Efficacy of plants extracts from the Cerrado against adult female of Dermacentor nitens (Acari: Ixodidae)

Dermacentor nitens tick is commonly found in the equine auditory canal, where it causes economic losses due to its direct damage, causing blood spoliation, stress, transmission of pathogens, and predisposition to myasis and secondary bacterial infection in its hosts. In this study we evaluated the effect of ethanolic extracts of Cerrado plants on biological parameters of engorged females of D. nitens. Ethanolic extracts were prepared from the leaves of Schinopsis brasiliensis, Piptadenia viridiflora, Ximenia americana, and Serjania lethalis at 25-150 mg mL^-1. Groups of 10 engorged adult females were treated with these extracts and compared with a control containing distilled water and another control with organophosphate, using five replicates for each group. Compared with the control with water, S. lethalis and X. americana extracts at 100 and 150 mg mL^-1 significantly inhibited the posture ability. Differently, extracts of S. brasiliensis and P. viridiflora were the most effective in inhibiting larval hatching. Extracts of X. americana and P. viridiflora showed effective inhibition of reproductive parameters of the tick, presenting dose-dependent effect with IC₉₀ 78.86 and 78.94 mg mL^-1, respectively. Theses effective extracts contained low condensed tannin levels and their HPLC chromatograms revealed the presence of flavonoids. The efficacies of P. viridiflora and X. americana extracts were higher than 90% indicating that these extracts are promising as alternative agents for D. nitens control.

In vitro and in vivo action of Piptadenia viridiflora (Kunth) Benth against Haemonchus contortus in sheep

Anthelminthic resistant populations of Haemonchus contortus are a major problem in sheep rearing, but plant extracts may offer viable alternative treatments. In our preliminary studies, Piptadenia viridiflora was frequently selected by sheep grazing in the Cerrado. The present research evaluated its in vitro and in vivo anthelmintic activity. The HPLC chromatograms of P. viridiflora aqueous extract (AE) and ethanolic extract (EE) showed the presence of flavonoids. The total condensed tannin (proanthocyanidin) was 0.2 and 1.01% in AE and EE, respectively. In an egg hatching inhibition (EHI) test, the LC90 of AE was 2.4mg/mL, and, of EE, was 2.1mg/mL. After tannin extraction, higher EHI and lower LC90 were observed. In a larval development inhibition test, the LC90 of AE was 13.66mg/g of fecal culture. The highest dose of AE administered to mice (203.0mg/kg bw) was well tolerated, suggesting low toxicity. In vivo, AE was orally administered to lambs at 283mg/kg bw, and, at weeks one, two, and three post-treatment, the mean fecal egg count (FEC) was significantly lower than in untreated lambs (P<0.05). Blood parameters were normal and similar in untreated and treated sheep. For all lamb groups, the mean total serum protein was significantly higher at week two post-treatment than at other evaluated periods (P<0.05). Piptadenia viridiflora extracts had low condensed tannin content and exhibited high anthelminthic efficacy in vitro and significantly reduced FEC. Tannins were not shown to be the principal components affecting EHI, hence it is necessary to isolate and characterize the principal active P. viridiflora compounds, and to assess their possible synergism.