Espécies de plantas do cerrado selecionadas por ovinos em pastejo com potencial na inibição do desenvolvimento de Haemonchus contortus

Abstract

Plant species naturally selected by sheep grazing in the Cerrado region of Brazil were assessed for in vitro or in vivo activity against Haemonchus contortus. After one year of observations, the plant families showing greatest richness in the region were Fabaceae, Rubiaceae, Malpighiaceae, Bignoniaceae, Myrtaceae and Annonaceae. Variation in the selectivity index for nine commonly plant species selected by grazing sheep was observed with respect to the dry and rainy seasons in the Cerrado. Coproculture was conducted in five replicates of 11 treatments: ivermectin, distilled water, or dehydrated leaves of nine selected plant species administered at 333.3 mg g-1 fecal culture (FEC). After seven days, the dried powder of Piptadenia viridiflora and Ximenia americana leaves, were effective at 86.5 and 99.8%, respectively, reducing significantly reduced the number of infective larvae compared to the control with sterile distilled water. The presence of tannins and flavonoids for aqueous and ethanolic extracts was indicated by HPLC (High-performance liquid chromatography). The extracts of P. viridiflora or X. americana (0.075-2.4 mg mL-1) was between 69.6-100% efficacy in the egg hatch inhibition (EHI). In larval development inhibition (LDI), the aqueous extract P. viridiflora (1.21-38.62 mg g-1) anthelminthic efficacies were between 55,63-100%, X. americana (1.42-22.70 mg g-1) efficacies were between 65,63-100% and showed mean of L3 and significantly lower than those observed for the control with water (P<0.05), for both species. The in vivo anthelminthic efficacies were between 32.9 - 47.2% for P. viridiflora, no efficacy for X. americana. Erythrocyte and hematocrit values were within the normal physiological patterns for lambs for P. viridiflora. For plasmatic albumin and total protein, significant effects between treatments were not found. P. viridiflora shows promising potential as alternative treatment of haemonchosis. The low concentrations of leaf extracts show high efficacy to EHI and LDI. Aqueous extract administered at 283 mg (dm) kg-1 bw during three consecutive days promotes efficacy 47,15% to FEC reduction and no clinical or blood disorders.