RESUMO
Methanol extracts of plant structures are promising alternatives to traditional pharmaceutical anthelminthic treatments. An in vitro evaluation was done of how methanol extracts of Diospyros anisandra bark and leaves, and Petiveria alliacea stems and leaves, collected during the rainy and dry seasons, effected cyathostomin larval development and egg hatching. Seven concentrations (600, 300, 150, 75, 37.5, 18.7 and 9.3µg/ml) were tested using the egg hatch assay. An ANOVA was applied to identify differences between the concentrations and the controls. Fifty percent lethal concentration (LC50) and the 95% confidence interval were calculated with a probit analysis. At and above 37.5µg/ml, the D. anisandra bark extracts from both seasons exhibited ≥95% egg hatch inhibition (EHI), while the D. anisandra leaf extracts had >90% EHI at and above 75µg/ml. For P. alliacea, the extracts from leaves and stems from either season exhibited >97% EHI at and above 300µg/ml, although similar efficacy was also observed at lower concentrations with the rainy season stems (75µg/ml) and leaves (150µg/ml). Values for LC50 were lowest for the rainy season D. anisandra bark (10.2µg/ml) and leaf extracts (18.4µg/ml), followed by the rainy season P. alliacea stems extract (28.2µg/ml). In the D. anisandra extracts, EHI was largely due to its ovicidal activity (≥96% beginning at 37.5µg/ml), whereas in the P. alliacea extracts it was due to L1 larval hatch failure (≥90% beginning at 75µg/ml). Overall, the rainy season D. anisandra bark extracts had a strong in vitro anthelminthic effect against cyathostomins by inhibiting larval development, and the rainy season P. alliacea stem extracts had a strong effect by preventing egg hatching. Both are possible control alternatives for these nematodes.