Aim: This study was conducted to determine the anthelmintic activity of aqueous and ethanol extracts of Paraserianthes falcataria bark against Haemonchus contortus.

Materials and Methods: Ethanol extract of bark (E.E.B.) waste and aqueous extract of bark (A.E.B.) waste of P. falcataria (at concentrations 0, 0.2, 0.4, 0.8, 1, 2.5, and 5%) and albendazole (2 mg/ml) as the positive control were placed in separate Petri dishes (50 mm). Twenty H. contortus worms were placed in Petri dishes and incubated at 37°C for 0.5, 1, 2, 3, 4, 5, 6, and 12 h. Mortality of each worm was ensured by pressing the body of the worm with a pair of tweezers and keeping it in lukewarm water for 5 min before declaring it dead. Mortality is defined as amount of death individuals and time of mortality of each worm was recorded. The parasites were then observed using scanning electron microscopy (SEM) at an accelerating voltage of 15 Kv. Statistical analysis was performed using SPSS 21.0 software, two-way ANOVA followed by Tukey's test to detect significant differences (p<0.05). The result was expressed as the mean ± standard deviation.

Results: The E.E.B. and A.E.B. of P. falcataria contained active compounds, such as tannin, alkaloid, flavonoid, saponin, steroid, and triterpenoid. E.E.B. had a higher content of phenol, while A.E.B. had a higher content of flavonoid. In this study, P. falcataria showed a significant effect (p=0.00) on H. contortus in vitro. E.E.B. (0.8%) was able to exterminate H. contortus completely after 6 h, more effective than A.E.B. (5%) while the positive control requires (2 mg/ml) after 2 h. SEM analysis of the worm treated with E.E.B. and A.E.B. showed damaged cuticle structure.

Conclusion: The aqueous and ethanol extracts of P. falcataria bark waste demonstrated anthelmintic activity against H. contortus.

Keywords: anthelmintic, bark, Haemonchus contortus, prevalence, scanning electron microscopy.