 0.01). With the probit regression analysis, we determined the lethal concentration for inhibition of 50 and 90% hatchability (LC 50 and LC 90 ). Still, the levels of condensed tannins from aqueous extracts of the leaves and fruit peels of C. brasiliense were quantified. In ILDA, the extract of C. brasiliense showed efficacy of 91.29% and did not differ from ivermectin (P < 0.01). The other extracts did not obtain satisfactory efficacy and were similar to water (P < 0.01). In IHA the efficacy was over 90% for the extracts of the fruit peels and the three largest concentrations did not differ levamisole phosphate. The greater efficacy of leaf extract was 89.15%, to 15.00 mg/mL. The LC 50 and LC 90 were 0.37 and 1.70 mg/mL for the aqueous extract of the fruit peels, respectively, and 0.043 and 15.88 mg/mL for the aqueous extract of leaves of C. brasiliense. The levels of condensed tannins expressed as cyanidin chloride were 2.7 and 8.3 mg/g of extract for crude extract of the fruit peels and leaves of C. brasiliense, respectively. Discussion: The results shows that of the extracts evaluated only the leaves and fruit peels of C. brasiliense have great potential in the control of gastrointestinal nematodes of cattle. Many research have reported the nematicidal, larvicidal and ovicidal effects of the plants. In general, this anthelmintic activity is due to secondary compounds. Several studies have demonstrated the potential of condensed tannins, saponins, flavonoids, alkaloids, among other metabolites in controlling parasitosis in many animal species. However, the effectiveness of plant extracts can vary with the bioavailability of these metabolites in different parts of the plant, season and sampling period, beyond the specificity of the parasite, producing divergent results between the same plant species. In the case of C. brasiliense, it is believed that anthelmintic potential is consequence of association between condensed tannins and other metabolites, since the extract of the fruit peels showed better efficacy and content of condensed tannins was higher in the leaf extract.